DVS_Berichte_334_Leseprobe

2017
DVS-BERICHTE
International
Electron Beam
Welding Conference

International
Electron Beam
Welding Conference
Lectures of the 4 th IEBW Conference
taking place in Aachen on March 21 – 22, 2017
Organized by
German Welding Society (DVS), Düsseldorf
International Institute of Welding (IIW), Villepinte
American Welding Society (AWS), Miami

Bibliographic information published by the Deutsche Nationalbibliothek
The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie;
detailed bibliographic data are available in the Internet at http://dnb.dnb.de.
DVS-Berichte Volume 334
ISBN 978-3-945023-97-6
The lectures are printed in form of manuscripts.
All rights, also for translation, are reserved. The reproduction of this volume or of parts of it only
with approval of the DVS Media GmbH, Düsseldorf.
© DVS Media GmbH, Düsseldorf ⋅ 2017
Printing: rewi druckhaus, Reiner Winters GmbH, Wissen/Sieg

Welcome
Are you interested in efficient and powerful electron beam welding technology and technological
leadership?
Well, you are at one of the best events in your industry.
The International Electron Beam Welding Conference, IEBW 2017, offers a forum at which
users and manufacturers of electron beam welding and processing technology can meet with
R&D specialists to share their experience and learn about the latest developments in the field.
You get together with like-minded professional people from different sectors of industries
around the world to discuss the latest trends in electron beam technology and gather ideas for
future activities, without the rush of overcrowded trade-shows.
Also, IEBW provides an excellent opportunity for experts not using the electron beam presently
but to getting to know the technical capabilities and advantages of the electron beam. Common
fields where the electron beam is used are for example aircraft and aerospace, automotive and
transportation, shipbuilding and off-shore constructions, rail, nuclear, oil gas and chemical,
military and defense, construction and general fabrication, electronics and medical.
The event is truly one that anyone involved in sophisticated joining challenges should plan to
attend.
Many thanks to International Institute of Welding (IIW), American Welding Society (AWS),
German Welding Society (DVS) and Japan Welding Society (JWS), moreover to the sponsors
PTR and SST of Global Beam Technologies, pro-beam and FOCUS and last but not least to the
ISF of RWTH Aachen University and Forschungszentrum Jülich for great assistance and
support.
We are pleased to welcome you to the 4 th International Electron Beam Welding Conference
here in the emperor city of Aachen.
Enjoy your stay in Aachen!
Wilfried Behr
Technical Chairman of Program Committee
and Chairman of DVS Working Group
“Electron Beam Welding”
Ernest Levert
Commission IV “Power Beam Processes”
International Institute of Welding (IIW)

Table of contents
Preface
Surface Treatment / Materials
C. Punshon, A. Ferhati, Cambrige/UK, M. Dear and A. Field, Halesowen/UK
Dissimilar metal joining for pressure plant and forge tools ......................................................... 1
M. Okubo and T. Hasegawa, Chiba/JP
Electron beam welding of cast iron and cast steel ..................................................................... 7
S. Valkov, P. Petrov, D. Dechev, N. Ivanov and R. Bezdushnyi, Sofia/BG
Study formation of aluminides in Al-Ti-X (X = Zr, Hf) systems induced by electron-beam
surface treatment ..................................................................................................................... 16
P. Hengst, Freiberg/DE, R. Zenker, Freiberg/DE and Mitweida/DE, T. Süß and K. Hoffmann, Chemnitz/DE
Electron beam profiling and electron beam remelt-bonding for improving the load-bearing
capacity of thermal spray coatings ........................................................................................... 19
Applications
A. Senger, S. Ufer, S. Olschok and U. Reisgen, Aachen/DE
Extension of the material and processing spectrum in wind energy plant through consistent
component safety certificates and welding process optimization ............................................. 27
H. Kendziora, Langenselbold/DE
The diversity of job shop by assistance of the electron beam .................................................. 34
M. Mücke, M. Merkel, Hünstetten-Kesselbach/DE, C. Otten, Aachen/DE, M. Escher, Hünstetten-Kesselbach/DE,
M. Paul, T. Flohr, K. Wrobel, Leipzig/DE, U. Reisgen and I. Balz, Aachen/DE
Advances in micro electron beam welding ............................................................................... 41
Innovations I
A. N. Black, Enfield/US
Electron beam welding of additively manufactured parts ......................................................... 46
L. Halbauer, P. Proksch, A. Buchwalder, Freiberg/DE, and R. Zenker, Freiberg/DE and Mittweida/DE
Using scanning electron beam technology in hard soldering TWIP-matrix composites ........... 52

Innovations II
C. N. Ribton, S. del Pozo, D. R. Smith and W. Balachandran, Cambridge/UK
Design of a plasma cathode electron gun using evolutionary optimization .............................. 58
N. Murray, G. Klimov, A. Beniyash and T. Hassel, Garbsen/DE
Non-vacuum electron beam technology as a universal tool for material processing ................ 65
U. Reisgen, S. Olschok and S. Gach, Aachen/DE
Residual stress reduction by low-transformation-temperature (LTT) filler materials in
electron beam welding ............................................................................................................. 72
Process Diagnostics / Simulation
S. Hellberg, Kassel/DE, S. Ufer, Aachen/DE, S. Böhm, Kassel/DE, and U. Reisgen, Aachen/DE
Influence of fluctuating cathode characteristics on beam quality and welding results in
electron beam welding ............................................................................................................. 78
P. Oving, Metz-Tessy/FR
Development of a new electron beam probing device and analyses method to ensure the
weld quality in time ................................................................................................................... 84
U. Reisgen, S. Olschok, S. Ufer, Aachen/DE, T. Graf and P. Berger, Stuttgart/DE
Observing weld pool dynamics of the vapour capillary by using the real-time polarization
intensity quotient goniometry ................................................................................................... 91
Additive Manufacturing I
G. Klimov, N. Murray, A. Beniyash, Garbsen/DE, A. A. Bataev, O. G. Lenivtseva, Novosibirsk/RU, and
T. Hassel, Garbsen/DE
Additive manufacturing using non-vacuum electron beam technology .................................... 99
S. Janson, B. Loitlesberger, J. Weirather and M. F. Zaeh, München/DE
Improvement of electric charge transportation in metal powders for increased process
stability in electron beam melting ........................................................................................... 104
B. Baufeld, R. Widdison and T. Dutilleu, Rotherham/UK
Electron beam additive manufacturing: Deposition strategies and properties ........................ 114
Additive Manufacturing II
N. Bagshaw, A. Buxton, T. P. Mitchell, V. Jefimovs and M. E. Nunn, TWI Limited, Cambridge/UK
Electron beam wire-fed additive manufacture and distortion control ...................................... 118
B. Klöden, A. Kirchner, T. Weißgärber, B. Kieback, M. Süß, C. Schöne and R. Stelzer, Dresden/DE
Additive manufacturing by electron beam melting – from powder to component ................... 131
List of authors and co-authors ........................................................................................... 137

Dissimilar metal joining for pressure plant and forge tools
C. Punshon, A. Ferhati, Cambrige/UK, M. Dear and A. Field, Halesowen/UK
Transforge aims to show that the fabrication of forged transitions from dissimilar materials can be achieved by
using single-pass electron beam welding followed by re-forging and appropriate heat treatment to develop the
required integrity and properties. This will allow the fabrication of higher quality and higher performance
components for the construction of new nuclear power plant, including newly developing Small Modular Reactors
(SMRs). The spin-off benefit will be in a possible production route for other dissimilar metal joints for use in marine
environments and oil and gas applications as well as for producing forge tools.
Introduction
The use of dissimilar metal joints is prevalent in oil and gas production plant, chemical plant and in the power
generation industries where there are frequent design requirements for materials with combination of corrosion or
oxidation resistance and high strength properties. These are not always readily met by one material without high
cost or the need to compromise. This dilemma can be avoided by employing high strength ferritic or bainitic steels
joined to austenitic or nickel alloy piping systems by dissimilar metal joints and the use of cladding on surfaces of
the high strength, pressure containment plant or components exposed to extremes of temperature and
environmental conditions.
Dating back to the 1940s in the fossil fuelled power sector, dissimilar metal joints are been traditionally produced
through the use of arc welding. In order to minimise the risk of fabrication defects and in-service failures multi-layer
welding or buttering, figure 1, is employed to minimise thermal expansion mismatch, accommodate differences in
hydrogen solubility and reduce the propensity for carbon diffusion, figure 2, in long term service leading to
embrittlement of certain weld interfaces.
Fig. 1 Schematic illustration of buttering in the fabrication
of dissimilar metal joints produced by arc welding
Fig. 2 Narrow region of martensite at dissimilar metal
arc weld interface associated with increased risk of
failure
When considering the fabrication of massive structures such as nuclear power generation plant there are a number
of practical issues which arise due to the necessity to make welds on site. This constraint leads to additional
difficulties in that:
! All-positional, manual welding is necessary, often with restricted access
! Non-destructive testing is more difficult particularly with ultra-sonic testing (UT) as dissimilar metal joints
exhibit varying attenuation, speed of sound and crystallographic differences leading to issues with
interpretation of UT signals
! Post weld heat treatment (PWHT) has to be carried out locally and, rather than achieve stress relaxation,
can induce tensile residual stresses through the differences in thermal expansion coefficients of the
combination of materials.
These issues can be overcome to an extent by the use of so-called “safe-ends” welded to branches or nozzles
during manufacture of vessels allowing simplified field or site welding of the branch connections to pipe work, figure
3. An alternative is to produce a well-characterised transition piece which can be manufactured, heat treated and
DVS 334 1

inspected under controlled conditions and introduced on site allowing similar metal welds to be produced under the
more difficult field welding conditions, figure 4.
Fig. 3 Illustration of safe-end principle fordissimilar metal
joints. (Courtesy of EPRI).
Fig.4 Schematic of pre-manufactured, heat
treated and validated, dissimilar metal
transition piece positioned for site welding.
The aim of the work reported here was first to examine alternative methods for producing dissimilar metal inserts or
transition pieces, which would allow simplified site welding and potentially improved structural integrity and
reliability in service and secondly, to demonstrate the preferred method.
Candidate Materials
Following discussions with potential users of nuclear power plant two material combinations were identified as
appropriate candidates for feasibility testing:
! ASTM SA 508 Gr3 Cl.2 – low alloy quenched and tempered pressure vessel steel
! ASTM B564 2010 N06600 – Inconel 600 nickel alloy used in reactor internals and pipe work
! DGS MS HAS 4304LE – 304 type austenitic stainless steel used in reactor internals and primary circuit
pipework.
In addition, in consultation with the potential industrial users, a typical pipe size where the potential use of
transitions was considered to be attractive was identified as being 364 mm OD by up to 60 mm wall thickness.
Manufacturing Options
A number of processes were considered and a down selection process conducted to define the process most
appropriate for more detailed examination. Although not exhaustive, the basic list is below in table 1:
Table 1. Selection of possible manufacturing methods for dissimilar metal transition joints
Transition joint manufacturing method Considerations
Arc welding Current practice with attendant difficulties due to
number of processes/materials for one joint and
inspection/performance requirements
Solid state welding
Attractive as minimal diffusion but limited by geometry
and overall size
Hot Isostatic Pressing
Attractive with additional benefit of ability to produce
graded composition and thermal expansion properties
– size limited by equipment availability
Additive layer manufacturing
Worthy of study but powder availability and equipment
driven size constraint
Explosive bonding
Well-developed but difficult to inspect and incomplete
bonding common
Power beam welding – laser or electron
beam
Fusion welding with attendant issues of metallurgical
compatibility and missed joint defects
EB Welding in vacuum and
re-forging to produce solid state transition
Not tested but no limit on size or geometry and
examination of feasibility worthwhile
2 DVS 334

On the basis of this rudimentary review, the use of electron beam welding followed by re-forging was adopted for
demonstration of feasibility. This method had been demonstrated already by TWI, Somers Forge and CVE in an
earlier research programme to show the potential of welding similar metals and re-forging. In this work it was
shown that by welding together two hollow part forgings and re-forging it was possible to eliminate any
microstructural evidence that the parts had been welded. The resulting joint was eventually detected using
ultrasonic testing only by virtue of the fact that the average inclusion size and was smaller and inclusions were
fewer in number with more uniform distribution.
Transforge method
The Transforge method was proposed for testing under the Innovate UK initiative for Nuclear Innovation feasibility
competition and awarded funding support.
In essence, the method involves preparation of Monobloc forgings either square or circular in section in different
materials and then joining them together by autogenous EB welding. The weld preparation is a simple machined
square butt joint and EB welding is performed under vacuum thus even when only partially welded the internal
space is evacuated.
Following welding and inspection to confirm sufficient integrity to survive the forging operation the assembly is
heated to the hot forging temperature (~1200 o C) and forged to the required geometry and size. In the feasibility test
the Monobloc forged parts were produced in two sizes, figure 5, viz:
! 175 mm square x 122 mm long
! 175 mm square x 183 mm long
The aim was to machine the rough forged parts to produce regular cuboidal blocks and weld these together to
produce short assemblies of 150mm square x 200mm for later forging into discs and then rings after piecing and
long assemblies of 150mm square x 350mm for later forging into solid discs, figure 6.
150mm
SA 508
Inconel 600
304
350mm
200mm
Fig. 5 Schematic representation of dissimilar metal parts arranged for welding
Fig. 6 Representation of proposed forging reduction to produce discs and piercing followed by mandrel forming to
produce rings
DVS 334 3

Transforge Practical work
Following cleaning, degreasing and assembly the parts were to be EB welded along each edge to produce a deep
penetration weld with either full depth or at least sufficient weld penetration depth to survive the rigours of the
forging process, figure 7.
After welding it was proposed that a shop tool ultrasonic examination be performed to assess weld depth and
integrity. This was carried out using phased array UT from both the ferritic and the austenitic ends of the joints,
figure 8 and readily indicated the weld depth and quality, figure 9. Some selected welds were later sectioned to
assess the reliability of the inspection process which was shown to be good, figure 10.
Fig. 7 As-welded
appearance of dissimilar
metal weld before forging
Fig. 8 Schematic
illustration of method for
phased array UT testing
Fig. 9 Phased array report showing
unfused region (red) in the centre of the
otherwise sound welded dissimilar metal
joint
Inconel 600
A508 steel
Fig. 10 Macro section from EB welded dissimilar metal joint showing partially penetrating EB weld and unfused
central section
The welded dissimilar metal assemblies were subsequently placed in an air furnace, figure 11, and heated to the
proposed forging temperature (~1200 o C) and forged into discs using either the 35cwt hammer forge for smaller of
the two sizes and a 500 ton hydraulic press, figure 12, for the larger parts, figure 13. The smaller discs were hot
pierced and ring forged on a mandrel to produce uniform rings of ~400mm diameter, figure 14.
Finally, after cooling and application of an appropriate conditioning heat treatment using conditions derived by
experiment on small samples, a number of parts were machined to produce complete rings and one sample was
machined with typical arc weld preparation details, figure 15. Some parts were subjected to more detailed UT
testing using TWI’s immersion test system and other samples were sectioned, figure 16, and destructively tested to
assess basic mechanical properties.
4 DVS 334

Fig. 11 Heating
dissimilar metal blocks
to forging temperature
Fig. 12 Forging on 500t
press
Fig. 13 Forged dissimilar
metal discs cooling down
from the forging operation
Fig 14 Forged dissimilar
metal discs and rings
SA 508/IN600
SA 508/304
Fig. 15 Rings machined with
transition piece weld details with
section removed to show position
of dissimilar joint interface
400mm
Fig. 16 Macro sections through forged dissimilar metal discs after heat
treatment and etching
Joint assessment
Whilst this programme was aimed at demonstrating feasibility, and was not intended to be an exhaustive study, a
number of rudimentary mechanical tests were performed on samples removed from the forged dissimilar metal
joints. Cross joint tensile testing, longitudinal and side bend tests, metallography, hardness testing and semi–
quantitative chemical analyses at the interface were performed. The results were generally good with properties
similar to the weakest base metal attained in each case, figure 17 and 18.
Fig. 17 Cross joint (SA 508/304) tensile test specimen
showing failure in the stainless steel with 0.2% proof
strength of 297MPa, UTS 612MPa, El 49% and RA
84%
Fig.18 Longitudinal bend test sample from dissimilar
forged joint between SA 508 and Inconel 600 having
achieved 180 o bend without issue.
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Concluding remarks
The work described above has demonstrated the feasibility of joining dissimilar metals by EB welding and
subsequent forging. For applications in nuclear power plant, conventional power plant and for use other pressure
containing systems there is more work to do to demonstrate structural integrity and reliable performance under
specific conditions including thermal aging, irradiation, cyclic loading etc. before such joints could be realistically
approved for use. Nevertheless, other applications exist which have less rigorous quality demands where this
technology could be used. One example is in the production of hot work forge tools where Ni alloy/ hot work steel
composite tools could be produced with equivalent performance to Monobloc nickel alloy tools but at significantly
lower cost. It is proposed that this programme is continued to examine the range of materials and applications that
can be addressed in this way and that more property and performance data is obtained for review with the
appropriate classification authorities and code bodies.
Acknowledgements
This work was supported with funding from the Innovate UK Civil Nuclear Innovation competition and the authors
would like to acknowledge the support and advice from many colleagues at TWI Ltd. and Somers Forge Ltd. as
well as industrial guidance from Rolls Royce Nuclear Power and Alstom Power
6 DVS 334

Electron beam welding of cast iron and cast steel
M. Okubo and T. Hasegawa, Narashino/JP
Cast iron and cast steel have high carbon content and the graphite, the selection of welding method has an
important item. EBW, when focusing on the behavior of the graphite has a characteristic of high density energy,
EBW is suitable welding process. In the research on cast iron, Fe-Ni and Ni-Cr filler metals, each of a sheet 0.5mm
thickness, was applied to cast iron of thickness of 18 mm. Under optimal welding processes, weld providing good
welded properties by tensile test and COD test. Using a filler supply system, Ni-Cr of 1.2 mm diameter filler wire
was applied to cast iron of thickness of 6 mm. Under the optimal process conditions and through post weld heat
treatment, the brittle region around graphite in the heat affected zone was decreased. In the research on cast steel
of thickness of 10 mm, the cast steel of about 1.2% carbon content and using materials obtained by adding about
2, 4, 6% Ni. Welding process, in addition to laser welding and manual metal-arc welding were also used. Welds of
cast steel by EBW, it became clear that low cracking tendency compared to laser welding. It was revealed by the
addition of about 2% Ni in cast steel, it is possible to reduce the hardness of the weld metal and suitable structure
control by EBW.
1 Introduction
Cast iron and cast steel are an extensively used for industrial materials. However, the welding charactristic of high
carbon cast iron and steel by convention fusion welding process are poore weldability. Various methods have been
investigated for improved weldability but problem still remain in the field of base metal, filler metal and process
parameters. For welding of cast iron, studies on the selection of filler metal [1,2] have been carried out, and
research on repair welding [3] of cast iron was subjective.
To improve the weldability of cast iron and cast steel, it is necessary to obtained attention to the following factors.
For weld metal, it is necessary to control the formation of cementite caused by dependent on welding thermal
cycle. On the other hand, in the heat affected zone, it is necessary to control the embrittlement structure around the
graphite by diffusion of carbon from graphite.
In the research on spheroidal graphite cast iron,the inside metal welding of nodular graphite cast iron by
continuous casting and filler supply system were examined in investigation of the welding of the higher quality
continuous cast material than sand mold cast material. In the research on spheroidal graphite cast steel, the
objective was to obtain welding conditions without cracking by adding EBW and laser welding by adding 2.0%,
4.0%, and 6.0% of Ni in the base material.
2 Experimental Procedures
2.1 Material and welding conditions
In the study, the developed nodular graphite cast iron as FCD450 according horizontal continuous casting process
was used for main base metal. It presented many advantages over the sand mold cast material such as less
internal defect, a lower area rate of graphite, smaller graphite grain diameter and a higher rate of graphite
nodulation. The inside metal plate are Fe-56Ni, 8Ni-18Cr and filler wire is10Ni-19Cr.
The EBW machine used has the highest output power of 6 kW. The base metal for butt welding was 18mm in
thickness, clamping torque vice, and one pass welding was made. Figure 1 shows process configuration for
welding of inside metal palate. Application of filler wire supply system to nodular cast iron, the filler wire is solid wire
in 1.2 mm diameter. The base metal for filler wire system was 6mm in thickness. Figure 2 shows process
configuration for welding of filler wire supply system.
The base metal is a graphite cast steel to which a graphite promoting element is added to a steel of a
hypereutectoid component. In order to clarify the influence of Ni in the base metal on weldability, Ni was added by
2 to 6%. First, about pig iron and steel materials were melted in a high frequency induction electric furnace, and Ni
2%, 4% and 6% Ni were added in the furnace. As the graphite spheroidizing agent, 2% of Ca - Si is added.The
size of the base metal is 10 (t) x 35 (w) x 28 (L) and the welding length is 35 mm. The microstructure of the base
metals are shown in The microstructure of the base materials are shown in Figure 3.
In study cast steel, there are three types of welding methods: electron beam welding, laser welding and manual
metal-arc welding.
The EBW condition was an accelerating voltage of 150 kV and a beam current of 32 mA, and a welding speed of
1,000 mm / min was selected in order to completely penetrate the base material having a thickness of 10 mm. For
laser welding, CO2 laser welding equipment was used. The welding condition was a beam power of 10 kW, and the
DVS 334 7

welding speed was selected to be 1500 mm / min in order to completely penetrate the base material with a
thickness of 10 mm.
For the manual metal-arc welding, a power source of AC arc characteristic was used. In the welding operation, a
U-shaped groove portion was machined on the surface of the base material. The depth of the groove was 7 mm
and the width was 14 mm. Welding is hand welding and construction with four layers. The coating welding rod had
a composition of D308 (19Cr-10Ni), the welding current was 180 A, and the welding speed was 60 mm / min. The
inter-pass temperature was 423 K.
Fig. 1. Welding of inside metal plate procedure.
Fig. 2. Welding of filler wire supply procedure.
8 DVS 334

2.2 Evaluation of welded joints
In case of cast iron, observation of defects in welds and measurement of the penetration was made of the cross-section
of welds. Micro Vickers hardness test was performed on the cross section. Next, with optimal welding condition chosen,
tensile test, impact test, COD test, analysis of chemical components of fusion zone, and EPMA analysis of welds.
In case of cast steel, crystallization tendency, hardness measurement and morphology of electron beam weldability, laser
weldability and manual metal-arc welded zone were observed by adding 2 to 6% Ni to graphite cast steel.
Fig. 3. The microstructure of the cast steel.
3 Results and discussions
3.1 Welding of cast iron
3.1.1 Welding of inside metal plate procedure
(1) Prevention of defects
In the welding of the cast iron, the selection of the filler metal and the welding heat source is to be important. With
the beam current changed at two levels of 30 and 40mA, welding speed at three levels of 450,500 and 550
mm/min and active beam parameter of for levels at 0.8, 0.9, 1.0 and1.1, the forms of the bead cross-section were
observed. Both Fe-Ni and SUS304 showed, under the condition of the beam current at 30mA, with the active beam
parameter at 0.8, wedge type; at 0.9 well type; at 1.1, wedge type.
DVS 334 9