Materials and Design 30 (2009) 4236–4242

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Materials and Design

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Hybrid (plasma + gas tungsten arc) weldability of modified 12% Cr ferriticstainless steel

Emel Taban a,*, Erdinc Kaluc a,b, Alfred Dhooge c,d

a Mechanical Engineering Dept., Engineering Faculty, Kocaeli University, 41200 Kocaeli, Turkeyb Welding Research Center, Kocaeli University, 41200 Kocaeli, Turkeyc Research Center of the Belgian Welding Institute, B-9000 Ghent, Belgiumd Mechanical Engineering Dept., Engineering Faculty, University of Ghent, B-9000 Ghent, Belgium

a r t i c l e i n f o

Article history:Received 16 February 2009Accepted 24 April 2009Available online 3 May 2009

Keywords:Ferritic stainless steel12% Cr stainless steelEN 1.4003UNS S41003Hybrid weldingPlasma + gas tungsten arc weldingWeldability

0261-3069/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.matdes.2009.04.031

* Corresponding author. Tel.: +1 614 906 0086; faxE-mail addresses: emelt@kocaeli.edu.tr, emel.taba

edu (E. Taban).

a b s t r a c t

This paper deals with the hybrid (plasma + gas tungsten arc) welding properties of 12 mm thick modified12% Cr ferritic stainless steel complying with EN 1.4003 and UNS S41003 steels with a carbon content of0.01% to improve the weldability. The root passes of the butt welds were produced with plasma arc weld-ing (PAW) without filler metal while gas tungsten arc welding (GTAW) was used to accomplish fillerpasses with 309 and 316 austenitic stainless steel type of consumables, respectively. The joints were sub-jected to tensile and bend tests as well as Charpy impact toughness testing at �20 �C, 0 �C and 20 �C.Examinations were carried out in terms of metallography, chemical analysis of the weld metal, ferritecontent, grain size and hardness analyses. Although 309 consumables provided higher mean weld metaltoughness values compared to 316 (90 J vs. 75 J), 316 type of consumables provided better mean HAZtoughness data for the joints (45 J vs. 20 J) at �20 �C. Toughness properties of the welds correspond withthose of microstructural features including grain size and ferrite content.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Mild steels suffer from corrosion, however in many situationsgalvanic protection or painting of a steel surface is not practical.For long term service, corrosion protection requires maintenanceand highly expensive measures to prevent or delay the onset ofcorrosion with associated expenses. Stainless steels are in manycases a proper option to replace carbon steels for numerous struc-tural applications. They have extensively been used in a variety ofindustries and environments such as chemical and power engi-neering, food and beverage industry, health applications, petro-leum and petrochemical plants, textile plants, transportation,elevated or cryogenic temperature applications, architecture etc.[1–8]. For most cases, welding is an inevitable production tech-nique in fabrication of stainless steels. In general, most gradesare considered as weldable, however many problems are associ-ated with improper control of the weld microstructure and alliedproperties, or the use of welding procedures that are inappropriatefor the material unless some rules have been followed. Good wel-dability can be effective to determine common application of anyalloy and this factor alone has previously restricted the exploita-tion of ferritic and martensitic grades more than any other mainly

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due to toughness reduction and high carbon levels, respectively.For instance alloy 420 is one of the few stainless steels with almostno practical arc welding history. Development of new steels inev-itably brings new problems in manufacturing and joining. There isa continuous demand for increased productivity in welding, whilemaintaining the parent metal properties. In almost all cases, weld-ing results in a significant alteration of the weld metal and heat af-fected zone (HAZ) microstructure relative to the base metal. Thiscan constitute a change in the desired phase balance, formationof intermetallic compounds, grain growth, segregation of alloyand impurity elements, and other reactions. In general, these leadto some level of degradation in properties and performance andmust be factored into the manufacture [1–5]. Depending on the lifecycle costs analysis and improved steel producing technologies,lean alloyed chromium stainless steels gained a new status basedon 10.5–14% Cr system. The reasons for the renewed interest inthis group of materials are that these steels can provide goodmechanical properties and useful corrosion resistance for manyapplications and at a relatively low cost. 12% Cr stainless steelsare sufficiently corrosion resistant in atmospheric and non-aggres-sive aqueous conditions in many applications and are widely usedas low cost, utility stainless steels. In some predominantly ferriticsteels, a small amount of austenite forms at high temperaturesand may transform to martensite on cooling. This property hasbeen used to develop 12% Cr transformable stainless steels withbetter weldability than either fully ferritic or fully martensitic

E. Taban et al. / Materials and Design 30 (2009) 4236–4242 4237

steels. They should be produced with close control of the carboncontent and martensite/ferrite balance to avoid the extremes ofcompletely ferritic or martensitic structures. The hardness and det-rimental effect of the martensite on toughness is limited by the lowcarbon levels [1,3–5,9–16].

3Cr12 stainless steel which was developed with 0.03% C in thelate 1970s making use of the minimum chromium content re-quired to impart acceptable corrosion resistance is known as thefirst generation of 12% Cr steels. Originally 3Cr12 is a trademarkand was not included in any international specifications. Howevera 12% Cr steel developed from 3Cr12 has been designated DIN type1.4003 and ASTM/ASME 41003. 3Cr12 now appears in ASTM A240as UNS S41003 and in Europe as Material Number 1.4003, althoughthe two specifications are not exactly the same. In particular, con-formance to S41003 does not require nickel as an alloying element,although it is permitted, while conformance to 1.4003 does requiresome nickel. In addition to the composition ranges of S41003 and1.4003, some suppliers, but not all include a deliberate additionof titanium. Because of the low alloying content, 1.4003 alloysmay lie in the dual phase region consisting of a mixture of untrans-formed delta ferrite, alpha ferrite which transformed from austen-ite on cooling and martensite depending on the cooling rate,consequently they are variously described as ‘‘ferritic” or ‘‘fer-ritic–martensitic” 12% Cr stainless steel. In comparison to fully fer-ritic grades like 409 and 430, 3Cr12 is considered to have betterweldability and HAZ toughness in thick as well as thinner gauges,and it is supplied in thicknesses up to 30 mm. Relatively low frac-ture toughness of the HAZ has restricted their use where dynamicloads are concerned. Although 5Cr12HT was developed later as asecond generation to give better toughness, weldability remainedlimited due to the carbon content [5,11,16–28].

It is clear from the previous published literature and industrialapplications that the 12% Cr type of steels had not achieved its fullpotential so far, because the possible alloy combinations were notfully understood. And usually weldability is not concerned a lot,since 3Cr12 was mainly used for applications without welding.There is limited weldability data in the published literature. EN1.4003 steel is modified from conventional 3Cr12 stainless steelby decreasing the C content to well below 0.03% which is regardedas the limit for low carbon steels to improve the weldability. Also,the amount of titanium is limited, because titanium tends to formbrittle carbide phases in the HAZ of a welded joint. Advanced steelmaking technology now enables tight control of composition andcan provide extremely low levels of carbon and nitrogen with sig-nificant improvement in the as welded HAZ properties, as well asthe reduction of chromium carbides which degrade corrosion per-formance. Modified X2CrNi12 stainless steel still conforming togrades 1.4003 in EN 10088-2 and EN 10028-7 and UNS S41003in ASTM A240, with a quite low carbon level of 0.01% enhancingthe weldability and mechanical properties has recently been pro-duced. This modified 12% Cr low carbon ferritic stainless steel pro-vides an alternative which displays both the advantages ofstainless steels and engineering properties of carbon steels. In caseattention is paid for using the correct welding parameters to en-sure good joint integrity, this combination opens up a wide rangeof applications. Initial applications of these 12% Cr stainless steelswere consisted of materials handling equipment in corrosive envi-ronments, but the 1.4003 type of steels are now extensively used inthe coal and gold mining industry, for sugar processing equip-ments, road and rail transport, power generation, for petrochemi-cal, metallurgical, pulp and paper industries and in aerospaceengineering. Although it has higher initial cost, modified X2CrNi12stainless steel provides lower total life costs due to longer life withless coating renewals and lower maintenance offering significanteconomic and environmental advantage with regard to carbon

steels. For other applications, it would be more economical com-pared to higher alloyed stainless steels [3,14–18,22,29–49].

Recent years, the interest has been increased in applying plas-ma arc welding (PAW) process in industry due to the higher weld-ing speeds providing improved productivity and producing weldswith high penetration/width ratios [48]. Since modified X2CrNi12stainless steel is relatively new, plasma arc or hybrid weldabilityor welding properties of this modified 12% Cr stainless steel gradehas not been well determined yet. Taking into account of theincreasing interest in demands of using this steel as high strengthstructural stainless steel and hybrid welding for industrial applica-tions, this study focused on hybrid (plasma + gas tungsten arc)welding of modified X2CrNi12 ferritic stainless steel plates.

In this study, properties of hybrid (PAW + GTAW) welded jointsof modified 12% Cr stainless steel conforming to EN 1.4003 andUNS S41003 steels using austenitic stainless steel type of consum-ables such as 309 and 316 have been investigated. Mechanical andimpact toughness testing and microstructural examinationsincluding macro-microstructures, grain size and ferrite contentanalyses were carried out to evaluate the welds. Effect of consum-able type on the properties has been discussed. In addition, prop-erty-microstructure relationship was analyzed and explained.

2. Material and experimental studies

Chemical composition data obtained from chemical analysisand transverse tensile properties provided from the steel producerfor the 12 mm thick modified 12% Cr stainless steel conforming togrades 1.4003 and UNS S41003, respectively in EN 10088-2 and EN10028-7 and in ASTM A240 are given in Table 1.

To ensure tougher weld metal yielding adequate properties re-quired for structural purposes and to minimise the risk of heat af-fected zone (HAZ) hydrogen cracking, austenitic stainless steelfiller metals are generally recommended in producing arc weldsof 1.4003 type of grades in applications where dynamic loadingis anticipated. [3,5,14,15,39]. Hybrid welded joints of modified12% Cr stainless steel were obtained by hybrid (plasma + gas tung-sten arc) welding process. Two types of hybrid welded panels wereproduced with 309L and 316LSi type of austenitic stainless steelconsumables. The chemical composition of the filler metals are gi-ven in Table 2. First welded joint-named as L9 was produced withan ER309L wire of 1.2 mm diameter protected by Ar as plasma gasand 30He/70 Ar as shielding gas. Y groove preparation with anopening angle of 90� was used. Similar conditions were used withan ER316LSi wire of 1.2 mm diameter to produce second weldedjoint-named as L6. Root passes were produced with plasma arcwelding (PAW) in one pass while multi passes with gas tungstenarc welding (GTAW) were used for filler passes for both joints,The total heat input varied from 4.1 kJ/mm to 4.3 kJ/mm for eachweld.

Transverse tensile specimens were prepared with respect to EN10002-1-EN 895 from both welds and tested at room temperatureby a servohydrolic tensile test machine at room temperature. Faceand root bend test specimens removed from both welds transverseto the weld seam were prepared with a nominal specimen width of30 mm, a mandrel diameter of 55 mm. Bending test was executedtill 180� according to EN 910 unless severe cracking was observedbefore. Notch impact test samples were extracted transverse toeach weld and notched at the weld metal centre (WM), the fusionline (FL), at the heat affected zone 2 mm from the fusion line(FL + 2 mm). Testing was performed due to EN 10045-1 at�20 �C, 0 �C and 20 �C. Cross-sections from both welds were pre-pared, polished and etched with proper reagent for metallographicexamination. Macro- and micrographs of the weld zones were ob-tained. Complete HV5 traverses were made according to EN 1043-1

Table 1Chemical composition (in wt.%) and tensile properties of the modified 12Cr ferritic stainless steel base metal.

C Si Mn P S Cr Cu Ni Mo Ti V Al Nb N (ppm)

0.01 0.32 0.97 0.033 0.003 12.2 0.39 0.52 0.14 0.001 0.039 0.027 0.031 90

Yield strength (MPa) Ultimate tensile strength (MPa) % Elongation

362–363 500–502 30–32

Table 2Chemical composition in wt.% of the consumables [1].

Type of consumable C Si Mn P S Cr Ni Mo

309L 0.04 1.0 0.5–2.5 0.04 0.03 22.0–25.0 12.0–14.0 0.75316LSi 0.03 0.65–1.0 1.0–2.5 0.03 0.03 18.0–20.0 11.0–14.0 2.0–3.0

40

80

120

160

Mea

n im

pact

ene

rgy

(J)

WM

FL

FL+2mm

a

4238 E. Taban et al. / Materials and Design 30 (2009) 4236–4242

at sub-surface from both face and root sides of each weld. Longitu-dinal sections entirely located at the weld metal were preparedperpendicular to the plate surface for the chemical analysis of allweld metal samples. Three measurements were taken by glow dis-charge optical emission spectrometry (GDOES) and averaged foreach element. Ferrite content of the weld metals for both jointswas calculated and predicted by chemical analysis results. Ferritecontent was determined by Fisher Ferritscope measurementsacross the weld metal and compared with the predicted data.Macro sections of all welds were examined at the HAZs adjacentto the fusion line from both right and left sides and the ASTM grainsize numbers were measured at four thickness positions from sub-surface to mid-thickness [32].

3. Results and discussion

Overmatching transverse tensile results were obtained whilefracture occurred at the base metal. Splitting close to the fracturesurfaces parallel with the plate surface was observed, Fig. 1. It isattributed to intergranular decohesion along ferrite and martensitegrain boundaries [28].

None of the face and root bend samples failed during bendingrevealing no defects after testing till 180�. The mean notch impactvalues of the joints expressed in J are illustrated in Fig. 2. In generalweld metal toughness values of weld L9 which was produced with309 type of consumables reveal better results, Fig. 2a, compared tothose from weld L6 with 316 type of filler metals, Fig. 2b. Although309 consumables led increased weld metal toughness properties,316 type of consumables provided better HAZ toughness data forhybrid welded joints of modified 12% Cr ferritic stainless steel at

Fig. 1. Fractograph from Weld L9 exhibiting splitting of the base metal.

sub-zero temperatures. When 27 J and 20 J at �20 �C are taken intoaccount as required mean and individual toughness values, respec-tively [32,42–49], all samples from both joints passed the requiredconditions by means of impact toughness except the samples fromthe joint-L9 at the notch position of FL+2 mm.

Relevant photomacrographs obtained from the hybrid (plas-ma + gas tungsten arc) welded joints of modified 12Cr ferriticstainless steel are given in Fig. 3. Similar amount of distortion oc-curred for both joints, while weld bead of the second joint-L6 pro-duced with 316 type of consumables is wider with regard to that ofL9 with 309 type of consumables.

The microstructural examination has been carried out on themetallographic specimens of the joints using a light optical micro-scope (LOM) mainly with 200x magnification, Figs. 4 and 5. Theinvestigation of the welds has been performed from base metal(BM) across the heat affected zone (HAZ) to weld metal (WM),

0 -40 -20 0 20 40Temperature (°C) - [L9]

0

40

80

120

160

-20 -20 -20Temperature (°C) - [L6]

Mea

n im

pact

ene

rgy

(J)

WM

FL

FL+2mm

b

Fig. 2. Charpy impact toughness graphs of the hybrid welds of modified 12% Crstainless steel (a) Weld L9 with 309, and (b) Weld L6 with 316 type of consumables,respectively.

Fig. 3. Macrographs from the hybrid welded joints (a) L9 and (b) L6.

Fig. 4. Micrographs of 12 mm thick hybrid (PA + GTA) weld with 309 type of filler metal (L9) (a) BM 200�, (b) root WM by PAW without filler metal 200�, (c) filler pass WMby GTAW with 309 type of filler metal 200�, (d) root HAZ 50�, (e) face HAZ 50� and (f) face HAZ 200�.

E. Taban et al. / Materials and Design 30 (2009) 4236–4242 4239

Fig. 5. Micrographs of 12 mm thick hybrid (PA + GTA) weld with 316 type of filler metal (L6) (a) BM 200�, (b) root WM by PAW without filler metal 200�, (c) filler pass WMby GTAW with 316 type of filler metal 200�, (d) root HAZ 50�, (e) face HAZ 50� and (f) face HAZ 200�.

4240 E. Taban et al. / Materials and Design 30 (2009) 4236–4242

respectively. WM of root pass by PAW and WM of filler passes byGTAW are presented.

HAZ for 12% Cr stainless steels have two visually distinct zones,the high-temperature HAZ (HTHAZ) and the low temperature HAZ(LTHAZ) [14,15,32]. The steel is heated close to the liquidus duringwelding and transforms completely to delta ferrite and rapid graingrowth occurs. On cooling, the reversion to austenite occurs andthe HTHAZ frequently consists of coarse-grained delta ferrite, Figs.4d–f and 5d–f with islands of martensite at the grain boundaries.For the sample from both welds, lath martensite has also been ob-served at the fused metal, Figs. 4b and 5b. When the material tem-perature reaches 1050 �C within 1–2 s, no reversion to austeniteoccurs and the delta ferrite structure maintains to room tempera-ture. However, material heated to the temperatures between Ac1and Ac5 contains significant fractions of austenite which trans-forms to martensite, results in a tougher finer-grained structure[15,16], left parts of Figs. 4f, 5e and f. Depending on the austenitictype of filler metals at the weld deposit, increased austenitic struc-

ture has been observed for both welds, Figs. 4c and 5c, compared toroot passes without filler metal, Figs. 4b and 5b. The microstruc-tural and mechanical properties of the weld bead can be improvedby proper selection of filler metals by the addition of alloying ele-ments or the electromagnetic stirring, however properties of theHAZ are mainly dependent on the base metal’s [51]. This is con-firmed by the weld metal toughness data which are better thanthose of HAZ for both welds in Fig. 2.

The experimental data obtained from chemical analysis for theall weld metal are given in Table 3.

Depending on the chemical composition of all weld metal dataobtained by GDOES and according to the Balmforth and Lippoldconstitution diagram for as solidified weld metal [52], 15.4 and3.38 were calculated as Creq and Nieq values of weld metal for weldL9, while 16.21 and 3.89 were found, respectively for Creq and Nieq

of weld L6. When related data is shown on the diagram, the weldmetal was predicted to contain approximately about 70% ferritefor L9 and about 75% ferrite for L6. Ferrite content of the weld me-

Table 3Chemical composition of the weld deposits (in wt.%) of modified 12% Cr stainless steel hybrid welds.

Joint code C Si Mn P S Cr Cu Ni Mo Ti V Al Nb

L9 0.01 0.35 1.07 0.030 0.003 14.80 0.34 3.03 0.14 0.003 0.053 0.029 0.001L6 0.01 0.47 1.08 0.031 0.004 14.40 0.32 3.54 0.74 0.003 0.055 0.030 0.001

Table 4Ferrite percentage analysis of the hybrid welded joints.

Joint code Root pass (PAW) (ferrite %) Filler passes (GTAW) (ferrite %)

1 2 3 4 5

L9 69.02 88.97 15.32 14.27 18.48L6 36.83 89.33 17.63 25.97 19.96

E. Taban et al. / Materials and Design 30 (2009) 4236–4242 4241

tal of the samples prepared from hybrid welds were measured byFisher Ferritscope and the data are given in Table 4.

Approximately 15% and 20% ferrite were measured on GTAWfiller passes and 80% and 60% ferrite were measured on the rootpasses of weld (fused) metals produced by PAW for weld L9 andweld L6, respectively. Average weld metal ferrite content ofapproximately 40% was measured for both joints which is far fromthe predicted data due to two different types of processes usedwith various consumables. Taking into account that the root passesof both welds were produced with plasma arc welding processwithout filler metal, more ferrite is expected and was measuredat the root parts (fused metal) of both welds. Depending on the in-creased Mo and Ni content of 316 type of consumables, increasedferrite content was determined at the GTA filler passes of weldL6. On the micrographs as illustrated in Figs. 4 and 5, grain coars-ening has been observed mainly at the root HAZs of both weldssince the solidification structure was almost 80% and 60% of ferritefor the joints-L9 and L6 for root passes which was produced byPAW without filler metal. According to impact testing results, itis observed that the grain coarsening of the welded joints have af-fected the low temperature (such as at �20 �C) impact toughness

140160180200220240260280300

BM BMHAZ

HAZHAZu

HAZdWMWM

HAZdHAZu

HAZHAZ BM BM

BM BMHAZ

HAZHAZu

HAZdWMWM

HAZdHAZu

HAZHAZ BM BM

L9

Har

dnes

s (H

V5)

Har

dnes

s (H

V5)

FaceRoot

140160180200220240260280300

L6

FaceRoot

(a)

(b)

Fig. 6. HV5 graphs of (a) L9 and (b) L6.

values. One of the factors of resulting low toughness at the HTHAZof L9 might be this high level of ferrite at the root HAZ since no fil-ler metal was used leading to 80% ferrite content at this particularzone for weld L9. And due to the tougher austenitic type of fillermetal deposition for filler passes with GTAW in both welds, HAZreveals finer-grained structure compared to root passes withPAW without filler metal. This microstructural difference betweenfiller passes and root passes are confirmed with the lower ferritecontent measurements of both L9 and L6 joints, Table 4.

ASTM grain size numbers were measured to investigate the cor-relation between toughness and microstructure. In general poorfusion line toughness corresponds with coarse grains such as ASTMgrain size numbers of about 4 at the FL notch position and about 3at the FL+2 mm notch position of L9 while finer grain size such asASTM No. 4 or 5 was measured from the samples of L6 for FL andFL+2 mm notch positions of 12% Cr stainless steel hybrid welds.Studies [1,5,14,15,39,50] reveal that impact toughness of the HAZof 12% Cr steels are significantly affected by increased ferrite. Ingeneral, microstructural properties in terms of micrographs, grainsize and ferrite content correspond to toughness properties ofthe welds. Finer ferrite grain size led to improved toughness forthe hybrid welds of modified 12Cr ferritic stainless steels. Thepresence of ferrite–austenite transformation in 12Cr ferritic (–mar-tensitic) stainless steels leads decrease in grain coarsening of HAZcompared to fully ferritic stainless steels providing better welda-bility. Although martensite formation decrease toughness and duc-tility deterioriating the mechanical properties, the martensiteformed in these type of steels is low carbon martensite whichhas better ductility and toughness compared to high carbon mar-tensite phase [5,51].

Hardness measurements carried out with 5 kg load over theweld cross-sections are illustrated in Fig. 6.

WM hardness for L9 varied between 166 HV5 and 190 HV5while data between 162 HV5and 198 HV5 were measured for L6WM. Maximum hardness of 262 HV5 and 267 HV5 were measuredat the face of the HAZ for L9 and L6, respectively.

4. Conclusions

Modified 12% Cr stainless steel with a carbon level of 0.01% con-forming to EN 1.4003 and UNS S41003 steels were welded via hy-brid (plasma + gas tungsten arc) welding process with austeniticstainless steel consumables of 309L and 316LSi. The mechanical,impact toughness and microstructural properties were investi-gated. Main conclusions are as follows:

(1) Sound joints of modified 12Cr ferritic stainless steel could beobtained by means of hybrid welding since tensile and bendtesting exhibited satisfactory results.

4242 E. Taban et al. / Materials and Design 30 (2009) 4236–4242

(2) Toughness testing results at �20 �C, 0 �C and 20 �C revealthat weld metal toughness values are generally better forthe joint-L9, compared to those from the joint-L6 due tothe tougher 309 type of consumables used to produce L9while better HAZ toughness data were obtained from thejoint-L6 produced with 316 type of consumables for sub-zero temperature.

(3) In microstructural examinations, some grain coarsening wasdetermined mainly at the HTHAZs and fused metal at theroot weld metal produced by plasma arc welding without fil-ler metal. Coarse ferrite grains do not have any adverseeffect on tensile nor on bend properties but they lead to rel-atively low impact toughness only for sub-zero temperaturedepending on the amount of grain coarsened microstruc-tures, such as ASTM numbers of between 3 and 4 deter-mined by grain size analysis and ferrite content (in %), i.e.between 60% and 80% for the fused metal at the root for bothwelds.

(4) Hardness at the HAZ can be limited to 270 HV5 for thehybrid welds which is within the safe frame for structuralapplications.

In case the hybrid welding of modified 12% Cr ferritic stainlesssteel with controlled welding conditions is provided and micro-structure-property relation of the joints is well understood, theproductivity and the application of this modified low carbon 12%Cr ferritic stainless steel as a high strength structural steel wouldsignificantly increase.

Acknowledgements

The authors would like to acknowledge for the technical sup-port of all colleagues at the Belgian Welding Institute and espe-cially to Ir. Eddy Deleu. In addition, the support of IWT, TechnicalCentre for Welding Applications (CTAS) at Paris, University ofGhent, WTCM are very much appreciated and acknowledged. Verymuch thanks to Ir. Eric Sterkx for his technical support. The firstauthor would like to thank to Tubitak for the support.

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