Finite Element Analysis of Residual Stress Level Prediction for TIG Welding Process

Abstract

Tungsten Inert Gas (TIG) welding process requires high heat input during the process, when the material is cooled down non-uniform distribution of thermal strain causes residual stress which can weaken the material and fatigue life of the material. The residual stress can be measured from method such as x-ray diffraction (XRD), using strain gage of drilled hole and so on. A numerical method of constructing a finite element analysis (FEA) model can be used for predicting the residual stress level of the welding process. This paper uses the TIG welding condition for stainless steel grade 304 that the material provided the highest level of tensile strength, obtained from previous study, as a condition for the FEA model. The residual stress results from the FEA predictive model and the results from XRD were compared. In the FEA model, the workpiece, heat affected zone (HAZ), and filler metal assumed to be the same. The results showed consistent residual profile between the model and the actual measurement from XRD, but there was some discrepancy of the magnitude of residual stress which can due to the type of filler material that was used.

Finite element analysis of the effect of porosity on residual stress in 2024 aluminium alloy GTAW

“…This finite element analysis model used a SOLID 90 element for welding analysis [43] and was constructed from a double-ellipsoid heat source on the same surface. Then, heat flux was moved from the surface of one element onto the next element until the welding process was complete using the birth and death technique [44]. Porous simulation in welding can only assume that the reduction in a cross-sectional area associated with porosity is what affects residual stress.…”

“…We compared the differences in the residual stress values between all three methods. The longitudinal residual stress results of references [22,44] and GTAW of 304 stainless steel (size of 150×100 mm and thickness of 0.3 mm) with a single heat source and residual stress from the XRD measurements of the actual welding are shown in table 7. A comparison of longitudinal residual stress results between the XRD measurement, single heat source, and double-ellipsoid heat source of 304 stainless steel is shown in table 5.…”

“…In this research, welding conditions were generated by the use of a full factorial experimental design technique. The variables used were arc current, welding speed, and wire feeding rate [44]. The residual stress measurement of sample number 7, which produces the most porosity, was performed with a Stresstech x-ray diffraction machine (X-STRESS 3000) [26,44], which uses a copper-containing x-ray tube.…”

“…The variables used were arc current, welding speed, and wire feeding rate [44]. The residual stress measurement of sample number 7, which produces the most porosity, was performed with a Stresstech x-ray diffraction machine (X-STRESS 3000) [26,44], which uses a copper-containing x-ray tube. The machine is equipped with a Cr x-ray tube source radiation of wavelength λ = 2.084 87 Å. Baisukhan et al [22] used XRD to measure non-destructively and predict residual stresses in the large welds for GTAW.…”

“…The non-uniform cooling rate within the materials induced residual stress after 2 specimens were welded together [22]. From these angles, the atomic spacing of the diffracting lattice planes is received by using Bragg's law [44,46]. Researches, residual stresses were analyzed various methods by curvature measurement [47], hole drilling [48], synchrotron x-ray [49], and magnetic & electrical techniques [11], etc.…”