Numerical simulation of residual stresses induced by TIG butt-welding of thin plates made of AISI 316L stainless steel

The paper herein presented refers to the numerical simulations of a TIG butt-welding process applied to thin plates made ​​of an AISI 316L austenitic stainless steel. Finite element (FE) thermal analyses were initially carried out in order to obtain the transient temperature distributions in the plates, and, subsequently time-dependent thermal results were used in the FE structural analyses, in order to calculate the residual stresses and deformations introduced by the welding process. A double Gaussian distribution - namely a double ellipsoid -, with front and rear dimension's areas of the arc defined based on real weld bead's measurement, was used as the heat source model (power density), and it was considered that it moved at constant speed. Numerical results calculated were in good agreement with the experimental residual stresses measured by the hole-drilling method, showing the adequacy of the method implemented and its potential to estimate residual stresses and distortions. In fact, it was found a deviation of 19 % for the maximum principal stress calculated, while for the minimum principal stress a deviation value of 9 % was obtained; in addition, the simulated weld bead presented slight deviations from the macrograph sample and the differences related to the depth of the weld pool were around 2%.