ThermalandResidualStressDistributionsinInconel625 Butt

Research ArticleThermal and Residual Stress Distributions in Inconel 625Butt-Welded Plates Simulation and Experimental Validation

Harinadh Vemanaboina1 Edison Gundabattini2 Kaushik Kumar 3 Paolo Ferro4

and B Sridhar Babu5

1Department of Mechanical Engineering Sri Venkateswara College of Engineering and Technology (Autonomous)Chittoor 517127 India2School of Mechanical Engineering Vellore Institute of Technology Vellore 632014 India3Deaprtment of Mechanical Engineering Birla Institute of Technology Mesra Ranchi India4Department of Engineering and Management University of Padova Stradella S Nicola 3 Vicenza 36100 Italy5Deaprtment of Mecanical Engineering CMR Institute of Technology Hyderabad India

Correspondence should be addressed to Kaushik Kumar kkumarbitmesraacin

Received 9 August 2021 Revised 13 September 2021 Accepted 23 September 2021 Published 19 October 2021

Academic Editor Abılio De Jesus

Copyright copy 2021 Harinadh Vemanaboina et al +is is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited

+ermal and residual stress distributions induced by the gas tungsten arc welding (GTAW) process on Inconel 625 were studiedusing numerical simulation and experiments A multi-pass welding model was developed that uses a volumetric heat source+ermomechanical analysis is carried out to assess the +ermal and residual stress distributions Experiments were carried outwith 5mm thick Inconel 625 plates X-ray diffraction techniques were used to measure residual stresses and IR thermometry wasemployed to capture the temperature values on the welded joints Simulations were performed with ANSYS numerical code and aclose agreement was found between the predicted and experimentally measured residual stress +ermal measurements werecollected pass by pass from the analysis and the agreement was 908+e agreement between the measured and analysed residualstress was 11

1 Introduction

Fusion welding is one of the major joining techniquesemployed in industrial applications In particular gastungsten arc welding (GTAW) allows yielding sound weldswith different alloys +e selection of welding process pa-rameters is one of the major challenging tasks to controlwelding residual stresses and distortions Further thesewelding process parameters will affect structural integrityExperimental tests can be performed to estimate the im-provement in parameters but they are expensive and alsoquite time-consuming in this scenario welding numericalsimulation may help avoid such drawbacks Kermanpuret al [1] developed an FEA model for multi-pass GTAWprocess of Incoloy 800 pipes Temperature results obtainedby using volumetric heat source were in good agreement

with those obtained employing thermocouples located at theheat-affected zone of the joints However the authors didnot focus on residual stresses caused by the joining processIn another recent work Balram and Rajalakshmi [2] re-ported the experimental results regarding thermal stressesand thermal fields developed in the GTAW process appliedto similar and dissimilar welded joints +e ERNiCrMo-3alloy was used as filler wire Tensile tests showed that thefailure occurred within the parent metal proving the highquality and strength of the welded joints obtained Korrapatiet al [3] investigated the weldability and metallurgical andmechanical properties of the PCGTA welded Inconel 625alloy employing ERNiCrMo-3 filler wire In this case despitethe fact that defect-free welded joints were obtained failuresoccurred at the weld region and the average tensile strengthof the weldments was found to be 8524MPa

HindawiAdvances in Materials Science and EngineeringVolume 2021 Article ID 3948129 12 pageshttpsdoiorg10115520213948129

In order to decrease the computational time withoutlosing accuracy Peric et al [4] proposed a T-joint numericalmodel conducted by combining the shell and 3D finite el-ements Results of thermal and displacement distributionswere found in good agreement with those measured in realjoints Finally the influence of the 3D model size on thetemperature residual stress and displacement distributionswas investigated Vemanaboina et al [5] studied the residualstress evolutions in multi-pass dissimilar joints (IN 625-AISI316L) +e L4 orthogonal array was chosen for the tests Twolevels of each welding factor filler wire and root gap pa-rameters were chosen for the experiments It was concludedthat the pulsed current-induced low residual stresses in theweld region were within the factor of safety of parent ma-terials In subsequent work [6] they deepened the weld-ability of such similar and dissimilar welded jointsWeldments free from defects and stresses within the yieldlimits of the base materials were obtained In computationalweld mechanics (CWM) [7 8] the thermal load is obtainedby using power density distribution functions that calibrateparameters using experimental results +is approach allowsreducing the computational time required to calculate theresidual stresses and distortions compared to that needed bymodels based on fluid dynamic analyses

Nine different welding sequences [9] were used to find thebest conditions that minimized distortions and residualstresses in a T-weldment +e simulation was carried out byusing ABAQUS numerical code As expected the best con-ditions were achieved when joining both sides in the samedirection and at the same time Kamble and Rao [10] de-veloped a three-dimensional sequentially coupled thermo-mechanical model of 10mm thick plate +e GMAW processwas used for joining two 3Cr12 stainless steel plates +ethermal study was carried out at different time intervals+ermally induced residual stress was predicted using ANSYSnumerical code In that work the authors described the effectof process parameters on thermal and structural behaviour ofthe welded joints Attarha and Sattari-Far described a thermalstudy of similar and dissimilar single-pass butt-welded joints[11] A 3D numerical model was developed with ABAQUSregand the Goldak heat source was used to simulate the thermalinput of the process (GTAW) Excellent agreement was ob-served between numerical and experimental temperaturevalues measured with k-type thermocouples located in theheat-affected zone (HAZ) Capriccioli and Frosi [12] carriedout a computational analysis of the multi-pass weldingprocess for dissimilar materials +e 316L stainless steel toIN625 welding simulation was carried out for both TIG andlaser welding using ASNSYSreg +e mechanical results werefound very sensitive to the mesh shape which had to be veryfine and regular close to the fusion zones In that work aneffort was made to reduce the CPU time that is the majorobjective to achieve when simulating a multi-pass weldingprocess Lostado et al [13 14] used finite element models tobetter understand heat behaviour and its impact on angulardistortion and bead shape in GMAW butt weldments +estudy employed genetic algorithms with multi-objectivefunctions+e influence of heat input reveals growing angulardistortion and weldment bead shape +e FEA models and

experimental findings correlate well Another work reportedthat the tensile residual is maximum at the fusion zone andalso stated that the findings of the FEA were in agreementwith the experimental results [15]

Weld beads and related regions undergo plastic defor-mation during the welding process as a result of heating andcooling cycles resulting in residual stress +ermal andlattice spacing impact residual stresses in weldmentsresulting in microstructure changes and thermomechanicalstresses With the help of FEA it is possible to forecast thedegree of heat effect in the weldment Since no work hasbeen published on the in situ thermal behaviour studyduring GTAW for Inconel 625 material the authors believethat there is a lack of confirmation on simulations for theestimate of temperature profiles and residual stressesMultipass welding of Inconel 625 with GTAW processconditions is the major focus in the present planned studyWelded components are analysed in 3D to determine theirthermal and residual stresses With the ANSYSreg packageAPDL code is used to do thermomechanical analysis In-frared thermography is used to measure welding tempera-tures X-ray diffraction is used to evaluate residual stresses ina weldment after it has cooled to ambient temperature forverification

2 Finite Element Analysis

Figure 1 shows an overview of the present numerical modelANSYS package was used to develop the welding simulation+e plate has a square butt groove with no gaps between thetwo parts According to the real butt-welded joint thicknessthe FZ height was increased by 17mm at each run takingadvantage of the activation-deactivation function of ele-ments implemented in ANSYS code (Figure 2) roughlyequal to that of weld bead measured by experiment +ethermal analysis was computed with the 8-node thermalelement [16] SOLID70 and then switched to the 8-nodefinite element SOLID45 for the subsequent structural cal-culation +e two types of mesh options are used for thesimulation models +e finer mesh is applied at fusion zonewith a mesh size of 15mm and coarse mesh is applied to therest of the plate with a mesh size of 3mm as shown inFigure 3 In this study an equal time interval is assumed forevery pass as heating time +e temperature-dependent [12]thermal and mechanical properties considered for Inconel625 for the present study have been depicted in Figure 4

Goldak et al proposed double ellipsoidal heat sourcemodel for the arc welding process [17] For present weldsimulations the moving heat source model is treated asvolumetric heat flux with constant heat input throughout thelength For each weld pass the bead size initial boundaryconditions are defined along with volumetric heat flux +econstant heat input loads are calculated as per the weldingprocess parameters shown in Table 1

+e volumetric heat flux [18 19] of each weld pass isdetermined using the following equation

Q ηUI

V (1)

2 Advances in Materials Science and Engineering

where η is the arc welding efficiency U is the voltage I is thewelding current and V is the volume of weld pass +evolume of the bead is added for each as shown in Figure 2+e value of arc efficiency is assumed to be 065 for theGTAW welding process +e heat conduction equation forwelding simulation is given by

z

zxk

zT

zx1113888 1113889 +

z

zyk

zT

zy1113888 1113889 +

z

zzk

zT

zz1113888 1113889 + Q minusρCp

zT

zt

(2)

where ρ is the density Cp is the specific heat under constantpressure and k is the parent material conductivity +ecoefficient of heat transfer rate was calculated for theweldment (equation (3)) Heat loss by convection was ap-plied at the top and side faces of the weldment while heatloss by both convection and radiation (equation (4)) wastaken into account over the surface of the third weld beadobtained during the last welding run In equations (4) and

(5) T0 is the ambient temperature εis the emissivity of theparent material σ is the StefanndashBoltzmann constant and h isthe convective heat coefficient

H 241lowast 10minus4 εT161 (3)

qc h T minus T0( 1113857 (4)

qr εσ T4

minus T04

1113872 1113873 (5)

Boundary conditions were applied in order to simulatethe thermal behaviour induced by the three passes

(1) For pass-1 initial temperature was ambienttemperature

(2) Convention was applied at the root opening of theplates for pass-1 and pass-2

(3) In pass-3 both convection and radiation werespecified only on the top surface of the weld plate

TypicalWeld Joint

WeldingConditions

WeldingMaterials

FEM Model Heat Input ermo-PhysicalProperties

InitialBoundaryConditions

MechanicalBoundary

Conditions

Transient ermalAnalysis FEM

ermo-mechanical

MechanicalProperties

Results(Residual stress Distortion)

Temperature Results

Figure 1 Overview of the thermo-elastic-plastic FEM analysis procedure

(a)

(b)

(c)

Figure 2 Simulation models for each pass (a) Model for pass-1 (b) Model for pass-2 (c) Model for pass-3

Advances in Materials Science and Engineering 3

8450

8400

8350

8300

8250

8200

8150

8100

8050

750

700

650 Specific heat (Jkg K)

600

550

500

450

400

200 400 600 800 1000 1200 1400 1600

Temperature (K)

Den

sity

(kg

m^3

)

Density

Specific heat

200 400 600 800 1000 1200 1400 1600

Temperature (K)

30

25

20

15

10

er

mal

cond

uctiv

ity (W

m K

)

ermal conductivity

(a)

200E+011

180E+011

160E+011

140E+011

120E+011

100E+011200 400 600 800 1000 1200 1400

Temperature (K)

Elas

tic m

odul

us (P

a)

IN625

200 400 600 800 1000 1200 1400 1600

Temperature (K)

400E+008

300E+008

250E+008

200E+008

150E+008

100E+008

350E+008

500E+007

000E+000

Yiel

d St

reng

th (P

a)

IN625

(b)

Figure 4 Temperature-dependent material properties

Figure 3 Meshing of the model


(4) +e inter-pass [20] temperature is considered forpass-2 and pass-3 to avoid hot cracking +e initialtemperature for pass-I is ambient ie 30degC and forpass-2 and pass-3 it was maintained at about200ndash250degC

3 Experimentation Procedure

+e real butt-welded joint was produced by the GTAWtechnique +e dimensions of the plates were100mmlengthtimes 60mm widthtimes 5mm thickness as shown in Fig-ure 5 +e single V-groove angle of 60deg was used +e gapbetween the plates was filled with three passes pass-1 (rootpass) pass-2 (filler pass) and pass-3 (cap pass) ERNiCrMo-3 was used as filler wire Base material and filler wirechemical composition are given in Table 2+e base materialmechanical properties are listed in Table 3 +e processparameters chosen for experimentation are welding current(I) root gap (RG) and shielding gas flow rate (G) and aresummarized in Table 1

Welding current root gap and Argon flow rate were setto 145 A 2mm and 15LPM respectively +e same pa-rameters are used for all passes To avoid the hot cracking inthe weld an inter-pass temperature [21] (sim150ndash2500C) ismaintained between the runs Sound welded joints wereobtained and surface cracks and defects are verified byvisual inspection and X-ray radiography

31 Measuring Techniques

311 Infrared ermography Infrared thermography andX-ray diffraction techniques are employed to measure thermaland residual stresses in the welded joints +e weld pooltemperatures are recorded during each pass of the weldingprocess with infrared thermography +e temperatures weremeasured using the FLIR infrared thermography with anaccuracy of plusmn01C +e thermal imager measures the amountof heat emitted by the surface +e infrared thermography isused for measuring the temperature in the weldment+e basematerial surface-emission efficiency is necessary for measuringthe surface temperature of the joint In this work the emissivitywas taken equal to ε 09 Figure 6 shows how the infraredthermography works

312 X-Ray Diffraction +e weld area undergoes a heatingand cooling cycle during the welding process +e thermalexpansion and contraction of the parent material affectresidual stresses and distortions Figure 7 displays the BrukerD8-DiscoverTM diffractometer for measuring residualstresses Figure 8 shows the VantecTM area locator and

goniometer head is used for microfocus with laser trackingTable 4 summarizes the measuring parameters

+e residual stresses were calculated by using Braggrsquoslaw(equation (6))

nλ 2d sin θ (6)

where n refers to the order of reflection beam d is theinterplanar lattice spacing λ is the wavelength of the inci-dent wave and θ is the scattering angle In the transversedirection the residual stresses are measured on the topsurface and calculation [22] of the residual stress is carriedout by using the following equation

σϕ m

d0

E

1 + ]1113874 1113875 (7)

where E is Youngrsquos modulus ] is Poissonrsquos coefficient d0 isthe stress-free lattice spacing andm is the slope of the curvedrawn between d (spacing) and sin2Ψ

4 Result and Discussion

ANSYS (APDL) was used for modelling meshing andtransient thermal and static structural analysis +e com-putational welding mechanics technique was applied toreduce the CPU time by solving in a consecutive manner thethermal and the mechanical analysis for each welding passTemperatures and residual stresses at nodes were analysed inthe transverse direction of the weldments +e details areillustrated in further sections given below

41 ermal Distribution +e welding cycle time was 40 sfor all the passes+e cooling cycle was maintained for about1000 s after the last welding run Between a welding pass andthe other one an inter-pass temperature of about 250degC wasmaintained to avoid hot cracking Figure 9 illustrates thenumerically assessed temperature map During the firstwelding pass a maximum temperature of 2080degC was ob-served whereas the second pass induced a maximumtemperature equal to 2158degC and a minimum temperature of250degC (imposed inter-pass temperature) Finally the pass-3produced a maximum temperature of 1707degC +e maxi-mum temperature was experimentally seen at the weld zoneof the real joints +e heat is collected at the weld zone of thejoint and extends in the transverse direction which leads toform the HAZ A narrow FZ was observed due to the lowthermal conductivity of the analysed alloy

42 ermal Analysis Using Infrared ermography+ermal distribution during the welding is displayed inFigures 10(a)ndash10(c) Line-1 represents the longitudinal and

Table 1 Multi-pass welding process parameter

Pass no Welding current (I) Root gap Argon gas flow rate Time for each passA mm LPM s

Pass-1 1452 12

36Pass-2 145 27Pass-3 145 31


60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP

INCONEL625INCONEL625

20200

Figure 5 Multi-pass welding process

Table 2 Base plate and filler material chemical properties (wt )

Samples Ni C Mn S Cu Si Cr P Fe Al Mo Ti OthersInconel 625 58 01 05 0015 05 05 20ndash23 0015 5 040 8ndash10 01 mdashFiller wireERNiCrMo-3 64 01 05 0015 050 05 22ndash23 0015 1 040 0015 040 Nb 36ndash45

Table 3 Parent material mechanical properties

Material Yield strength (YS) (MPa) Poissonrsquos ratio Coefficient of thermal expansionInconel 625 254 028 123eminus6

Infraredscanner

ControlConsole

B amp W colourmonitor

Personalcomputer

Video thermalrecorder

Colour printer

Figure 6 Illustration of thermography system

Figure 7 Bruker X-ray diffraction


line-2 for the transverse direction of the weld plate re-spectively as shown in Figure 10(a) +e temperatures canbe recorded at any point of time and the current ther-mography results are reported at the welding zone in thelongitudinal and transverse directions at the instance oftime Figure 10(a) shows the temperature distribution rangesfrom 500degC to 17795degC in the transverse direction and from500degC to 1580degC in the longitudinal direction During thesecond welding pass the measured maximum temperatureswere 1838degC and 1867degC in the transverse and longitudinaldirections respectively (Figure 10(b)) +e temperaturedistribution as shown in Figure 10(b) was waving up anddown because the material was filled in the root gap fillerand cap (Figure 5) +e maximum interpass temperature250degC was maintained in between the passes Figure 10(c)shows the final welding pass the maximum temperatureswere reported to be 1325degC and 1878degC for the longitudinaland transverse directions respectively +e measured torchtemperature value was1000degC

+e experimental and numerical peak temperaturevalues at each welding pass are compared in Figure 11 It isobserved that the thermal results of FEA simulation slightlydiffer from experimental ones +is phenomenon is due tothe fixed time assumption for all the welding passes ie 40 s

+e FZ geometry and dimensions are shown in themacrograph of Figure 12 It was wide with 1138mm on thetop of the weld 569mm in the midsection (25mm thick)and 67mm on the bottom of the plate Metallographicexaminations revealed a sound weld without defect and afully penetrated bead +e filler wire is mixed well withparent material and homogeneous joint was formed

43 Residual Stresses +e residual stress developed acrossthe welding direction of various weldments using simulationis reported here +e residual stress distribution is shown inFigure 13 After pass-1 the weldment experiences com-pressive stress of minus200MPa at fusion zone and minus120MPa atthe end of the plate as shown in Figures 13(a) Figure 13(b)shows the residual stresses induced by pass-2 +ey rangefrom minus110MPa in fusion zone to 120MPa close to the HAZ+e parent metal is stress free After pass-3 the total plateexperiences tensile stresses with a value of 178MPa in theFZ and 18MPa far from it (at the end of the plate)(Figure 13(c))

+e measured tensile residual stress distribution wasobserved at weld zone and compressive stress in remainingzones +is is due to the expansion of the material duringwelding and high temperatures at the fusion zone howeverthis expansion is retarded by the neighbouring base metalregion +e material experiences contraction while coolingto maintain the platersquos original dimension which generatesplastic deformation At HAZ it undergoes high-stressconcentration to maintain the equilibrium betweenshrinkage action of the base plate and the solidification of themolten weld pool It is determined that balanced stressdistribution in the weldment is due to uniform thermalconductivity along the plates Figure 14 shows the com-parison between experimentally measured and numericallypredicted residual stresses analysed for a welded joint It isobserved that the material experiences tensile stresses nearthe weld bead +e maximum experimental and numericaltensile stress was observed to be 200MPa and 178MParespectively Further it was verified that the stresses were not

Detector

2θ rotationω rotation

Primary X-ray beam

SampleDiffracted beam

X rotation

φ rotation

Figure 8 Goniometer head with a detector

Table 4 XRD measuring parameters

Measurement Transverse directionTube Mn_K-AlphaBragg angle 1550degPeak location Gaussian-80D-spacing (Angstroms) 10771016Wavelength 2103


309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)

Figure 9 Distribution of temperatures in the weldment (a) Weld pass-1 (b) Weld pass-2 (c) Weld pass-3

6275 degC degC600

2000

1000

0

Li1 Cursor - Min lt2000 Max 15800Li2 Cursor - Min lt2000 Max 17795

400

2000

(a)

Figure 10 Continued


self-balanced in the structure Temperature measurementswere collected pass by pass from the analysis and theagreement was 908+e agreement between the measuredand analysed residual stress was 11 Due to the influence ofheat input in small areas during establishing the weld jointthe regions next to the weld line undergo severe thermalcycles resulting in an increase in residual stresses +e result

will be a reduction in the structurersquos life +e same was seenin the current investigation for welding simulation resultswith an increase in the error percent of residual stressesStudies have shown that the maximum residual stress occursdue to the assumption of a constant welding duration in thesimulation In the experiment the welding duration ischanged depending on the weld machinersquos duty cycle and

degC

2000

3000

1000

0

Li1 Cursor - Min 2992 Max 18672Li2 Cursor - Min lt2000 Max 18380

12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)

Figure 10 Infrared thermography pass-wise analysis during the process (a) Pass-1 IN625 to IN625 (b) Pass-2 IN625 to IN625 (c) Pass-3IN625 to IN625

2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2

Pass wise measurement

Pass-2

ermography

Simulation

Figure 11 Comparison of thermal distribution


Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0

Various Zones of measurement

1 2

Pass-1 Residual Stresses (MPa)

(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0

Various Zones of weldment

1 2

Pass-3 Residual Stress (MPa)

(c)

Figure 13 Distribution of residual stress using FEA (a) Weld pass-1 (b) Weld pass-2 (c) Weld pass-3

Figure 12 Weld bead geometry of the final weldment


when the filler wire melts and solidifies Additionally inLostado et alrsquos research [15] they noted that the weldedjoints can be expanded greatly if nonlinearities are present+is influence results in the dropping of structural integrity

5 Conclusions

Computational welding mechanics used ANSYS to predictresidual stresses and temperature distribution arising fromthe Inconel 625 multi-pass GTAW process A double el-lipsoidal volumetric heat source model with boundaryconditions was used for the thermal analysis

(i) +e multi-pass welding process was establishedsuccessfully for Inconel 625 by the GTAW processfor 5mm thick plate free from flaws and defects

(ii) +e hot cracking flaws were eliminated by includinginter-pass temperatures between the second andthird passes +e results are in good agreement withthe predicted thermal and mechanical boundaryconditions

(iii) +e residual stresses generated were within the yieldlimits of the parent material

(iv) +e factor of safety was 127 for experimentationand 142 for simulation of the Inconel 625 weldingprocess

(v) Temperature measurements were collected pass bypass from the analysis and the agreement was908 +e agreement between the measured andanalysed residual stress was 11

Data Availability

+e data used to support the findings of this study are in-cluded within the article

Conflicts of Interest

+e authors declare that they have no conflicts of interest

References

[1] A Kermanpur M Shamanian and V E Yeganeh ldquo+ree-dimensional thermal simulation and experimental investi-gation of GTAW circumferentially butt-welded Incoloy 800pipesrdquo Journal of Materials Processing Technology vol 199no 3 pp 295ndash303 2008

[2] Y Balram and G Rajyalakshmi ldquo+ermal stress analysis ofsimilar and dissimilar welded jointsrdquo UPB Sci Bull SeriesD vol 80 no 4 pp 1ndash7 2018

[3] P K Korrapati V K Avasarala M BhushanK D Ramkumar N N Arivazhagan and S NarayananldquoAssessment of mechanical properties of PCGTA weldmentsof Inconel 625rdquo Procedia Engineering vol 75 pp 9ndash13 2014

[4] M Peric Z Tonkovic A Rodic et al ldquoNumerical analysis andexperimental investigation of welding residual stresses anddistortions in a T-joint fillet weldrdquo Materials amp Designvol 53 pp 1052ndash1063 2014

[5] H Vemanaboina G Edison and S Akella ldquoEffect of residualstresses of GTA welding for dissimilar materialsrdquo MaterialsResearch vol 21 no 4 pp 1ndash7 2018

[6] H Vemanaboina G Edison and S Akella ldquoWeld beadtemperature and residual stresses evaluations in multipassdissimilar INCONEL625 and SS316L by GTAW using IRthermography and x-ray diffraction techniquesrdquo MaterialsResearch Express vol 6 no 9 Article ID 0965a9 2019

[7] P Ferro ldquoMolten pool in welding processes phenomeno-logical vs fluid-dynamic numerical simulation approachrdquoMaterials Science Forum vol 884 pp 26ndash40 2017

[8] H Vemanaboina G Edison S Akella and R K Budduldquo+ermal analysis simulation for laser butt welding ofInconel625 using FEArdquo International Journal of Engineeringamp Technology vol 7 no 4 pp 85ndash89 2018

Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50

0Base Plate Base PlateHAZ HAZFusion Zone

Various Zones of the weldment

Figure 14 Comparison of residual stresses


[9] R Keivani M Jahazi T Pham A R Khodabandeh andM R Afshar ldquoPredicting residual stresses and distortionduring multisequence welding of large size structures usingFEMrdquo International Journal Of Advanced ManufacturingTechnology vol 73 no 4 pp 409ndash419 2014

[10] A G Kamble and R V Rao ldquoEffects of process parametersand thermo-mechanical simulation of GMAW process forwelding of 3Cr12 steelrdquo Advances in Materials and ProcessingTechnologies vol 2 no 3 pp 377ndash400 2016

[11] M J Attarha and I Sattari-Far ldquoStudy on welding temper-ature distribution in thin welded plates through experimentalmeasurements and finite element simulationrdquo Journal ofMaterials Processing Technology vol 211 no 4 pp 688ndash6942011

[12] A Capriccioli and P Frosi ldquoMultipurpose ANSYS FE pro-cedure for welding processes simulationrdquo Fusion Engineeringand Design vol 84 no 2ndash6 pp 546ndash553 Jun 2009

[13] R Lostado R F Martinez B J Mac Donald andP M Villanueva ldquoCombining soft computing techniques andthe finite element method to design and optimize complexwelded productsrdquo Integrated Computer-Aided Engineeringvol 22 no 2 pp 153ndash170 2015

[14] R Lostado Lorza R Escribano Garcıa R Fernandez Marti-nez and M Martınez Calvo ldquoUsing genetic algorithms withmulti-objective optimization to adjust finite element modelsof welded jointsrdquo Metals vol 8 no 4 p 230 2018

[15] R Lostado Lorza M Corral Bobadilla M Martınez Calvoand P Villanueva Roldan ldquoResidual stresses with time-in-dependent cyclic plasticity in finite element analysis of weldedjointsrdquo Metals vol 7 no 4 p 136 2017

[16] H Vemanaboina S Akella and R K Buddu ldquoWeldingprocess simulation model for temperature and residual stressanalysisrdquo Procedia Materials Science vol 6 pp 1539ndash15462014

[17] J Goldak A Chakravarti and M Bibby ldquoA new finite ele-ment model for welding heat sourcesrdquo Metallurgical Trans-actions B vol 15 no 2 pp 299ndash305 1984

[18] D Deng and H Murakawa ldquoPrediction of welding residualstress in multi-pass butt-welded modified 9Cr-1Mo steel pipeconsidering phase transformation effectsrdquo ComputationalMaterials Science vol 37 no 3 pp 209ndash219 2006

[19] D Deng and S Kiyoshima ldquoNumerical simulation of weldingtemperature field residual stress and deformation induced byelectro slag weldingrdquo Computational Materials Sciencevol 62 pp 23ndash34 2012

[20] ldquo+e importance of interpass temperature welding innova-tionrdquo vol 15 no 1 1998

[21] H Vemanaboina G Guruvaiah Naidu D Satya AbhinavN Krishna and D Ramachandra Reddy ldquoEvaluation of re-sidual stress in multipass dissimilar butt joints using X-raydiffractionrdquo Materials Today Proceedings vol 19 pp 283ndash288 2019

[22] A Osman Residual Stress Measurement Using X-ray Dif-fraction Texas A andMUniversity College Station TX USA2004


In order to decrease the computational time withoutlosing accuracy Peric et al [4] proposed a T-joint numericalmodel conducted by combining the shell and 3D finite el-ements Results of thermal and displacement distributionswere found in good agreement with those measured in realjoints Finally the influence of the 3D model size on thetemperature residual stress and displacement distributionswas investigated Vemanaboina et al [5] studied the residualstress evolutions in multi-pass dissimilar joints (IN 625-AISI316L) +e L4 orthogonal array was chosen for the tests Twolevels of each welding factor filler wire and root gap pa-rameters were chosen for the experiments It was concludedthat the pulsed current-induced low residual stresses in theweld region were within the factor of safety of parent ma-terials In subsequent work [6] they deepened the weld-ability of such similar and dissimilar welded jointsWeldments free from defects and stresses within the yieldlimits of the base materials were obtained In computationalweld mechanics (CWM) [7 8] the thermal load is obtainedby using power density distribution functions that calibrateparameters using experimental results +is approach allowsreducing the computational time required to calculate theresidual stresses and distortions compared to that needed bymodels based on fluid dynamic analyses

Nine different welding sequences [9] were used to find thebest conditions that minimized distortions and residualstresses in a T-weldment +e simulation was carried out byusing ABAQUS numerical code As expected the best con-ditions were achieved when joining both sides in the samedirection and at the same time Kamble and Rao [10] de-veloped a three-dimensional sequentially coupled thermo-mechanical model of 10mm thick plate +e GMAW processwas used for joining two 3Cr12 stainless steel plates +ethermal study was carried out at different time intervals+ermally induced residual stress was predicted using ANSYSnumerical code In that work the authors described the effectof process parameters on thermal and structural behaviour ofthe welded joints Attarha and Sattari-Far described a thermalstudy of similar and dissimilar single-pass butt-welded joints[11] A 3D numerical model was developed with ABAQUSregand the Goldak heat source was used to simulate the thermalinput of the process (GTAW) Excellent agreement was ob-served between numerical and experimental temperaturevalues measured with k-type thermocouples located in theheat-affected zone (HAZ) Capriccioli and Frosi [12] carriedout a computational analysis of the multi-pass weldingprocess for dissimilar materials +e 316L stainless steel toIN625 welding simulation was carried out for both TIG andlaser welding using ASNSYSreg +e mechanical results werefound very sensitive to the mesh shape which had to be veryfine and regular close to the fusion zones In that work aneffort was made to reduce the CPU time that is the majorobjective to achieve when simulating a multi-pass weldingprocess Lostado et al [13 14] used finite element models tobetter understand heat behaviour and its impact on angulardistortion and bead shape in GMAW butt weldments +estudy employed genetic algorithms with multi-objectivefunctions+e influence of heat input reveals growing angulardistortion and weldment bead shape +e FEA models and

experimental findings correlate well Another work reportedthat the tensile residual is maximum at the fusion zone andalso stated that the findings of the FEA were in agreementwith the experimental results [15]

Weld beads and related regions undergo plastic defor-mation during the welding process as a result of heating andcooling cycles resulting in residual stress +ermal andlattice spacing impact residual stresses in weldmentsresulting in microstructure changes and thermomechanicalstresses With the help of FEA it is possible to forecast thedegree of heat effect in the weldment Since no work hasbeen published on the in situ thermal behaviour studyduring GTAW for Inconel 625 material the authors believethat there is a lack of confirmation on simulations for theestimate of temperature profiles and residual stressesMultipass welding of Inconel 625 with GTAW processconditions is the major focus in the present planned studyWelded components are analysed in 3D to determine theirthermal and residual stresses With the ANSYSreg packageAPDL code is used to do thermomechanical analysis In-frared thermography is used to measure welding tempera-tures X-ray diffraction is used to evaluate residual stresses ina weldment after it has cooled to ambient temperature forverification

2 Finite Element Analysis

Figure 1 shows an overview of the present numerical modelANSYS package was used to develop the welding simulation+e plate has a square butt groove with no gaps between thetwo parts According to the real butt-welded joint thicknessthe FZ height was increased by 17mm at each run takingadvantage of the activation-deactivation function of ele-ments implemented in ANSYS code (Figure 2) roughlyequal to that of weld bead measured by experiment +ethermal analysis was computed with the 8-node thermalelement [16] SOLID70 and then switched to the 8-nodefinite element SOLID45 for the subsequent structural cal-culation +e two types of mesh options are used for thesimulation models +e finer mesh is applied at fusion zonewith a mesh size of 15mm and coarse mesh is applied to therest of the plate with a mesh size of 3mm as shown inFigure 3 In this study an equal time interval is assumed forevery pass as heating time +e temperature-dependent [12]thermal and mechanical properties considered for Inconel625 for the present study have been depicted in Figure 4

Goldak et al proposed double ellipsoidal heat sourcemodel for the arc welding process [17] For present weldsimulations the moving heat source model is treated asvolumetric heat flux with constant heat input throughout thelength For each weld pass the bead size initial boundaryconditions are defined along with volumetric heat flux +econstant heat input loads are calculated as per the weldingprocess parameters shown in Table 1

+e volumetric heat flux [18 19] of each weld pass isdetermined using the following equation

Q ηUI

V (1)



z

zxk

zT

zx1113888 1113889 +

z

zyk

zT

zy1113888 1113889 +

z

zzk

zT

zz1113888 1113889 + Q minusρCp

zT

zt

(2)




qc h T minus T0( 1113857 (4)

qr εσ T4

minus T04

1113872 1113873 (5)





TypicalWeld Joint

WeldingConditions

WeldingMaterials



MechanicalBoundary

Conditions


ermo-mechanical



Temperature Results


(a)

(b)

(c)



8450

8400

8350

8300

8250

8200

8150

8100

8050

750

700


600

550

500

450

400

200 400 600 800 1000 1200 1400 1600

Temperature (K)

Den

sity

(kg

m^3

)

Density

Specific heat

200 400 600 800 1000 1200 1400 1600

Temperature (K)

30

25

20

15

10

er

mal

cond

uctiv

ity (W

m K

)

ermal conductivity

(a)

200E+011

180E+011

160E+011

140E+011

120E+011

100E+011200 400 600 800 1000 1200 1400

Temperature (K)

Elas

tic m

odul

us (P

a)

IN625

200 400 600 800 1000 1200 1400 1600

Temperature (K)

400E+008

300E+008

250E+008

200E+008

150E+008

100E+008

350E+008

500E+007

000E+000

Yiel

d St

reng

th (P

a)

IN625

(b)













nλ 2d sin θ (6)


σϕ m

d0

E

1 + ]1113874 1113875 (7)








Pass-1 1452 12

36Pass-2 145 27Pass-3 145 31


60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP


20200






Infraredscanner

ControlConsole


Personalcomputer


Colour printer









Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50





















z

zxk

zT

zx1113888 1113889 +

z

zyk

zT

zy1113888 1113889 +

z

zzk

zT

zz1113888 1113889 + Q minusρCp

zT

zt

(2)




qc h T minus T0( 1113857 (4)

qr εσ T4

minus T04

1113872 1113873 (5)





TypicalWeld Joint

WeldingConditions

WeldingMaterials



MechanicalBoundary

Conditions


ermo-mechanical



Temperature Results


(a)

(b)

(c)



8450

8400

8350

8300

8250

8200

8150

8100

8050

750

700


600

550

500

450

400

200 400 600 800 1000 1200 1400 1600

Temperature (K)

Den

sity

(kg

m^3

)

Density

Specific heat

200 400 600 800 1000 1200 1400 1600

Temperature (K)

30

25

20

15

10

er

mal

cond

uctiv

ity (W

m K

)

ermal conductivity

(a)

200E+011

180E+011

160E+011

140E+011

120E+011

100E+011200 400 600 800 1000 1200 1400

Temperature (K)

Elas

tic m

odul

us (P

a)

IN625

200 400 600 800 1000 1200 1400 1600

Temperature (K)

400E+008

300E+008

250E+008

200E+008

150E+008

100E+008

350E+008

500E+007

000E+000

Yiel

d St

reng

th (P

a)

IN625

(b)













nλ 2d sin θ (6)


σϕ m

d0

E

1 + ]1113874 1113875 (7)








Pass-1 1452 12

36Pass-2 145 27Pass-3 145 31


60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP


20200






Infraredscanner

ControlConsole


Personalcomputer


Colour printer









Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50




















8450

8400

8350

8300

8250

8200

8150

8100

8050

750

700


600

550

500

450

400

200 400 600 800 1000 1200 1400 1600

Temperature (K)

Den

sity

(kg

m^3

)

Density

Specific heat

200 400 600 800 1000 1200 1400 1600

Temperature (K)

30

25

20

15

10

er

mal

cond

uctiv

ity (W

m K

)

ermal conductivity

(a)

200E+011

180E+011

160E+011

140E+011

120E+011

100E+011200 400 600 800 1000 1200 1400

Temperature (K)

Elas

tic m

odul

us (P

a)

IN625

200 400 600 800 1000 1200 1400 1600

Temperature (K)

400E+008

300E+008

250E+008

200E+008

150E+008

100E+008

350E+008

500E+007

000E+000

Yiel

d St

reng

th (P

a)

IN625

(b)













nλ 2d sin θ (6)


σϕ m

d0

E

1 + ]1113874 1113875 (7)








Pass-1 1452 12

36Pass-2 145 27Pass-3 145 31


60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP


20200






Infraredscanner

ControlConsole


Personalcomputer


Colour printer









Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50





























nλ 2d sin θ (6)


σϕ m

d0

E

1 + ]1113874 1113875 (7)








Pass-1 1452 12

36Pass-2 145 27Pass-3 145 31


60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP


20200






Infraredscanner

ControlConsole


Personalcomputer


Colour printer









Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50




















60

PASS-1ROOT

PASS-2FILLER

50

PASS-3 CAP


20200






Infraredscanner

ControlConsole


Personalcomputer


Colour printer









Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50

























Detector


Primary X-ray beam


X rotation

φ rotation





309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50




















309836

506552 899983

10967

129341

149013 188356

208028168685

703268

(a)

471515

658908

8463

103369

122109

140848

159587

178326

197066

215805

(b)

482485

618586

754686

890786

102689

116299

129909

143519

157129

170739

(c)


6275 degC degC600

2000

1000

0


400

2000

(a)

Figure 10 Continued




degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50






















degC

2000

3000

1000

0


12647 degC

1000

500

2000

(b)

degC

2000

3000

1000

0


9809 degC

800

600

400

2000

(c)


2100

2000

Tem

pera

ture

degC

1900

1800

1700

Pass-1 Pass-2


Pass-2

ermography

Simulation



Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50




















Com

pres

sive S

tres

ses

-180

-2 -1

-40

-60

-80

-100

-120

-140

-160

-200

0


1 2


(a)


-2 -1 0


Tensile Stress

Com

pres

sive S

tres

s 1 2

-120

80

120

-80

40

-40

0

(b)

Tens

ile S

tres

s

200

175

150

125

100

75

50

25

0-2 -1 0


1 2


(c)





5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50





















5 Conclusions







Data Availability




References









Resid

ual S

tres

ses (

MPa

)

FEA

Experimentation

200

150

100

50



































Documents

ThermalandResidualStressDistributionsinInconel625 Butt