Finite Element Modeling of Hybrid Laser-TIG Welding of Type 316L(N) Stainless Steel

Abstract

In the present study, thermomechanical analysis of autogenous hybrid laser-TIG welding of type 316L(N) austenitic stainless steel has been carried out. It has been realized that the residual stress due to welding plays a vital role in the mechanical properties of the joint and its performance during service. Therefore, it is important to study the residual stress of type 316L(N) stainless steel weld joint produced by hybrid welding process. First, the thermal analysis was carried using a hybrid heat source consisting of conical and double ellipsoidal models. The heat source was calibrated by comparing the simulated weld bead profile with that of the experimentally obtained weld bead profile. Then, the obtained temperature distribution was sequentially coupled to the mechanical analysis. The simulated thermal cycle was validated by temperature measurements using noncontact real-time IR thermography. The simulated residual profile was validated by an ultrasonic technique employing critically refracted longitudinal waves. The ferrite content of the weld metal was measured using ferrite scope. Distortion in the weld joint is measured using digital vertical height gauge. Optical microscopy is employed for microstructural characterization of the weld joint. The weld metal exhibited a peak tensile residual stress value of 320 MPa. The predicted distortion values were very low. There was a good agreement found between the predicted and experimentally measured thermal cycles, residual stresses, and distortion.