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METALURGIJA – ČASOPIS OSNOVAN 1962.

OSNIVAČ – DRUŠTVO INŽENJERA I TEHNIČARA ŽELJEZARE SISAK

METALURGIJA – JOURNAL FOUNDED IN 1962

FOUNDER – SOCIETY OF ENGINEERS AND TECHNITIANS OF STEELWORKS SISAK

UDK 669+621.7 + 51/54 (05) = 163.42 = 111

ISSN 0543-5846

METABK 50 (4) 217-288 (2011)

th

4

METALURGIJA, vol. 50, br. 4, str. 217-288 Zagreb, listopad / prosinac (October / December) 2011.


UDK 669+621.7+51/54(05)=163.42=111 ISSN 0543-5846

METABK 50 (4) 217-288 (2011)

METALURGIJA, vol. 50, br. 4, str. 217-288 Zagreb, listopad / prosinac (October / December) 2011.

Izdava~ / Publisher: Hrvatsko metalur{ko dru{tvo (HMD) - Croatian Metallurgical Society (CMS)

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T. Lis

Content – Sadr`aj

Original Scientific Papers – Izvorni znanstveni radovi

Optimisation of metal charge material for electric arc furnace

Optimizacija metalnog ulo{ka elektrolu~ne pe}i 219

T. Merder, J. Pieprzyca

Numerical modeling of the influence subflux controller of turbulence

on steel flow in the tundish

Numeri~ko modeliranje utjecaja pomo}nog regulatora turbulencije

na protjecanje ~elika u me|uloncu 223

B. Mate{a, D. Kozak, A. Stoi}, I. Samard`i}

The influence of heat treatment by annealing on clad plates residual stresses

Utjecaj toplinske obradbe `arenjem na zaostala naprezanja platiranih plo~a 227

A. Ko{nik, J. Tu{ek, L. Kosec, T. Muhi~

The manufactoring of a two–layered injection mold by welding

Izrada dvoplastnog alata za ubrizgavanje termoplasta postupkom zavarivanja 231

D. Klob~ar, M. Muhi~, J. Mo`ina, J. Tu{ek

Laser grooving of surface cracks on hot work tool steel

Lasersko `ljebljenje povr{inskih pukotina na alatnom ~eliku za vru}i rad 235

J. Przondziono, W. Walke, A. Szu³a, E. Hadasik, J. Szala, J. Wieczorek

Resistance to corrosion of magnesium alloy AZ31 after plastic working

Otpornost na koroziju magnezijeve legure AZ31 nakon plasti~ne obrade 239

S. Legutko, P. Kluk, A. Stoi}

Research of the surface roughness created during pull broaching process

Istra`ivanje povr{ine hrapavosti povr{ine nastale postupkom provla~enja 245

Preliminary Notes – Prethodna priop}enja

I. Bernáthová, M. Bur{ák

Properties of pure titanium and ultra fine grained titanium

Svojstva ~istog titana i ultra fino zrnatog titana 249

Z. Guli{ija, A. Patari}, M. Mihailovi}

The possibility of increasing production efficiency of al alloys applying electromagnetic field

Mogu}nost pove}anja efikasnosti proizvodnje Al legura primjenom elektromagnetnog polja 253

M. Saternus

Modelling research of hydrogen desorption from liquid aluminium and its alloys

Modelsko istra`ivanje desorpcije vodika iz rastaljenog aluminija i njegovih legura 257

A. Fornalczyk, M. Saternus

Catalytic converters as a source of platinum

Kataliti~ki konverteri kao izvor platine 261


J. £abaj, B. Oleksiak, G. Siwiec

Study of copper removal from liquid iron

Studija odstranjivanja bakra iz teku}eg `eljeza 265

I. Samard`i}, M. Dun|er, A. Pintari}

Possibilities of joining techniques application at railway lines joining and maintenance

Mogu}nosti primjene tehnika spajanja izgradnja i odr`avanje tra~ni~kih linija 269

J. Tepi}, V. Todi}, D. Luki}, M. Milo{evi}, S. Borojevi}

Development of the computer-aided process planning (CAPP) system for polymer

injection molds manufacturing

Razvoj CAPP sustava za izradu kalupa za injekcijsko pre{anje polimera 273

A. W. Byda³ek

The analysis of the carbon attendance in copper alloys

Analiza prisutnosti ugljika u bakrenim slitinama 278

W. Ptaszyñski, A. Gessner, P. Fr¹ckowiak, R. Staniek

Straightness measurement of large machine guideways

Mjerenje ravnosti duga~kih strojnih vodilica 281

Review Paper – Pregledni rad

YU. G. Gulyayev, I. Mamuzi}, YE. I. Shyfrin, M. Bur{ak, D. YU. Garmashev

Perfection of processes of seamless steel tubes production

Usavr{avanje postupaka proizvodnje ~eli~nih be{avnih cijevi 285

Croatian Metallurgical Society / Hrvatsko metalur{ko dru{tvo

I. Mamuzi} / Ure|iva~ki odbor

Acknowledgement to Reviewers / Zahvala recenzentima, volume 50(2011) 244


T. LIS

OPTIMISATION OF METAL CHARGE

MATERIAL FOR ELECTRIC ARC FURNACE

INTRODUCTION

Steel has remained the most crucial of all structural

materials. However, the steel production processes have

changed over the years. Currently, due to the tendency

of eliminating high energy consuming technologies, in

both the international and domestic steel industry, liquid

steel is manufactured in two basic aggregates: oxygen-blown

converters and electric arc furnaces �1�. The

development of technique and technology in the scope

of steel production in an arc furnace is aimed at improving

the efficiency of the installations used, increasing

the quality of steel and reducing the production costs.

The basic iron-bearing medium for EAF is steel

scrap. Strong competition requires efficient utilisation

of raw materials, especially secondary raw materials

like steel scrap. Bearing in mind the contemporary tendencies

to implement and develop technologies contributing

to protection of natural resources and environment,

including those reducing the carbon dioxide emission,

an EAF as a scrap-based steel smelting aggregate

is a particularly attractive solution. Steel smelting in an

electric furnace enables steel recycling, which can be

stressed as its great environmental advantage �2�. In

Received – Prispjelo: 2010-06-21

Accepted – Prihva}eno: 2010-10-25

Original Scientific Paper – Izvorni znanstveni rad

The analysis of the changes in the crude steel production volumes implies gradual increase of production since

the mid 20 th century. This tendency has been slightly hampered by the economic depression. At the same time,

the market requirements enforce improvement of the quality of the products manufactured on simultaneous minimisation

of the production costs. One of the tools applied to solve these problems is mathematical optimisation.

The author of this paper has presented an example of application of the multi-criteria optimisation method

to improvement of efficiency of steel smelting in an electric arc furnace (EAF) through appropriate choice of the

charge scrap. A measurable effect of applying such a methodology of choosing the metal charge is the ability to

reduce the unit cost of steel smelting.

Key words: EAF, multi-criteria optimisation, charge scrap, crude steel

Optimizacija metalnog ulo{ka elektrolu~ne pe}i. Analiza promjena proizvodne mase sirovog ~elika ukazuje

na zna~ajno pove}anje proizvodnje od sredine 20. stolje}a. Ta tendencija neznatno je usporena uslijed ekonomske

depresije. Istodobno, zahtjevi tr`i{ta prisilili su pobolj{anje kvalitete proizvoda simultanom

minimizacijom proizvodnih tro{kova. Jedan od alata koji se primjenjuje za rje{avanje tih problema je matemati~ko

optimiziranje. Autor ovog rada prikazao je primjer primjene metode multi-kriterijskog optimiziranja na pobolj{anje

efikasnosti taljenja u elektrolu~noj pe}i (ELP) odgovaraju}im izborom otpatka u ulo{ku. Mjerljiv utjecaj

primjene takve metodologije izbora metalnog ulo{ka je mogu}nost smanjenja jedini~nih tro{kova taljenja ~elika.

Klju~ne rije~i: ELP, multi-kriterijsko optimiziranje, ulo`ni otpadak, sirovi ~elik

T. Lis, Department of Metallurgy, Silesian Technical University, Katowice,

Poland

ISSN 0543-5846

METABK 50(4) 219-222 (2011)

UDC – UDK 669.187:669:18:669.1.009.8=111

light of the market economy requirements and strong

competition in the global market, the fact of undertaking

various subjects in the field of economic optimisation of

steel production seems completely justified. The presented

paper constitutes an analysis of the example of

application of two criteria optimisation solution where

one of the criteria is the cost of the charge scrap and the

second one is the yield of crude steel smelting in EAF.

OPTIMISATION

AND CHOICE OF A CRITERION

The contemporary economy is characterised by an

increase in the number of manufacturers of identical

products competing with one another. The same phenomenon

can be noticed in the steel industry and it occurs

in all stages of the final product manufacture. In

practice, there is usually a problem a solution of optimisation

task covering two functions: achievement of a

maximum effect (e.g. yield of crude steel) on simultaneous

minimisation of expenditures. Such problems are

considered to function under the class of multi-criteria

optimisation models the most common of which are

two-criteria problems. The examinations in question

were performed at an electric steel-smelting shop assuming

a quotient programming model �3,4� being one

METALURGIJA 50 (2011) 4, 219-222 219


T. LIS: OPTIMISATION OF METAL CHARGE MATERIAL FOR ELECTRIC ARC FURNACE

Figure 1 Block diagram presenting components of the

variable steelmaking cost in EAF �6�

of the methods of finding compromising solutions under

the tasks of multi-criteria optimisation with two contradictory

functions.

Two constituents comprise an overall product cost:

constant cost and variable cost. Only the variable cost

can be altered during current production. The relevant

calculations imply that the share of variable cost in the

overall cost of steel smelting in EAFs is 75 – 85 %, therefore,

from the perspective of the steel production optimisation

process for an electric furnace, one of the most

significant criteria is the minimisation of the production

cost variable constituent.

Based on the cause and effect analysis (diagram by

Ishikawa) conducted �5�, a block diagram was prepared

for the variable cost components for crude steel smelted

in the EAF – Figure 1.

The Pareto-Lorenz analysis conducted showed that

two cost components, namely the metal charge costs and

the electric power costs, out of all crude steel production

variable cost components (metal charge, electric power,

graphite electrodes, sag-forming additives, mould powders,

auxiliary materials, refractory materials, technological

oxygen, natural gas, technical gases), accounted

for more than 85 % including the scrap material cost of

ca. 70 % �5,6�. Therefore, one of the optimisation criteria

chosen was the metal charge cost. It was determined

that the crude steel cost was also significantly influenced

by the efficiency of the steel smelting process

conducted in the EAF. Consequently, the second criterion

assumed was the yield of mass from scrap materials,

being a parameter particularly significant for the

furnace capacity.

EXAMINATIONS

The examinations were conducted at a steel-smelting

shop equipped with an UHP electric arc furnace with ec-

centric bottom tapping (EBT) manufactured by

Mannesmann Demag. The variables assumed for the

steel manufacture in the EAF were the masses of the individual

sorts of charge materials. A problem of quotient

programming with a hyperbolic objective function

was established to find a compromise solution in which

one of the functions was to be the cost minimisation and

the other – maximisation of the metal yield from scrap.

The quotient programming task model is composed of

limiting conditions in a linear form, boundary conditions

as well as objective functions in a fractional form �7�.

The objective function was established as follows:

n


cj � X j

j�1

FX ( ) � � min

n


j�1

d � X

j j

(1)

where:

cj – unit cost of scrap material (for j = 1,2 ...n scrap

sorts),

dj – yield of scrap mass (for j = 1,2 ...n scrap sorts),

Xj – share of steel scrap in the charge burden (for

j = 1,2 ...n scrap sorts; X1 �X2�..... Xn�1). An additional limitation was the non-negativeness of

decisive variables. In the example being analysed, the

following optimum values must be obtained:

n

F1( X) �� dj �X j �max

(2)

j�1

n

F2( X) �� cj �X j �min

(3)

j�1

The solution to such a problem is an attempt to find a

certain compromise, since it is impossible to come to a

solution enabling that criterion F1 (yield of crude steel

from the charge scrap) reaches its maximum, and criterion

F2 (cost of charge scrap) reaches its minimum.

While creating a mathematical model the task of

which is to optimise the metal charge material for EAF,

one must identify the classification of the charge scrap

being applied. It is very diverse and depends on the

grades of steel manufactured and the sorts of charge

scrap available commer-cially in the market �8,9�. The

following properties should be entailed for the sake of

the scrap material classification:

– content of alloying elements possible to be reclaimed

in the steel smelting process;

– content of harmful elements (including sulphur,

phosphorus, copper, zinc) and undesirable elements

(e.g. chromium, nickel, molybdenum, tin);

– geometry of scrap (mass density and scrap size) –

the knowledge of the scrap material geometry enables

optimum filling of the EAF charge baskets.

In terms of the scrap material origin, one can speak

of home scrap and outside scrap (scrap from fully depreciated

machines, tools). Within the last twenty five

220 METALURGIJA 50 (2011) 4, 219-222


years, the share of post-depreciation scrap in use has

risen considerably due to the development of the continuous

casting technology and the increase in manufacture

of steel-containing products replaced by users with new

ones (e.g. cars, household appliances) �9,10�. However,

due to the large share of outside scrap in the overall mass

of charge materials, its quality drops, which applies particularly

to the increase of the content of undesirable elements

and copper.

The classification of scrap assumed in the case being

analysed was the one applied in the electric steel smelting

shop entailing the individual sorts (Table 1) without

the home scrap due to the impossibility of determining

its price.

Table 1 Metal charge scrap classification (scrap sorts)

Scrap

(independent variable)

Name Signify

Bulk

density /

Mg·m -3

Light scrap X1 0,7

Dimensions

max. /

mm

1 000 x

500 x 500

1 200 x

500 x 500

1 200 x

500 x 500

Scrap in package X4 to 1,0

1 000 x

500 x 500

Pressed steel chips X5 0,6 – 0,8 50 - 150

Special scrap

(Cu < 0,15 %)

X6

> 0,7

1 200 x

500 x 500

Since the purpose of the mathematical model being

developed was to find a compromising solution between

minimi-sation of the charge scrap cost and maximisation

of the metal yield from this scrap, in the first instance,

both the metal yield from the individual sorts of

scrap material (crude steel mass) and the scrap material

prices needed to be estimated. In order to estimate the

mass of crude steel, data from 3 638 melts were used after

the initial selection by the 3S method �11� (assuming

that the variables are subject to normal distribution), and

on such a basis, a specific dependence in the form of a

multiple regression equation was established to enable

programming of the crude steel yield depending on the

composition of the metal scrap. Table 2 contains a collation

of the metal yield ratios obtained for the individual

sorts of scrap material as well as the price relations between

these sorts.

The problem of quotient programming with an objective

function (1) entailed the limiting conditions related

to the scrap material geometry (optimum filling of

charge baskets and time required to melt the heavy

scrap) as well as the technological conditions applicable

in the steel smelting shop (assuming that the charge was

loaded into the EAF with two charge baskets):

– on the bottom of both charge baskets, there should

be light scrap in the quantity not exceeding 15 %

T. LIS: OPTIMISATION OF METAL CHARGE MATERIAL FOR ELECTRIC ARC FURNACE

Table 2 Empirical metal yield ratios for the individual

sorts of scrap and their price relations

Variable

of the scrap mass, the mass of pressed steel chips

should not exceed 5 % of the charge scrap mass,

and the volume of light scrap and pressed steel

chips should not exceed 38 % of the capacity of

both charge baskets, this is about 32 % of the

charge scrap mass:

X 1 � 015 ,

X 5 � 005 ,

X1 �X5�032 ,

– the mass of heavy scrap including the special

scrap should not exceed 40% of the overall charge

scrap mass, and its minimum share should not be

smaller than 20 %:

020 , �X3 �X6�040 ,

– the mass of packed scrap should not exceed 5 % of

the charge scrap mass:

X 4 � 005 ,

– for the steel of the Cu content < 0,4%, the special

scrap (X6) share in the overall charge scrap mass

should be smaller than 7 %,

– for the steel of the Cu content < 0,35%, the special

scrap (X6) share in the overall charge scrap mass

should be smaller than 10 %.

Based on dependence (2) and (3), the objective function

in the optimisation problem being analysed assumes

the following form (data in Table 2):

cX ( 1 �1385 , �X2 �1175 , �X3 �

FX ( ) �

08135 , �X1 �08646 , �X2 �0,

9143�X3�

�131 , �X4 �1225 , �X5 �1586 , �X6

�08541 , �X�0832 , 7� �09253� �

(4)

min

X , X

4

5 6

The metal charge was chosen for the following

grades of steel:

– for the grades most commonly manufactured at

the steelworks examined (normal quality structural

steel – without special scrap) – set I,

– for the steel of copper content below 0,35 % – set

II,

– for the charge scrap without packed scrap – set III.

The shares of the individual grades of steel obtained

as well as the values of the objective function, the assumed

yield of crude steel from metal charge and its

prices have been provided in Table 3.

METALURGIJA 50 (2011) 4, 219-222 221

Xj

Yield of scrap

mass / dj

Unit cost of scrap

material / cj

X1 0,8135 1,000 c

X2 0,8646 1,385 c

X3 0,9143 1,575 c

X4 0,8561 1,310 c

X5 0,8327 1,225 c

X6 0,9253 1,586 c


T. LIS: OPTIMISATION OF METAL CHARGE MATERIAL FOR ELECTRIC ARC FURNACE

Table 3 Optimum composition of metal charge for EAF

The calculations performed imply that under the

conditions present at the steel smelting shop examined,

entailing the limiting conditions, the minimum price of

metal charge on maximum yield of crude steel from

scrap can be attained if the charge material is composed

of 32 % of light scrap, 38 % of medium-weight scrap, 5

% of pressed steel chips and packed scrap respectively

and 20 % of special scrap. Such a composition of the

metal charge can be used for smelting of both standard

structural steel and the steel with copper content not exceeding

0,35 % of Cu. The share of packed scrap exerts

an influence on the price reduction, whereas the share of

special scrap may increase the yield of crude steel. If in

set I, the heavy scrap is replaced with special scrap, then

the yield of crude steel will come to 0,859863, and the

price of 1 Mg of scrap will equal 1,29825 of the light

scrap. Consequently, the share of special scrap in the

charge material exerts a positive influence on the yield

of crude steel from scrap material, and at the same time,

it does not cause a significant increase in the price of the

charge material (assuming the share of special scrap on

the level of 20 %).

CONCLUSIONS

share in the charge scrap mass / %

Set I Set II Set III

X1 0,32 0,32 0,32

X2 0,43 0,38 0,48

X3 0,20 0 0

X4 0,05 0,05 0

X5 0 0,05 0

X6 0 0,20 0,2

F(X) 1,51141c 1,503318c 1,513271c

F1(X) 0,857663 0,858268 0,860388

F2(X) 1,29605c 1,29025c 1,302c

It is the market economy that requires the criterion of

production optimisation to remain in the economic domain,

and in most cases, it can be the variable cost of the

product manufactured. Striving to solve such optimisation

tasks, as e.g. attaining the maximum yield of crude

steel from metal scrap on minimum steel scrap costs, it

is reasonable to find a compromising solution by apply-

ing the quotient programming method with a hyperbolic

objective function. An additional advantage resulting

from application of mathematical, multi-criteria optimisation

models is the possibility of using common

spreadsheets featuring the basic tools of mathematical

analysis.

The optimisation solution defined for the EAF

charge material implies that under the conditions present

at the electric steel smelting shop examined and assuming

the aforementioned limiting conditions:

– the cost of 1 Mg of scrap in the EAF charge material

should not exceed 1,3 of the price of 1 Mg of

light scrap, and at the same time, it enables attaining

the yield of crude steel on the level of 0,857 ÷

0,86,

– the metal charge optimisation under the conditions

of the steelworks examined should lead to reduction

of the price of 1 Mg of metal charge by ca.

0,15 ÷ 0,52 of the price of 1 Mg of light scrap.

REFERENCES

[1] Lis T., Metalurgia stali o wysokiej czystoœci, Wyd. Pol. Œl.,

Gliwice, 2009

[2] Birat J.B., La Revue de Metallurgie - CIT“, 11 (2000),

1347-1363

[3] JóŸwiak J., Podgórski J.: Statystyka od podstaw, Wyd.

PWE, Warszawa, 2006

[4] Szymszal J., Blacha L.: Wspomaganie decyzji optymalnych

w metalurgii i in¿ynierii materia³owej, Wyd. Pol.Œl., Gliwice,

2003.

[5] Lis T., Jama-Labusek B.: Zastosowanie diagramu Ishikawy

do analizy kosztu zmiennego wytapianej stali surowej w

EAF, Konf. Nauk-Techn.: Zarz¹dzanie i Produkcja w Hutnictwie,

Ustroñ, 5-8.07.2004, vol. 1, 304-307.

[6] Lis T., Jama-Labusek B., Hutnik-Wiadomoœci Hutnicze, 7

(2006) 332-336.

[7] Szapiro T.: Decyzje mened¿erskie z Excelem, Wyd. PWE,

Warszawa. 2000.

[8] Ankier E.J.: Scrap Supply and Electric Steelmaking Development

in EU 15, Proc. Of the 7-th European Electric Steelmaking

Conf., Venice (Viena), 2 (2002) 69.

[9] Sabela W., Derda W., Hutnik-Wiadomoœci Hutnicze, 11

(2003) 426-431.

[10] Huskonen W.D.: Charging Options in EAF Operations, 33

Metal Prod., 39 (2001) 2, 17-18.

[11] Zaj¹c K.: Zarys metod statystycznych, Wyd. PWE, Warszawa,

1994.

Note: The responsible for English language is P. Nowak, Katowice, Poland.

222 METALURGIJA 50 (2011) 4, 219-222


T. MERDER, J. PIEPRZYCA

NUMERICAL MODELING OF THE INFLUENCE

SUBFLUX CONTROLLER OF TURBULENCE

ON STEEL FLOW IN THE TUNDISH

INTRODUCTION

In recent years, numerical simulations have become

an integral part of research on the optimization of the

continuous steel casting technology. The dynamic development

of computational codes and constantly increasing

processing power of computers have provided

an excellent work tool. Due to that fact, mathematical

modelling enables the understanding of metallurgical

processes to the extent of something that was not possible

previously. High temperatures prevailing in metallurgical

equipment restrict research conducted on real

facilities. Numerical studies concerning the hydrodynamics

of steel flow in tundishes are being successfully

carried out at present. These are targeted at the optimization

of the working space of facilities. This is associated

with additional furnishing the tundish with flow control

devices (dams, subflux controllers of turbulence). However,

interfering in the working space of the tundish will

result in a change in the operation conditions of the entire

continuous casting machine (CCM). Therefore, any

proposed modifications of tundish furnishing must be

supported by studies. Both physical and numerical mod-

Received – Prispjelo: 2010-06-21

Accepted – Prihva}eno: 2010-11-05

Original Scientific Paper – Izvorni znanstveni rad

The paper presents the results of computer simulation of steel flow in the two-nozzle tundish of a T-shaped

type. The tundish is symmetrical, relative to the transverse plane. The nominal capacity of the tundish is 7,5 Mg

of liquid steel. The Fluent program was used to solve the mathematical model of steel casting process. In numerical

simulation for modification of steel flow in the tundish subflux controller of turbulence was used. Three

variants of subflux controller of turbulence configurations in the tundish were tested. As effect of mathematical

calculations liquid steel velocity, turbulence intensity, turbulent kinetic energy and characteristic of Residence

Time Distribution (RTD) have been obtained.

Key words: steel, tundish, numerical modeling, mixing time, subflux controller of turbulence

Numeri~ko modeliranje utjecaja pomo}nog regulatora turbulencije na protjecanje ~elika u

me|uloncu. U radu se prikazuju rezultati ra~unalne simulacije protjecanja ~elika u me|uloncu s dva otvora u

obliku slova T. Me|ulonac je simetri~an s obzirom na transverzalnu ravninu. Nominalni kapacitet me|ulonca je

7,5 Mg teku}eg ~elika. U numeri~kog simulaciji za modificiranje protjecanja ~elika u me|uloncu kori{ten je

pomo}ni regulator turbulencije. Testirane su tri varijante pomo}nog regulatora turbulencije u me|uloncu. Kao

rezultat matemati~kog prora~una dobiveni su brzina teku}eg ~elika, intenzitet turbulencije, kineti~ka energija

turbulencije i karakteristika raspodjele vremena zadr`avanja (RVZ).

Klju~ne rije~i: ~elik, me|ulonac, numeri~ko modeliranje, vrijeme mije{anja, pomo}ni regulator turbulencije

T. Merder, J. Pieprzyca, Silesian University of Technology, Department

of Metallurgy, Katowice, Poland

ISSN 0543-5846

METABK 50(4) 223-226 (2011)

UDC – UDK 669.186:518.1:531.3=111

elling are used for this purpose �1-4�. A commonly used

variant of tundish working space furnishing involves

equipping the tundish with a subflux controller of turbulence.

The subflux controller of turbulence helps to control

the steel flow in the tundish in order to improve the

casting process. The subflux controller of turbulence device

is placed in the tundish below the teaming stream of

the ladle and creates a flow pattern that supports inclusion

flotation and “plug flow” and thus helps the

steelplant to produce a clean steel.

Figure 1 shows the directions of steel flow in the tundish

with impact pad and subflux controller of turbulence

installed.

Figure 1 Inlet stream of the steel flow in the tundish

with impact pad and subflux controller of turbulence

METALURGIJA 50 (2011) 4, 223-226 223


T. MERDER et al.: NUMERICAL MODELING OF THE INFLUENCE SUBFLUX CONTROLLER OF TURBULENCE...

The subflux controller of turbulence is a device that

embodies several constructional solutions. Therefore,

it’s geometrical parameters must be adjusted to the specific

tundish geometry.

The paper present the results of numerical simulation

of steel flow in a two-nozzle tundish. For the modification

of steel flow in the tundish under investigation,

subflux controllers of turbulence were used. Three geometrical

variants of the subflux controller of turbulence

were considered. Results of the testing of changes in the

characteristics of steel flow in the variants considered

are presented. Numerical computation under transient

conditions enabled RTD curves to be plotted. The obtained

results have enabled the selection of the optimal

geometrical variant of the subflux controller of turbulence

for the facility under study.

TUNDISH DESCRIPTION

The object of the study is a “T”-type tundish designed

for the continuous casting of slabs intended for

small cross-section rolled products. The tundish is symmetrical

relative to the lateral plane. The nominal capacity

of the tundish is 7,5 Mg of liquid steel. The geometric

dimensions and configuration of the industrial tundish

are shown in Figure 2.

The effects of subflux controller of turbulence on

flow characteristics in the tundish with different configurations

were investigated. Three different flow control

arrangements were studied. Different tundish configurations

studied in present work are shown in Figure 3.

MATHEMATICAL MODEL

Fundamental equations

A typical three dimensional fluid flow model is based

on the continuity equation and Reynolds-averaged

Navier-Stokes equations for incompressible Newtonian

fluids, conserving mass momentum and energy at every

point in a computational domain. Additionally an equation

Figure 2 Geometry dimensions of industrial tundish,

�mm�

Figure 3 Different tundish configurations studied in present

work

describing the turbulence of liquid steel motion in the tundish

is used. For the modelling of turbulence, the semi-empirical

two-equation k-� model proposed by Launder and

Spalding �5� was employed, which is commonly used in

the analysis of engineering problems. This model, in many

cases of turbulent flows, gives result close to those of an

experiment, with limited computational outlays. The equations

are described in detail in papers �6,7�.

Residence time distribution model

Residence Time Distribution (RTD) is a statistical

representation of time spent by an arbitrary volume of

the fluid in the tundish. It is obtained by creating a

change at the inlet and measuring of the system response

at the outlet with time. When the dimensionless concentration

at the outlet is registered against dimensionless

time, it creates the RTD curve. For generating the curve,

scalar or species transport model is used. It solves the

following equation for the time evolution of the species

mass fraction C, giving the steady flow velocities calculated

previously from the turbulence model.

�� ( cC) �� ( cuC i ) � �C

� � � cDeff �t

�xi

�xi

�xi

� �




� (1)

� �

where the effective diffusion coefficient (Deff) is the sum

of the molecular diffusion coefficient and the turbulent

diffusion coefficient

Deff =Dm +Dt

(2)

The turbulent diffusion coefficient is determined

from the following relationship (assuming that the turbulent

Schmidt number is equal to unity).

Initial and boundary conditions

Half of the tundish was chosen for the mathematical

analysis. The computational space discretization has

been made with use of the computational mesh consisting

of 250000 control volumes. Figure 4 shows the computational

mesh employed in these simulations.

In the object under study, a hybrid computational

grid ware generated in the GAMBIT program �8�. Appropriate

boundary conditions were chosen for the system

of differential equations. As the considered spatial

system is symmetrical relative to the plane passing

through the pouring gate axis, this resulted in the zeroing

of the first derivatives in relation to the direction nor-

224 METALURGIJA 50 (2011) 4, 223-226


T. MERDER et al.: NUMERICAL MODELING OF THE INFLUENCE SUBFLUX CONTROLLER OF TURBULENCE...

Figure 4 Three-dimensional view of the unstructured

mesh and boundary conditions for simulations

mal to the plane of symmetry. The boundary conditions

for momentum transfer were those of non-slipping at the

solid surfaces, zero normal velocity gradients at the

symmetry planes, and the free surface of the liquid. The

standard wall function is used to calculate the value of a

node near a solid wall. The other parameters and boundary

conditions of the tundish are listed in Table 1.

In order to develop concentration characteristics

(RTD) corresponding to normalized conditions, the

boundary condition was applied at the pouring gate in

the form of a stepwise change of concentration (C = 1).

Mathematical method

The fluid flow and heat transfer model was solved

using standard k-� turbulece model with second-order

upwind discretization scheme �9�. The model formulation

utilized segregated study state solver with implication

formulation. Discretization equations were derived

from the governing equations and were solved by using

an implicit finite difference procedure called SIMPLEC

�10� algorithm. The solution was started with the default

under-relaxation variables, which were later reduced to

achieve the converged solution. Convergence criteria of

1·10 -6 were fixed for all the equations. Velocity fields at

steady state were first calculated and later they were employed

to solve the mass transfer equation. For the species

transport model, the solution was considered converged

when the residual for mass fraction was below

1·10 -5 . Time step of 0,5 s with approximately 20 iterations

in each time step was utilized to generate the RTD

curve. Calculation was performed by using the commercial

program FLUENT �9�.

RESULTS AND DISCUSSION

The turbulence kinetic energy field of liquid steel at

the symmetric plane in the impact zone of the incoming

stream from the ladle shroud in the tundish is shown in

Figure 5.

From figure 5A in can be seen, that the liquid steel

from the shroud impacts the tundish bottom directly

with very high velocity (turbulence intensity). Then it

flows fast along the bottom. Such flow can cause serious

erosion of the tundish bottom and side walls in this zone

and arise large exogenous inclusions.

Table 1 Parameters and boundary conditions used

in modeling

Parameter Value

Depth of molten steel / mm 600

Shroud diameter / mm 50

Inlet turbulence intensity / % 5

Casting speed / m·min -1

1

Operating temperature / K 1 828

Density of molten steel / (kg·m -3 ) 7 000

Viscosity of molten steel / (kg·m -1 ·s -1 ) 0,007

Specific heat / (J·kg -1 ·K -1 ) 830

Thermal conductivity / (W·d -1 ·K -1 ) 40,5

Heat flux at free surface / (kW·m -2 ) 15

Heat loss from wall / (kW·m -2 ) 3,8

Heat loss from internal wall / (kW·m -2 ) 1,75

Figure 5 Isolines of steel turbulence kinetic energy a)

configuration A, b) configuration B, c) configuration

C, d) configuration D

Figures 5B, 5C and 5D show that the turbulence energy

of the incoming stream is depressed with the turbulence

inhibitor. It is shown in figures 5B and 5C that the

surface turbulence kinetic energy is high and eddies exist

near the shroud, which will result in slag entrapment.

The turbulence kinetic energy fields and the distribution

of velocity vectors provide a significant knowledge

of steel casting conditions, however, these characteristics

do not directly explain of whether the tundish condition

is suitable for nonmetallic inclusion removal or agi-

METALURGIJA 50 (2011) 4, 223-226 225


T. MERDER et al.: NUMERICAL MODELING OF THE INFLUENCE SUBFLUX CONTROLLER OF TURBULENCE...

tation processes in the sequential casting of different

steel grades, or not. The answer to this question is provided

by RTD curves. Quantitatively one can assess the

intermediate area through determination of it’s range

(�t) determined on the base of difference in times necessary

for obtaining concentrations at the levels of 20 and

80 % of the concentration anticipated for the given steel

grade. The characteristic mentioned is commonly used

to assess and compare the working areas of different

tundishes �11� and casting conditions. Assuming that

value of 0 on the ordinate axis of the presented curve

corresponds to the current sort of the steel cast, while the

value of 1 corresponds to the subsequent one, we can determine

the dimension of the area range (in other words,

the range of 0,2÷0,8 of the dimensionless concentration).

The �t values for separate curves, obtained as a result

of the investigations, are shown in Table 2.

Figure 6 shows the comparison of four studied cases.

In order to allow the direct comparison the results, the

marker concentration is presented in the dimensionless

form.

It can be seen from Figure 6, that the behaviour of the

curves is practically identical, but the obtained times of

the transient zone range differ from each other considerably.

The presented computations show clearly that the

smallest value of the transition zone has been obtained

for Configuration C, use and is equal to 255,5 seconds

(Table 2). This indicates the appropriateness of selection

of the tundish working space furnishing variant as

against the unfurnished tundish (Configuration A). In

the case of Configuration D, the longest time of the transient

zone range occurs.

Table 2 The results of transient zone

Tundish Transient zone /s

Configuration A 313,5

Configuration B 276,5

Configuration C 255,5

Configuration D 319

CONCLUSION

For developing the characteristics of the flow in the

steel continuous casting tundish and evaluating the effect

of the modification of the internal tundish geometry

on basic casting parameters, a numerical modelling

technique was used. The simulation results made it possible

to obtain detailed distributions of velocity, temperature

and turbulence kinetic energy fields, as well as the

characteristics of the distribution of tracer concentration

in the steel.

Observations collected during the investigations can

be summarized in a following manner:

– In the bare tundish, the liquid steel flow velocities

in the impact zone of the incoming stream are high

and eddies form easily on the free surface around

the long shroud.

– Subflux controller of turbulence can effectively

control and improve the fluid flow in the impact

Figure 6 RTD curves for the different configurations studied

zone of the tundish. Such improvement in molten

flow characteristic in the tundish would be benefited

to the flotation for the non-metallic inclusions

and the decrease in the exogenous inclusions.

– The installation of the subflux controller of turbulence

in the tundish has resulted in a reduction of the

transient zone range in two cases. The most advantageous

casting conditions are met for Configuration

C - the transient zone range is the shortest one.

– The use of an inappropriate geometry of the

subflux controller of turbulence in the tundish will

result in a worsening of the hydrodynamic conditions

of steel flowing through the tundish (Configuration

D).

The tundish upgrading process has not to be ended at

this stage, as further modifications are still possible,

such as installing additional dams.

REFERENCES

�1� S. M. Lee, Y. S. Koo, T. Kang, I. R. Lee, Y. K. Shin, Sixth

International Iron and Steel Congress ISIJ, (1990) 3,

239-245

�2� R. K. Singh, A. Paul, A. K. Ray, Scand. J. Metall., 32

(2003), 137

�3� A. Robert, D. Mazumdar, Steel Research, 71 (2001), 97-102

�4� T. Merder, J. Pieprzyca, Z. Kudliñski, L. Bulkowski, U. Galisz,

H. Kania, Wiadomoœci Hutnicze, (2009) 3, 178-184.

�5� B. E. Launder, D.B. Spalding, Methods in Applied Mechanics

and Engineering, 3 (1974), 269-289.

�6� J. F. Wendt, Computational fluid dynamics, Springer-Verlag,

Germany, 1996.

�7� T. Merder, J. Jowsa, M. Warzecha, Brno, Czech Republic,

(2005), 593-560.

�8� Gambit User’s Guide, Fluent Inc., 2005.

�9� FLUENT User’s Guide, Fluent Inc., 2007.

�10� SV. Pathankar, Numerical heat transfer and fluid flow, Hemisphere

Publishing Corporation, NY, 1980.

�11� M. Clark, T. Wagner, A. Trousset, IOM Annual Ceramics

Convention, (2002), 14-19.

Note: The responsible translator for English language is P. Nowak,

Katowice, Poland.

226 METALURGIJA 50 (2011) 4, 223-226


B. MATE[A, D. KOZAK, A. STOI], I. SAMARD@I]

THE INFLUENCE OF HEAT TREATMENT

BY ANNEALING ON CLAD PLATES RESIDUAL STRESSES

INTRODUCTION

Establishing size and nature of residual stresses at

plated construction of dissimilar steel is very important.

Knowledge of tensile residual stresses is essentially due

to possible appearance of cracking tendency of corrosion

resistant steel to stress corrosion, while knowledge

of pressured residual stresses is important because of

their influence on construction stability �1-2�.

Quantitatively, determination residual stresses on

surface of plated austenite corrosion resistant steel was

performed using semi-destructive method i.e. centre

blind-hole drilling procedure by relaxed deformations

with electrical gauge measurement (rosettes).

MEASUREMENT OF RESIDUAL

STRESSES AND ANALYSIS

Intention of specified experiment was establishing of

annealing influence on residual stresses of plating stainless

steel surface depending on clad procedure.

The experiments plan of measuring residual stresses

by centre-hole drilling using electric-resistant measuring

strain gauges (rosettes) is presented in the Table1.

Received – Prispjelo: 2010-07-30

Accepted – Prihva}eno: 2010-12-03

Original scientific paper – Izvorni znanstveni rad

The influence of applied clad procedure as well as heat treatment by annealing (650 °C/2h) on level and nature

of residual stresses was researched. Three clad procedures are used i.e. hot rolling, submerged arc welding

(SAW) with strip electrode and explosion welding. The relaxed deformation measurement on clad plate surfaces

was performed by applying centre-hole drilling method using special measuring electrical resistance strain

gauges (rosettes). After performed measuring, size and nature of residual stresses were determined using analytical

method. Depending of residual stresses on depth of drilled blind-hole is studied.

Key words: residual stresses, heat treated clad plates; centre-blind holes drilling, electrical resistance strain gauges

(rosettes)

Utjecaj toplinske obradbe `arenjem na zaostala naprezanja platiranih plo~a. U ~lanku su prikazani

rezultati istra`ivanja utjecaja toplinske obradbe `arenjem(650 °C/2h) na veli~inu i narav zaostalih naprezanja

platiranih limova. Kori{tena su tri postupka platiranja tj. toplo valjanje, elektrolu~no navarivanje pod pra{kom

(EPP) elektrodnim trakama te platiranje eksplozijom. Provedena su mjerenja relaksiranih deformacija metodom

bu{enja sredi{njeg provrta koriste}i elektro-otporni~ke mjerne rozete. Nakon provedenih mjerenja, veli~ina i

narav zaostalih naprezanja su odre|eni koriste}i analiti~ku metodu. Istra`ivana je ovisnost vrijednosti zaostalih

naprezanja o dubini zabu{ivanja sredi{nje rupe.

Klju~ne rije~i: zaostala naprezanja, toplinska obradba platiranih plo~a, bu{enje sredi{njeg provrta, elektro-otporni~ke

mjerne rozete

B. Mate{a, D. Kozak, A. Stoi}, I. Samard`i}, Faculty of Mechanical Engineering

in Slavonski Brod, University of Osijek, Slavonski Brod, Croatia

Dimensions of examined plates were 100 � 100 ��

mm. The base material ASTM A387 Gr.12 is delivered

in normalised and plating ASTM A240 TP304L in

quenched state (Tables 2-3).

Table 1 Plan of performed experiments on residual

stresses measurement

Residual stresses

measurement

Sample plated by hot

rolling A1

Sample plated by SAW

with striped electrodes A2

Sample plated by explosion

welding A3

ISSN 0543-5846

METABK 50(4) 227-230 (2011)

UDC – UDK 620.182.2:669.866.67.68=111

B1

no heat

treatment

B2

heat treatment

/ 650 °C/2h

A1B1 A1B2

A2B1 A2B2

A3B1 A3B2

The procedure is established on fact that using

hole-drilling in elastic body in which exist strain state,

changing of strain state the elastic deformations occurs

on surface of body. Drilling of very small holes dimension

in elastic body it could be established strain state

practically in one point and by in this resulting in insignificantly

damage of construction. The great influence

on accuracy of measured relaxed deformation by centre

hole-drilling method has possible un-centricity of centre-drilled

blind hole. Improved method use very pre-

METALURGIJA 50 (2011) 4, 227-230 227


B. MATE[A et al.: THE INFLUENCE OF HEAT TREATMENT BY ANNEALING ON CLAD PLATES RESIDUAL STRESSES

Figure 1 Rosettes plan for measurement of residual

stresses using centre-hole drilling procedure

ciously optical devices as well as rosettes are supplied

with special centric alignment in her centre. Today technique

will lead to slight misalignment errors reflecting

the skill of the operator. Concentricity misalignment

(within 0,15 mm) will produce much lower errors in recorded

strain values than will the holes oval (typically

0,24 mm).When the workpiece is thick, it’s enough to

drill a hole no deeper than its diameter, this leads to the

relaxation of the major part of residual stresses �3-5�.If

the depth of the hole is smaller, an amount of the stresses

may not be released. In case of the thin plates, when the

diameter of the hole is larger than the thickness, the relaxation

of the residual stresses appears when the hole is

drilled. Using this method, the determination of residual

stresses by drilling of very small holes depth is enabled.

Use of rosettes with electrical measuring strain gauges

and angles between ones 0/90/225 ° are common. Using

this configuration of tension gauges, three radial deformations

could be measured (Figure 1).

Table 2 Mechanical properties of base and plating materials

Mechanical properties of materials

Yield Strength

Rp0,2/MPa

In case of drilling penetrate-hole, with radius ’a’ (Figure

1), the base stress distribution in accordance with

Kirsch’s solution will be determined by equations �2-4�:

� � a � � a

� r � �

r

r

� � �

�� � ���

� �


2 � 2 �

1 2

1 2

1

�� 1�4 �� cos2

2

2

2

2 � �

� � � �

� � � �

� � �

�� � ���

� �


2 � 4 �

1 2 a 1 2��

a

1

1�3 �� cos 2 (1)

2

4

2 r 2 � r �


r�

� � a a

�� �

r r

� � 2 ��

2 �

1 2��1�����1�3

�� sin 2

2

2

2 � ��


as well as deformations are determined with:

a a

E�

r �

r r

� ��

2 � � 2

� ��

1 �2

� ���

1�������1� ��

2

2 ��

2 ��

� � ��

2 4

4

� 1���� 2

� ��

a a � �

1�4 �3

��� ��

a ��


� 1�3 ��

2 4

4 �cos2�

2 ��

r r � � r ��

a a

E�


r r

� ��

2 � � 2

� ��

1 �2


���

� ��� �� � ��


1 � 1

2

2 ��

2 ��

� � ��

4

2 4

� 1���� 2

� ��

a � �

1�3 ��� ��

a a ��


� 1�4 �3

��

4

2 4 �cos2�

2 ��

r � � r r ��

(2)

� � 2

a � � 2

� a �

1 �2

E��

r �� ��

�� � ����� � ��

� 21 ( ) 1 1 3 sin2�

2

2

2 � r � � r �

The equipment used for this work is known as the

RESTAN (REsidual Stress ANalysis) system and was

purchased from HBM of Germany �6-8�. Deformations

determination is on plated samples surfaces performed

and at the same time for each level of influences factors

are (joints procedure and heat treatment) two plates examined.

On Figure 2 is presented plan of rosettes connection

with measuring amplifier. The greases and surfaces

impurities are cleaned and the measurement

gauges (rosettes) bond by viscous adhesive HBM Z70.

Tensile Strength

Rm/MPa

Elongation

A5/%

Impact Energy

Kv/ J

ASTM A387, Gr. 12, (�=14mm) 421 598 26 169

ASTM A240 TP304L (�=2mm) 218 591 63 210

Table 3 Chemical analysis of materials in joints

Chemical compositon of elements / %

Materials

C Si Mn P S Cr Mo Ni

ASTM A 387 Gr.12, �=14mm 0,13 0,28 0,78 0,008 0,010 1,07 0,52 -

ASTM A 240 TP 304L, �=2mm 0,026 0,48 1,33 0,030 0,030 18,7 - 10,8

First bead SAW strip

60x0,5mm, AWS E 309L, �=3mm

0,013 0,29 1,68 0,013 0,003 23,92 - 13,05

Second bead, �=3mm SAWstrip

60x0,5mm, AWS E 308L

0,021 0,94 1,00 0,017 0,006 20,50 - 11,4

228 METALURGIJA 50 (2011) 4, 227-230


B. MATE[A et al.: THE INFLUENCE OF HEAT TREATMENT BY ANNEALING ON CLAD PLATES RESIDUAL STRESSES

Figure 2 Connection plan of measurement gauges (rosettes)

type HBM 1.5 / 120RY61, with measuring

amplifier KWS 3050.

Compensative measurement gauge HBM 1,5 / 120

LY11 is placed on extra tile from austenite corrosion resistant

steel.

The rosettes are connected with measuring devices

by classic telephone wiring 1 mm of diameter and 50 m

of length. The others installed equipment was digital indicator

DA 3415A and installed printer D21.

Holes drilling device is centered and stick on surface

of corrosion resistant steel.

After bringing into balance of measuring amplifier

the drilling was performed using special drill 1,5 mm of

diameter.

The drilling was performed manually by low number

of revolutions per minute as well as the measurement of

elastic deformations simultaneous. The elastic deformations

are measured on drill deepness (Z): 0,5; 1,0; 1,5

and 2,0 mm (Figure 3).

The principal stresses are calculated in accordance

with equation (Table 4):

�12 , �A�( ��a ���c) �

2 2

�B� ( �� ��� ) �( �� �2�� ���

)

c a a b c

Table 4 Calculated values of maximum and minimum principal stresses �1(SIGMA1), �2(SIGMA2) at surface of clad plate

depend on blind hole depth Z

Residual stresses measurement by centre hole drilling

procedure

Principal stresses

�1; �2; MPa depth of holes Z

Samplesplated by hot rolling A1

Samples plated by SAW stripped-2beads

beads electrode A2

Samples plated by explosion welding A3

Figure 3 Photographs record of HBM manual mechanical

drilling and centre alignment device

no heat treatment B1

(delivered condition)

heat treatment by annealing

B2(650 C / 2 hours)

Plate1,(P1) Plate2,(P2) Plate1,(P1) Plate 2,(P2)

�1 �2 �1 �2 �1 �2 �1 �2

Z1=0,5mm - - -21 -39 - - -65 - 97

Z2=1,0mm +68 - 15 -39 -92 +65 -139 -120 164

Z3=1,5mm - - -32 -82 - - -130 -174

Z4=2,0mm +86 - 26 -50 -101 +59 -145 -127 -170

Z1=0,5mm - - +69 +29 - - +44 +20

Z2=1,0mm +44 - 64 +70 -35 +71 -60 +34 +19

Z3=1,5mm - - +87 -41 - - +85 +8

Z4=2,0mm +50 - 58 +108 -31 +36 -87 +92 +5

Z1=0,5mm - - - - - - - -

Z2=1,0mm -139 +279 - - -191 -235 - -

Z3=1,5mm - - - - - - - -

Z4=2,0mm +208 -324 -258 +444 -233 -297 -369 -440

METALURGIJA 50 (2011) 4, 227-230 229


B. MATE[A et al.: THE INFLUENCE OF HEAT TREATMENT BY ANNEALING ON CLAD PLATES RESIDUAL STRESSES

Figure 4 Maximum and minimum principal stress distribution

�1 �2 at surface of clad plate for model

A2B1 depending on depth blind hole Z (plated-overlayed

by SAW strip-electrode- clad state)

THE RESULTS ANALYSES OF RESIDUAL

STRESSES MEASUREMENT

On the basis after drilling measured relieved deformations

values �a, �b and �c as well as materials and

measuring rosettes characteristics, calculated residual

stresses (in acc. with equation 3) depend on blind- and

for rosettes HBM 1.5 / 120 RY61 are:

E E

A*

� �

4A 01894 . ( 1�

�)

(3)

E

E

B*

� �

4B 0. 7576�0. 0606�( 1��)

for clad material: Ea =190x10 3 MPa; � = 0,3.

On the basis after drilling measured relieved deformations

values �a, �b and �c as well as materials and measuring

rosettes characteristics, calculated residual

stresses in accordance with equation (3) depending on

blind hole depth (Z), are presented on Table 4.

At all applied kind of cladding procedures using heat

reatment by anealing a drop of residual stresses is established.

The changing of residual stresses (size and nature)

specimens plated by submerged-arc welding(SAW) by

striped electrodes in two beads are graphicaly presented

in Figures 4-5.

Even the nature of residual stresses changed from

pressured into tensile stresses by anealling.

This alternation is unfavourable from the standpoint

of plating corrosion resistant steel inclination to stress

corrosion fissure.

CONCLUSIONS

Type of plating procedures has significantly influence

on value of residual stresses more than applied heat

treatment by anealing.

Figure 5 Maximum and minimum principal stress distribution

�1 �2 at surface of clad plate for model

A2B2 depending on depth blind hole Z (plated-overlayed

by SAW strip-electrode-anealed

state)

At specimens plated by rolling and explosion procedure

high pressured residual stresses are not significantly

changend (in range and nature) after used heat

treatment.

Significant influence of used heat treatment on range

and nature of plating surface residual stresses is present

at specimens plated by submerged-arc welding (SAW)

with strip electrodes in two beads.

The transformation of pressured stresses into tensile

stresses is very unfavourable from viewpoint tendency

of plating corrosion resistant steel to stress corrosion

cracking.

After drilling max. depth of holes Zmax =2mmthe

major part of residual stresses is relaxed.

REFERENCES

�1� E. Macherauch, HTM Beiheft, Carl Hanser Verlag, Muenchen.

1985.

�2� A., S. Kobayashi, Handbook on experimental mechanics,

SEM N.Y. USA, 1993.

�3� S. Keil, Beanspruchungsermittlung mit Dehnungsmesstreifen,

Cuenes Verlag, Zwingenberg, 1995.

�4� W. Dally, F.;Riley, Experimental stress analysis, Int. Student

Edit, Mc Graw-Hill Book Co., N.Y., 1987.

�5� B. Mate{a, International Conference on welding of corrosion

resistant materials, Dubrovnik, October 1997.

�6� B. Mate{a, M. Husnjak, EUROJOIN 4 , Cavtat-Dubrovnik,

May 2001. pp. 637 - 643.

�7� M. Husnjak, S. Kralj, International conference on residual

stresses in welding joints, Zagreb, 1982.

�8� Standard method for determining residual stresses by the

hole-drilling strain gauge method, ASTM 837.94(a), - 1994.

NOTE: Responsible translator: @eljka Rosandi}, Faculty of Mechanical

Engineering, University of Osijek, Slavonski Brod, Croatia

230 METALURGIJA 50 (2011) 4, 227-230


A. KO[NIK, J. TU[EK, L. KOSEC, T. MUHI^

THE MANUFACTORING

OF A TWO–LAYERED INJECTION MOLD BY WELDING

INTRODUCTION

To optimize the surface properties of the moulds,

special cladding techniques have to be used because the

majority of tool steels are commonly considered as

non-weldable due to their high carbon and alloy elements

content. The parameters influencing the selection

of cladding technology are: the properties of base material,

structure and state of heat treatment of base material,

mould function and loads acting upon the weld,

treatment after the welding, and defects that may occur

upon welding (weld undercuts and cracks). In the case

of welding of injection molds for thermoplastic both laser

welding (fine welding) and TIG-welding process

(larger-scale repairs) are commonly used �1-3�. In both

processes welding is done in a protective atmosphere of

inert gas that shields the weld from the influence of surroundings

(atmospheric gases). In both cases, the filler

material is an uncoated welding wire.

The injection molds for thermoplastic are usually

made of two halves – a fixed part and a sliding part. The

latter houses an ejector package that ejects the product

Received – Prispjelo: 2010-08-11

Accepted – Prihva}eno: 2010-10-16

Original Scientific Paper – Izvorni znanstveni rad

The article presents the technology of deposit cladding different materials, using the injection molds for thermoplastic

as a case study. The aim of the study is to surface weld to the working surface of the mold a different

material with corresponding physical properties. Steel (1.1141) and a copper alloy were used as the base, onto

which different materials were surface-welded. Tungsten inert gas (TIG) welding was employed to make molds

inserts. An analysis of cross-sectioned specimens was made by optical microscopy, and chemical and hardness

profiles were measured too. The thermal conductivity of base and cladded layer was also tested. Finally, a thermal

fatigue test was employed to investigate the thermal fatigue properties of such surfaces.

Key words: injection mold, surface welding, copper alloy, thermal and chemical analysis

Izrada dvoplastnog alata za ubrizgavanje termoplasta postupkom zavarivanja. U ~lanku predstavljena

je tehnologija navarivanja razli~itih materijala na primjeru alata za ubrizgavanje termoplasta. Cilj istra`ivanja

je navarivanje druk~ijeg materijala s odgovaraju}im fizikalnim svojstvima na radnu povr{inu alata. Ulo{ci

alata izra|eni su postupkom zavarivanja volframovom elektrodom uz za{titu inertnog plina (TIG). Kao osnova

na koju su navareni razli~iti materijali kori{teni su ~elik (1.1141) i bakarna slitina. Popre~ni presjek uzoraka analiziran

je opti~kim mikroskopom, izmjereni su i kemijski profil i profil tvrdo}e. Testirana je i toplinska provodljivost

osnovnog i navarenog materijala. Na kraju je izvr{en i test termi~kog zamora u svrhu istra`ivanja svojstava

termi~kog zamora takvih povr{ina.

Klju~ne rije~i: alat za ubrizgavanje, navarivanje, bakarna slitina, termi~ka i kemijska analiza

A. Ko{nik, Hella saturnus Slovenija d.o.o., Ljubljana, Slovenia, J. Tu{ek,

Faculty of Mechanical Engineering, Ljubljana, Slovenia, L. Kosec, Faculty

of Natural Sciences and Engineering, Ljubljana, Slovenia T. Muhi~,

TKC d.o.o., Ljubljana, Slovenia

ISSN 0543-5846

METABK 50(4) 231-234 (2011)

UDC – UDK 678.027.74: 621.791: 669.3: 615.074=111

when the injection cycle is completed. The fixed part includes

a runner system used to feed the thermoplastic,

heated above the flowing temperature, into the mold

cavity situated between the fixed and sliding part of the

mold. After the molten thermoplastic fills up the cavity,

secondary pressure is applied to the injection-molded

part to ensure the part is stable and completely filled (no

air inclusions or sink marks). This is followed by the

longest part of the cycle – cooling �4�.

The area where both mold halves contact is called

the parting line. The parting line is exposed to mechanic

(melt abrasion, secondary pressure during injection

molding), thermal (temperature differences during the

injection process – elongation and shrinkage) and chemical

influences caused by the thermoplastic �5�.

Figure 1 Reduction of injection moulding cycle by switching

from a steel mould (a) to a mould with

copper alloy inserts (b).

METALURGIJA 50 (2011) 4, 231-234 231


A. KO[NIK et al.: THE MANUFACTORING OF A TWO–LAYERED INJECTION MOLD BY WELDING

Figure 2 Part warpage vs. time

The use of different alloys results in shorter cycle

times (Figure 1) and uniform heat removal from the plastic

part, which, in turn, creates lower unit production costs

over the life cycle of the tool and leads to more uniform

dimensional parameters for the plastic parts (Figure 2).

This is why materials with a large thermal conductivity

have to be used. Cladded layers also have to be wear

resistant in order to endure the abrasion �6�. Main problem

occurring in injection molding are sink marks on the

product. Sink marks occur in the areas where the product

wall thickness is too big, causing uneven cooling.

Sink marks can be avoided by corresponding modifications

of geometry in the design phase, or through more

rapid cooling of an existing mold. In the latter case,

cooling channels have to be made in the mold (Figure 3)

in order to facilitate the flow of cooling water.

But in most cases even this is not enough, as there is

a large amount of heat to be removed from the critical

areas. In such cases, materials with good thermal conductivity

have to be used.

Figure 3 Removal of heat from an injection-moulded

product in a) mould and sink marks on the final

product (right) b) mould with copper-alloy

insert, successfully removing sink marks (right).

a) b)

Figure 4 (a) Surface-welded specimens after grinding

and polishing. Base and filler materials: 1–copper

alloy surface welded with AlCu, 2 – 1,1141

steel surface welded with AlCu (b) A schematic

of the thermal conductivity test set-up

EXPERIMENTAL PROCEDURE

In order to reach the proposed objectives, welds were

made on two base materials: 1.1141 (structural low-carbon

steel) and copper alloy. To obtain satisfactory results,

the filler material was chosen according to a significant

difference in thermal conductivity to the base

metal. But for an injection mold that must be polished

after welding, it is essential that the welded surface has a

similar hardness with respect to the base metal. Otherwise,

marks can remain in the contour of the weld after

the polishing that would be reproduced in the injection

part. Aluminium bronze (trade name: Ampco 10) and

1.4370 (trade name: Inox B 18/8/6) were used as filler

materials. Welded specimens were prepared with slots

dimension 15 x 10 x 1,5 mm and then filled by TIG

welding procedure (Figure 4a).

The specimens were cut to obtain the cross-section

of the clad passes. Specimens for optical metallography

were obtained from the transverse direction of the weld,

followed by mechanical polishing by standard technique

and etching.

EKSPERIMENTAL RESULTS

Heat conduction

Based on the temperature measurements, it was

found out that copper alloy and steel behave differently

during heating (Figure 4b). The temperature difference

between the two materials on the upper (cold) side is 38

°C, indicating a greater heat conductivity of copper alloy.

Due to a larger heat conductivity, the temperature

gradient of copper alloy over the cross section is smaller

(the temperature difference between the heated and cold

side is minimal, i.e. 8 °C). The same temperature difference

in steel with the same thickness (8,2 mm) is 47 °C.

From the viewpoint of heat transfer (in our case, a faster

removal of heat from the mold) this means one can

achieve better control of mold temperature. The use of

cooling channels therefore enables us to achieve the desired

temperature across the mold more quickly and

with greater accuracy. The effect of residual heat is

thereby practically cancelled out, contributing significantly

to the stability of the injection molding process.

232 METALURGIJA 50 (2011) 4, 231-234


Microstructures and

Vickers hardness of clad layer

A. KO[NIK et al.: THE MANUFACTORING OF A TWO–LAYERED INJECTION MOLD BY WELDING

Figure 5 The course of hardness in base material, heat-affected zone and surface weld a) Base material is copper alloy,

surface welded with AlCu. (b) Base material is 1,1141 steel, surface welded with AlCu.

Macro specimens were prepared from all welded

pieces for the measurement of hardness. It is evident

from Figures 5a and 5b that the hardness of AlCu surface

weld is 140 to 170 HV in the case of surface welding

onto copper alloy, and 180 to 240 HV in the case of

surface welding onto steel. In the first case the hardness

of surface weld does not deviate significantly from the

hardness of base material as a consequence of good

remelting and separation. The situation is different for

surface welding of AlCu onto steel (1.1141). The scatter

is large due to imperfect mixing of filler and base materials,

which are of a very different composition. The

heat-affected zone exhibits areas of material with a different

microstructure and partial separation. The inclusions

of precipitated metal have a considerable effect on

the variations of measured hardness.

The chemical analysis was conducted with an electron

microscope which enables the observation and comparison

of content of individual metals in the surface weld,

heat-affected zone and base material. In the case of surface

weld AlCu on a copper base a typical case of good

separation with a uniform structure can be observed. The

copper content is constant over the whole cross section

and there is no saturation. It can also be seen that the content

of aluminum is greater in the surface weld. Such a

weld is homogeneous and more stable with respect to

strength (there are no inclusions or precipitated material

at the transition that could reduce the strength).

Figure 6 shows the heat-affected zone where the

fraction of Al is reduced (transition from dark to light

area) on the account of increased fraction of Cu, Co and

Ni. The chemical composition measured along the line

of measurement is as follows: surface weld (95,8 % Cu,

Figure 6 Heat-affected zone between the surface weld

made of copper alloy and AlCu

2,5 % Al, 0,8 % Ni, 0,5 % Co, 0,4 % Fe, HAZ (95,6 %

Cu, 2,5 % Al, 0,9 % Ni, 0,6 % Co, 0,4 % Fe), base

material (96,6 % Cu, 2 % Ni, 1,4 % Co). Hardness is

reduced in this transition, too.

In the case of surface welding AlCu onto steel

(1.1141), the microstructure of the surface weld varies

with respect to the depth. Beginning at the depth of 0,3

mm, the structure changes from coarse-grained to

fine-grained, which is better for taking mechanical

loads. Long crystals are composed of iron (5 %) and aluminium

(5 %) inside copper. The fine-grained structure

includes a larger fraction of iron (up to 17 %) with the

same content of aluminium (5 %).

Melt mixing, shown in Figure 7, contributes to

jumps in measured material hardness. A part of iron

penetrates the surface weld and mixes with the copper,

whereas the migration of copper into the base material is

much weaker than the migration of aluminum.

Molten copper diffuses into base material in the

heat-affected zone, as it is clearly visible in Figure 8, with

METALURGIJA 50 (2011) 4, 231-234 233


A. KO[NIK et al.: THE MANUFACTORING OF A TWO–LAYERED INJECTION MOLD BY WELDING

Figure 7 Microstructure (a) and distribution of individual

metals in the surface weld (AlCu) and

base (1.1141).

the following compositions: area 1 (91,6 % Cu, 4,3 % Al,

3,7 % Fe, 0,3 % Mn, 0,1 % Co), area 2 where molten copper

diffuses into base material (84,4 % Fe, 12,4 % Cu, 3,2

% Al), area 3 (92,1 % Fe, 6,8 % Cu, 1,1 % Al) and area 4

(99,6 % Fe, 0,4 % Mn), as the base material. Figure 8 also

shows the diffusion of copper (light channels in a grey

area) and the dendritic structure of iron that solidifies

first. The thickness of transient area is 70 �m. Copper inclusions

are present in area 3 (precipitated light dots).

Thermal Fatigue

The research was conducted to test thermal fatigue

resistance and thermal stability of cladded material

based on the conductive heating and subsequent cooling

by air yet. A schematic of thermal fatigue test apparatus

is shown on Figure 9a. It enables a controlled thermal fatigue

cycling test of materials. The test specimen (Figure

9 b) was subjected to up to 20 000 thermal cycles

(Figure 9c). After the completion of 7 000, 14 000 and

20 000 cycles the specimen surface was inspected (Figure

9d). The surface of cladded area shows superior

thermal fatigue resistance since no cracks were observed.

CONCLUSIONS

It follows from the results obtained by theoretic considerations

and practical tests that it is possible to obtain

very different combinations of base and filler material

by welding. This is practical for the manufacturing of injection

molds for thermoplastic, where both heat removal

and mechanic endurance are important. It has to

be mentioned that the effect of abrasion is not as large as

Figure 8 Heat-affected zone between the surface weld

made of AlCu and 1.1141 steel as base material.

with die-casting molds, so softer copper alloys can be

used. Priority is given to thermal properties. TIG-welding

process is estimated to be the most suitable process

with respect to the mold size and material type. From all

combinations of different injection molds for thermoplastic

researched, steel with surface-welded copper alloy

is the most suitable. This finding is based on technological

and economic indicators.

REFERENCES

�1� D. Klob~ar, J. Tu{ek and L. Kosec: Suitability of maraging

steel weld cladding for repair of die-casting tooling, International

journal of materials research, 99 (2008) 9,

1006-1014.

�2� T. Muhi~, J. Tu{ek, D. Bomba~, M. Pleterski: Problems in

repair welding of duplex treated tool steels, Metalurgija 48

(2008) 1, 39-42.

�3� M. Vedani: Microstructural evolution of tool steels after

Nd:YAG repair welding, Journal of materials science 39

(2004) 1, 241-249.

�4� D. M. Bryce: Plastic injection molding, (1996).

�5� V. Goodship: Troubleshooting injection moulding,

15(2004) 4.

�6� Wei-Nien Su: Layered fabrication of tool steel and functionally

graded materials with a Nd:YAG pulsed laser (2002).

Note: The responsible for English language is Marko Ore{kovi},

Ljubljana, Slovenia

Figure 9 (a) Thermal fatigue testing machine Gleeble 1 500 D (b) Test specimen (c) thermal cycle (d) surface of test

specimen after 20 000 cycles.

234 METALURGIJA 50 (2011) 4, 231-234


D. KLOB^AR, M. MUHI^, J. MO@INA, J. TU[EK

LASER GROOVING OF SURFACE

CRACKS ON HOT WORK TOOL STEEL

INTRODUCTION

Repair welding (RW) with wire cladding is a common

procedure to extend the in-service life of heavily

loaded tool parts for die and mould industries �1-5�. The

main advantages of repair welding are short downtime

and cost efficiency compared to production of new tool

part. Repair welding in general lowers the tool cost in

the final part and enables higher added value to the die

casting and injection moulding industry.

The in-service life of die casting dies and injection

moulding tools is correlated with the thermo-mechanical

loads during production. The production of 300000

castings is a common series for die-casting industry and

1000000 mouldings for injection moulding industry.

The in-service tool life is affected by (a) thermal fatigue,

which causes heat marks on the surface of the die, (b)

corrosion and soldering of aluminium to the die surface,

(c) erosion due to melt flow, and (d) catastrophic failures

�6-9�. Generally the tool steels are considered as

non-weldable or hard to weld materials due to its high

carbon and alloying element composition. A repair

welding of dies and mould tools, which are made of tool

steels, are done using tungsten inert gas (TIG) welding

or a new technology called laser cladding by wire

(LCW), which is a new alternative technology for repairing

of small failures.

For a quality laser RW a clean welding surface is

necessary beside suitable welding wire. In many cases

Received – Prispjelo: 2010-09-23

Accepted – Prihva}eno: 2011-01-20

Original Scientific paper – Izvorni znanstveni rad

The paper presents the analysis of laser grooving of 1.2343 tool steel hardened to 46 HRC. The effect of laser

power and grooving speed on groove shape (i.e. depth and width), the material removal rate and the purity of

produced groove as a measure of groove quality was investigated and analyzed using response surface methodology.

Optimal parameters of laser grooving were found, which enables pure grooves suitable for laser welding.

Key words: laser beam machining, laser grooving, 1.2343 tool steel, thermal cracks

Lasersko `ljebljenje povr{inskih pukotina na alatnom ~eliku za vru}i rad. U radu je prikazana analiza

laserskog `ljebljenja alatnog ~elika 1.2343 pobolj{anog na 46 HRC. Ispitani i analizirani su u~inci laserske energije

i brzine `ljebljenja na dubinu i {irinu `ljeba, brzinu skidanja materijala i ~isto}e izra|enih `ljebova, kao mjerilo

kvalitete `ljeba pomo}u metodologije odziva povr{ine. Prona|eni su optimalni parametri laserskog

`ljebljenja, {to omogu}ava izradu ~istih `ljebova pogodnih za lasersko zavarivanje.

Klju~ne rije~i: laserska obrada, lasersko `ljebljenje, 1.2343 alatni ~elik, toplinske pukotine

D. Klob~ar, J. Tu{ek, J. Mo`ina, Faculty of Mechanical Engineering,

University of Ljubljana, M. Muhi~, TKC d.o.o., Ljubljana, Slovenia

ISSN 0543-5846

METABK 50(4) 235-238 (2011)

UDC – UDK 621.9.048:621.7.019.1 =111

when RW is done on surfaces of the dies and moulds, the

cracked surface must be removed and/or cleaned. The

cracks are usually filled with oil or grease and/or the

casting materials and oxides �6-8�. To prepare the surface

for LCW a laser grooving (LG) or laser beam machining

(LBM) could be used.

The LBM has many variants: drilling, cutting and

grooving, turning and milling, and micromachining �10,

11�. The mechanism of material removal during LBM

includes three different stages i.e.: (i) melting, (ii)

vaporisation and chemical degradation, at which chemical

bonds are broken, which causes the materials to degrade.

When a high energy laser beam is focused on

work surface the thermal energy is absorbed. That heats

and transforms the work volume into a molten, vaporised

or chemically changed state that can easily be removed

by flow of high pressure assisted gas jet. This jet

accelerates the transformed material and ejects it from

machining zone �10, 11�. The effectiveness of LG depends

on thermal properties and partly on the optical

properties of the grooved material, whereas less on mechanical

properties. The materials that exhibit a high degree

of brittleness i.e. hardness and have low thermal

diffusivity and conductivity are well suited for laser machining,

since they are not so easily machined conventionally

�10, 11�. Another benefit of LG is that there are

no cutting forces generated by the laser, therefore any

machine vibration, tool ware or mechanical damage is

induced to the material. The main obstacles in LG are

the changing of groove geometry (GG) with LG param-

METALURGIJA 50 (2011) 4, 235-238 235


D. KLOB^AR et al.: LASER GROOVING OF SURFACE CRACKS ON HOT WORK TOOL STEEL

eters �10-16�, slag or dross formation on the surface by

groove or inside the groove due to inability to remove it

from it, and thermal damage of the material by the

groove by formation of oxidized layer, recast layer and

heat affected zone (HAZ).

Many researchers studied the LG and micromachining

on sapphire, silicon, alumina ceramic, carbon fibre,

titanium alloy, stainless steel, and mild steel �10�, but no

research was done on the tool steels. The aim of this

study was to analyze the material removal rate (MRR),

GG and metallurgical characteristics. The response surface

methodology (RSM) was used to develop the models

for prediction of GG and its surface as well as MRR.

The results showed that with the proper LG parameters

clean grooves with suitable groove geometry for further

laser repair welding can be made.

EXPERIMENTAL WORK

Material

For LG experiments 1.2343 (X38CrMoV5-1) tool

steel was used with the chemical composition: 0,38 % C,

5,1 % Cr, 1 % Si, 0,4 % Mn, 1,25 % Mo, 0,4 % V and the

rest Fe. The workpiece dimensions were 110 x 50 x 10

mm. The specimen was quenched and tempered to 46

HRC, similarly as die casting tools.

Laser grooving

The experimental configuration is shown in Figure

1. A Lasag KLS-522 Nd-YAG laser was used for LG.

The movement of the workpiece was done by a computer

controlled motorised moving table. The laser

beam was conducted through the optical fibre to the focusing

head with a blow through nozzle. The focal point

of laser beam was held constant at 2 mm above the

workpiece surface, and the angle between the focusing

head and workpiece surface was 80°. With the preliminary

trials the basic LG parameters were determined according

to the laser power source. The grooving length

was 20 mm, repetition rate (�) 70 Hz and pulse duration

time (�) was 0,7 ms. A compressed air at 6 bar was used

to remove the remelted material out of the groove.

A plan of experiments was prepared using RSM at

which laser beam pulse energy (LBPE-Ep) varied between

1,05 and 2,15 J and the grooving speed (v) from

0,59 and 3,4 mm/s (Figure 2). These values were chosen

regarding the laser power and the moving table capabilities.

After the grooving the specimens were transversally

sectioned and microsections were prepared for observation

on the microscope. These samples were finely

grinded, polished and etched ina4%Nital (4 % HNO3

in ethyl alcohol) solution. Specimens were examined on

a light and scanning electron microscope (SEM). The

transversally sectioned samples (without grinding and

Figure 1 Experimental setup for LBM

Figure 2 Plan of experiments

polishing) were also examined on SEM from the top and

the side view to determine the interactions between the

LB and material during LBG.

For each groove sample a groove depth (d), width

(w) and groove area (A) were measured. The material

removal rate (MRR) was calculated as a quotient of

groove surface (A / mm 2 ), grooving speed and material

density (�) / 0,0078 g/mm 3 :

MRR / g/min/=A� v � ρ (1)

The average LB pulse power (Pa) was calculated like

a product of � and pulse energy (Ep / Ws):

Pa /W/=��Ep (2)

The average LB energy per unit length (Pamm) was

calculated as quotient of a average pulse power (Pa) and

grooving speeds (v):

Pamm / Ws/mm / = Pa / v (3)

We defined the grooving efficiency as quotient between

MRR and Pamm:

Eff /gmm/Jh/=MMR/Pamm (4)

The RSM was used to develop the models for prediction

of groove geometry and its surface as well as for

MRR, Pamm and Eff.

RESULTS AND DISSCUSION

To determine suitability of LG parameters on the

quality of the groove, the grooves were examined using

SEM. Figure 3 shows the SEM pictures of the grooves

236 METALURGIJA 50 (2011) 4, 235-238


from the top view. The grooves produced with the parameters

10 and 11 shows clean grooves without any

traces of slag. They were produced at pulse energy 1,05

J i.e. average power of 73,5 W and at different grooving

speed. At the LG made with higher pulse energy 1,21 J,

some traces of slag is present on the top right, beside the

groove. More slag is present beside the groove and inside

of it if LG is done with the parameters 8 i.e. pulse

energy 2,15 J and grooving speed of 3 mm/s. If at the

same pulse energy, grooving speed is reduced to 1

mm/s, the groove is filled with slag (Figure 3(7)). The

produced slag is similar to the products from the process

of atomisation, which is used for extraction of powders

for powder metallurgy. The micro-section pictures of

experimental grooves are shown on Figure arranged according

to the plan of experiments (Figure 2). The result

shows that clean grooves are obtained at lower values of

pulse energies. At the lowest energy pulses the examined

grooving speed has no influence on slag formation,

only on the groove shape. At higher pulse energies,

more slag is observed at slower grooving (Figure 4 (4,

5)). At higher pulse energies more slag is present in the

groove and beside the groove. If grooving with this

pulse energy, clean grooves can be obtained, if the

grooving speed is higher than 3,4 mm/s.

The LG parameters have an influence on the groove

shape. Grooving with higher speeds produces shallower

grooves. Increasing of LB peak power produces deeper

grooves, similarly as decreasing of grooving speed. An

approx. 30 to 80 �m thick heat affected zone is observed

in LG with various parameters.

Developed RSM models

The experimental results of groove geometry and

MMR were statistically evaluated with RSM. The models

for prediction of groove depth, width and removed

area as well as MRR were developed. They are presented

graphically in Figure 5. Grooving speed increase

decreases groove width, depth, area and MRR, while increasing

of LB pulse energy increases all observed parameters.

The influence of LB pulse energy on groove

width is one time higher than grooving speed and

approx. ten times higher as weld depth.

Figure 6 shows how the average LB energy per unit

length changes according to pulse energy and grooving

speed. More Pamm is located at the left side of the plot at

slower grooving speeds.

D. KLOB^AR et al.: LASER GROOVING OF SURFACE CRACKS ON HOT WORK TOOL STEEL

Figure 3 The SEM top views of the grooves produced with different LG parameters

Figure 4 Microsections of laser grooves

Figure 5 The influence of LBPE and grooving speed on:

a) groove width / �m, b) depth / �m, c) surface

/ �m 2 and d) MMR / g/min

Model for grooving energy efficiency is presented

on the Figure 6b. It shows that more material is removed

quicker and with less energy if higher pulse energy and

grooving speed is used. If the quality aspect of the produced

grooves is considered (grooves without slag), it is

better to use lower pulse energy or at least higher groov-

METALURGIJA 50 (2011) 4, 235-238 237


D. KLOB^AR et al.: LASER GROOVING OF SURFACE CRACKS ON HOT WORK TOOL STEEL

Figure 6 The influence of LBPE and grooving speed on:

a) Pamm / Ws/mm and b) Eff / gmm/Jh

ing speeds (Figure 6b). If the ability to make a sound laser

cladding is considered the grooves with small traces

of slag are good enough. However grooving parameters

must be properly selected to completely remove the

cracks and make a clean groove.

CONCLUSIONS

Laser grooving is an appropriate technology for

elimination of surface irregularities as cracks. The following

conclusions can be summarized:

– With the proper selection of laser grooving parameters

surface cracks can be eliminated and at the

same time appropriate grooves can be made for

the following LCW.

– LG with high laser pulse energy (higher than 1,8 J

and grooving speeds up to 2,6 mm/s) produces

deep grooves with the slag stuck at the bottom and

at the surface by the groove.

REFERENCES

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process parameters and materials on clad shape in repair

using laser cladding by wire, J. Mater. Process. Technol.,

174 (2006) 223-232.

�2� M. Pleterski, J. Tu{ek, L. Kosec, D. Klob~ar, M. Muhi~, T.

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�3� T. Muhi~, L. Kosec, G. Liedl, M. Pleterski, Assessment of

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2–17.

�12� Z. Bai, A. Wang, C. Xie, Laser grooving of Al2O3 plate by a

pulsed Nd:YAG laser, MSEA, 435 (2006), 418-424.

�13� A. Stournaras, P. Stavropoulos, K. Salonitis, G. Chryssolouris,

Theoretical and experimental investigation of pulsed

laser grooving process, Int. J. Adv. Manuf. Technol., 44

(2009), 114-124.

�14� V. Phanindranath, N.R. Babu, A theoretical model for prediction

of groove geometry on laser dressed grinding wheel

surface, Int. J. Mech. Tools Manufact., 36 (1996) 1, 1-16.

�15� P. Sheng, G. Chryssolouris, Investigation of acoustic sensing

for laser machining processes, Part 2: Laser grooving

and cutting, J. Mater. Process. Technol., 43 (1994) 145-163.

�16� W.C. Choi, G. Chryssolouris, Analysis of the laser grooving

and cutting processes, J. Phys. D: Appl. Phys., 28 (1995)

873-878.

Acknowledgments

The authors wish to thank Dr. Andrej Horvat, Dr. Ale{

Gorki~ and Prof. Dr. Ladislav Kosec for the help at this

research.

Note: The responsible translator for English language is Ur{ka Letonja,

Moar. Prevajanje, Slovenia

238 METALURGIJA 50 (2011) 4, 235-238


J. PRZONDZIONO, W. WALKE, A. SZU£A, E. HADASIK, J. SZALA, J. WIECZOREK

ISSN 0543-5846

METABK 50(4) 239-243 (2011)

UDC – UDK 669.7.018:669.721:539:374:620.193=111

RESISTANCE TO CORROSION

OF MAGNESIUM ALLOY AZ31 AFTER PLASTIC WORKING

INTRODUCTION

The interest of aircraft and automotive industry in

magnesium alloys results from many favourable physical

properties of those materials, and most of all - from

their high relative strength. Design engineers take into

consideration substantial decrease in vehicles weight

and decrease in fuel consumption, that will contribute to

the reduction of pollution and decrease in greenhouse

effect. Advantages of magnesium are at present used intensively

in cast products. In the last couple of years a

substantial technological progress took place, regarding

the technology of magnesium alloys casting. Magnesium

alloys after plastic forming have been scarcely

used so far. The main reason was low availability of

semi-products made of plastic-formed alloys, as well as

their high price. A crucial disadvantage connected with

the development of magnesium alloys processing techniques

by means of plastic forming is their limited plasticity.

Tests of manufacturing processes of semi-prod-

Received – Prispjelo: 2010-06-21

Accepted – Prihva}eno: 2010-12-15

Original Scientific Paper – Izvorni znanstveni rad

The study presents results of electrochemical and chemical corrosion resistance tests of magnesium alloy AZ31

after plastic working. Electrochemical measurements were carried out in 1,35 % solution of NaCl. On the ground

of registered polarisation curves, typical features characterising resistance to electrochemical corrosion,

were determined. Resistance to chemical corrosion was tested by means of immersion in 3,5 % solution of NaCl

for the period of 1�5 days. By means of scanning electron microscope with field emission FE SEM S-4 200 Hitachi,

qualitative and quantitative analysis of chemical composition in microareas was made. Results of surface

layer morphology tests were presented. In order to compare corrosion properties, analogical tests were carried

out for the alloy AZ31 obtained by means of pressure die casting.

Key words: magnesium alloy AZ31, rolling, pressure die casting, electrochemical and chemical corrosion, potentiodynamic

tests

Otpornost na koroziju magnezijeve legure AZ31 nakon plasti~ne obrade. Istra`ivanje pokazuje rezultate

ispitivanja elektrokemijske i kemijske korozijske otpornosti magnezijeve legure AZ31 nakon plasti~ne obrade.

Elektrokemijska mjerenja su provedena u 1,35% otopini NaCl. Na osnovi registriranih polarizacijskih

krivulja, odre|ene su tipi~ne karakteristike elektrokemijske korozijske otpornosti. Otpornost na kemijsku koroziju

je testirana pomo}u uranjanja u 3,5% otopinu NaCl u trajanju od 1 do 5 dana. Pomo}u elektronskog skening

mikroskopa FE SEM S-4200 Hitachi napravljene sus kvantitativne i kvalitativne analize kemijskog sastava u

mikropovr{inama. Pored toga su dani i rezultati ispitivanja morfologije povr{inskih slojeva. Da bi usporedili korozijska

svojstva, provedeni su analogni testovi na leguri AZ31 dobivenoj tla~nim lijevanjem.

Klju~ne rije~i: magnezijeva legura AZ31, valjanje, tla~no lijevanje, elektrokemijska i kemijska korozija, potenciodinami~ki

test

J. Przondziono, A. Szu³a, E. Hadasik, J. Szala, J. Wieczorek, Faculty of

Materials Science and Metallurgy, W. Walke, Faculty Of Mechanical Engineering,

Silesian University of Technology, Katowice-Gliwice, Poland

ucts made of plastic-formed magnesium alloys are currently

in the phase of intensive development. Application

of non-conventional methods of strain enables to

obtain grain size reduction up to submicrometric or

nano-metric dimensions and those methods of strain facilitate

the techniques of conventional strain �1�.

Application of magnesium alloys is limited to a great

extent by insufficient corrosion resistance. Lately,

chemical and electrochemical corrosion resistance tests

of casting alloys have been carried out in various countries

�2-6�. Together with the increase of applications of

alloys manufactured by means of plastic forming in the

industry, it is necessary to evaluate their corrosion characteristics.

This study presents the results of electro-chemical

and chemical corrosion resistance tests of plastic-formed

magnesium alloy AZ31. Electrochemical

measurements were carried out in 1,35 % solution of

NaCl. Typical elements describing resistance of alloy to

electrochemical corrosion resistance were determined

on the ground of registered polarisation curves. Chemical

corrosion resistance was tested by means of immersion

method in 3,5 % solution of NaCl during 1¸5 days.

METALURGIJA 50 (2011) 4, 239-243 239


J. PRZONDZIONO et al.: RESISTANCE TO CORROSION OF MAGNESIUM ALLOY AZ31 AFTER PLASTIC WORKING

By means of scanning electron microscope with field

emission FE SEM S-4 200 Hitachi, qualitative and

quanti-tative analysis of chemical composition in micro-areas.

It also presents the results of measurements of

geometrical characteristics of the surface of alloy AZ31

after corrosion tests. In order to compare corrosion

properties, analogical tests were carried out for the alloy

AZ31 obtained by means of pressure die casting.

MATERIALS AND

TESTING METHODO-LOGY

Electrochemical corrosion resistance was evaluated

on the ground of registered anodic polarisation curves.

In potentiodynamic tests measurement system Volta-

Lab®PGP201 made by Radiometer was used. Saturated

calomel electrode (NEK) of KP-113 type served as reference

electrode, whereas platinum electrode of PtP-201

type was used as auxiliary electrode. The tests started

with determination of opening potential EOCP. Later, anodic

polarisation curves were registered, beginning with

the measurement of potential with the value of

Einitial =EOCP-100 mV. Potential changed in the anodic

direction at the rate of 1 mV/s. When anodic current

reached density of 10 mA/cm 2 , polarisation direction

was changed. Thus, return curve was registered. Opening

potential EOCP of tested samples steadied after 30

minutes. The tests were realised in 1,35 % solution of

NaCl. Solution temperature during the test was

21±1 0 C.

On the ground of registered curves, typical elements

describing resistance to electrochemical corrosion were

determined, i.e.: corrosion potential, polarisation resistance,

corrosion current density and corrosion rate.

Chemical corrosion resistance was tested in ambient

temperature by means of immersion method in 3,5 % solution

of NaCl for 1,5 days. By means of electron scanning

microscope with field emission FE SEM S-4 200

Hitachi in cooperation with spectrometer EDS Voyager

3 500 Noran Instruments, qualitative and quantitative

analysis of chemical composition in micro-areas.

The study also presents the results of measurements of

geometrical features of AZ31 alloy surface after corrosion

tests. The tests were carried out by means of optical

profile measurement gauge Micro’prof. (CWL 3 000)

made by FRT. Parameters of carried out surface geometry

measurement were as follows: measurement field 4×2

mm, resolution 2 000× ×1 000 pixels.

Samples made of magnesium alloy AZ31 after pressure

die casting and after hot rolling were used as initial

testing material. Chemical composition of the alloy is

presented in Table 1. After casting, AZ31 alloy went

through homogenising annealing in the temperature of

450 °C for 24 h. After hot rolling, the alloy was annealed

in 350 °C for 1 h, and then cooled with air.

Table 1 Chemical composition of magnesium alloy

AZ31 type/% of weight

Al Zn Mn Cu Mg

2,83 0,80 0,37 0,002 rest

TEST RESULTS

Electrochemical tests carried out in 1,35 % solution

of NaCl showed resistance to pitting corrosion for samples

made of magnesium alloy AZ31, which varied depending

on the condition of the delivery. Opening potential

EOCP for all tested samples steadied after 30 minutes.

Average value of corrosion potential for rolled

samples equalled Ecorr = -1 367 mV, whereas for cast

samples was smaller by 100 mV and equalled Ecorr =

= -1 467 mV. Anodic polarisation curves for both forms

of AZ31 alloy are shown in Figure 1 and Figure 2.

For all analysed samples no passivation current was

determined and it proves that no passive layer has been

created on the surface of the alloy during polarisation.

The determined average corrosion current density icorr

and polarisation resistance Rp for rolled samples were:

icorr = 80,5 µA/cm 2 and Rp = 330,3 �cm 2 , whereas average

values of corrosion current density icorr and polarisation

resistance Rp for cast samples were respectively:

icorr = = 15,2 µA/cm 2 and Rp = 2 915,3 �cm 2 .

The results of corrosion tests of the alloys are shown

in Table 2.

By means of scanning microscope, the structure of

AZ31 alloy that underwent chemical corrosion in 3,5 %

solution of NaCl was tested. Immersion test for rolled

Table 2 Test results of electrochemical corrosion resistance

of magnesium alloy AZ31 type

Sample Ecorr/ icorr/

No /mV /�A/cm 2

Rp/

/�cm 2

Corr./

/mm/year

Magnesium alloy AZ31 after rolling

1 -1 350 97,4 267 0,90

2 -1 384 63,9 407 0,59

3 -1 377 80,2 324 0,75

Magnesium alloy AZ31 after pressure casting

1 -1 521 11,6 2 248 0,17

2 -1 430 29,5 881 0,28

3 -1 463 4,6 5 617 0,05

Figure 1 Anodic polarisation curves recorded for rolled

samples

240 METALURGIJA 50 (2011) 4, 239-243


J. PRZONDZIONO et al.: RESISTANCE TO CORROSION OF MAGNESIUM ALLOY AZ31 AFTER PLASTIC WORKING

Figure 2 Anodic polarisation curves recorded for cast

samples

samples showed that after the first day of the test a specific

band-shaped system with areas affected by corrosion

of various degrees appeared on the surface.

Non-corroded and corroded areas are places next to one

another (Figure 3). There is also visible presence of pits

(Figure 4). Pictures were taken on the surface cleaned of

corrosion products.

Before cleaning the alloy surface it was found that

mainly crystals of NaCl are the product of corrosion

(Figure 5).

Figure 3 Surface of rolled alloy after 1-day of immersion

in 3,5 % NaCl

Figure 4 Pits on the surface of rolled alloy

Figure 5 NaCl crystals created on the surface of the alloy

after 1-day immersion test

Figure 6 Pits and the surface of rolled alloy AZ31 after

3-day immersion test

Figure 7 Pits and the surface of rolled alloy AZ31 after

5-day immersion test

After 3-days immersion test on the surface of the

rolled alloy small but deep pits were observed. The

course of the corrosion is in accordance with the direction

of rolling (Figure 6). Further tests showed that after

5 days of immersion in 3,5 % solution of NaCl, very

deep pits appeared on the surface of the alloy (Figure 7).

After 1-day immersion test of samples made of cast

AZ31 alloy it was found that their surface is extremely

oxidised. There are also visible non-corroded, random-shaped

areas. These areas are distributed evenly on

the whole surface of the material. It proves that the corrosion

of the material is uniform (Figure 8). Corroded

areas are visible as unevenly solved areas. On the surface

of the material there are also dendritic releases of

METALURGIJA 50 (2011) 4, 239-243 241


J. PRZONDZIONO et al.: RESISTANCE TO CORROSION OF MAGNESIUM ALLOY AZ31 AFTER PLASTIC WORKING

Figure 8 Surface of cast alloy AZ31 after 1-day immersion

test

Figure 9 Dendritic release of phase Mg-Si and phase

Mg-Si running along the grain boundary

Figure 10 Surface of cast alloy AZ31 after 3-day

immersion test

Figure 11 Surface of cast alloy AZ31 after 5-day

immersion test

phases Mg-Si (Figure 9). These phases are permanently

isola-ted and feature higher resistance to corrosion. This

Figure also presents more complex phase running along

the grain boundary.

After 3 days of tests it could be seen that there very

few areas remained non-corroded (Figure 10). After 5

Figure 12 Surface topography 3D and roughness of cast

(a) and rolled (b) AZ31 alloy

days of tests it was found that corrosion of cast alloy

AZ31 still proceeded at a uniform rate (Figure 11).

Figure 12 presents topography of the surface of alloys

and distribution of roughness. The results of geometrical

features measurements of the surface of alloys

(after immersion test and removal of corrosion products)

have been shown in Table 3).

SUMMARY

Potentiodynamic tests carried out in 1,35 % solution

of NaCl enabled to obtain information concerning development

of resistance to pitting corrosion of AZ31 alloy

in relation to the condition of its delivery. Compara-

242 METALURGIJA 50 (2011) 4, 239-243

a)

b)


J. PRZONDZIONO et al.: RESISTANCE TO CORROSION OF MAGNESIUM ALLOY AZ31 AFTER PLASTIC WORKING

Table 3 Parameters representative to AZ31 alloy roughness

Parameter / �m Rolled alloy Cast alloy

Ra 3,14 3,07

Rq 5,53 5,44

Rp 13,1 14,9

tive analysis of anodic polarisation curves showed that

cast alloy features higher corrosion resistance in the

temperature of 21 0 C. Even though its corrosion potential

was slightly smaller, the other determined parameters

were much more favourable (higher polarisation resistance,

lower current density and corrosion rate). However,

substantial discrepancy between its corrosion parameters

(for example, polarisation resistance falls in

the range Rp = 881,5 617 �cm 2 ). It is considered that the

reason for such a huge discrepancy in corrosion properties

of cast alloy are rattails (previous structural tests

showed the presence of micro-caverns �7�).

Corrosion test results after immersion test show that

cast alloy is subject to uniform corrosion. Depth of pits

does not exceed 100 �m. On the surface of rolled alloy

there are visible corroded as well as non-corroded areas.

Due to the fact that in rolled alloy the pits can be really

deep (up to �230 �m), it may result in fast and complete

destruction of the material. In non-corroded areas

roughness does not exceed 5 �m.

Test results prove the necessity of application of protective

layers on elements made of magnesium alloy

AZ31, irrespective of the condition of its delivery.

Acknowledgements

Financial support of Structural Funds in the Operational

Programme – Innovative Economy (IE OP) fi-

nanced from the European Regional Development Fund

- Project “Modern material technologies in aerospace

industry”, No POIG.0101.02-00-015/08 is gratefully acknowledged.

REFERENCES

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�2� Song G., Trens A., Wu X., Zhang B.: Corrosion behaviour

of AZ21, AZ501 and AZ91 in sodium chloride. Corrosion

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�5� Amira S., Dubé D., Tremblay R., Ghali E.: Influence of the

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59 (2008) 1508-1517.

�6� Guo X.W, Chang J.W, He S.M., Ding W.J., Wang X.: Investigation

of corrosion behaviors of Mg–6Gd–3Y–0.4Zr alloy

in NaCl aqueous solutions. Elektrochimica Acta 52

(2007) 2570–2579.

�7� Szu³a A., Hadasik E., Kuc D.: Badania plastycznoœci

i struktury stopu magnezu typu Mg-Al-Zn. Praca zbiorowa:

Wybrane zagadnienia badawcze obróbki plastycznej i cieplnej

metali oraz przetwórstwa tworzyw. Wyd. Naukowe Gabriel

Borowski, Lublin 2009, 133-140.

Note: The responsible translator for English language is Agata Budziak,

Siemianowice, Poland.

METALURGIJA 50 (2011) 4, 239-243 243


I. Mamuzi}, UREDNI^KI ODBOR / EDITORIAL BOARD

Glavni i odgovorni urednik / Editor-in-chief

ACKNOWLEDGEMENT TO REVIEWERS

ZAHVALA RECENZENTIMA

The Editorial Bord of Journal Metalurgija gratefully acknowledges assistance

given during 2011 (volume 50) by the following Reviewers :

Alfirevi} Ivo, Croatia

Aronin Aleksandar, Russia

Baji} Darko, Montenegro

Baji} Dra`en, Croatia

Bari{i} Branimir, Croatia

Bocko Jozef, Slovakia

Ba~ova Viera, Slovakia

Balakin Vladimir, Ukraine

Bohomolov Anatolij, Ukraine

Bokuvka Otokar, Slovakia

Bratutin Vladimir, Ukraine

Brezinova Janetta, Slovakia

Brezo~nik Miram, Slovenia

Bukhanovski Viktor, Ukraine

Bur{ak Marian, Slovakia

Constantinescu Dan, Romania

^igurinski Jurij, Ukraine

Dinik Julija, Ukraine

Dobatkin Sergej, Russia

Dol`anski Aleksej, Ukraine

Dun|er Marko, Croatia

Eremia{ Boleslav, Czech Republic

Fajfar Peter, Slovenia

Franz Mladen, Croatia

Gari{i} Ivica, Croatia

Glava{ Zoran, Croatia

Gmiterna Aleksander, Slovakia

Goji} Mirko, Croatia

Grizelj Branko, Croatia

Grabulov Vencislav, Serbia

Grozdanovi} Vladimir, Croatia

Guljajev Jurij, Ukraine

Hajduk Daniel, Czech Republic

Herold Zvonko, Croatia

Hidveghy Julius, Slovakia

Hloch Sergej, Slovakia

Holtzer Mariusz, Poland

Hornak Peter, Sloavkia

Ikoni} Milan, Croatia

Imri{ @eljko, Croatia

Ivandi} @eljko, Croatia

Jankura Daniel, Slovakia

Kampu{ Zlatko, Slovakia

Kander Jaroslav, Czech Republic

Kavi~ka Franti{ek, Czech Republic

Kelemem Michal, Slovakia

Kijac Josef, Slovakia

Kladari} Ivica, Croatia

Kladari} [tefanija, Croatia

Kliber Jiri, Czech Republic

Kniewald Du{an, Slovakia

Kolmasiak Cezary, Poland

Kolumbi} Zvonimir, Croatia

Kormanikova Eva, Slovakia

Kostur Karol, Slovakia

Kosec Ladislav, Slovenia

Kozak Dra`en, Croatia

Kreibick Vimotor, Czech Republic

Kva~kaj Tibor, Slovakia

Lamut Jakob, Slovenia

Lazi} Ladislav, Croatia

Le{{o Igor, Slovakia

Longauer Margita, Slovakia

Lovrin Neven, Croatia

Lui} Roberto, Croatia

Luka~ Ivan, Slovakia

Luka~ Pavel, Czech Republic

Magli~ Leon, Croatia

Mamuzi} Ilija, Croatia

Markoli Bo{tjan, Slovenia

Martin Vlado, Slovenia

Math Miljenko, Croatia

Michel Jan, Slovakia

Mihok Lubomir, Croatia

Mikac Ton~i, Croatia

Mironenko Aleksandar, Ukraine

Nikulin Sergay, Russia

Novak-Marcingin Jozef, Slovakia

Pandula Bla`ej, Slovakia

Pe{ek Ladislav, Slovakia

Pindor Jaroslav, Czech Republic

Pinjak Ivan, Ukraine

Plan~ak Miroslav, Serbia

Polajner Ivan, Ukraine

Projdak Jurij, Ukraine

Purmensky Jaroslav, Czech Republic

Raab Jaroslav, Czech Republic

Ra|enovi} Ankica, Croatia

Raos Pero, Croatia

Rastov~an Mio~ Alenka, Croatia

Roubi~ek Vaclav, Czech Republic

Rutkovski Anatolij, Ukraine

Rybar Pavol, Slovakia

Samard`i} Ivan, Croatia

Sanin Anatolij, Ukraine

Sedmak Aleksandar, Serbia

Siwka Jerzy, Poland

Sko~ovsky Petr, Slovakia

Skuza Zbigniew, Poland

Stoji} Antun, Croatia

Stolyarov Vladimir, Russia

[emberger Jaroslav, Czech Republic

[ercer Mladen, Croatia

[ev~ikova Jarmila, Slovakia

[im~ak Franti{ek, Slovakia

[imunovi} Katica, Croatia

[imunovi} Goran, Croatia

[trkalj Anita, Croatia

Terpak Jan, Slovakia

Tka~ Michalik, Slovakia

Trebuna Franti{ek, Slovakia

Tripalo Aleksandar, Croatia

Tuleja Stanislav, Slovakia

Turk Rado, Slovenia

Unneka Petr, Chech Republic

Va{ek Zdenek, Czech Republic

Ve`a Zdenek, Czech Republic

Vitez Ivan, Croatia

Vodarek Vladimir, Czech Republic

Vodopivec Franc, Slovenia

Weis Gabriel, Slovakia

Zabavnik Viktor, Slovakia

Zela Ladislav, Czech Republic

Zrnik Jozef, Czech Republic

@a~ek Oldrich, Czech Republic

@ivi} Marija, Croatia

244 METALURGIJA 50 (2011) 4, 244


S. LEGUTKO, P. KLUK, A. STOI]

RESEARCH OF THE SURFACE ROUGHNESS

CREATED DURING PULL BROACHING PROCESS

INTRODUCTION

At present, the industry and the market require products

to possess the best utilizable properties possible.

The setting up of higher and higher demands is caused

by the development of motor-car industry, air-industry,

space-industry, precision engineering and other advanced

technologies. At the same time a great emphasis

is put on the reduction of production times, increasing

the speed of processing, as well as seeking new technologies

and expanding the old ones. In precise technologies

the utilizable qualities of surface layers of

workpieces are very important, since they are a major

influence on the quality and working life of a device.

With the help of pull broaching it is possible to obtain all

shapes by use of linear motion of the tool. Pull

broaching advantageously influences the condition of

the surface layer of the machined workpieces.

Surface layer has direct influence on friction and

wear processes of rolling and sliding surfaces �1, 2�,

contact strength, corrosion resistance, tightness etc.,

therefore it is so important to assure of its appropriate

formation, what influences the prolongation of exploitation

time of a unit �3-6�.

Received – Prispjelo: 2010-07-30

Accepted – Prihva}eno: 2010-12-03

Original scientific paper – Izvorni znanstveni rad

The paper characterizes the surface layer roughness formed in the process of pull broaching. The factors influencing

the roughness of a workpiece subjected to pull broaching were analyzed. As a result of the measurements

the basic roughness parameters as well as isometric images of the surface layer for different samples

taken from production were obtained. 3D images were also obtained in the investigations of the surface layer

of pull broached driving plate.

Key words: broaching, surface layer, roughness

Istra`ivanje povr{ine hrapavosti povr{ine nastale postupkom provla~enja. Rad obrazla`e karakteristike

hrapavosti povr{inskog sloja nastalog procesom povla~enja. Analizirani su utjecajem faktori hrapavosti

obradka nakom postupka provla~enja. Osnovni parametri hrapavosti kao i izometrijske slike povr{inskog sloja

razli~itih uzoraka iz proizvodnje su dobiveni eksperimentalnim mjerenjem. U istra`ivanju povr{inskog sloja su

tako|er dobivene 3D slike povr{inskog sloja.

Klju~ne rije~i: povla~enje, povr{inski sloj, hrapavost

S. Legutko, P. Kluk, Poznan University of Technology, Institute of Mechanical

Technology, Poland, A. Stoi}, Mechanical Engineering Faculty

in Slavonski Brod, University of Osijek, Croatia

ISSN 0543-5846

METABK 50(4) 245-248 (2011)

UDC – UDK 621.795.2:532.696=111

SURFACE LAYER AFTER THE PROCESS OF

PULL BROACHING

Because the shape of the tool is transformed from an

object, all tool errors influence both dimensional and

shape quality as well as the condition of the surface.

With the help of pull broaching it is possible to obtain

surfaces of roughness ranging from Ra = 2,5 µm to Ra =

1,25 µm in exact processing as well as, depending on

needs, to Ra = 20 µm - in case of roughing �7�.

While analyzing the literature it is possible to state

that the following factors influence the roughness of surface

after pull broaching:

– the condition of cutting edges of the pull broach,

– the cutting fluid and type of cooling �4�,

– the value of tool rake and orthogonal clearance angle,

– the thickness of machined layer by one cutting

wedge �1, 2, 5�,

– the number of concurrently cutting wedges,

– construction and condition of the broaching machine

�7�,

– the characteristics of the machined material: mechanical,

physicochemical and structure �4, 5, 7�.

Among the mentioned factors the condition of cutting

wedge is of greatest influence. All the errors of the

condition of cutting wedge impair the condition of the

machined surface. Therefore, in practice, the tools are

subjected to control and regeneration at a specific period

of time.

METALURGIJA 50 (2011) 4, 245-248 245


S. LEGUTKO et al.: RESEARCH OF THE SURFACE ROUGHNESS CREATED DURING PULL BROACHING PROCESS

EXPERIMENTAL INVESTIGATIONS

Methodology

The subject of investigations of the surface layer was

the driving plate produced as a distributor unit of DPA

type injection pump made on Lucas company license

used in engines of: tractors, delivery vans, buses, working

machine engine generators. The mentioned plate is

produced by Wytwornia Sprzetu Komunikacyjnego

Poznan (Poland).

Regarding the assurance of appropriate accuracy the

semi-manufactured part in the form of plate (Figure 1)

was subjected to pull broaching.

Pull broaching was executed on perpendicular

broaching machine with hydraulic drive manufactured

by an English company MATRIX type BVR 15-48.

During the machining the cooling - lubricant oil

sulfofrezol 1 was applied.

Samples were marked in order of pull broaching (every

hundredth sample in unchanged machining conditions)

and subsequently subjected to measurements of

roughness in the Division of Metrology and Measuring

Systems at Poznan University of Technology.

a)

b)

Figure 1 The drawing of the machined semi-manufactured

part (a); example of the investigated test

piece of the driving plate (b)

The measurements of surface roughness were conducted

on a profilometer Perthometer 58P equipped

with FRW - 750 head and measuring probe 6851410.

The measuring perpendicular range of the device, in

which the probe can move in allowable limit of error,

was 125 µm. The side length of the sampling area was 4

mm. 33 sections of the surface were measured giving the

basic parameters of roughness such as: Rz, Ra, Rq, Rt, Rsm

and Rsk.

Due to dispersions in individual measurements the

following are marked for each parameter: mean value,

the value of standard deviation S, MAX - MIN value,

MAX value, MIN value.

In the studied samples the following isometric images

were calculated: positive and negative image of the

surface as well as the waviness of the surface and additionally

3D image.

Presentation and analysis of results

From the taken test samples the basic parameters of

roughness were obtained which were then represented

in form of tables (Figure 2) and graphs, thanks to which

a wider analysis of the individual roughness parameters

can be conducted.

On the basis of measurements’ results the graphical

charts of relationship between the roughness parameters

and the sample number were obtained.

The graphs show that in the initial pull broaching

phase (up to 600 pieces) the values of roughness parameters

Rz, Ra, Rq, Rt and Rsm grow, and then they begin to fall,

as exemplified by Ra parameter below (Figures 3, 4).

The Ra parameter for the arithmetical mean of ordinates

of roughness section acts similarly to Rz. This parameter

is often in use, but it does not provide the information

about the shape of the section. It is similarly insensitive

as Rz on all valleys and elevations.

The parameter of square average of roughness section

ordinates, Rq is the standard statistical deviation, and the

individual elevations and valleys of the section influence

PARAMETER

STATISTICS N=33

LC GS 0,800

mm

X S R MAX MIN

1 Rz �m 16,26 2,77 10,32 21,78 11,46

2 Ra �m 2,96 0,62 2,13 4,24 2,11

3 Rq �m 3,70 0,73 2,44 5,17 2,73

4 Rt �m 20,30 4,04 15,64 29,67 14,03

5 Rsm �m 210,7 66,37 250,0 400,0 150,0

6 Rsk �m -0,153 0,314 1,176 0,401 -0,776

7 Rdq µm 0,347 0,021 0,007 0,393 0,386

8 Rlq µm 67 13 44 92 49

Figure 2 Exemplary results of measurements for sample

number 401

246 METALURGIJA 50 (2011) 4, 245-248


S. LEGUTKO et al.: RESEARCH OF THE SURFACE ROUGHNESS CREATED DURING PULL BROACHING PROCESS

Figure 3 Diagram of Ra parameter for mean values X

Figure 4 Diagram of Ra parameter for standard deviation

values S

its value more significantly. However, this parameter

does not provide information about distribution of peaks.

It is also not possible to distinguish whether the specified

parameter value is caused by a peak or an elevation.

The total height of roughness section, Rt is sensitive

to individual elevations and valleys. Therefore, in comparison

to Rq and Ra the value of Rt parameter falls starting

with the 600 th sample more softly. Rt higher than 0,5

�m implies that the peaks are acute.

The average width of grooves of section roughness

elements, Rsm is useful in characterizing the functional

behavior of the workpiece. The average width of roughness

section units grooves, Rsm shows that up to the 500 th

sample the distance of grooves (the spacing) grows and

then it decreases. In this case the individual high elevations

do not have any significant influence on the Rsm parameter.

The Rsk parameter illustrates the symmetry of distribution

of the section ordinates in relation to the average

line. The negative value indicates concentrations of material

in the vicinity of peaks of the section, which marks

the surfaces of elevated plane shape. This parameter in

case of symmetrical section has zero value. The received

exemplary results are represented by the following

graphs (Figures 5, 6).

The coefficient of asymmetry, Rsk of the roughness

section has in this case positive value, which means that

the studied section has acute elevations and valleys.

From the diagram of standard deviation it is visible how

the parameter grows, which indicates the growth of elevations

and the deterioration of the surface quality. In

Figure 5 Diagram of Rsk parameter for the values of standard

deviation S

Figure 6 Diagram of Rsk parameter for the values Max

case of maximum values Rsk initially diminishes and

subsequently grows violently, being a further evidence

of the decrease in surface quality.

The exemplary isometric images of waviness are presented

in Figures 7 and 8. From two (samples 201 and

1101) selected images of waviness it is visible that the

surface properties deteriorate. By comparing them it is

possible to state that the surface of the first one is far more

flat, while in the second one large individual valleys are

visible, which diminish the quality of the surface.

Figure 7 The image of waviness for sample 201

Figure 8 The image of waviness for sample 1101

METALURGIJA 50 (2011) 4, 245-248 247


S. LEGUTKO et al.: RESEARCH OF THE SURFACE ROUGHNESS CREATED DURING PULL BROACHING PROCESS

Figure 9 Isometric negative image of sample 101

Figure 10 Isometric negative image of sample 1201

The exemplary isometric negative images are presented

in Figures 9 and 10. The inverse displays show

the appearance of surfaces of individual samples. It is

possible to state on their basis how the surface of the pull

broached workpiece has deteriorated. Samples from 101

(Figure 9) to 701 are characterized with surface of good

roughness properties.

However, samples from 801 to 1201 have surfaces of

worse properties. Sample 1201 in particular (Figure 10)

has elevated planes and deep valleys which practically

disqualify its surface.

Figures 11 and 12 show the three-dimensional images

of samples 201 and 1101, which unambiguously illustrate

the differences in geometrical structure of the

surface.

CONCLUSIONS

The conclusion relating measurements has to be the

following: basic roughness parameters do not reflect in

this case the real state. From the investigations of roughness

parameters it appears that in the initial phase (up to

sample 600) the parameters grow and then decrease,

which contradicts the actual state. Therefore, spatial 3D

images allow better understanding of surface. For some

surfaces, 2D parameters are sufficient and do not require

broadening to the third dimension. The contact surfaces

most often do not exceed several per cent. In such case

the measurement of a given section can understate the

height of irregularities. One passage of probe cannot

provide the complete image of real surface and sometimes,

as it took place here, it can be outright misguiding.

Such passage can contain information which is not

representative for the surface as a whole. Measurement

of the parameters of surface stereometry would be a

Figure 11 3D image of the surface of sample 201

Figure 12 3D image of the surface of sample 1101

good solution in this case, but at present these parameters

are not yet standardized.

REFERENCES

�1� Kawalec M., Rybicki M., Surface Formation during Face

Finish Milling of Hardened Steels, Archives of Mechanical

Technology and Automation, Poznan, 2002, 22(2002)

61-66.

�2� Kawalec M., Roughness and Structure of Surface of WNL

Steel after Laser Hardening and Turning, Archives of Mechanical

Technology and Automation, Poznan, 2002,

22(2002) 13-19.

�3� Starzynski G., Surface Layer and its Modeling, IPP PAN,

(in polish).

�4� Kiepuszewski B., Legutko S., Wieczorowski K., Cutting of

Metals, Publishing House of Poznan University of Technology,

Poznan 1980 (in polish).

�5� Legutko S., Nosal S., Forming of Technological Surface Layer

of Machine Parts, Center of Scientific Publications of

Polish Academy of Science, Poznan 2004 (in polish).

�6� Gorecka R., Polanski Z., Metrology of Surface Layer,

Scientific – Technical Publisher, Warsaw, 1983 (in polish).

�7� FORST HANDBOOK, Hints on broaching, Oswald Forst

GMBH, Solingen 1973.

NOTE: Responsible translator: Natalia Trawinska, Poznan College of

Modern Languages, Poznan, Poland

248 METALURGIJA 50 (2011) 4, 245-248


I. BERNÁTHOVÁ, M. BUR[ÁK

PROPERTIES OF PURE TITANIUM

AND ULTRA FINE GRAINED TITANIUM

INTRODUCTION

Medical applications are a new field for Titanium

known for its high biocompatibility in living bodies. In

some cases the medical replacements should be very

small in size, bearing high loads. That is why, new technologies

are sought to improve the load carrying capacity

of used materials. Pure Titanium 99,9 % is a preferred

material for medical application. The actual life

span of the applied materials depends first on the correct

loading, strain, environment, and adverse effects assessment

in the design.

Materials with high mechanical properties are preferred

with low Young’s modulus not exceeding 100

GPa. This time the solid nano structure Titanium (nTi)

with the ultra fine grained structure is tested for applications

in dental implants. The ultra fine grain means material

with grain size from 1 to 100 nm.

As testing showed, proteins can adhere to nTi more

than 30 % more than can to common Titanium of the

same �1�. In the field of implants there are very strict rules

prescribing the safe, nontoxic quality of the used material.

All other properties of the used material which can be

important during service life in the human body should be

inspected. Corrosion resistance is one of them.

Received – Prispjelo: 2010-08-11

Accepted – Prihva}eno: 2011-04-14

Preliminary Note – Prethodno priop}enje

The properties of ultra fine grained nano Titanium made by ECAP technology and pure cold drawn Titanium are

analyzed in this contribution. Mechanical properties, resistance to wear by a ZrO2 ball friction test, corrosion in

a Hank solution by the Tafel’s method at temperatures 21 °C and 37 °C, and fatigue properties in torsion were

evaluated and compared. The fatigue fracture started with crack formation parallel to the specimen axis and it

was finalized by cracking in the angle of maximum shear stress. Titanium powder has been observed on the

sample surfaces which indicated the crack initiation. Nano structure Titanium showed higher resistance to corrosion

less wear by friction, and to a limited number of cycles higher fatigue strength.

Key words: fatigue in torsion, biocompatibility, nano Titanium, resistance to corrosion, wear

Svojstva ~istog titana i ultra fino zrnatog titana. ^lanak analizira svojstva ultrafino zrnatog nanotitana

ECAP tehnologijom i ~istog, hladnim vu~enjem. Izu~avana su i uspore|ivana mehani~ka svojstva, otpor habanja

sa pokusom trenja kuglicama ZrO2, korozija u Hank otopini sa Tafel’ metodom na temperaturama 21 °C i 37

°C, te svojstva zamora torzijom. Zamorni prijelom je zapo~injao sa obrazovanjem pukotine, usporedno sa osi

uzorka i finalizirana je pucanjem pod kutom maksimalnih smicajnih naprezanja. Titanin pra{ak je zapa`en na

povr{ini uzorka koji ozna~ava inicijalnu pukotinu. Nanostrukturni titan pokazuje visoku korozijsku otpornost,

otpornost na habanje te pove}ani broj optere}enja na ~vrsto}u zamaranjem.

Klju~ne rije~i: zamor torzijom, bioprihvatljiv, nanotitan, otpornost koroziji, habanje

I. Bernáthová, M. Bur{ák, – Faculty of Metallurgy, Technical University

of Ko{ice, Ko{ice, Slovakia

ISSN 0543-5846

METABK 50(4) 249-252 (2011)

UDC – UDK 669.14-418:539.37:620.17=111

Fragments released by corrosion can be harmful or

toxic �2,3�. The human body is self-controlled to keep the

acidity around pH 7,4 and all the degradations are processed

at body temperature 37 °C. Good electric conductivity

is secured by the high content of dissolved salts in

the fluids of the human body, supporting the electro

chemical mechanism of corrosion and hydrolysis.

The tested material showed excellent resistance to

corrosion. It can last for supposed service life in the human

body, without harm. The biocompatibility and corrosion

resistance of Titanium is achieved by natural passive

TiO2 films 2 to 6 nm thick formed in the surface of

Titanium �1,2,4-6�.

There are a few works reported only dealing with the

micro structure and the properties of nano Titanium

made by severe plastic deformation during angular extrusion.

The technology is known as Equal Channel Angular

Pressing (ECAP). Common static mechanical

properties test results of pure commercial Titanium are

compared to the results of Titanium after severe plastic

deformation in works �1,7�. As mentioned the wide

range application of Titanium is calling for a better

knowledge of the fatigue properties, too. Fatigue test results

in tension are in works �8-10�.

The aim of this contribution is to update the information

about fatigue properties in torsion, compare the cor-

METALURGIJA 50 (2011) 4, 249-252 249


I. BERNÁTHOVÁ et al.: PROPERTIES OF PURE TITANIUM AND ULTRA FINE GRAINED TITANIUM

rosion properties of nano Titanium and commercial pure

Titanium (cp Ti) and test the tribology in their surfaces.

MATERIAL AND

EXPERIMENTAL METHODS

Nano structure Titanium nTi was used for the experiments

prepared by the ECAP technology. Rods were

produced Ø 7,56 mm in diameter. For comparison commercial

pure Titanium was used delivered as cold drawn

rods Ø 9,96 mm purified by zonal refinement.

Metallographic images of polished samples and foils

were studied by electron microscopy.

Sub micro structures were studied by the method of

thin foils in a transition electron microscope (TEM)

JEOL JEM 2000 FX with acceleration voltage 200 kV.

The thin foils were prepared by electrolyte thinning in a

stream of HClO4: methanol alcohol: butyl alcohol =

6:59:35 at 11 V.

Resistance to corrosion was tested by immersion in

the Hank solution (simulated body fluid SBF) using the

Tafel’s evaluation method �11� of polarization curves at

two temperatures 21 °C and 37 °C. The common 3 electrode

circuit was used with the main electrode (Ti sample),

with the saturated calomel electrode (SCE) and a

Platinum keep alive electrode, all connected to a Potentiostat

VOLTALAB 21 controlled by a PC. The electro

chemical characteristics were evaluated using VOLTA-

MASTER 4.0 software. The main electrode working surface

was 0,7 cm 2 exposed to the Hank solution.

Tribology by a ball tester was tested at the following

conditions:

– ZrO2 ball, diameter 6 mm, dry surfaces, speed 10

cm/s, runway radius 2 mm, distance 50 m, load 1

N and 2N.

Fatigue properties were tested by cyclic loading in

torsion using the PWOG tester from Carl Schenck. The

used asymmetry rate was R= -1 and the loading frequency

was 35 Hz. Test pieces for fatigue tests were machined

to shape shown in Figure 1.

RESULTS AND DISCUSSION

Micro structures in the longitudinal direction shown

�11� by scanning electron microscope (SEM) are in Fig-

Figure 1 Fatigue test sample with logitudinal surface

crack covered by Titanium powder

Figure 2 Micro structure of nTi and cpTi

Figure 3 Sub micro structure of nTi and cpTi

ure 2. The nano structure of nTi (a) is finer and more homogeneous

than the micro structure of cp Ti (b).

The sub micro structure for both tested materials is

documented in Figure 3a,b.

The cpTi material was before drawing purified by

zonal refining. During purification elongated needle like

grains were formed with typical signs of the

Widmanstätten morphology. The dislocation density in

the matrix was increased by cold work after the refinement,

but not to the extent of forming cellular sub micro

structure. There were in some grains areas with a different

diffraction contrast, characteristic for different angles

of the crystalline lattice a sign of a start to build cellular

sub micro structure.

Diffraction spectra made on cp Ti showed the alignment

of the sub micro structure, again a sign of some

start to build cellular sub micro structure. The cp Ti material

had a coarse Widmanstätten grain morphology, no

signs of cellular sub micro structure and this way higher

ductility and lower strength properties. On the other

hand sever plastic deformation and strengthening of the

nTi sub micro structure, along with the high dislocation

density in the ultra fine micro structure resulted decrease

of ductility and a significant increase of yield point and

ultimate tensile strength.

The resistance to corrosion was evaluated by differences

in the potentials for the tested materials or micro

structures in the SBF solution at two vital temperatures

and they are listed in Table 1. To improve the possibility

of comparison, to the corrosion resistance data in Table 1

data for Ti6Al4V were added. The last one is a material

most frequently used for implants in medicine nowadays.

Sever plastic deformation by ECAP formed high

density of grain boundaries in nTi. This led to the increase

of passive film adhesion by penetration of pro-

250 METALURGIJA 50 (2011) 4, 249-252


I. BERNÁTHOVÁ et al.: PROPERTIES OF PURE TITANIUM AND ULTRA FINE GRAINED TITANIUM

Table 1 Corrosion potentials in simulated body fluid

(SBF)

Material

21 °C

E /mV

37 °C

Ti6Al4V -403 -434

cpTi -283 -294

nTi -94 -213

Figure 4 Coefficient of friction for nTi and cpTi

Figure 5 Wear track and the track damage mechanism

in more detail

truding oxide parts into the grain boundaries �3,12�. At

the human body temperature 37 °C the behavior of the

Titanium materials changed. The order of nobility did

not change, but there was a more negative voltage for

nTi than it was at room temperature 21 °C. Also, the protective

character of the passive films is significantly

lower for cp Ti and nTi materials at the human body

temperature.

The resistance to wear is an important characteristic

for implants. Coefficients of friction were calculated

from the results of the ZrO2 ball rolling at two load levels.

Comparison of wear results at the load of 2N for the

tested materials on 50 m distance is in Figure 4. In Figure

5 is documented the track of wear. In more detail it is

described in �13�.

Track profiles were measured after wear tests. The

lost material volumes were calculated in dependence on

the unity distance and unity load and they can be found

in Table 2.

Static tensile testing was used to evaluate the mechanical

properties. The results are in Table 3 and show

the improvement of strength by the ECAP technology.

The fatigue test results in torsion are in dependence

of stress on the number of cycles to fracture in Figure 6.

Table 2 Wear rate

Load /N

Wear rate / mm 3 .m -1 .N -1

cpTi nTi

1 1,148 x 10 -3

0,892 x 10 -3

2 0,896 x 10 -3

0,584 x 10 -3

Table 3 Mechanical properties

Material Rp0,2 / MPa Rm /MPa A5 �% Z % HV

nTi 1290 1310 10 51 327

cpTi 645 665 17 66,5 210

Figure 6 Wöhler curves for cp Ti and nTi in torsion

Figure 7 Wöhler curve for nTi in torsion

The crack initiation was monitored at fatigue test of

Titanium with nano structure. It became evident by the

appearance of Ti powder on the surface of the tested

sample (as can be seen in Figure 1). The fatigue process

products on the test piece surface are the remnants of repeated

extrusions. With a small delay it is the time of

crack initiation and it is marked with green marks in Figure

7. On a few samples multiple initiation areas were

observed around the sample stem. The cracks grew with

the number of cycles in the longitudinal direction. The

cracked sample is in Figure 8.

After crack propagation in longitudinal direction the

failure ended with final cracks angled 45° to the axis of

the sample.

The semi logaritmic plots of points at different stess

levels � in torsion defined by the number of cycles to

fracture log N were plotted and a straight line across the

points was calculated by the method of mean squares.

The parametric equations of the lines for nTi and cpTi

are in Figure 6.

METALURGIJA 50 (2011) 4, 249-252 251


I. BERNÁTHOVÁ et al.: PROPERTIES OF PURE TITANIUM AND ULTRA FINE GRAINED TITANIUM

Figure 8 Longitudinal cracks, final fracture

in 45° in the sample of nTi

CONCLUSION

From the results obtained by testing samples of pure

Titanium with nano structure nTi and commercial pure

Titanium cpTi the following can be concluded:

– Pure nTi prepared by ECAP technology has an ultra

fine microstructure with high dislocation density

and a low occurrence of preferred sub structure

orientation.

– In pure cpTi micro structure the Widmanstätten

morphology of grains was found with signs of a

start to build cellular sub micro structure.

– Polarization curves both 21 °C and 37 °C showed

higher nobility of nTi when compared to cp Ti.

– The protective character of the passive films of

nTi was 5 times more efficient than that for cpTi

materials at room temperature.

– At 37 °C was the protective character of the passive

films about equal, though for both materials

decreased, compared to 21 °C

– Wear at friction was for nTi about 35 % lower

than that of cpTi.

– Nano Titanium made by ECAP had about 2 times

higher strength properties, at the decrease of ductility

from 18 % to 10 %.

– Nano structure Titanium showed to a limited number

of cycles 5,7·10 5 higher fatigue strength, over

this number of cycles it was lower

REFERENCES

1. Balakrishnan A., Lee B. C., Kim T. N., Panigrahi B. B.:

Corrosion Behaviour of Ultra Fine Grained Titanium in Simulated

Body Fluid for Implant Application, Trends Biomater.

Artif. Organs, 22(2008)1, 58-64.

2. Arenas M.A., Tate T.J., Conde A., Damborenea J.: Corrosion

behaviour of nitrogen implanted titanium in simulated

body fluid, In: British Corrosion Journal, 35(2000)3,

232-236.

3. Bernáthová, I., Milkovi~ O., Chemické listy

105(2011)645-646.

4. Marc Long H.J., Rack.: Titanium alloys in total joint replacement

- a materials science perspective, Biomaterials

(1998) 1621 - 1639, USA.

5. Li D.I.: Electron work function at grain boundary and the

corrosion behaviour of nanocrystalline metallic materials,

In: Mater Res Soc Symp Proc., 887(2006) 227-235.

6. Esposito M., Lausmaa J., Hirsch J.M.: Surface analysis of

failed oral titanium implants, In: J. of Biomed Mater Res,

48(1999) 559-568.

7. Greger M., Kocich R., ^erný M., Kander L., Properties of

comercial pure titanium after Equal Channel Angular Pressing,

Metal 2009, 19.- 21. 5 2009, Hradec nad Moravicí.

8. Semanova I.P., et al.: Enhanced fatigue strength of commercially

pure Ti processed severe plastic deformation, Material

Science and Ingineering A 503 (2009) 92-95.

9. Valiev R.Z., et al.: Nanostructured Titanium for Biomedical

Aplications, Advanced Engeneering Materials 10(2008)8,

1-3.

10. Cavaliere P., Fatigue properties and crack behavior of ultra-fine

and nanocrystalline pure metals, International Journal

of Fatigue 31 (2009) 1476-1489.

11. Bernáthová, I., Halama, M., Fujda, M., Sta{ko, I.: Chemické

listy 105(2011), 558-560.

12. Petru`elka J., et al.: Nanostrukturní titan – nový materiál

pro dentální implantáty, ^es. Stomat., ro~. 106(2006)4.3,

72-77.

13. Bernáthová, I., M.Sopko.: Chemické listy 105(2011),

593-595.

Note: The responsible translator for English language is Ladislav Kova~,

IMR SAS Ko{ice, Slovakia

252 METALURGIJA 50 (2011) 4, 249-252


Z. GULI[IJA, A. PATARI], M. MIHAILOVI]

THE POSSIBILITY OF INCREASING PRODUCTION EFFICIENCY

OF AL ALLOYS APPLYING ELECTROMAGNETIC FIELD

INTRODUCTION

Aluminum alloys of high strength have diverse and

wide application in almost all fields of industry. Due to

their specific properties, mainly the strength to mass ratio,

even though their production price is higher compared

to iron alloys, these alloys took up a significant

position at the world market. Alloys applied in this investigation

are EN AW 2007 (AlCu4PbMg) and EN

AW 2024 (AlCu4Mg1Mn). They are heat treatable alloys

and are intending for plastic processing.

They belong to high strength group of alloys with

wide application in almost all fields of industry. They

have long production and processing time, because they

involve a series of technological operations (modification,

casting, homo-genization, pressing forming and

thermal treatment). The homogenization is a long-lasting

and expensive process, because of high consumption

of electrical energy. The main idea is shortening

this process for increasing production process. It is well

know that conventional horizontal or vertical continuous

casting process due to unbalanced strengthening

conditions, leads to appearance of many defects �1-3�.

These are inhomogeneous microstructures, porosity, hot

cracks, non-uniform grain size and crystal segregation

Received – Prispjelo: 2009-08-11

Accepted – Prihva}eno: 2010-10-20

Preliminary note – Prethodno priop}enje

The relationships between electromagnetic frequency, microstructure and mechanical properties of continuous

casting aluminum alloys were studied in this paper. EN AW 2024 and EN AW 2007 aluminum alloys ingots

were produced by electromagnetic continuous casting process. The microstructure and mechanical properties

of as cast ingots were examined. The results showed that electromagnetic field, especially low frequency electromagnetic

field, greatly influenced the microstructure and mechanical properties of as cast ingots. The significant

energy savings and product quality can be achieved by the application of a proper frequency.

Key words: Al alloy, electromagnetic field, casting

Mogu}nost pove}anja efikasnosti proizvodnje Al legura primjenom elektromagnetnog polja. U

radu je prikazan utjecaj frekvencije na mikrostrukturu i mehani~ka svojstva Al legura dobijenih kontinuiranim

elektromagnetnim postupkom ljevanja. Ispitivanja su obavljena sa dvije legure EN AW 2024 i EN AW 2007.

Mikrostrukturna i mehani~ka karakterizacija ura|ena je na uzorcima u ljevanom stanju. Rezultati istra`ivanja

pokazuju da elektromagnetno polje, posebno polje ni`e frekvencije, utje~e na mikrostrukturu i mehani~ka svojstva

ljevanih ingota. Na osnovu dobijenih rezultata mo`e se zaklju~iti da se primjenom elektromagnetnog polja

odgovaraju}e frekvencije mo`e posti}i zna~ajna u{teda energije kao i pobolj{anje kvaliteta dobijenih ingota.

Klju~ne rije~i: Al legura, elektromagnetno polje, ljevanje

Z. Guli{ija, A. Patari}, M. Mihailovi}, Institute for Technology of Nuclear

and Other Raw Materials, Belgrade, Serbia

in the ingot. All this leads to deterioration of mechanical

properties of strength and toughness first of all. The

electromagnetic casting of aluminum alloys is of great

interest in metallurgical industry and intensive study has

been made in recent years, because it presents the ability

of improving product quality which could never been

achieved by conventional casting process. In this new

process, the induction coil surrounds the ingot mold, an

alternating current is applied, thus the coil generates a

time varying magnetic field and the melt can be inductively

stirred �4, 5�. In that way, the more balanced temperature

field is established. The experiment shows that

this process is an efficient dynamic method of grain refinement,

surface quality can be improved and the thickness

of the segregation layer can be also reduced because

of the contact line between the metal and the mold

can be adjusted. Moreover, this method can be put into

industrial practice relatively easily.

EXPERIMENTAL

ISSN 0543-5846

METABK 50(4) 253-256 (2011)

UDC – UDK 621.74.04:669.715:538.69=111

The chemical composition of used alloys EN AW

2007 (AlCu4PbMg) and EN AW 2024 (AlCu4Mg1Mn)

is shown in Table 1.

For melting alloys, induction furnace of medium frequency

with capacity of 100 kg was used. The both ingots,

of alloy 2007, with diameter � 50 mm and of alloy

METALURGIJA 50 (2011) 4, 253-256 253


Z. GULI[IJA et al: THE POSSIBILITY OF INCREASING PRODUCTION EFFICIENCY OF AL ALLOYS APPLYING...

Table 1 The chemical composition of used alloys / wt. %

Wt./%

Alloy

2024, with diameter � 60 mm were obtained by horizontal

continual casting with pulse draw-out. At the bottom

of the furnace there is a drainpipe with graphite

crystallizer that is intensively cooled with water. The

electromagnetic field is present around the crystallizer

itself, Figure 1.

The temperature of casting was 710 – 720 °C and average

casting speed was 1,5 mm/s. The operating parameters,

during the casting of ingots, were strictly controlled

and defined by various values of current (A), frequency

(Hz) and strength of electromagnetic field (At).

The number of turns in the coil was N=40. Table 2

shows some of operating parameters of casting.

Table 2 Operating parameters upon casting of samples

Sample

mark

Si Fe Cu Mn Mg Pb

2 007 0,3 0,3 3,9 0,8 0,9 1,1

2 024 0,1 0,2 4,1 0,6 1,2 -

Figure 1 Schematic illustration of the electromagnetic

process

Alloy

Frequency/

Hz

Number of

turns /N

1 2007 0 40

2 2024 50 40

3 2024 30 40

4 2007 1 100 40

5 2007 1 830 40

Frequencies were selected in broad diapason ranging

from 1 830 to 30 Hz. There are literature data only for

low frequencies (� 100 Hz). Since we had the opportunity

to test the influence of high frequencies as well,

such tests were also performed on the alloy 2007, similar

with the alloy which is the main subject of our interest,

i.e. 2024. The sample 1 was casted without the presence

of electromagnetic field to enable the observation

of field effect on mechanical properties and microstructure

with other samples.

Before the mechanical characterization was done the

complete microstructure assessment was carried out.

The microstructure parameters describe the structure

dispersivity and directly affect the mechanical properties

of the alloy. The microstructure was examined on a

cross section of a sample after the usual metallographic

preparation and etching in Keller’s reagent (revealing

morphology of Al segregation-solid solution and

inter-metallic phase) and anode oxidation with Barker’s

reagent (revealing size and shape of the grain in presence

of dendrite segregation). For the quantitative

microstructure analysis the image analysis device Leica

Q500MC was used. Dendrite arm spacing (DAS),

interdendritic space width (LIMF), where inter-metallic

phases and eutecticum were separated, as well as their

volume fraction, were acquired using linear method,

through the measuring of total length of the line segments

belonging to each phase and calculating the

amount of intersects with phase boundaries. These parameters

are the consequence of the solidification conditions.

RESULTS AND DISCUSSION

The microstructure obviously has shown that Al segregation

from the solid solution resulted in celluar/dendritic

morphology, �6,7�. Upon that, the structures of

sample 1, without the electromagnetic field effect, and

samples 4 and 5, with electromagnetic field of high frequency,

are more dendritic compared to the samples 2

and 3, which are casted with the presence of low-frequency

electromagnetic field. It is obvious that the application

of high frequency has no effect on the improvement

of microstructure. Quite oppositely, at 1 830

Hz the structure was rougher compared to one obtained

without the influence of electromagnetic field. On the

other hand, the regions of extracted inter-metallic phase,

in the form of eutecticum or individually, become finer

by the introduction of electromagnetic field and by decreasing

of frequency, (from 50 Hz in sample 2 to 30 Hz

in sample 3). The decrease of microstructural parameters

DAS and LIMF, observed in samples 2 to 3, was confirmed

by the analysis of cumulative distribution curves.

However, the effect of electromagnetical field on parameter

DAS is greater compared to LIMF. By detailed

analysis of samples, the presence of interdentritic type

was established, as can be seen in Figure 2.

It is determined that the porosity of interdendritic

type is reduced from sample 2 (50 Hz) towards the sample

3 (30 Hz), i.e. with the decrease of electromagnetic

field frequency. It is also found that the grain size is significantly

reduced from the sample 2 to the sample 3.

This is important because the less amount of porosity

254 METALURGIJA 50 (2011) 4, 253-256


and the smaller grain contributes the better quality of ingots

and thus to mechanical properties.

Since it was concluded that there are no positive effects

of high frequency to the obtained microstructure, the

further investigation included only the mechanical properties

of samples obtained by application the frequency of

50 Hz and 30 Hz, and also of the one obtained without the

influence of electromagnetic field from the same alloy

EN AW 2024. For mechanical testing, the Zwick/Roell Z

100 device was used. The samples for this tensile testing

were prepared according to JUS C.A4.002 and for the

hardness according to JUS C.A4.103.

The values of mechanical properties are given in Table

3.

Table 3 Mechanical properties of alloy 2024 ingots

Sample

mark

Z. GULI[IJA et al: THE POSSIBILITY OF INCREASING PRODUCTION EFFICIENCY OF AL ALLOYS APPLYING...

(a) sample-2 (b) sample-3

Figure 2 The porosity of interdentritic type

(a) sample-2 (b) sample-3

Figure 3 The grain size

Rp0.2

/Mpa

Rm

/Mpa

A

/%

HB5/25/30

2 198,1 243,2 1,2 93,5

3 246,6 274,2 0,7 107,0

The stress-strain curves can be seen in Figure 4.

On the basis of previous microstructural analysis,

such trend of change of alloy resistance properties, i.e.

their increase, could have been expected. However, the

decrease of plasticity for specimen 3 can be interpreted

by the appearance of rough continually extracted particles

of IMF, Figure 5, in relation to specimen 2. This

continually grid of IMF particles has detrimental effect

on mechanical properties, especially on plasticity. Furthermore,

one should bear in the mind the fact that the

values of mechanical properties for specimens of alloy

2024 casted without the influence of electromagnetic

field were: Rp0.2= 162,5 MPa, Rm=179,9 MPa and

A=0,49 %. i.e. they were the lowest.

This means that by the good combination of casting

operating parameters, a priori frequency, the increase of

(a) sample 2

(b) sample 3

Figure 4 Stress-strain curves

Figure 5 Interdendrite extracted inter-metallic phase

resistance properties can be achieved, and also the plasticity

increase by the use of microstructure control. This

is significant because the good mechanical properties, in

the initial stage of production process, mean a great savings

in all the following production stages.

CONCLUSION

The investigations results of alloy EN AW 2024 and

EN AW 2007 ingots obtained with different operating

conditions, with or without the presence of electromagnetic

field, clearly show its effect on the microstructure

and mechanical characteristics. It has been proved that

only the application of low frequency electromagnetic

METALURGIJA 50 (2011) 4, 253-256 255


Z. GULI[IJA et al: THE POSSIBILITY OF INCREASING PRODUCTION EFFICIENCY OF AL ALLOYS APPLYING...

field (� 50 Hz) has the positive effects, which obviously

change strengthening conditions. Namely, when the frequency

decreases (from 50 Hz in sample 2 to 30 Hz in

sample 3), the DAS and grain size decrease as well, that

is noticeable through the finer microstructure and its

uniformity throughout the cross-section. It is also determined

that the porosity of interdendritic type is reduced

from sample 2 (50 Hz) towards the sample 3 (30 Hz). All

of this contributes the better mechanical properties and

thus the quality of ingots. The better mechanical properties

in the initial stage of production process provide less

consumption of electrical energy. Obtained results indicate

that some steps in current technological process can

be avoided, namely better surface quality contributes the

surface machine processing elimination. Besides, the

finer microstructure contributes the shortening or eliminating

of homogenization process, one of the longest

and the most expensive processes during the aluminum

alloys production. The literature data show that the intensity

of electromagnetic field has also great effect on

microstructural and mechanical properties, �8,9�. So, the

further work in this area should be focused towards the

intensity of electromagnetic field and encompass the

other aluminum alloys which are aimed for forging.

Acknowledgement

The Authors wish to acknowledge the financial support

from the Ministry of Science and Technological Development

of the Republic Serbia through the Project 34002.

REFERENCES

�1� S. W. Kim and H. Hao, Mettal. Mater. Trans. A. 34A

(2003), 1537 – 1543.

�2� C. Zhiqiang, J. Fei, Z. Xingguo, H. Hai, J. Junze, Mater. Sci.

Eng. A 327 (2002), 133-137.

�3� Z. Zhao, J. Cui, J. Dong, Z. Eang, B. Zhang, J. Alloys and

Compounds (2005), 587-593.

�4� B. Zhang, J. Cui, Mater. Let. 57(2003) 1701-1711.

�5� B. Zhang, J. Cui, Mater. Sci. Eng. A355 (25) (2003)

325-330.

�6� A. Patari}, Z. Guli{ija, S. Markovi}, Practical Metallography,

44 (2007) 6, 290-298.

�7� A. Patari}, Z. Gulisija, B. Jordovi}, Metalurgija, 47 (2008)

4, 343-346.

�8� J. Dong, Z. Cui, T. Lui, the Chinese Journal of Nonferrous

Metals 13 (2003) 6, 1494.

�9� J. C. Li, Y. L. Ma, B. F. Wang, Special Casting & Nonferrous

Alloy 25 (2005) 3,133.

Note: The responsible for English language is the lecturer from Institute

(ITNORM), Belgrade, Serbia.

256 METALURGIJA 50 (2011) 4, 253-256


M. SATERNUS

MODELLING RESEARCH OF HYDROGEN

DESORPTION FROM LIQUID ALUMINIUM AND ITS ALLOYS

INTRODUCTION

Barbotage is one of the most universal methods used

for refining process of aluminium and its alloys. In this

process tiny gas bubbles are generated and during their

rising up to the surface the hydrogen is removed. In the

same time some inclusions such as sodium, calcium and

non-metallic particles, like oxides or borides can be also

eliminated from the liquid metal due to flotation �1�.

There are several technological solutions of the

barbotage process. The method of gas introduction to

the metal such as lance, ceramic porous plugs, nozzles

or rotary impellers plays an important role in these solutions.

Nowadays many batch reactors are replaced by

continuous reactors and the continuous refining process

becomes more and more popular �2�.

URO-200 AND URC-7000 RECTORS

Several reactors are used for the refining process of

aluminium and its alloys. In Poland typical representative

of reactors that can be used for the barbotage process are

URO-200 and URC-7000 reactors. These reactors were

designed in the Lights Metals Division OML Skawina,

Received – Prispjelo: 2010-06-21

Accepted – Prihva}eno: 2010-10-25

Preliminary Note – Prethodno priop}enje

The refining process is essential for the removing undesirable hydrogen and harmful impurities from liquid aluminium

and its alloys. Physical modelling allows to observe the level of refining gas dispersion in the liquid aluminium.

Test stand for physical modelling of the barbotage process of aluminum for the bath reactor

(URO-200) and continuous reactor (URC-7000) were built. Measurements of the oxygen removal from water

were carried out as analogy of the hydrogen desorption process from liquid aluminium. In the research the distilled

water saturated with the compressed oxygen was used. The level of water saturation with oxygen and

then oxygen desorption from water was reached by means of the dissolved oxygen meter Elmetron CO-401.

Key words: aluminium refining process, physical modelling, hidrogen desorption, Al and Alloys

Modelsko istra`ivanje desorpcije vodika iz rastaljenog aluminija i njegovih legura. Proces rafiniranja

je vrlo zna~ajan zbog odstranjivanja nepo`eljnog vodika i drugih {tetnih ne~isto}a iz rastaljenog aluminija. Fizikalno

modeliranje dopu{ta da se uo~i razina disperzije rafiniranog plina u teku}em aluminiju. Izra|en je

pristup za fizikalno modeliranje procesa rafiniranja aluminija. Mjerenja odstranjivanja kisika iz vode su provedena

po analogiji procesa desorpcije vodika iz teku}eg aluminija. U istra`ivanju je kori{tena destilirana voda

zasi}ena komprimiranim kisikom. Razina zasi}enosti kisikom i desorpcija kisika iz vode je postignuta pomo}u

okigenometra Elmetron CO-401.

Klju~ne rije~i: proces rafiniranja aluminija, fizikalno modeliranje, desorpcije vodika, Al i Al slitine

M. Saternus, Department of Metallurgy, Silesian University of Technology,

Katowice, Poland

ISSN 0543-5846

METABK 50(4) 257-260 (2011)

UDC – UDK 669.71:66:067:62.001.57=111

the branch of the Institute of Non-Ferrous Metals IMN -

Gliwice. URO-200 and URC-7000 reactors are presented

in Figure 1 and Figure 2 respectively.

URO-200 reactor is used for batch refining process.

It consists of a rotary impeller and a power feed. The rotary

impeller is put into liquid metal in furnace or crucible.

To obtain the uniform mixing of the refining gas in

the liquid metal, it is very important to choose properly

the processing parameters like flow rate of refining gas

and rotary impeller speed. The refining time is rather

short – about ten minutes.

Figure 1 View of URO-200 reactor

METALURGIJA 50 (2011) 4, 257-260 257


M. SATERNUS: MODELLING RESEARCH OF HYDROGEN DESORPTION FROM LIQUID ALUMINIUM AND ITS ALLOYS

Figure 2 View of URC-7000 reactor �3�

URC-7000 reactor consists of two chambers: refining

and filtration. The ceramic porous plugs are located

inside the refining chamber. Removal of hydrogen and

non-wettable nonmetallic particles from liquid metal is

the main task of this chamber. In filtration chamber the

filter is installed, and above it in the upper part of the

cover - a burner used to warm the filter and chambers.

PHYSICAL MODEL OF THE

URO-200 AND URC-7000 REACTORS

In the laboratory of Metallurgy Department at the Silesian

University of Technology there are two test stands

for modelling research. The first test stand is used for

simulating conditions that can be reached during the work

of URO-200 reactor. This test stand is at the 1:1 scale.

Figure 3 presents the scheme of this test stand. It consists

of the transparent tank with modelling agent, power feeding

for the change the rotary impeller speed and the

rotameter to control the flow rate of the refining gas.

For modelling research of the URC-7000 reactor the

second test stand at the 1:4 scale was built (see Figure 4).

This modelling unit consists of the transparent tank with

modelling agent for observation of gas dispersion, two

rotameters to control the flow rate of refining gas introduced

by the ceramic porous plugs and the flow meter of

a modelling agent. In both cases water is used as a modelling

agent, and argon as a refining gas.

The results obtained from physical models can be representative

only if could be transformed to real conditions,

the built test stands have to fulfill the rules from the

theory of similarity �4,5�. It is possible to solve these

problems using appropriate criterial numbers, which values

should be the same in case of model and real object.

For the refining process of aluminium and its alloys with

barbotage the most important numbers are: Reynolds,

Weber and Froud. The values of these numbers for water

and aluminium for both reactors: URO-200 and

URC-7000 were calculated and are shown in Table 1.

TEST OF OXYGEN

REMOVAL FROM MODELLING AGENT

The test of oxygen removal from water was carried

out as analogy of hydrogen desorption from liquid alu-

Figure 3 The view of test stand for the modelling research

in the URO-200 reactor

Figure 4 The view of test stand for the modelling research

in the URC-7000 reactor

minium. This method is commonly used by the company

producing reactors for refining process �7�. Laboratory

tests for the URO-200 reactor were carried out using

distilled water oxygenated to the level of full saturation

at the particular temperature. The level of oxygen

saturation in water was measured by means of the oxygen

meter Elmetron CO-401 (see Figure 5). The meter

was calibrated and operated in the mg O2/dm 3 . The meter

was equipped with automatic temperature compensation.

The oxygen sensor was placed vertically downward

near the shaft which aim is to reduce existing whirl

when the speed of rotary impeller is high.

After full saturation the refining gas was introduced

to water. The flow rate of refining gas was changed from

5 through 10 to 15 dm 3 /min. The influence of the rotary

impeller speed was also investigated. Laboratory tests

258 METALURGIJA 50 (2011) 4, 257-260


M. SATERNUS: MODELLING RESEARCH OF HYDROGEN DESORPTION FROM LIQUID ALUMINIUM AND ITS ALLOYS

Table 1 Comparison of the criterial numbers values

calculated for water and aluminium for the

URO-200 and URC-7000 reactor �6�

Criterial number Water Aluminium

Temperature

URO-200 reactor

293 K 973 K

Reynolds, Re 27 802 67 392

Weber, We 84,24 21,41

Froud, Fr 2,9 �10 -4

Figure 5 Oxygen meter Elmetron CO-401

were carried out for the rotary impellers speed in the

range from 200 to 500 rpm taking into account every

100 rpm. Dissolved oxygen readings were taken every

minute for ten minutes – the work time (every refining

process) in the URO-200 reactor. The obtained results

are presented in Figure 6. For each rotary impeller speed

the comparison of removed oxygen level for three different

flow rates of refining gas were determined.

For the URC-7000 reactor running water was used as

a modelling agent. After measuring its level of oxygen

(in the range 7,67-7,73 mg/dm 3 ) the test started.

The flow rate of water was constant of 11 dm 3 /min.

The influence of flow rate of refining gas on the level of

oxygen removal was investigated. The flow rate of

refining gas changed from 2 through 6 to 10 dm 3 /min.

Dissolved oxygen readings were taken every minute for

six minutes and after, the readings were at the constant

level. The results, for three different flow rate of refining

gas, are presented in Figure 7.

DISCUSSION OF

RESULTS AND CONCLUSIONS

2,9�10 -4

URC-7000 reactor

Reynolds, Re 1 905,9 4 620,0

Weber, We 0,467 0,118

Froud, Fr 2,8�10 -4

2,8 �10 -4

The built test stands give the possibility to observe

what happens during the refining process. Process of

creating the bubbles and then the mixing of gas bubbles

Figure 6 Results of oxygen removal from water in

URO-200 reactor

with liquid metal is rather complex and difficult to describe

it in analytical way. For this reason, the modelling

research is carried out. In this research oxygen was removed

from water as analogy of hydrogen desorption

from liquid metal. The test stand for modelling research

was build in accordance with the theory of similarity.

In case of URO-200 reactor the research was carried

out considering the different flow rate of refining gas

(5-15 dm 3 /min) and of the rotary impeller speed

(200-500 rpm). From the industrial point of view the

most satisfactory results are obtained applying the following

parameters:

– flow rate of refining gas – 15 dm 3 /min, rotary impeller

speed – 300 rpm,

METALURGIJA 50 (2011) 4, 257-260 259


M. SATERNUS: MODELLING RESEARCH OF HYDROGEN DESORPTION FROM LIQUID ALUMINIUM AND ITS ALLOYS

Figure 7 Results of oxygen removal from water in

URC-7000 reactor

– flow rate of refining gas – 10 dm 3 /min, rotary impeller

speed – 400 rpm.

In both cases the refining gas dispersion with liquids

is uniform – see Figure 8.

It seems that the rotary impeller speed of 200 rpm

and 500 rpm is not efficient. At the lower speed the level

of oxygen removal is not satisfactory because the refining

gas dispersion with liquids is minimal (there are

places without bubbles). The higher speed of rotary impeller

is not the best solution because requiring great argon

consumption. Almost the same results can be obtained

at the speed of 400 rpm. Thus, there is also the

possibility of swirls especially on top of liquids that can

make the removed hydrogen return to the liquids.

The results of oxygen removal from water in the

URC-7000 reactor confirm that the flow rate of refining

gas influences the refining process. When the flow rate

of refining gas equaled 2 dm 3 /min, the removal of oxygen

was slower than the flow rate was 10 dm 3 /min. The

higher the flow rate of refining gas, the higher the level

of gas dispersion in liquids. Also, the gas bubbles are

better mixed with liquids and the area of dispersion is

bigger. By bigger interfacial area between refining gas

bubbles and liquids, the oxygen is more efficiently removed.

However, when the flow rate of refining gas is

higher than 10 dm 3 /min the surface of liquids is more

turbulent – see Figure 9. As mentioned before, this is not

advisable, since removed hydrogen can return to the liquid

metal.

A further research concerning the type of head of rotary

impellers and the optimal refining parameters will

be scheduled.

Acknowledgements to the Ministry of Science and

Higher Education (MNiSW) for financial support (project

No 4432/B/T02/2009/36).

Figure 8 Uniform dispersion of refining gas in the liquid

metal (400 rpm, 10 dm 3 /min)

Figure 9 The view of turbulent surface of liquids

(15 dm 3 /min)

REFERENCES

�1� M.B. Taylor, Aluminium, 79 (2003), 44-50.

�2� M. Saternus, J. Botor, Aluminium, 81 (2005), 209-216.

�3� Urz¹dzenie do rafinacji ci¹g³ej URC-7000 - dokumentacja

techniczno – ruchowa, IMN-OML Skawina, 2003.

�4� L. Müller, Zastosowanie analizy wymiarowej w badaniach

modeli, PWN, Warszawa, 1983.

�5� K. Michalek, Vyuziti fyzikalniho a numerickeho modelovani

pro optimalizaci metalurgickych procesu, VSB-TUO,

Ostrawa, 2001.

�6� M. Saternus, J. Botor, Materials Science Forum, 654-656

(2010), 1553-1556.

�7� K.A. Carpenter, M.J. Hanagan, Light Metals, TMS, 2001,

1017-1020.

Note: The responsible translator English language is M. Kingsford,

Gliwice, Poland.

260 METALURGIJA 50 (2011) 4, 257-260


A. FORNALCZYK, M. SATERNUS

CATALYTIC CONVERTERS AS A SOURCE OF PLATINUM

INTRODUCTION

Catalytic converters are widely applied in industry.

They are so popular because they give possibility to accelerate

and increase the yield of processes, for example

the combustion process. The auto catalytic converters

consist of the stainless steel shell and metallic or ceramic

carrier with a honeycomb structure and the catalytic

system. The honeycomb structure means that there

is a dense net of squares holes through which the combustion

gas flows. Platinum group metals (Pt, Pd, Rh)

are responsible for the catalytic function. Combustion

gases due to the contact with the platinum group metals

undergo much faster oxidation in case of hydrocarbons

and carbon monoxides and reduction in case nitrogen

oxides. Products such as: carbon dioxides, water and nitrogen

obtained after catalyzed combustion process are

not harmful to the natural environment.

Today almost half of produced platinum, the majority

of palladium and 80 % of rhodium is used for the

production of auto catalytic converters. The used auto

catalytic converters give possibility to recover the considerable

amount of platinum. Taking into account the

price of platinum and the harmful influence of the metal-

Received – Prispjelo: 2010-06-21

Accepted – Prihva}eno: 2010-11-10

Preliminary Note – Prethodno priop}enje

The increase of Platinum Group Metals demand in automotive industry is connected with growing amount of

cars equipped with the catalytic converters. The paper presents the review of available technologies during

recycling process. The possibility of removing platinum from the used catalytic converters applying pyrometallurgical

and hyrdometallurgical methods were also investigated. Metals such as Cu, Pb, Ca, Mg, Cd were used

in the pyrometallurgical research (catalytic converter was melted with Cu, Pb and Ca or Mg and Cd vapours

were blown through the whole carrier). In hydrometallurgical research catalytic converters was dissolved in

aqua regia. Analysis of Pt contents in the carrier before and after the process was performed by means of atomic

absorption spectroscopy. Obtained result were discussed.

Key words: auto catalytic converter, recycling process, platinum removal

Kataliti~ki konverteri kao izvor platine. Porast zahtjeva za materijalima iz grupe platina u automobilskoj

industriji je povezan s pove}anim brojem automobila opremeljenim kataliti~kim konverterima. Rad prezentira

pregled dostupnih tehnologija tijekom procesa recikliranja. Tako|er je istra`ena mogu}nost izdvajanja platine

iz kori{tenih kataliti~kih konvertera primjenom pirometalur{kih i hidrometalur{kih metoda. Metali kao Cu, Pb,

Ca, Mg, Cd su kori{teni pri pirometalurgijskom istra`ivanju (kataliti~ki konverter je rastaljen s Cu, Pb i Ca ili s Mg

i Cd parama koje se ispuhavaju kroz cijeli nosa~). Kod hidrometalurgijskog istra`ivanja kataliti~ki konverter je

otopljen u carskoj vodici. Analiza sadr`aja Pt u nosa~u prije i nakon procesa je izvedena pomo}u spektroskopije

atomskom apsorpcijom. Dobiveni rezultati su obrazlo`eni.

Klju~ne rije~i: auto kataliti~ki konverter, postupak recikliranja, izdvajanje platine

A. Fornalczyk, M. Saternus, Metallurgy Department, Silesian University

of Technology, Katowice, Poland

ISSN 0543-5846

METABK 50(4) 261-264 (2011)

UDC – UDK 669.23:629.113:541.128=111

lurgical process of obtaining platinum on the natural environment

platinum recovery in the recycling way is

very advantageous. Recycling gives such benefits as

limiting the number of waste disposal, saving of natural

resource, limiting the electricity consumption and diminishing

pollutant emission. To get 1 kg of platinum

for example it is necessary to output 150 Mg of ores

from 1 000 meters depth. During this process 400 Mg of

waste is obtained. The same amount of platinum can be

obtained from the recycling process of 2 Mg of used

auto catalytic converters �1-3�.

RECYCLING OF THE USED AUTO

CATALYTIC CONVERTERS

The technology of the recycling process is rather complex

and consist of many technological stages such as:

– preparation and homogenisation of carrier, Figure

1 presents picture of the catalytic converter that is

installed in car, Figure 2 present picture of the catalytic

converter carrier with the honeycomb structure,

– upgrading of PGM content by the pyro- or hydrometallurgical

methods,

– PGM concentrate refining which consists of the

following operations: dissolving and removal of

METALURGIJA 50 (2011) 4, 261-264 261


A. FORNALCZYK et al.: CATALYTIC CONVERTERS AS A SOURCE OF PLATINUM

Figure 1 View of the used auto catalytic converter

Figure 2 View of the carrier with honeycomb structure covered

with the fibrous material

non PGM elements, separation of PGM from one

another, PGM purification giving the high grade

sponge or powder.

PGM purification let to obtain very high purity

metal, but the process is still very expensive.

In hydrometallurgical methods in the first stage the

chloro- complexes of PGM (for example PtCl6 2- ,

PdCl4 2- , RhCl6 3- ) are obtained. This is because the catalytic

converters are dissolved in the liquid solutions of

chlorides, chlorans, hydrogen peroxide and the aqua

regia. Such solutions have rather low level of Pt concentration,

so must be concentrated and then the extraction

of platinum is done. The advantage of this method is the

low need of energy. The average efficiency of platinum

recovery is about 90 %.

In pyrometallurgical method the most important

stage is melting the grinded catalytic carrier with some

metal, for example copper. Platinum goes to alloy, ceramic

carrier is removed and scraped. Obtained alloy

which is rich in platinum is later refined �4�. The average

efficiency of recovery equals 90-95 % �4,5�.

Table 1 and Table 2 show the available processes

used for platinum and other precious metals recovery

from the used auto catalytic converters taking into ac-

count the hydrometallurgical and pyrometallurgical

method respectively.

Table 1 Available hydrometallurgical processes used

in PGM recovery from the used auto catalytic

converters �1,4�

Hydrometallurgical processes used in PGM recovery from the

used auto catalytic converters

Process Specification

segregation

aqua regia

chlorination

During the grinding process the small addition

of KCl and NaCl is used, heating is applied to

concentrate the solution; as a consequence a

part of solution is evaporated; during the platinum

extraction the oxygen blow is used.

Catalytic converter is dissolved in aqua regia

(mixture of HNO3 and HCl in the ratio 3:1). As a

result H2PtCl6 is obtained, then this solution is

precipated, by the Al/Zn powder. The last stage

is platinum refining process.

Used auto catalytic converters are chlorinated in

the high temperature. The temperature must be

higer than 1 200 °C to evaporate the metallic

fraction.

Table 2 Available pyrometallurgical processes used in

PGM recovery from the used auto catalytic

converters �4,7�

Pyrometallurgical processes used in PGM recovery from the

used auto catalytic converters

Process Specification

Rose method

Melting method

RESULTS OF RESEARCH

Grinded (milled) catalytic converter is melted

in the electric furnace with the copper

oxide, coke, calcium, iron oxide and silica.

After melting copper with platinum and

slag are obtained. Slag consists of ceramic

carrier, calcium, silica and iron oxide. The

alloy is proceeded in oxidaizing furnace

where copper is oxidized and platinum

(does not react with oxygen) is separated.

Obtained product contains 75 % of metal

and go to refinning section.

The catalytic converters are melted with

iron in temperature higher than 2 000 °C.

Slag from the metallic phase is separated

due to the difference between its density.

Obtained metallic phase is leached in the

H2SO4. As a result iron is removed from the

platinum solution. In the lower temperature

other metal can be also used for collecting

platinum. The obtained slag is less aggressive

and the condition are less reactive.

Research of platinum recovery from used auto catalytic

converters by means of hydro- and pyrometallurgical

method were carried out. First, the catalytic converters

were grinded and milled.

In pyrometallurgical tests catalytic converter was

melted with chosen metals such as Pb, Cu, Ca - the reactor

used in this test is presented in Figure 3. There were

also tests in which metal vapours (Mg, Cd) were blown

262 METALURGIJA 50 (2011) 4, 261-264


Figure 3 Scheme of reactor used during melting the catalytic

converters with Cu, Pb or Ca

through the whole carrier. Figure 4 presents the reactor

used in this test.

Used metals were chosen taking into accounts the

system of platinum solubility in these metals or melting

temperature of these metals. Analysis of PGM contents

in the carrier before and after melting/blowing process

was performed by means of atomic absorption spectroscopy.

Table 3 presents parameters of pyrometallurgical

treatment of catalytic converter and the results obtained

from the these tests.

In hydrometallurgical tests, grinded catalytic converter

was dissolved in aqua regia or in mixture of aqua

regia with fluoric acid. Some of the test probes were

heated. Than these probes were filtrated to separate the

solution from the insoluble remains of the carrier. Anal-

Figure 4 Scheme of reactor used during Cd and Mg vapours

treatment of catalytic converters.

A. FORNALCZYK et al.: CATALYTIC CONVERTERS AS A SOURCE OF PLATINUM

Table 3 Pyrometallurgical treatment of catalytic converter

– processing parameters and results

T/°C Contents of Pt R/%

Metal

*

after % before % **

Test with metal as a collector

Platinum is collected in obtained Cu alloy after melting the

grinded catalytic converter with the molten pure Cu.

1 550 0,196 0,036 85.2

Cu

1 700

1 550

0,196

0,281

0,050

0,08

62,8

95,2

1 700 0,281 0,06 70,1

Platinum is collected in obtained Pb alloy after melting the

grinded catalytic converter with the molten pure Pb.

1 150 0,129 0,031 88

Pb

1 200 0,26 0,05 93

Platinum is collected in obtained Ca alloy after melting the

grinded catalytic converter with the molten pure Ca.

1 000 0,28 0,11 69

Ca

1 200 0,11 0,061 82

Test with metal vapour

The tests was carried out with Mg and Cd as a metal which

can dissolve Pt and decrease its melting temperature. The loss

of Pt content in the carrier after the Cd vapour treatment was

observed but there was no success in the concentration of

Mg/Cd vapours with Pt.

ysis of PGM contents in the carrier before and after dissolving

process was performed by means of atomic absorption

spectroscopy.

Table 4 shows parameters of this research and their

results.

METALURGIJA 50 (2011) 4, 261-264 263

Mg

Cd

1 150 0,160 0,074 11,1

1 200 0,220 0,121 12,5

1 150 0,220 0,097 17,0

1 200 0,192 0,084 16,8

* - temperature, ** - recovery of platinum

Table 4 Hydrometallurgical treatment of catalytic

converter – processing parameters and results

Solution

t/s

*

Contents of platinum

after % before %

R /%

**

Test with aqua regia.

Platinum is disolved in mixture of acid HCl and HNO3 in the ratio

3:1.

0 0,230 0,154 86,6

HCl:

1 200 0,230 0,163 90,1

HNO3 1 500 0,230 0,191 93,3

1 800 0,230 0,207 94,2

Test with solution of aqua regia and fluoric acid.

Platinum is solved in mixture of acid HCl and HNO3 in the ratio

3:1 and HF.

HCl:

HNO3:HF

0 0,015 0,010 48

* - time of heating, ** - recovery of platinum


A. FORNALCZYK et al.: CATALYTIC CONVERTERS AS A SOURCE OF PLATINUM

SUMMARY

1. In the research thee metals were used as a material

which can dissolve platinum and decrease its

melting temperature: lead, copper and cadmium.

Test with lead did not give satisfactory results because

almost all lead oxidized in the furnace atmosphere,

so the kinetic conditions were not

good enough to use lead in this kind of tests (Pb

very easily oxidized during the melting process

and we obtained alloy Pt+PbO instead of Pt+Pb).

The second metal, cooper gave better results. The

calculated yields were very promising. However, there

can be a problem with removing platinum from cooper,

so the other tests are planned.

Calcium as a collector metal is better than lead.

However, the best results are obtained in the temperature

of 1 200 °C. In this case the process have to be lead

very carefully, especially in argon atmosphere because

of high reactivity of calcium.

2. The tests with magnesium and cadmium as a

metal which can dissolve platinum and decrease

its melting temperature are being done. The initial

results are promising. The loss of platinum

content in the carrier after the cadmium vapour

treatment (Table 3) can be observed. However no

success has been reached in improving the concentration

of Mg/Cd vapours with platinum.

3. Hydrometallurgical method of platinum recovery

from the used auto catalytic converters gives 85

% of metal recovery. Heating test probe slightly

increases the concentration of platinum in the solution.

The addition of fluoric acid to aqua regia

does not influence the increase of platinum recovery.

Acknowledgements: Financial support from the Ministry

of Science and Higher Education is acknowledged

(N N508 3811 33).

REFERENCES

�1� A. Fornalczyk, M. Saternus, Rudy Metale, 52 (2007),

326-332.

�2� C. Hagelüken, Metall., 1-2, (2006), 31-42.

�3� A. Fornalczyk, M. Saternus Metalurgija, 48 (2009) 2,

133-137.

�4� J. S. Yoo: Catalysis Today 44, (1998), 27-46.

�5� C. Hagelüken, M. Buchert, H. Stahl, Enmetall, 9, (2003) 56,

529-540.

�6� S. R. Rao: Resource recovery and recycling from metallurgical

wastes, Oxford University, Elsevier 2006.

�7� Y. Kayanuma, T. Okabe, M. Maeda, Metall. Trans, 35B

(2004), 817-824.

Note: Responsible for English language is M. Kingsford, Katowice,

Poland.

264 METALURGIJA 50 (2011) 4, 261-264


J. £ABAJ, B. OLEKSIAK, G. SIWIEC

STUDY OF COPPER REMOVAL FROM LIQUID IRON

INTRODUCTION

The global metallurgical industry is currently dominated

by two technologies. One of them is based on the

concept of obtaining pig iron in a blast furnace and its

subsequent transformation into steel in oxygen-blown

converters, whereas the second one consists in steel

smelting based on secondary raw materials in electric

arc furnaces (EAF). Within the recent years, the latter’s

share in the global production of steel varied from ca. 28

to 33 %, The forecasts imply that the proportions between

the share of the EAF process and the conventional

one (oxygen-blown converter) in the steel production

will have been reversed by 2 050 a compared with the

current status �1�. Thus the share of scrap used in the

overall steel production is expected to increase from the

present level of 45 % to 60 % at the expense of iron ores.

The steel scrap utilised under the technologies discussed

is characterised by highly variable chemical

composition. This results mainly from the fact that there

are considerable changes taking place in the generic

structure of the scrap processed in metallurgical aggregates.

The share of the so-called home scrap in the

charge material decreases with a simultaneous increase

of the share of demolition (post-consumption) scrap.

The noticeable decrease in the input of home scrap has

Received – Prispjelo: 2010-09-09

Accepted – Prihva}eno: 2011-01-20

Preliminary Note – Prethodno priop}enje

The technology of steel is projected to increase in the share-based processes for processing recyclable materials.

On the one hand it creates the possibility of lowering the cost of producing steel, while the other is causing

the pollution, which because of its physicochemical properties are difficult to remove. The group of this

type of pollution is classified as copper. The lower reactivity to iron requiring the analysis of thermodynamic parameters

of Fe-Cu system to identify how best to allocate them. The study was conducted for the basic kinetic

analysis of Fe-Cu alloy containing 0,5 % wt. Cu and 1,5 % wt. Cu in the pressure range from 0,06 to 1 074 Pa

and a temperature of 1 923 K The study was conducted in a vacuum induction furnace VIM-20-50 Seco Warwic.

Key words: copper, iron alloys, vacuum refining, induction furnace

Studija odstranjivanja bakra iz teku}eg `eljeza. Tehnologija ~elika planira se tako da se pove}a udio temeljenih

na preradi recikliraju}ih materijala. S jedne strane to stvara mogu}nost smanjenja cijene proizvodnje

~elika, dok s druge strane uzrokuje one~i{}enje, uslijed fizikalnokemijskih svojstava, koje je te{ko ukloniti. U

skupinu takve vrste one~i{}enja ulazi i bakar. Ni`a reaktivnost sa `eljezom zahtijeva analizu termodinami~kih

parametara sustava Fe-Cu da se odredi kako ih je najbolje predvidjeti. Studija je provedena za bazi~nu kineti~ku

analizu slitine Fe-Cu koja sadr`i 0,5 % Cu i 1,5 % Cu u intervalu tlakova od 0,06 do 1 074 Pa i temperaturi od

1 923 K. Studija je provedena u vakuumskoj indukcionoj pe}i VIM-20-50 Seco Warwic.

Klju~ne rije~i: bakar, slitine `eljeza, vakuumska rafinacija, indukciona pe}

J. £abaj, B. Oleksiak, G. Siwiec - Silesian Technical University, Department

of Metallurgy, Katowice, Poland

ISSN 0543-5846

METABK 50(4) 265-268 (2011)

UDC – UDK 546.56:669:3:669.1:669.083.4=111

necessitated in using increased amounts of demolition

scrap, which may constitute one of the possible sources

of the steel impurities, in the metallurgical processes.

The foregoing mainly results from the fact that the said

scrap ma contain steel components combined with other

materials the occurrence of which in the metallic charge

is considered detrimental. Such a group of contaminants

includes non-ferrous metals (copper, tin, lead, zinc, bismuth,

etc.) originating from metallic coatings, varnish

or components of electrotechnical devices. When one

deals with contaminants easily removed in the metallurgical

process, the increase of their content in the charge

material does not pose a serious problem. It is otherwise

when the charge material contains increased contents of

non-ferrous metals the removal of which in the steel

smelting process is particularly difficult. An example of

such a contaminant may be copper.

The high content of copper in scrap is to a considerable

extent reflected by this metal’s content in, for instance,

steels manufactured by application of the EAF

technology. Due to the fact that copper, similarly to tin,

forms low-melting eutectic compounds with iron, that

are released during the solidification at the grain boundary,

it is possible that, on high content of the problematic

metal, the hot steel becomes brittle. Furthermore, copper

exerts a negative influence on impact resistance and

fatigue strength of steel. Indeed, it was the negative influence

of copper on the properties of steel that has led

METALURGIJA 50 (2011) 4, 265-268 265


J. £ABAJ et al.: STUDY OF COPPER REMOVAL FROM LIQUID IRON

to the necessity of undertaking studies concerning the

possible options of removing it from liquid steel alloys.

This paper constitutes a discussion on the analysis of

the options of copper removal from iron by evaporation

under the conditions of reduced pressure.

EXPERIMENTAL PART

The studies consisted in examining synthetic Fe-Cu

alloys based on the ARMCO iron and grade M00B oxygen-free

copper through melting in an induction furnace

in the inert gas atmosphere.

All the experiments were performed using the VIM

20-50 one-chamber vacuum induction furnace manufactured

by SECO-WARWICK. The equipment diagram

has been provided in Figure 1.

At the beginning of the experiment, a sample of alloy

of specific weight was placed in a magnesite or zirconium

melting pot mounted inside the furnace coil. After

the furnace was closed, a system of pumps was switched

on to attain the pressure assumed for the aggregate.

At the beginning of the experiment, a sample of alloy

of specific weight was placed in a magnesite or zirconium

melting pot mounted inside the furnace coil. After the furnace

was closed, a system of pumps was switched on to

attain the pressure assumed for the aggregate. The pressure

was obtained through a cooperation between a mechanical

pump, a Roots pump and, when necessary, a diffusion

pump. Another stage of the experiment was heating

of the charge material up to the specific temperature.

After the metal had reached the temperature assumed,

melting was conducted for 30 minutes. Samples

of the metal were collected at specific and precise time

intervals. The process temperature measurement was

performed using a pyrometer and type PtRh-Pt thermocouples

for the sake of the process control. After the test

was completed, the liquid metal was poured into a

graphite ingot mould. After the metal had solidified and

the furnace cooled down, the chamber was opened. The

copper content in the alloys tested was determined by

atomic absorption spectrometry using an apparatus

manufactured by Perkin Elmer.

The basic furnace parameters have been summarised

in Table 1.

Table 1 Basic experimental parameters

Temp.

/K

1 923

Cu content in alloy

/ % wt.

0,509;

1,518

TEST RESULTS

Working pressure

/Pa

from 0,06

to 1,074

Sample weight

/g

12 000

The change of the copper concentration in the liquid

iron during the melting process was correlated by the

following logarithmic function:

Figure 1 Diagram of the installation used in the Fe-Cu

alloys vacuum refining test.

1 – ingot mould with a preheating unit,

2 – induction coil with a ceramic melting pot,

3 – outlet to the system of vacuum pumps,

4 – mounting of the temperature measuring

system and the sampling mechanism.

�log � �

C

t

Cu

A t

(1)

0

C Cu

where:

t

C Cu – copper concentration in the alloy after time

t / % wt.,

0

C Cu–

initial copper concentration / % wt.,

t – time / s,

A–equation constant.

In order to determine the value of the total mass

transfer coefficient based on the experimental data obtained

and entailing the process velocity, the following

dependency was applied �2-7�:

C

2, 303log k ( )

0

C

F

t

Cu

�� � t� to

(2)

V Cu

where:

F–vaporisation areas (interfacial areas),

V–volume of liquid metal,

(t-to) – process duration time.

For the sake of the calculations, the value of coefficient

A from equation (1) was applied as describing the

change of the copper concentration in the function of

time.

The values calculated for the total experimental mass

transfer coefficient based on equation (2) for the copper

vaporisation from liquid metal have been summarised in

Table 2.

ANALYSIS OF THE RESULTS

The research consisted in a kinetic analysis of the

copper evaporation from iron entailing the impact of

pressure on the said process. Under all the experiments

conducted, the copper mass decrement was noticed on

266 METALURGIJA 50 (2011) 4, 265-268


Table 2 Experimental mass transfer coefficients for

the process of copper vacuum evaporation

from Fe-Cu alloys

Item

Cu content

in alloy

/ % wt.

Temp.

/K

Pressure

/Pa

kexp.·10 -5

/ m·s -1

1 1,518 1 923 1,074 0,42

2 1,518 1 923 1,074 0,41

3 1,518 1 923 212 0,69

4 1,518 1 923 212 0,65

5 1,518 1 923 101 1,00

6 1,518 1 923 101 0,97

7 1,518 1 923 56 1,46

8 1,518 1 923 56 1,53

9 1,518 1 923 49 1,79

10 1,518 1 923 49 1,68

11 1,518 1 923 40 2,19

12 1,518 1 923 40 2,31

13 1,518 1 923 5 4,12

14 1,518 1 923 5 4,19

15 1,518 1 923 0,5 4,90

16 1,518 1 923 0,5 4,70

17 1,518 1 923 0,06 4,43

18 1,518 1 923 0,06 4,81

19 0,509 1 923 1,013 0,17

20 0,509 1 923 1,013 0,36

21 0,509 1 923 526 0,61

22 0,509 1 923 526 0,59

23 0,509 1 923 425 0,58

24 0,509 1 923 425 0,57

25 0,509 1 923 202 0,79

26 0,509 1 923 202 0,74

27 0,509 1 923 101 0,89

28 0,509 1 923 101 0,86

29 0,509 1 923 101 0,83

30 0,509 1 923 101 0,84

31 0,509 1 923 5 2,85

32 0,509 1 923 5 3,08

33 0,509 1 923 1,2 3,77

34 0,509 1 923 1,2 3,75

35 0,509 1 923 0,13 4,51

36 0,509 1 923 0,13 4,38

37 0,509 1 923 0,06 4,78

38 0,509 1 923 0,06 4,95

39 0,509 1 923 0,06 4,58

40 0,509 1 923 0,06 4,74

41 0,509 1 923 0,06 4,58

42 0,509 1 923 0,06 4,65

J. £ABAJ et al.: STUDY OF COPPER REMOVAL FROM LIQUID IRON

Figure 2 Change of copper mass decrement for the experiments

conducted on various pressure levels

the level of 5 to 56 %. The foregoing data have been illustrated

in Figure 2.

Based on the examinations conducted, values of the

total experimental mass transfer coefficient (kCu) have

been determined. They amounted from 0,17 · 10 -5 to

4,8·10 -5 (Table 2). The results obtained conform well

with the values provided in various publications (Table

3) as reported by other authors.

The largest impact of pressure on the process being

examined was observed in the pressure range from 10 to

100 Pa. An identical impact was also noticed in other

processes including evaporation of manganese from liquid

iron �4�, lead from copper �5� and zinc from the

Zn-Ag-Pb alloy �8�. Therefore, one could assume that

for the said range of pressure values, the process in question

is determined by the mass transfer in the liquid and

gaseous phase.

The studies conducted have implied a considerable

impact of pressure on the process rate. For the pressure

below 10 Pa, there was practically no pressure impact on

the process rate observed (Figure 3). This means that for

such pressure values, the process analysed is not determined

by the mass transfer in the gaseous phase �9-11�.

CONCLUSIONS

The analysis of the results obtained in the experiments

of vacuum refining of Fe-Cu alloys in an induction

furnace conducted under the study discussed have

led to the following conclusions:

Table 3 Experimental mass transfer coefficients determined

for the process of copper evaporation

from iron alloys

METALURGIJA 50 (2011) 4, 265-268 267

Item

Temp.

range

/K

Pressure range

/Pa

Experimental

mass transfer

coefficient

/ms -1 ·10 -5

Refer. item

1 1 873 no data 2 – 2,3 �9�

2

3

4

1 683

- 1 873

1 923

- 1 973

1 898

-1 998

1-100 1,95-6,38 �10�

133-101,325 0,1-4 �11�

0,06

-1,074

0,17-4,8

author’s

studies


J. £ABAJ et al.: STUDY OF COPPER REMOVAL FROM LIQUID IRON

Figure 3 Pressure impact on the mass transfer coefficient

for the process of copper evaporation

from liquid iron

1. Within the whole range tested, in terms of pressure,

temperature and chemical composition, the

change in the copper concentration in iron during

melting in a vacuum induction furnace can be described

by means of an equation of the 1 st order

chemical reaction;

2. Within the range of pressure values from 10 to

100 Pa, a strong dependence between the mass

transfer coefficient and pressure is observed in

the system which may indicate that, within the

said range of pressures, a change in the process

control takes place and the mass transfer

resistances in the gaseous phase overlap with the

resistances occurring in the liquid phase; On the

pressure values below 10 Pa, the kinetic parameters

are stabilised, therefore one deals with a process

determined by the mass transfer in the liquid

phase as well as with the phenomena taking place

in the interfacial area. However, within the range

of pressure values above 100 Pa, one can assume

that the process takes place in the diffusion region

and it is controlled by the mass transfer

resistances in the gaseous phase;

3. The results obtained enable determination of an

optimum set of technological parameters of the

vacuum refining process for iron containing copper.

The process in question should be conducted

under the pressure of ca. 10 Pa, since further pressure

reduction in the system does not influence

the process rate and may cause a considerable increase

of its costs.

REFERENCES

�1� J. P. Birat: La Revue de Metallurgie, 99 (2002), 957-960.

�2� E. Ozberk, R. Guthrie: Inst. Min. Metall. Trans. C, 94

(1985), 146-157.

�3� E. Ozberk, R. Guthrie: Metall. Trans. B, 17 (1986), 87-103.

�4� R. Ward: Journal of the Iron and Steel Inst. 201 (1963),

920-923.

�5� L. Blacha: Archives of Metallurgy 48 (2003), 105-127

�6� B. Oleksiak, L. Blacha: 2 nd International Conference Simulation

and Modelling of Metallurgical Processes in Steelmaking

Steelsim, Graz (2007).

�7� J. £abaj: Kinetyka parowania miedzi z ciek³ego ¿elaza.

Wyd. Oldprint, Katowice (2010).

�8� J. £abaj, R. Sosnowski, J. Botor: Archive of Metallurgy, 47

(2002), 307-320.

�9� R. Ohno, T. Ishida: Japan Inst. Met., 31 (1967), 1164-1169 .

�10� L. Savov, D. Janke: ISIJ International, 40 (2000), 95-104.

�11� A. I. Zaitsev.: ISIJ International, 44 (2004), 639-646.

Note: Nowak P. is responsible for English language, Katowice, Poland.

268 METALURGIJA 50 (2011) 4, 265-268


I. SAMARD@I], M. DUN\ER, A. PINTARI]

POSSIBILITIES OF JOINING TECHNIQUES APPLICATION

AT RAILWAY LINES JOINING AND MAINTENANCE

INTRODUCTION

Thermit welding was appeared in application at the

end of XIX century. It is still in application with some

improvements in relation to beginning of application.

Beside that welding process, very important process in

joining of railway lines is flash welding. It is modern

high efficiency welding process suitable for workshop

and on site application. The equipment for flash welding

is not so simply as equipment for thermit or arc welding

but it is reasonable to expect more better quality at flash

welding due to more suitable performing of welding as

well as control of welding parameters during welding

process. All afore mentioned welding processes are still

in application and play significant role in installation

and maintenance of railway as well as streetcar lines.

Beside short overview of thermit and flash welding processes

authors give some results of quality investigation

on welded joints performed bz these welding processes.

The importance of joining and maintenance of railway

lines is of national interest of each country because of

fact that railway transport plays and will play very important

role in goods transport. Especially today in the

time of rational energy consumption and savings and environmental

protection.

Received – Prispjelo: 2010-08-31

Accepted – Prihva}eno: 2011-02-23

Preliminary Note – Prethodno priop}enje

This paper presents most important techniques which is possible to apply at joining of railway lines as well as

maintenance procedure. Beside thermit welding as a older joint process for that job (since 1895.) it is mentioned

flash welding as a modern joining technique interesting from the point of cost efficiency. In a case of maintance

tasks it is necessary to caunt arc welding processes and thermit welding, too. Authors gave some

experimental date collected during investigation on railway lines joining techniques application.

Key words: welding, railway lines, thermit welding, flash, arc welding, microstructure

Mogu}nosti primjene tehnika spajanja izgradnja i odr`avanje tra~ni~kih linija. U radu se opisuju

najzna~ajniji postupci zavarivanja pogodni za spajanje i odr`avanje `eljezni~kih tra~nica. Pored aluminotermijskog

postupka spajanja tra~nica (u primjeni od 1895. god.), spominje se i elektrootporno zavarivanje iskrenjem

kao suvremeni postupak spajanja sa stajali{ta tehnologi~nosti. Kod odr`avanja `eljezni~kih tra~nica va`no je

ra~unati i sa elektrolu~nim zavarivanjem i sa aluminotermijskim zavarivanjem. Autori daju eksperimentalno dobivene

podatke prikupljene tijekom ispitivanja mogu}nosti primjene tehnika spajanja `eljezni~kih tra~nica.

Klju~ne rije~i: zavarivanje, tra~ni~ke linije, aluminotermijsko zavarivanje, elektrolu~no zavarivanje, mikrostruktura

I.Samard`i}, Mechanical Engineering Faculty, J.J. Strossmayer University

of Osijek, Slavonski Brod, Croatia.

M. Dun|er, Politechnique department of Philosophy faculty, University

of Rijeka, Croatia

A. Pintari}, Univeristy of applied sciencies, Vukovar, Croatia

ISSN 0543-5846

METABK 50(4) 269-272 (2011)

UDC – UDK 621.791.052:625.143:620.18=111

THERMIT AND FLASH

WELDING FUNDAMENTALS

Thermit welding is a welding process which produces

coalescence of metals by heating them with superheated

liquid metal from a chemical reaction between a

metal oxide and aluminium with or without the application

of pressure. The heat for welding is obtained from

an exothermic reaction between iron oxide and aluminium

by the following formula: �1�

8Al+3Fe3O3 =9Fe+4Al2O3 + Heat (1)

Figure 1 shows steps of thermit welding. Maximal

temperature as a result of aforementioned reaction is approximately

2 500 o C. Before railway lines welding by

thermit welding process the preheating by gas flame is

applied. The effective time of chemical reaction and

welding is less than minute but whole procedure with

preparing time and post processing time is over 30 minutes

(depending on weather conditions, access to workpiece,

shape and dimensions of workpiece etc.).

Cleanness is generally very important at welding. At

thermit welding it is extremely important because of direct

influence on weld joint quality and weldment properties.

Flash upset welding (Figure 2) is resistance welding

process which produce coalescence simultaneously

over the entire area of abutting surfaces or progressively

along a joint, by the heating obtained from resistance to

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I. SAMARD@I] et al.: POSSIBILITIES OF JOINING TECHNIQUES APPLICATION AT RAILWAY LINES JOINING...

Figure 1 The steeps of thermit welding �1�

electric current through the area where those surfaces

are in contact. �1� For all resistance welding processes it

is important Joule’s low:

Q = I 2 ⋅ R ⋅ t, J (2)

From this equation it is possible to detect main welding

parameters: welding current (A), resistance (�) and

time (s). Another one important parameter is pressure

which is applied during whole welding cycle. The main

influence on obtained heat quantity has current which is

in function of time during the welding cycle (Figure 3).

EXPERIMENTAL INVESTIGATION OF

THERMIT WELD MICROSTRUCTURE

After application of thermit welding (Figure 4) on

steel for railway lines (type 900 A according to UIC 860

V standard) it was prepared specimen for macro and

microstructure analysis. Figure 5 shows macro section

of welded joint based on which are made microstructure

Figure 2 Sketch of flash welding process �1�

t1 = flashing time, s

t2 = upset current time, s

I1 = flashing current, A

I1 = upset current, A

Figure 3 An example of welding current (I) as a function

of time during flash upset welding �2�

photographies of individual parts of welded joint (Figures

6 to 9).

Figure 7 shows „border line“ or „fusion line“ between

weld metal and heat affected zone.

Figure 4 Location of specimen for metalographical and

hardness examinations

Figure 5 Macro section of thermit welded joint on railway

line

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Figure 6 Microstructure of weld metal (Figure 5, location

1)

Figure 7 Microstructure zone between weld metal and

heat affected zone (Figure 5, location 3)

Figure 8 Microstructure of heat affected zone (Figure 5,

location 4)

Hardness HV 1 distribution on weld joint specimen

is shown on Figure 10. It is evident not high hardness

value in weld metal (average value 150 HV 1), but it is

increased in heat affected zone on bit over 250 HV 1.

After flash upset welding it is prepared macro section

of welded joint (Figure 11 a and b). Weld joint is

performed on professional welding machine by the

Figure 9 Microstructure of heat affected zone (Figure 5,

location 5)

Figure 10 Hardness HV 1 in heat affected zone (darker,

left area on Figure) and weld metal

a) b)

Figure 11 Front view and lomgitudinal cross section of

flash resistance upset welded joint

same welding parameters as production welding. After

that it is prepared micro photographies of individual

zones of welded joint shown at Figure 11 a and b. Microstructures

of weld metal and heat affected zone are presented

on Figures 12 and 13. Figure 14 shows hardness

distribution in welded joint.

Welding technologies for railway lines setting are

still in progress �3�. There are wide range of welding

processes with strong stress on productivity and safety.

Inspection of rail welds �4� is important due to fact that

there are huge number of risks at railway lines transport.

New and modern technologies are very important in that

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Figure 12 Microstructure of middle of weld joint from

Figure 11.

Figure 13 Microstructure of heat affected zone of weld

joint from Figure 11.

sense for productivity and cost efficiency as well as

quality and safety.

CONCLUSION

Application of welding processes is still important

for building and maintenance of railway lines due to fact

that railway traffic will play very important role in

Figure 14 Hardness HV 1 distribution heat affected zone

(darker, left area) to middle of the welded

joint (right area)

global traffic of people and goods. Thermit welding and

flash welding are processes used in construction of railway

lines. They are cost effective and reliable if they are

performed under strict conditions and welding parameters

in workshop as well as on site. Beside short fundamentals

of those welding processes authors gave experimental

results of microstructure examinations of individual

zones in welded joint (weld metal and heat affected

zone) and hardness distribution in welded joints.

Presented results confirmated satisfactory quality of

welded joints performed by both aforementioned welding

processe. Presented results are base for the next investigations

relating to reliability and safety of welded

joint at railway lines as well as investigations of repair

procedure influence on quality of these weldments.

REFERENCES

�1� B.C. Howard Modern welding, Prentice-Hall, Inc., Englewood

Cliffs, N. J. 07632, 1979.

�2� B. Lundquist, Sandvik Welding handbook, Sandvik AB publication,

Göteborg, Sweden, 1977.

�3� http://onlinepubs.trb.org/onlinepubs/tcrp/tcrp_rpt_71c.pdf

�4� http://www.aws.org/itrends/2004/07/it0704-19.pdf

Note: Responsible translator: @eljka Rosandi}, Faculty of Mechanical

Engineering, University of Osijek, Slavonski Brod, Croatia

272 METALURGIJA 50 (2011) 4, 269-272


J. TEPI], V. TODI], D. LUKI], M. MILO[EVI], S. BOROJEVI]

DEVELOPMENT OF THE COMPUTER-AIDED

PROCESS PLANNING (CAPP) SYSTEM FOR

POLYMER INJECTION MOLDS MANUFACTURING

INTRODUCTION

Modern organization of manufacturing, featuring

novel design and manufacturing technologies, with emphasis

on flexible automation and extensive application

of computers. Automation of manufacturing systems is

primarily focused on product design, process planning,

production planning and control, as well as manufacturing.

Design automation is successfully solved using

CAD/CAE systems, manufacturing is automated using

CAM and NC (numerical control) systems, production

control is solved using MRP and ERP (enterprise resource

planning) systems, while the process planning is

solved by CAPP systems �1�. Due to a relatively low

level of CAPP systems, process planning activities represent

a significant problem in integration of manufacturing.

To corroborate this claim, Figure 1 shows application

of CIM elements in small and medium-sized

enterprizes (SMEs).

Certain terms in Figure 1 are: concurrent engineering

(CE), automated guided vehicle (AGV), flexible manufacturing

systems (FMS), group technology (GT), mul-

Received – Prispjelo: 2010-08-11

Accepted – Prihva}eno: 2011-02-25

Preliminary Note – Prethodno priop}enje

Beginning of production and selling of polymer products largely depends on mold manufacturing. The costs of

mold manufacturing have significant share in the final price of a product. The best way to improve and rationalize

polymer injection molds production process is by doing mold design automation and manufacturing process

planning automation. This paper reviews development of a dedicated process planning system for

manufacturing of the mold for injection molding, which integrates computer-aided design (CAD), computer-aided

process planning (CAPP) and computer-aided manufacturing (CAM) technologies.

Key words: process plans, CAPP, polymer injection molds, materials

Razvoj CAPP sustava za izradu kalupa za injekcijsko pre{anje polimera. Po~etak proizvodnje i plasmana

polimernih proizvoda u velikoj mjeri ovisi od vremena izrade odgovaraju}eg kalupa, ~iji tro{kovi ~ine veliki udio u

ukupnoj cjeni proizvoda. Osnovni pravac unapre|enja i racionalizacije procesa proizvodnje kalupa za injekcijsko

pre{anje polimera usmjeren je na automatizaciju projektiranja kalupa i tehnolo{kih procesa njihove izrade. U radu

je prikazan razvoj specijaliziranog programskog sustava za automatizirano projektiranje tehnolo{kih procesa izrade

kalupa za injekcijsko pre{anje polimera, zasnovanog na integraciji CAD, CAPP i CAM aktivnosti.

Klju~ne rije~i: tehnolo{ki procesi, CAPP/RPPP (Ra~unalno podr`an proces planiranja), kalupi za injekcijsko

pre{anje polimera, materijali

J. Tepi}, V. Todi}, D. Luki}, M. Milo{evi}, Faculty of Technical Sciences,

University of Novi Sad, Novi Sad, Serbia,

S. Borojevi}, Faculty of Mechanical Engineering, University of Banja

Luka, Banja Luka, Bosnia and Herzegovina.

ISSN 0543-5846

METABK 50(4) 273-277 (2011)

UDC – UDK 621.824:621.886.6:621.887=111

Figure 1 Application of CIM elements in SMEs �2�

timedia (MM), electronic data interchange (EDI), material

requirements planning (MRP).

Process planning is mostly based on the know-how and

experience of engineers. Intensive use of computers has allowed

significant advances, resulting in a number of CAPP

systems. The basic goal of developmental activities in

manufacturing technologies is the integration of all segments

of manufacturing and a set up of computer integrated

manufacturing (CIM). CAPP systems have key role

in the integration of design and manufacturing, i.e. they are

a bridge between CAD and CAM systems �3, 4�.

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This paper shall review the development and application

of a dedicated CAPP system for molds for injection

moldings of polymers (in further text molds), which is

custom-made for a specific manufacturing environment.

DEVELOPMENT OF

A INTEGRATED CAPP SYSTEM

Production process of polymer products depends

significantly on cost of quality, time to market and cost

to produce appropriate molds.

Previously, the design and manufacturing of molds

largely based on individual approach, with unfavourable

techno-economic effects. It has been noted that the majority

of parts, i.e. mold parts, can be standardized,

which allows the concept of group technology to be applied

on mold design and manufacturing. As a result,

mold standardization and batch manufacturing were introduced,

allowing shorter lead times and delivery, high

quality, low manufacturing costs, etc �5, 6�.

The ever-intensive application of polymer products

has, in the last decade, inspired CAx manufacturers to develop

systems which allow improvement of design and

manufacturing of polymer products and molds. A significant

advancement has been made considering the development

of CAD systems dedicated to mold design, as

well as the special CAE systems dedicated to simulation

and analysis of polymer injection moldings �7�. The manufacturing

process planning domain has become a bottleneck

in the overall system for manufacture of molds.

In order to rationalize and advance the manufacture

of mold, a model is proposed and the system for automated

process planning for mold manufacturing is developed.

The basic algorithmic structure of the proposed

system comprizes three distinctive modules according

to Figure 2 �8, 9�:

– Input data,

– Mold design (CAD module) and

– Process planning for mold parts manufacturing

(CAPP/CAM module).

The system relies on available commercial software

systems to complete particular stages: the systems for:

product design and NC programming, development and

management of relational data bases, development of

knowledge base and system integration.

The input into this system are polymer products and

the data on particular manufacturing conditions. Within

the first step, the CAD module can be used for mold design.

To support mold design, the system allows selection

of standard mold parts, as well as the selection of

the type of blank and material for particular mold parts.

The second CAPP/CAM module is dedicated to automation

of process planning for manufacture of mold

parts, including the generation of NC part programs.

Within the proposed system, process planning can be

performed for:

Figure 2 A diagram to determine reaction forces and moments

of the slide

– Typical, i.e. standard mold parts (the dotted line in

Figure 2 algorithm) for standard machining processes

and operations and/or

– Parts of a specific mold, which require particular

machining processes and operations such as engraving,

etc.

For the purpose of this review, prismatic parts of mold

be considered, together with the adequate process plans

for their manufacture under particular machining conditions.

In order to clearly define the processes which take

place within this dedicated CAPP system according to

algorithm goven in Figure 2, the diagrams of basic activities

shall be explained in detail by IDEFO methodology.

Figure 3 shows the diagram of basic activities

within the system: A1-Mold design, and A2-Process

planning for mold parts manufacturing.

Organization and management of data is based on a

relational data model, i.e. on a relational database. The

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J. TEPI] et al.: DEVELOPMENT OF THE COMPUTER-AIDED PROCESS PLANNING (CAPP) SYSTEM FOR POLYMER...

integrated knowledge base (KB) within this system was

developed by combining the data structure stored in the

database, and the VBA (Visual Basic for Applications)

procedures, using production rules technique. Within

the data base, there are distinguishable classes or parts

of database which allow decision-making �8, 10�:

– Knowledge base for mold part selection,

– Knowledge base for material selection,

– Knowledge base for blank selection,

– Knowledge base for manufacturing features determination,

– Knowledge base for standard process planning

(process sequences, standard processes, operation

group, standard operations),

– Knowledge base for machining resources selection

(machine tools, fixtures, modular cutting

tools, measuring devices), and

– Knowledge base for selection of machining parameters.

In the following paragraphs we will briefly present

the background for the development of a mold base

parts’ materials selection knowledge database.

DEVELOPMENT KNOWLEDGE BASE

FOR MOLD PARTS MATERIAL SELECTION

Molds are generally intended mass-production of

polymer products. That is why the molds quality and durability

greatly depend on particular mold parts’ material

selection. Mold base consists of a number of pieces

of rectangular or circular plate shape, or plate parts.

These parts form basic or support structure of molds.

Fixed and movable mold parts represents the most

important parts for molds, because they form mold cavities,

which are in direct contact with polymer melt. The

quality of mold manufacturing is directly reflected to the

Figure 3 Activity diagram for the dedicated CAPP system

quality of molding process and to the quality of produced

polymer parts.

In order to make an optimal selection of steel for

molds, it is necessary to consider the following requirements

�5�:

– The behavior during mold exploitation,

– Sufficient resilience,

– Consistency of dimensions during exploitation,

– Allowed tensile strength and yield strength,

– Resistance to the creation of surface cracks,

– Resistance to chemical influence, etc.

According to the type of steel that are most often

used for molds, they can be divided into: steel for hardening,

steel for improvement, steel for nitration, conventional

high strength tool steels, stainless steel.

With respect to the applied polymer material, mold

materials (steel) can be divided into the following

groups:

– Steel for chemical non aggresive polymers,

– Steel for chemical aggresive polymers,

– Steel for glassy polymers and polymers with other

admixtures.

Certain type of polymers have agreesive impact on

the mold’s parts, for example: aminoplastics, PVC, and

others. During the polymer injection process, chemical

byproducts such as amino acids are created. They affect

the surface of mold cavities by creating cracks and therefore

they have significant influence on the mold parts

wear. When glassy polymers are used, mold materials

must have high hardness and high wear resistance, due

to the effects of glassy particles on the surface of mold

cavity sprue and runner channels.

Table 1 presents a base for the development of a

knowledge database for suitable type of steel for the

mold base parts selection.

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J. TEPI] et al.: DEVELOPMENT OF THE COMPUTER-AIDED PROCESS PLANNING (CAPP) SYSTEM FOR POLYMER...

Table 1 The distribution of certain types of steel for making

mold plates

Polymermaterial

non aggresive

aggresive

Type of steel

and delivery

condition

Low alloy Cr-Mo

steel for improvement

(termally

unthreated)

Low alloy tool

steel (improved)

High alloy

Cr-Mo steel

(termally

unthreated)

High alloy Cr

stainless steel

(normalized)

Selected types of materials plays a significant role in

manufacturing process planing, as well as for the selection

of appropriate resources and parameters.

APPLICATION OF THE DEVELOPED

SOFTWARE SOLUTION -A CASE STUDY

The developed CAPP system shall be verified on a

study case dealing with the manufacture of an fixed

mold plate which is a constituent part of the mold of a

multi socket body (Figure 4).

Based on the input data, the selection of standard

mold parts (Figure 5) was performed within the CAD

module at the previous stage, and used as a prerequisite

for the design of the mold assembly, the selection of the

blank material for the fixed mold plate (Figure 6).

Based on the developed production rules shown in

table 1, the contents of the standard process plan, coded

TTP11A, for the manufacturing of the fixed mold plate

for the selected mold (Figure 7).

For each machining process by given program system

is able to obtain the content of proces, i.e. specified operation

and appropirate machining tools, cutting tools, fixtures,

measuring devices and machining parameters. For

typical machining proces that performed on NC machining

systems enables generation a control program, using

parametric programming by Pro/E �8, 9�.

CONCLUSIONS

Material (steel) code

1.7218 ^.4730 25CrMo4

1.7220 ^.4731 34CrMo4

1.7225 ^.4732 42CrMo4

1.2311 40CrMnMo7

1.2312 ^.4742 40CrMnMoS86

1.2738 40CrMnNiMo7

1.4110 ^.4770 X55CrMo4

1.2083 ^.4175 X43Cr13

Application of general-purpose CAD/CAM/CAE

software systems, the systems for database developments,

and systems for development of software applications,

allows development of software solutions for

automation of design and manufacture.

Figure 4 A 3D model of the multi socket body and the appropriate

fixed mold plate

Figure 5 Selection standard mold plates

Figure 6 Selection of fixed mold plate material

Figure 7 Generated process plan for the manufacturing

of the fixed mold plate

The dedicated software solution developed in this

work, i.e. the integrated CAPP system, allows automation

of a significant number of activities in the process of

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J. TEPI] et al.: DEVELOPMENT OF THE COMPUTER-AIDED PROCESS PLANNING (CAPP) SYSTEM FOR POLYMER...

mold design and manufacturing process planning,

which contributes to rationalization of activities proceeding

the manufacturing process.

In the future period, one should expect a significant advancement

in the development of a universal platform for

CAPP systems and their further integration with various

CIM-related activities, as well as other activities related to

product lifecycle. This integration means easier sharing of

product model data, which is already supported by a number

of specifications for product data exchange, among

which ISO 10303 (STEP) and ISO 14649 (STEP NC) is

most prominent. Internet technologies are also increasingly

used as support for integration processes. Globally

available data bases are used to support concurrent and collaborative

engineering, as well as in the development of

digital factories and E-manufacturing.

REFERENCES

�1� A. H. ElMaraghy, Evolution and Feature Perspectives of

CAPP, CIRP Annals-Manufacturing Technology, 42

(1993) 2, 739-751.

�2� H. B. Marri, A. Gunasekaran, K. Bulent. Implementation of

computer-integrated manufacturing in small and medium

enterprises, Industrial and Commercial Training, 35 (2003)

4, 151-157.

�3� C. A. Luttervelt, Research Challenges in CAPP, International

Journal of Production Engineering and Computers, 4

(2002) 5, 5-18.

�4� W. D. Li, S. K. Ong, A. Y. Nee, Integrated and Collaborative

Product Development Environment, World Scientific,

2006.

�5� M. Na|, Termoplasti~ne mase, prerada postupkom injekcionog

pre{anja, Publicitas, Zagreb, 1974.

�6� B. Bujani}, I. ^ati}, Grupna tehnologija kod injekcijskog

pre{anja, Polimeri, 28 (2007) 1, 40-45.

�7� J. Hodoli~, I. Matin, M. Stevi}, \. Vukeli}, Development of

Integrated CAD/CAE System of Mold Design for Plastics

Injection Molding, Materiale Plastice, 46 (2009) 3, 236-242.

�8� D. Luki}, Razvoj sistema za automatizovano projektovanje

tehnolo{kih procesa izrade alata za brizganje plastike, Magistarska

teza, Fakultet tehni~kih nauka, Novi Sad, 2007.

�9� V. Todi}, D. Luki}, M. Stevi}, M. Milo{evi}, Integrated

CAPP System for Plastic Injection Mold Manufacturing,

Materiale Plastice, 45 (2008) 4, 381-389.

�10� M. Kostelac, J. Tepi}, N. ]ular, Justification of the application

of tightening elements in the shaft-hub joint, Metallurgy,

50 (2011) 1, 57-61.

Note: The responsible translator for English language is J. Bajkin, Faculty

of Technical Science, Novi Sad, Serbia

METALURGIJA 50 (2011) 4, 273-277 277


A. W. BYDA£EK

THE ANALYSIS OF THE

CARBON ATTENDANCE IN COPPER ALLOYS

INTRODUCTION

It proves that there is a big discrepancy in the opinions

on the structure and the basic features of slag (S) as

well as the essence of their interaction with refined

metal (M) and the atmosphere (A) of melting (Figure 1).

There are three methods of slag refining in the copper alloys

melting conditions: the oxidising �1�, the neutral

and the alternative method of melting copper and its alloys

in conditions of reduction with an activator (R) introduced

into the slag �2-5�.The active components of

melting atmosphere influence the processes taking place

while slag refining. An alternative for that methods is

gas-slag refining �6-8� in where the concentration of impurities

extracted by the slag is obtained. Most of the experiments

have shown that in this way is possible to

achieve optimum economic and technological results.

The problem of interfacial reaction between liquid

slag and metal has been presented. On the basis of the

analysis of the problem and the results of the author research

�9,10� it is stated that the most promising are the

reducing conditions of refining. In the previously works

author �9� has been presented scheme of interaction of

chemical reagents in the melting copper conduction as:

Received – Prispjelo: 2010-06-27

Accepted – Prihva}eno: 2011-01-20

Preliminary Note – Prethodno priop}enje

In the work show, that opinions the leaning on it dissolubilities of carbon can be recognized (and only in approximation)

only for copper about large purity. They do not concern it her mostly multiple alloys, at which the

majority of alloy additions marks with possibility of creating carbides. Equally important the possibility of creating

of carbides of accidental dirts is. The analyses DTA of slags be remain showed with part of carbon and carbides.

Introduced and investigation own arguments authorize to conclusion that the technological process of

fusion of copper alloys does not it be to characterize in relation with separate guilds to different alloys and should

to be to hold on valid in steel - makes principles.

Key words: copper alloys, carbon refining, extraction slag, DTA, porosity

Analiza prisutnosti ugljika u bakrenim slitinama. U radu se prikazuje mi{ljenje koje se odnosi na topljivost

ugljika te se mogu potvrditi (i to jedino aproksimativno) samo za bakar velike ~isto}e. Ne razmatraju se

njegove ve}inom vi{estruke slitine kod kojih ve}inu legiranih dodataka ozna~avaju kao mogu}e tvorce karbida.

Jednako je va`na mogu}nost stvaranja karbida sa slu~ajnom ne~isto}om. DTA analiza preostale troske pokazuje

da je jedan dio s ugljikom a drugi s karbidima. Uvedeni i istra`eni vlastiti argumenti vode k zaklju~ku da tehnolo{ki

proces taljenja bakrenih slitina ne karakterizira vezu s pojedinim cehovima prema razli~itim slitinama

ve} ga treba zadr`ati kao valjan za osnove proizvodnje ~elika.

Klju~ne rije~i: bakrena slitina, rafinacija ugljika, ekstrakcijaska troska, DTA, poroznost

A. W. Bydalek, West Pomeranian University of Technology, Szczecin,

Poland

ISSN 0543-5846

METABK 50(4) 278-280 (2011)

UDC – UDK 669.3:66.067.669.784:666.88:620.1=111

Figure 1 A proposed scheme of refining process (real

conditions under the cover) of a liquid metal

with a carbon-carbide-cyjanamide slag solution,

where: ( ) – gas, X - reagent ,St – reaction stymulator,

��– ions in the slag, ��elements in the

melting metal

carbide compound, metal, cyjanamide or carbon. The

paper presents the analysis of the ion reaction in to the

slag during refining process with calcium carbide, oxygen,

nitrogen and carbon. It proves that there is a big discrepancy

in the opinions on the calcium and carbon role

in the slag and their interaction with refined metal and

the atmosphere of melting. Author shows on the most

278 METALURGIJA 50 (2011) 4, 278-280


important role of the carbon �C 2+ � and �C 4+ � ions on the

effectiveness of carbide slag metal extraction process.

EXPERIMENTAL, RESULTS AND DISCUSSION

Basic reaction describing the carbide dissociation

mechanism is:

� Xm Cn���X m+ � + � C n- � (1)

To stand of carbon as of ion �C - � is impossible acceptable,

because element this having construction 1s 2

s 2 p 2 can create following ions:

�C - ���C 2+ � + 3e (2)

or ��C 4+ � + 5e (3)

or ��C + � + 2e + 1e (4)

or ��C 4- � - 3e (5)

Described with equalizations 2-5 ionic reactions explain

specificity of influence of carbon in carbide slags.

Show, that his melting and strong influence reducing results

from occurrences in slag mostly of ions � C 2+ � or

� C 4+ �. Released in this manner in slag electrons are

main link in mechanism exchanges of ions on border of

distribution of phases slag-metal. In consequence after

carbon dissolution in including oxygen alloy is possible

setting reaction :

�C� +�O� = (CO) (6)

It taking into account reactions 2 and 3, the figure of

oxygen ions was put in to the liquid metals how �O 4+ �

as well as �O - �. It the possibility of setting reaction was

put additionally (6). Because carbon (how in reaction 6)

in solution of copper alloys come from carbides of alloy

additions (mainly M’C), it can the total figure of ion reactions

of carbon monoxides formation have figure:

�M’C� + �O� = �M’� + (CO) + 2e (7)

With introduced reactions (6) and (7) it is possible to

bring in, that possible is forming gas blisters - (CO).

They can be one of main causes of casts porosity. According

as with theory of segregation during solidification

in layer diffusive comes to crossing of value of

dissolubilities. It has similarly how in steel - makes in

ingot moulds, this to lead to dissolved reaction carbon

and oxygen (how at 7).

The oxygen can also react with the carbon in solid

state, coming from for example from facings of stove. It

melting near absence of oxygen in atmosphere such reaction

were it been possible to record:

�O� + < C >=(CO) (8)

Over presented analyses’ found affirmance in

founders’ opinions many times. It was affirmed the difficulties

of procurance from alloys with the silicon,

nickel, alluminium whether the iron the casts without

gas blisters. Exchanged alloy additions create carbides.

The increased content of carbon be moved also the porosity

in melting of alloys with different additions

(Table 1).

A. W. BYDA£EK: THE ANALYSIS OF THE CARBON ATTENDANCE IN COPPER ALLOYS

Table 1 The Results of the chemical analysis and the

mechanical properties of the B555, B101 alloys

If more rathe desoxygenation such alloys did not accomplished

deep, then reaction had to set (8). Numerous

blisters were in cast effect. In the melting atmosphere

the wide part of CO/CO2 and the vapors of the component

alloy (M’) or their oxides (M’O) was observed.

The author’s test and industrial investigations shown the

significant contents of carbon in some metallic phaze.

The microanalyses’ of silicon bronze confirmed clear

contents of carbon, mainly near smelting in graphite

crucibles (Figure 2).

On the basis of the thermo gravimetrical measurements

an original methods, which modulates real conditions

of reacting, was elaborated �1,9�. On the basis of

this measurements system a method of interpretation the

slag property was proposed. The method enables estimation

of refining features of slag (S). In the experiments

with derywatograph refined alloy is replaced with

non-metallic inclusions (WN) in the melting pot. The inclusions

are introduced into the slag in proportions

which respond with the melting losses of the alloy.

Al2O3 standard is proposed to be replaced with S+R

(where R-reducer) refining sample. This made it possible

to achieve thermal and mass effects concomitant

with reduction reactions of WN which are is in the slag.

The analysis of slag containing WN �4� allowed to establish

the possible combinations of EW and r values to-

METALURGIJA 50 (2011) 4, 278-280 279

Alloy

B555

CuSn5Zn5Pb5

B101

CuSn10P

Kind of

crucible

�O� /

ppm

Porosity

%

�C� /

ppm

ceramic 12 1,1 0-10

graphite 49 1,8 —

ceramic 10 0,7 0-10

graphite 86 3,2 10-20

a) b)

c) d)

Figure 2 Microanalysis of chosen components of bronze

(a) the be drowned in graphite crucible BK331:

b) - carbon, c) - silicon, d) - iron


A. W. BYDA£EK: THE ANALYSIS OF THE CARBON ATTENDANCE IN COPPER ALLOYS

a) b)

Figure 3 Probe - the macro (0,5x) of the industrial BK331

ingot before (a) and after (b) carbon-carbide

slag (with the carbon powder)

gether with a proposed explanation. On the basis of calculations

it was also found that due to the differences in

vaporisation or reaction with the atmosphere of compositions

the simultaneous consideration of two values (r

and EW) is necessary.

Proposed numerical indexes of EW and r are regarded

as a measure of refining abilities of the whole system

A-S-WN-R. It enabled optimisation of alternatives of

WN interactions with carbides and carbide-originating

metals in slag of various different chemical compounds.

It has been described the influences of same alloys

compounds on the structure, properties and segregation

effect of the ingot. The experiments on bronze melting

with the slag refining proved that optimum is achieved.

For example for silicon bronzes are selected refiner with

calcium carbide, carbon and aluminium as the complex

reagent (Figure 3). The reducers of this kind not only

make it possible to keep a constant deficit of impurities

in the slag layer but also let carbon in the melting

atmosphere. The efficiency of eliminating oxygen out of

the melting atmosphere is much bigger – 10 -6 –10 -9 hPa

oxygen partial pressure. The author slag constitution

with the carbon reagents has been applied in metallurgical

and foundry conduction.

SUMMARY

The active components of melting atmosphere influence

the processes taking place while slag refining An

alternative for that methods is gas-slag refining in where

the concentration of impurities extracted by the slag is

obtained. Most of the experiments have shown that in

this way is possible to achieve optimum economic and

technological results.

On the basis of the analysis of the problem and the

results of the author’s research it is stated that the most

promising are the reducing conditions of refining. In the

previously works author has been presented scheme of

interaction of chemical reagents in the melting copper

conduction as: carbide compound, metal, cyjanamide or

carbon. The paper presents the analysis of the ion reaction

in to the slag during refining process with the metal

carbide, oxygen, nitrogen and carbon. It proves that

there is a big discrepancy in the opinions on the calcium

and carbon role in the slag and their interaction with refined

metal and the atmosphere of melting. Author

shows on the most important role of the carbon �C 2+ �

and �C 4+ � ions on the effectiveness of carbide slag metal

extraction process.

It has been described the influences of same alloys

compounds on the structure, properties and segregation

effect of the ingot. The experiments on bronze melting

with the slag refining proved that optimum is achieved. For

example for silicon bronzes are selected refiner with calcium

carbide, carbon and aluminium as the complex reagent.

The reducers of this kind not only make it possible

to keep a constant deficit of impurities in the slag layer

but also let carbon in the melting atmosphere. The authors

slag constitution with the carbon reagents has been

applied in metallurgical and foundry conduction.

REFERENCES

�1� Fischer W.A., Jahnke D., Metall, 11(1972), 1123-1127

�2� Krasicka-Cydzik E., Journal of Applied Electrochemistry,

31(2001), 1155-1161

�3� Mysik R.K., Porucznikow J.P., Cuchlew S.M., Cwetnoje

Meta³³y, 11(1989), 88-96

�4� Nakamura T., Noguchi F., Neda Y., Metall, Review of

M.M.I.J., 2(1986) 3, 102-108

�5� Byda³ek A., Chem. Process, 10 (1971), 27-31

�6� Priminow A.M., Gofensofer L.I., Abramow G.V., Litejnoje

Proizwodstwo., 2 (1983), 34-40

�7� Rzadkosz S.,Wodecki R., Acta Metall. Slovaca, 5(1999),

422-427

�8� Gawroñski J., Solidification of Metals and Alloys, 24(1995)

201-2007

�9� Byda³ek A. W., Journal of Thermal Analysis, 45(1995),

919-922

�10� Byda³ek A. W., Archives of Foundry Engineering,

2(2009)9, 25-28

Note: The responsible translator for English language is professional lecturer

from West Pomeranian University of Technology, Szczecin, Poland

280 METALURGIJA 50 (2011) 4, 278-280


W. PTASZYÑSKI, A. GESSNER, P. FR¥CKOWIAK, R. STANIEK

STRAIGHTNESS MEASUREMENT

OF LARGE MACHINE GUIDEWAYS

INTRODUCTION

In case of small machine tools it is simple to machine

the base surfaces for the guideways correctly. Although

the structure of the body needs to be properly designed,

it demands only precise milling and grinding.

In case of large machine tools, with the guideways of

a few or more meters long, it is impossible to design and

to machine a rigid body with straight slides. The obtained

straightness of the slides depends mostly on the

accuracy of their assembly.

There are several tools available for machine guides

straightness measurement �1�. The common methods

are not always suitable for measuring the straightness of

long guideways. This is the reason why sometimes customized

tooling and programs have to be developed.

GUIDEWAYS OF THE

LARGE SCALE MACHINE TOOLS

Two solutions for the body design of the longest axis

of large scale machine tools are known:

– monolithic body on which two guideways are

placed,

– separated guideways – each guideway is a separate

part.

The monolithic bodies are used in gantry machine

tools in which a table is placed on the longest slide and

in horizontal mobile column machines in which the column

with headstock is moving on the longest slide, but

the table stays motionless.

Received – Prispjelo: 2010-08-31

Accepted – Prihva}eno: 2011-01-29

Preliminary Note – Prethodno prop}enje

This paper shows the guideway types of large machines and describes problems with their straightness measurement.

A short description of straightness measurement methods and the results of investigation in straightness

of 10 meter long guideways of a CNC machine by means of the XL-10 Renishaw interferometer are

also presented.

Key words: machine, straightness measurement, machine guideways

Mjerenje ravnosti duga~kih strojnih vodilica. Rad prikazuje tipove vodilica velikih strojeva i opisuje probleme

mjerenja njihove ravnosti. Dat je tako|er i opis metoda mjerenja ravnosti, te rezultati ispitivanja ravnosti

10 metarskih vodilica CNC stroja pomo}u XJ-10 Renishawovog interferometra.

Klju~ne rije~i: strojevi, mjerenje ravnosti, strojne vodilice

W. Ptaszyñski, A.Gessner, P.Fr¹ckowiak, R. Staniek, Institute of Mechanical

Engineering, Poznan University of Technology, Poznan, Poland

ISSN 0543-5846

METABK 50(4) 281-284 (2011)

UDC – UDK 621.9.002.53:621.81:513.3=111

Separated guideways are applied in mobile gantry

vertical machine tools in which the table is motionless,

but the portal moves.

Both the monolithic and the separated guideways

can be assembled from individual segments, which enable

creating very long slides.

Both kinds of slide design demand rigid foundation

and fixing to the ground. They are fixed with special

screws, usually arranged every 500 mm, with the possibility

to adjust the guideway in 2 directions (horizontally

and vertically). The screws are used for leveling as

well as for linear setting-up depicts the fixing of the

guideway to the foundation (Figure 1).

In case of the separated guideways, besides the precise

leveling, it is also required to set them on the same

level. Setting them parallel is very important as well.

Figure 1 The way of fixing the guideway to the ground

and joining two segments

METALURGIJA 50 (2011) 4, 281-284 281


W. PTASZYÑSKI et al.: STRAIGHTNESS MEASUREMENT OF LARGE MACHINE GUIDEWAYS

That could be complicated, when one considers the 7

meter span and lack of suitable measuring instruments.

THE METHODS

OF STRAIGHTNESS MEASUREMENT

According to the ISO-230 standard a line located on

a plane is considered as straight within given length, if

every of its points is enclosed between two lines at distance

equals tolerance, parallel to the main direction of

the straight �1�.

The main direction of the line or the representative

line should be taken, so that the straightness error is minimized.

It can be determined by means of:

– 2 points selected near the line that is being examined,

– a straight obtained on the basis of the measured

chart, e.g. with least squares method.

There are two groups of methods for straightness

measurement that base on:

– measuring the length,

– measuring the angle.

In the group based on length measuring there are

methods that use:

– precise ruler and gauge,

– string and microscope,

– laser and photosensitive detector,

– laser interferometer with optical set for straightness

measuring.

In the second group of methods that base on angle

measurement one uses:

– precise level,

– autocollimator,

– laser interferometer with optical set for angle measuring.

The Institute of Mechanical Technology owns a

Renishaw laser interferometer XL-10 with optical set

for straightness and angular measuring. The optical set

for straightness measurement is limited to 4 meters,

that’s why in the presented investigation the method

based on angle measurement was applied.

Measuring the guideway straightness by means of

angular measurement is presented in Figure 2. The depicted

optical set enables measuring angular displacement

in the range +/- 5 ° �1�. In case of the angular reflector

rotation, the laser beam A2 from interferometer to

reflector has longer distance than the beam A1. Asaresult,

a phase difference between A1 and A2 is noticed.

Considering the known distance of A2 and A1, the angular

displacement can be calculated.

The basic peripherals for that configuration (Figure

2) are:

– laser interferometer head,

– angular interferometer,

– angular reflector,

– flatness base.

Figure 2 Principle of straightness measurement �2�

Figure 3 Model for the straightness error calculation �2�

A flatness measurement is carried out by taking a series

of incremental height readings as the angular reflector

is moved along the measurement path (Figure 3).

On the basis of Figure 3 one can develop a rough

equation for the straightness error in a given location:

dn�dn�1�L�sin � n

(1)

where: dn – straightness error in the n point,

dn-1 – straightness error in the previous point,

L – the distance between the measurements,

� n – the measured deflection error.

Laser interferometer used in our investigation has

following main parameters �3�:

– axial range: 0-15 m,

– angular measurement range: ± 175 mm/m (± 10 °),

– angular accuracy: ± 0,1M µm/m (M- measurement

distance),

– resolution: 0,1 µm/m (0,01 arc sec).

RESULTS OF THE INVESTIGATION

INTO GUIDEWAY STRAIGHTNESS

As the investigated machine tool was a used one, the

slide surfaces showed some wear. One could also notice

a hard to remove dust layer. Every roughness of the slide

surface can influence the investigation results. Setting

the straightness of the slide top surface is presented in

Figure 4.

The Renishaw XL-10 measuring set includes measuring

bases of lengths 50 mm, 100 mm and 150 mm.

Considering the fact that the adjusting screws in that

particular slide are arranged every 500 mm, a special

measuring base of 500 mm was prepared. Thanks to

such a long foot it was possible to strongly limit the influence

of local roughness on the measurement �4-7�.

The foot and the measuring set are presented in Figure 5.

Figure 6 presents the angular displacements for the

measured straightness of the slide top surface with the

282 METALURGIJA 50 (2011) 4, 281-284


Figure 4 Setting the straightness of the slide top surface

Figure 5 View of the measuring set: 1 – investigated

surface (location of the carriage), 2 – prepared

500 mm foot, 3 – measuring optical set

Figure 6 Chart of the obtained angular displacements

for the measured straightness of the slide top

surface

use of the 500 mm foot. On the basis of that chart and the

equation (1) one can calculate the real straightness deviation.

To that end a computer program was developed. It

calculates the straightness deviation using the data obtained

from the measuring system. The program window

is presented in Figure 7.

The interferometer does not measure the absolute deflection

angle, so the absolute straightness error cannot

be obtained. For this reason the graph of the straightness

error was compared to a straight line (the curve was ro-

W. PTASZYÑSKI et al.: STRAIGHTNESS MEASUREMENT OF LARGE MACHINE GUIDEWAYS

Figure 7 Program for calculating straightness deviation

on the basis of angular measurement

Figure 8 Diagram for the calculated straightness deviation

of the top slide surface in relation to the

straight line

Figure 9 Diagram for the calculated straightness deviation

of the top slide surface

tated so that the start and the end of it were brought to

zero). The table deflection calculated according to the

described method is presented in the Figure 8.

The noticeable changes of the straightness, especially

in Figure 9, result from the imprecise connection

METALURGIJA 50 (2011) 4, 281-284 283


W. PTASZYÑSKI et al.: STRAIGHTNESS MEASUREMENT OF LARGE MACHINE GUIDEWAYS

Figure 10 Diagram of the calculated straightness

deviation for the side slide surface

in relation to the straight line

of the slide segments. In that particular machine tool the

slides are assembled from 3 m long segments.

For measuring the straightness of the side slide surface

an optical set presented in figure 5 was applied. Figure

10 presents a diagram for straightness deviation in

relation to the straight line.

RESULTS OF THE INVESTIGATION

INTO STRAIGHTNESS OF MOTION

After adjusting guideways and assembling the machine

tool an investigation into straightness of motion

was carried out. For the investigation the method described

in chapter 3 was used, with that difference that

the optical system was fixed to the movable part and its

angular displacement was measured. The machine tool

portal moves on 2 carriages on each side arranged in

2 500 mm distance. The side carriage is made of 4 parts.

The straightness error of the slide results in angular deviation

of the portal. The Motion straightness investigation

was carried out every 50 mm.

Figure 11 presents the calculated straightness deviation

in the vertical plane within the whole range of motion

– 6 900 mm.

SUMMARY

The accuracy of a machine tool is influenced not

only by the accuracy of the measuring system and the

servo drives, but also by geometrical accuracy, particularly

by guideways’ straightness. As already stated the

straightness of guideways of small machine tools is

quite easy to achieve. However, in case of large machine

tools the issue is more complicated. Longer guideways

result in lower rigidity of the body. Additionally, the

long guideways are assembled from segments that need

to be very precisely arranged.

Figure 11 Diagram for the calculated straightness

deviation of the portal for motion in the

vertical plane

Moreover, since the machine was used, the straightness

measurement was influenced by roughness and

dust on the slide surfaces.

On the basis of the summarized results one can state

that the aim of the study was achieved. For that class and

size of machine tools the straightness deviation of 0,045

mm within the whole range of motion is considered as

sufficient.

REFERENCES

�1� ISO 230-1 1996: Test code for machine tools. Part 1: Geometric

accuracy of machines operating under no-load or finishing

condition.

�2� XL laser measurement system manual. Renishaw.

�3� Ardelean F. A.: The measurement of the straightness in the

case of long guideways, using modern measurement methods,

namely, the laser. Annals of the Oradea University.

Fascicle of Management and Technological Engineering,

Volume VII (XVII), 2008.

�4� Ptaszynski W.: Laser Interferometer Straightness Measurement

of Machine Tool. The 8 th International Carpathian

Control Conference ICCC 2007, Strbske Pleso, Slovakia

2007, pp. 579-582.

�5� Poniatowska M.: Methods of spatial data analysis in research

on geometric deviations determined in coordinate measurements

of freeform surfaces. Archives of Mechanical

Technology and Automation, Vol. 29/2, Poznan, pp. 63-72.

�6� Poniatowska M.: Characteristics of geometric errors determined

using discrete measurement data. Archives of Mechanical

Technology and Automation, Vol. 28/2, Poznan,

pp. 51-58.

�7� Swornowski P. The optimum number and distribution of

measuring points for the circle with the shape deviation.

Archives of Mechanical Technology and Automation, Vol.

22/2, Poznan, pp. 79-86.

NOTE: Responsible translator: Natalia Trawinska, The Poznan College

of Modern Languages, Poznan, Poland

284 METALURGIJA 50 (2011) 4, 281-284


YU. G. GULYAYEV, I. MAMUZI], YE. I. SHYFRIN, M. BUR[AK, D. YU. GARMASHEV

ISSN 0543-5846

METABK 50(4) 285-288 (2011)

UDC – UDK 621.774.3:621.771:338.455=111

PERFECTION OF PROCESSES

OF SEAMLESS STEEL TUBES PRODUCTION

INTRODUCTION

Various hot rolling methods remain to be the most

widely used methods of making seamless steel tubes.

The more than a hundred year long history of development

of technology of seamless tube production can

be conditionally divided into three stages (till 2000.y.).

�1-3�

1. From the middle of 1880 y. to the middle of 1930

y., six basic processes of rolling shells into seamless

tubes have been developed: pilgrim rolling; longitudinal

plug rolling in Stiefel plug mill; mandrel drawing of

shells thru a system of rings in Erhard push bench; longitudinal

full-floating mandrel rolling in Fassel and

Kellog multi-stand (7 and more stands) tube rolling

mills; helical floating-mandrel rolling in a three-roll

Assel mill and helical disk reeling in a Diescher mill. By

the end of 1930 y., rolling schemes using plug and pilgrim

mills were used most widely. Small quantities of

tubes were produced using push benches and Assel and

Diescher mills and continuous mandrel rolling was not

actually used. Cast and forged ingots or rolled billets

were used as a starting material in the tube manufacture.

2. In the period from the middle of 1940 y. to the

middle of 1980 y., hot tube working processes were

strongly perfected. First of all, it should be mentioned

that a third hot working step has been introduced into

virtually all known processes: sink rolling in sizing or

Received – Prispjelo: 2010-05-14

Accepted – Prihva}eno: 2010-09-30

Review Paper – Pregledni rad

The article first give a review more of hundret years long history of seamless steel tube production, especially

during the last 15-20 years of the 20 th century. Prolongation, article give technological indices for 4 mills (automatical,

continuous mill, pilger, Assel), and perfectation of processes seamless steel tubes production at the

begining of 21 th century.

Key words: semless steel tubes, pipes mills, production, development

Usavr{avanje postupaka proizvodnje ~eli~nih be{avnih cijevi. Prvo, ~lanak daje pregled vi{e od sto godina

duge povijesti proizvodnje be{avnih ~eli~nih cijevi, naro~ito u posljednjih 15-20. godina 20. stolje}a. Nastavak

~lanka daje, uz tehnolo{ke parametre za 4 valjaonice i usavr{avanje postupaka proizvodnje be{avnih

~eli~nih cijevi po~etkom 21. stolje}a.

Klju~ne rije~i: be{avne ~eli~ne cijevi, valjaonice cijevi, proizvodnja, razvitak

Yu. G. Gulyayev, National Metallurgical Academy of Ukraine,

Dnepropetrovsk, Ukraine; I. Mamuzi}, University of Zagreb, Croatia, Ye.

I. Shyfrin,Tube Metallurgical Company, Moscow, Russia, M. Bur{ak,

Technical University of Ko{ice, Ko{ice, Slovakia, D. Yu. Garmashev,

OJSC “INTERPIPE NTZ”, Dnepropetrovsk, Ukraine

stretch-reducing mills. Just due to the use of sink rolling

as a final hot working step, continuous full-floating

mandrel longitudinal rolling mills with 7 to 9 stands

have got a wide-spread use. Beginning from 1960 y.,

due to the development of new lubricants, hot extrusion

method has become commercially used in the production

of tubes from hardly-deformed alloy steels and alloys.

By the middle of 1980 y., continuous mills with retained

and semi-floating mandrels have won recognition.

At the same time, a process of making tubes at push

benches by drawing tubes thru a roller cartridge instead

of rings has been developed. Continuously cast round

ingots were then used as a starting material.

3. During the last 15 – 20 years of the 20-th century,

the following technologies have become commercially

used - Table 1. �4�

a) elongation of hollow shells by helical rolling in

3-roll planetary mills;

b) reeling shells in modernized Assel mills with adjusted

feed angles and Diescher mills (in various

variants, including rolling with discs and driven

skew rolls, so-called Accu-Roll process);

c) continuous longitudinal retained mandrel rolling

in two-roll stands (ÌÐÌ mills);

d) elongation of shells in push benches with roller

cartridges where press piercing of solid billets

into shells was replaced with helical piercing in

mills with tapered rolls (CPE process).

The aim of this article give perfection of processes of

seamless steel tubes production.

Perfection of processes is an essential reserve of raising

efficiency of pipe and tube production.

METALURGIJA 50 (2011) 4, 285-288 285


YU. G. GULYAYEV et al: PERFECTION OF PROCESSES OF SEAMLESS STEEL TUBES PRODUCTION

Table 1 Development tendency at production of seamless tubes during the last 15-20 years of the 20 th century �4�

CHARGE ROLLING

Continuous casting of

round sections

Continuous cast hollow

shell

The charge with the

improved possibility

for hot and cold forming

and superior

surface quality

Application of centrifugal

cast raw pipes

and high alloy steel

pipes

PPM (Press piercing mill)

- pressure rolling mill for longitudinal charge piercing

MPM (Multi stand pipe mill)

- continuous mill with the mandrel retention device

- Ital. variant

MPM-SL (Multi standless pipe mill)

- continuous mill (without stands) with the common housing and a mandrel retention

device

- Ital. variant

NEUVAL process

-French variant of MPM with the retained mandrel by which a tube blank was previously

-pierced at the cross rolling stand

MPM -Aetna Standard Co.

- Continuous rolling mill with a free, half-retained and retained mandrel, example:

“VBC SUMITOMO”

MRK-S (Mannesmann Rohrkontiwalzwerk mit Striperverfahren)

- Mannesmann-variant of MRK with a stripper and half-retained mandrel

MRK-AR (Mannesmann Rohrkontiwalzwerk mit Ausziehrohrwalzwerk)

- Mannesmann-variant of MRK with a mandrel-retention device with a drawing

stand

CPE (Crossroll picrcing elongation)

- piercing by cross rolling with an elongation at the push bench

CPD (Crossroll piercing Diescher elongationl

-piercing by cross rolling with an elongation at the Diescher stand with the mandrel

retention

ACCU-ROOL (Procedure similar to CPD)

- piercing by cross rolling with an elongation at the cross rolling stand by Diescher’s

discs with the retained mandrel, developed by Aetna Standard Co. in 4 versions

PSW (Planeten -Schrägwalzerk)

-planetary cross rolling stand for pipes

TECHNOLOGICAL INDICES FOR

4 MILLS WITH GREATEST DISTRIBUTION

IN A WORLD (IN 20 TH CENTURY)

Tube rolling mill installations with automatical,

pilger, continuous mill and three-roll reeling (Assel) mills

for production of hot-rolled seamless tubes have received

(in 20 th century) the greatest distribution in a world.

These installations differ on the technological indices.

As for instance, Table 2 give the performance for this

mills. Table 3 give the change of indices by production

hot rolling of seamless tubess.

The installations with automatical and pilger mill

have the broadest sort. The installations with continuous

and three-roll reeling mill are applied to production of

small and angle diameter tubes, the first -for rather

thin-wall, and the second - for heavy-wall tubes.

The modern installations with continuous mill (mandrel

mill) have top performances. Seamless tube rolling

mill installation with three-roll reeling mill ensures deriving

tubes in a split-hair accuracy, in 1,5 to 2,0 times superior

an exactitude of tube than on other installations.

FINISHING, COLD

FORMING, HEAT

TREATMENT

Development of nondestructive

testing

procedures

High-efficiency devices

for development

Plastic coating, internal

grinding

Continuous cold rolling

of pipes Application

of multi-drawings

resp. tandem-and

multiple cold and pilger

machines High-efficiency

cold pilger

stands

Allowing, that the expenditures on metallurgical

process on all seamless tube rolling mill installations

compound 15 to 40 % from product cost, and 60 to 85 %

are necessary for the cost of metal, the major value is acquired

by (with) such an index, as account coefficient,

which is the greatest on installations with pilger (in connection

with availability pilger head) and three-roll

(considerable end pop and necessity a turning of tubes)

reeling mill.

Besides seamless tube rolling mill installations with

pilger and three-roll reeling mill at the least share of a

dead time in rhythm of rolling the continuous unsteady

stages of process of an expansion have.

The analysis of technological indices of production

of tubes on different seamless tube rolling installations

allows defining reference directions of improving of the

“know-how” of tubes encompassing by following:

– heightening of an exactness of tubes on installations

with self-acting. mandrel and pilger mill,

– expansion of a sort of installations with three-roll

reeling mill and heightening of their productivity,

286 METALURGIJA 50 (2011) 4, 285-288


YU. G. GULYAYEV et al: PERFECTION OF PROCESSES OF SEAMLESS STEEL TUBES PRODUCTION

Table 2. Performance of seamless tube mill �4, 5�

Indexes

Sort:

- diameter of rolled

tubes / mm

- a ratio D/S

Supposed aberrations:

/ %

- on diameter

- on wall thickness

Productivity, thousand

tonn annually

Account coefficient

Share of time in

rhythm of rolling:

- engine %

- supplementary %

- unsteady stages %

Coefficient of an

extract:

- at weaving

- at an expansion

automatical

57 -

426

4,45

±1

± 12,5

70-

340

1,08-

1,14

20-25

80-75

1

1,3 -5,2

1,2 -2,1

The type reeling mill

continuous

mill

30-

102

10-13

±1

± 12,5

110-

600

1,075-

1,090

150-60

50-40

1

1,8 -3,0

3,0 -6,5

pilger

22-

700

6 -40

±1

± 12,5

190 -

340

1,193-

1,227

75-80

25-20

15-18

1,3 -2,1

3,0 -15

three-roll

reeling

(Assel)

34-

200

4,12

± 0,5

± 6,0

22 -

230

1,175-

1,257

80-85

20-15

2-3

1,3 -2,1

1,8 -3,2

– decrease of account coefficient on installations

with pilger and three-roll mill,

– abatement of a dead time in rhythm of rolling on

automatical and continuous mill,

– abatement of time of unsteady stages of processes

of an expansion on pilger and three-roll mill.

At a solution of the question about perfecting production

it is very important to have an opportunity to institute

influencing technology, design and organization -

engineering measures on a production efficiency. It will

allow selecting for introducing those measures, which

can most contribute a production efficiency.

Table 3 Change of indices by production hot rolling

of seamless tube �4,5�

Indexes

Losses of metal at production

of tubes %

Capital of an expenditure/%

The cost 1 hour of operation

of installations / %

Annual working time

fund of installations /

hour

Annual working time

fund of installations /

hour

All

Openingup

of

performs

Including:

a strain

(deformation)

finish

5-60 1 - 25 2 - 10 2 - 30

100 2 -15 20 - 70 25 - 50

100 2 -15 30 - 70 15 - 60

7500-

8100

100-

800

6500-

7500

1000-

25 000

7500-

8100

1000-

25 000

For complex examination of process of deriving

hot-rolled of tubes irrespective of an expedient of a

strain and used inventory the universal mathematical

model of production linking technological parameters

of process, design features of installations, performance

of performing process and ready tubes with measure of

an estimation of an economic efficiency is created.

PERFECTION AT THE

BEGINNING OF 21 ST CENTURY

At the beginning of 21 st century, because of toughening

of customer requirements to the product and service

quality and globalization and aggravation of international

competition, the majority of hot-rolled tube producers

faced the problem of modernization of the existing

equipment and building new production lines. �6-8�

From a large number of ideas of improvement of technologies

and equipment for making hot-worked seamless

tubes, it is worth to mention the idea of orientation of the

mass production planning predominantly toward the

technologies using continuous MPM mills with two-roll

stands and continuous FQM and PQF mills with

three-roll stands as the main reeling units. It is supported

by a successful experience of operation of about 20 MPM

mills built at the end of the 20-th century and commissioning

of MPM, PQF and FQM units in China, Belarus,

Japan, Russia, Kazakhstan in the last years. At present,

installation of continuous mills at a number of tube works

in Saudi Arabia, China, Ukraine and other countries is

carried out or planned. It should be pointed out that MPM

mills were initially equipped with press piercing mills but

the modern continuous mills use skew roll piercing mills

with tapered rolls and guide discs. Taking into consideration

the fact that two or three billet sizes are rolled at a

same piercing mill, the future design of the roll piercing

mills will possibly provide for their possible operation

both with the guide discs (in piercing small diameter billets)

and shoes (when switching to piercing large diameter

billets). At the same time, mills with horizontal roll arrangement

should be preferred because shoe installation

is much easier in this case.

It is not excluded, what further continuous mills will

complete from two-roll “entrance” stands and three-roll

(or four-roll) “exit” stands.

Of all promising innovations in the field of manufacture

of hot-rolled tubes that can be used in production

conditions in the nearest future, shell rolling in a

stretch-reducing mill (CPS process) should be distinguished

as the most promising process. The CPS process

is a two-stage process where there is no second, main

forming operation, i.e. there is no a mandrel tube rolling

mill. Billets are subjected to helical piercing at elongation

ratios up to 12 in a mill with a vertical arrangement of tapered

rolls. The pierced billet is fed directly into a

stretch-reducing (sizing) mill. Advantages of this process

consist in that due to absence of a mandrel tube rolling

mill, main equipment list is reduced and consequently in-

METALURGIJA 50 (2011) 4, 285-288 287


YU. G. GULYAYEV et al: PERFECTION OF PROCESSES OF SEAMLESS STEEL TUBES PRODUCTION

vestments get smaller. Such technology can be used

above all in the production of conventional tubes.

At the present-day requirements to quality and dimensional

accuracy of the final products, the processes

of sizing or stretch reducing tubes as the final steps of

the hot working process have a paramount importance

�9-13�. Continuous sink rolling as the final production

step in the majority of rolling patterns, determines quality

of finished hot rolled tubes to a great extent. Based on

the trends of development of the process of continuous

sink rolling, it can be predicted that in the nearest future

this process will be grounded on the idea of using

three-roll stands. Stands must have individual drives ensuring

flexible adjustment of roll rpm both in the course

of rolling individual tubes (to reduce the length of thick

ends) and from tube to tube rolling (to compensate for

wall thickness variation in the mother tubes coming

from the mandrel mill). Beside the roll rpm, roll pass

shape plays an important role in ensuring quality of OD

and ID surface of the sized (especially, stretch-reduced)

tubes, and so the tool preparation stations should be

equipped with modern machines for individual machining

of the roll groves.

The continuous sink tube rolling process is usually

carried out in mills in which roll pass of each subsequent

stand is turned at angle �

(where n is the number of rolls

n

in the stand) relative to the preceding stand roll pass. It is

not inconceivable that this concept will be revised in the

nearest future basing on the theoretical evidences

worked out at State Scientific Research Tube Institute

and Dnepropetrovsk Metallurgical Institute (Ukraine)

as long ago as 1980 y. The calculations have shown that

a substantially lower level of cross-sectional wall thickness

variation can be achieved when using a mill which

has two stand groups and the stands in each group are

turned at a traditional angle �

but with the stand groups

n

turned at angle �

relative to each other. For the first

2n

time, this idea was realized in production conditions by

designers of EZTM JSC (Russia) at their mill installed at

Dnepropetrovsk Tube Works (Ukraine) in 2008.

In the improvement of the tube making processes,

equipping process lines and individual units with computer-aided

control systems is of especial urgency at present.

Practically all modern tube rolling installations are

already furnished or being furnished with the means of

objective control of main process and product parameters.

CARTA (Computer Aided Rolling Technology Application)

process control system developed by SMS

Meer has become a widely known and applied system

currently. The system task consists in ensuring a high

level of product yield and quality in the tube manufacture.

Smaller diameter and wall thickness variations result in

metal saving and cost reduction both in the course of production

and during subsequent tube processing. �12�

At present, the problem of application of on-line tube

dimension control systems is of high urgency. Obvi-

ously, practically all processing units will be furnished

with systems for measuring tube wall thickness and diameter

in the nearest future. Multichannel sensors measuring

linear dimensions and allowing not only recording

of the mean wall thickness variation during the tube

travel along the process line but also determining the

character of cross-sectional wall thickness variation will

be given preference despite their relatively high price.

CONCLUSION

1. From a large number of ideas of improvement of

technologies and equipment for making hot-worked

seamless tubes, it is worth to mention the idea of orientation

of the mass production planning predominantly toward

the technologies using continuous MPM mills

with two-roll stands and continuous FQM and PQF

mills with three-roll stands as the main reeling units.

2. It is not excluded, what further continuous mills

will complete from two-roll “entrance” stands and

three-roll (or four-roll) “exit” stands.

3. Of all promising innovations in the field of manufacture

of hot-rolled tubes that can be used in production

conditions in the nearest future, shell rolling in a

stretch-reducing mill (CPS process) should be distinguished

as the most promising process.

4. At the present-day stage, development of the

drawing processes is aimed at the growth of cost effectiveness

and intensification of speed parameters.

REFERENCES

�1� J. Perc Boore. The Seamless Story. – Los Angeles, The

Commonwealth Press, 1951.-286

�2� Manufacture of Steel Tubular Products. – Pittsburgh, United

States Steel, 1966.-64

�3� H.G. Müller, M. Opperer. Das Stahlrohr. – Düsseldorf, Verlag

Stahleisen, 1974.-370

�4� I. Mamuzi~, V. M. Drujan. Metalurgija 43(2004)3, 181-186

�5� V.M. Drujan, Yu. G. Gulyayev, S.A. Chukmasov. Theory

and Technology of tubes production. – Dnepropetrovsk,

Dnepr – VAL, 2001.

�6� C. K. Shin, R. Q. Hsu, Ch. Hung. Journal of Materials Processing

Technology 121(2002)2-3, 273-284.

�7� M. Reggio, F. Mc Kenty, L. Gravel, J. Cortes, G. Morales.

M.-A. Landron de Guevara. Applied Thermal Engineering

22(2002)4, 459-470

�8� Tube and Production News Releases of the fabricator

www.thefabricator.com

�9� Latest & Future development trend in metallurgical plan

and rolling mill technology (stell Research Papers)

www.steelword.com 2009.

�10� New development of seamless steel tube manufacturing technologies

www. shuoong.com 2009.

�11� New steel tube & pipe conference, March 24-26, 2008

�12� First seamless tubes symposium in Pittsburgh - March,

2009. www.sms-meer.com

�13� 2nd Annuel Steel Tube & Pipe Conference 30-03-01-04,

2009, www.amm.com

Note: The responsible translator for English language is lecturer from National

Metallurgical Academy of Ukraine, Dnipropetrovsk, Ukraine.

288 METALURGIJA 50 (2011) 4, 285-288

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