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ISO 9001 ISO 14001 ISO/TS 16949



• Consistency in base irons leading to more uniform casting properties

• Improved graphite morphology

• Reduced shrinkage and carbide formation

• Improved mechanical properties

• Reduction in pig iron usage

Preseed preconditioner has been

proven to be an effective furnace

addition for cast irons.

Small additions of Preseed preconditioner

both increase the levels of

nucleation in the base iron and at the

same time stabilise these crucial particles

to give a long lasting effect that

can be measured right through to the

final properties of the solidified iron.

Increased nucleation levels in the base

iron can reduce the reliance on inoculant

additions which, if the base level of

nuclei is low, may not have the power

to give the desired structures and properties.

This can lead to inconsistencies

which can be equalised through the

use of Preseed preconditioner.

Further, increased nucleation levels and

subsequent improvements in graphite

morphology acts to reduce shrinkage

tendency during the later stages of

solidification and improves mechanical

properties such as tensile strength.

What is Preseed Preconditioner

Preseed preconditioner is a 75% Si

based ferroalloy containing balanced

amounts of the active elements zirconium,

aluminium and calcium. Research

has shown that these elements are

necessary to form stable nuclei in the

melt and, by creating these nuclei early

in the melting process, then consistent

iron is produced for sub sequent treatment

and casting.

The stability of these nuclei can be

demonstrated through measurement of

the graphite activity in the iron, thermal

analysis being an excellent tool to do

this. The positive effects of Preseed

preconditioner can be shown when iron

is held for extended periods of time,

even over a weekend when metal is

contained in a holding furnace.

Typically, in electric induction melting,

a 0.1% addition of Preseed preconditioner

together with the ferrosilicon/recarburiser

additions early in the melting

cycle will show positive effects. This

low addition rate makes Preseed preconditioner

a very cost effective method

of obtaining consistent and well nucleated

cast irons. By creating stable

nuclei at this stage of the process and

stabilising nuclei formed from the

charge materials, then the natural loss

of nucleation is prevented. Normally

nuclei are lost to oxidation, agglomeration

and to the slag, how ever, Preseed

preconditioner created nuclei are

retained within the melt and are thus

available for subsequent initiation of

graphite precipitation in the desired


Preseed preconditioner is produced

at the Elkem Bremanger plant in Norway,

a world renowned producer of high

quality inoculants, such as Superseed ® ,

Superseed ® Extra and Ultra seed ®

in oculants. Elkem Bremanger has ISO

9001, ISO 14001 and ISO/TS 16949


Preseed preconditioner is produced

in a 0 – 10 mm grading in a variety

of packaging to suit the customer’s

require ments, however most customers

find 25 kg bags very convenient for

storage by the furnace. Preseed preconditioner

is produced to the following


Chemical Specification

Silicon 62 – 69%

Zirconium 3 – 5%

Aluminium 3 – 5%

Calcium 0.6 – 1.9%



Barinoc ® , Foundrisil ® , Reseed ® , SMZ ® , Superseed ® , Ultraseed ® , Vaxon ® and Zircinoc ®

are registered trademarks of Elkem AS. Preseed is a trademark of Elkem AS.

Traditional Preconditioning

The advantages of preconditioning cast

irons are well known in the industry.

Typically, materials such as silicon carbide,

ferrosilicon, and, more recently,

high barium containing ferrosilicons

have been used at a relatively late

stage in the casting process. Whilst

providing a short-term benefit, all of

these mate rials suffer from fade and the

“preconditioning” effect is lost within

minutes. In many respects, these

materials may be regarded as pre-inoculants

rather than preconditioners.

base metal, if held for 50 minutes, would

be expected to lose nucleation with consequent

reduction in the low eutectic

temperature (LET) and increases in

re calescence (R). This would indicate

a loss of nucleation that may lead to

unsatisfactory and inconsistent castings

being produced. Chill and shrinkage

could be two of the factors found in

these castings.

With a small 0.1% addition of Preseed

preconditioner, the casting properties

have not only been maintained, but the

nucleation level can actually be seen

to be higher, even after 50 minutes,

than in the untreated iron which has

not been held. The LET is higher and

this leads to a reduction in the recaleascence.

Sound castings can be

safely made from this iron.

Preseed preconditioner acts in a

different way. The traditional method

of preconditioning has been to add the

alloy at a fairly late stage, together with

the nodulariser or immediately prior to

tapping from the furnace for example.

Preseed preconditioner is added to

the iron early in the melting cycle, normally

together with the ferro silicon and

recarburiser. Preseed preconditioner

creates stable and long lasting nuclei

which are resistant to the rigours of

melting and subsequent treatments.

Figure 1 shows the long-evity effect of

Preseed preconditioner through the

use of thermal analysis curves.

The curves clearly show the effects of

Preseed preconditioner. The untreated

Figure 1: The effects of Preseed preconditioner: Initial base iron without

Preseed , LET at 1139°C (left). Base iron with 0.1% Preseed , LET at 1145°C

after 50 min holding time in a furnace (right).

Reduction in Pig Iron Usage

In many countries, there is a significant

differential in the prices of steel scrap

and pig iron. Pig iron is a source of

carbon or carbon/silicon units and

makes a contribution to the nucleation

state of the iron through the inherent

nuclei in the pig iron and through the

rust (iron oxide) coating.

The use of Preseed preconditioner to

replace partially or wholly the pig iron

has been shown to be possible, allowing

foundries to increase the amounts of

returns as a replacement for the pig

iron. In cases where the pig iron has

been replaced by Preseed preconditioner

plus steel scrap, then compensation

must be made to balance the

carbon (and silicon) levels in the iron.

Consistency in Base Irons

Many foundries suffer from occasional

structural problems, whether it be a

sudden increase in shrinkage, poor

graphite structures or iron carbides

(chill). The natural tendency is to look

at the inoculating process and to

attempt to cure the problem by adding

more inoculant. Often, the fundamental

cause is further back in the iron preparation

process and can be related to

inconsistencies in the base iron.

Variations in steel scrap, charging

sequences, power inputs, unavoidable

holding times and fluctuating temperatures

can all affect the base iron nucleation.

Many foundries use quantitative

chemical analysis, such as a spectro,

to determine the level of carbon, silicon

etc in the base iron before casting,

although these analyses do not indicate

the level of nucleation, or graphite

activity, in the iron. Two furnaces may

have the same chemical analysis,

however one may have been held for

some time, due to a breakdown, for

example, and have a significantly lower

nucleation than one poured within the

normal time. This can lead to two completely

different sets of castings being

produced, albeit within specification

according to the spectro.

Figure 2 demonstrates the effect of

variations in the base iron nucleation

level. The inoculant addition has a finite

effect and a good base nucleation plus

the inoculant will give the desired structure

and properties. If the base iron

nucleation is low, then the inoculant

may not have the capability to give

sufficient nucleation. Conversely, if the

base nucleation is too high, then an

over-inoculation state can be reached

with the danger of shrinkage.

The use of Preseed preconditioner has

been demonstrated to equalise the base

iron variations to give a much more

consistent iron from the furnace, thus

leading to more consistent casting

properties. As Preseed preconditioner

has been shown to have a long term

effect, any delays in pouring will not

result in sub-standard castings.

Figure 2: Effect of variable base iron

nucleation levels.

Case Studies

Increases in the base nucleation and

nuclei stability through the use of Preseed

preconditioner have led to

foundries reporting improved graphite

morphology, physical and mechanical

properties in grey, ductile and compacted

graphite irons:

Grey iron brake discs are produced by

induction melting of iron in this European

foundry. In competing for a major

Elkem AS

Foundry Products

Hoffsveien 65B

P.O. Box 5211


N-0303, Oslo, Norway

Telephone : +47 22 45 01 00

Telefax : +47 22 45 01 52


automotive manufacturer’s contract

they produced sample discs with the

use of Preseed preconditioner. Compared

to their nor mal process they

achieved virtually 100% type A graphite

and no edge carbides. Their mechanical

properties increased by 10%. They won

the contract and now use Preseed

preconditioner in every melt.

Large, high volume automotive component

producer with Disamatic moulding

lines. Problems with occasional subnodular

structures causing delays to

production. The use of Preseed preconditioner

has virtually eliminated

sub-nodular treatments.

High strength large diesel blocks and

heads are made in this foundry. If the

nucleation is too high, they get shrinkage,

if it is too low, they get carbides.

The use of Preseed preconditioner has

helped them to stabilise their metal and

the occurrence of such defects is now

very rare.

This concast bar producer uses

Preseed preconditioner in every melt

to ensure stability in grey and ductile

bars. Since Preseed preconditioner

was introduced, they have had no failures

due to low mechanical properties

Producer of compacted graphite piston

rings reports that the use of Preseed

preconditioner has considerably improved

the dispersion of compacts

within the structure and led to more

consistent castings and machining


This medium sized ductile iron jobbing

foundry used to add 25% pig iron to

all melts. They have now replaced half

of the pig iron with cheaper steel scrap

+ 0.1% Preseed preconditioner. Over

a long period, they have seen no

changes to their final iron properties,

but have saved large amounts of money

by reducing the pig iron addition.

Revised April 2012 © Copyright Elkem AS

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