Influence of Hardening Models on the Estimation of Residual Stresses by Finite Element Modeling in Type 316LN Stainless Steel Weld Joints

In the present study, residual stress distribution in Activated-Tungsten Inert Gas (A-TIG) welded type 316LN stainless steel weld joints is estimated by using finite element model (FEM). The objective of the modeling is to estimate the influence of welding thermal cycle and various hardening models, namely isotropic, kinematic, mixed kinematic–isotropic and ideal plasticity on the welding residual stress distribution. The weld joints fabricated by utilizing single-pass and double-pass A-TIG welding technique were modeled by considering Goldak's double ellipsoid heat distribution model. The calculated thermal cycles were validated using experimental data and sequentially coupled to mechanical analysis for residual stress prediction. The computational results show that the weld metal volume significantly influences welding residual stress distribution. Meanwhile, isotropic hardening model results exhibited good comparison with the experimentally measured data obtained from x-ray diffraction and ultrasonic L_CR-based measurements from the joints welded by A-TIG process. It is shown that residual stress prediction accuracy depends on hardening models. Both single-pass and double-pass A-TIG weldments exhibited a negligible distortion.