Numerical simulation of residual stresses induced by laser beam welding in a SUS316 stainless steel pipe with considering initial residual stress influences

With the development of computer hardware and software, numerical simulation technology has been widely used to predict welding temperature field, residual stresses and distortion. However, till now the influences of initial stresses induced by the manufacturing process before welding on the welding-induced residual stresses are rarely investigated experimentally and numerically. In the present work, we have developed a computational approach based on thermal elastic plastic FEM to clarify how the initial stresses due to heat treatment affect the welding-induced residual stresses in an austenitic stainless steel pipe. A heat treatment process, which is similar to solution heat treatment, is employed to produce initial stresses in the pipe before welding. After the heat treatment, the laser beam welding is used to perform a girth weld in the middle of the pipe. Through comparing the residual stress distributions after heat treatment and laser beam welding, we have investigated the influence of the initial residual stresses on the welding-induced residual stresses. The numerical results suggest that the initial residual stresses prior to welding have significant effects on the residual stresses after welding in the pipe model.