Analysis Of Temperature And Stress-Strain Field In Laser Welding Of 409L Stainless Steel Tube

In this paper, we use the combined numerical simulation and experimental method to study the generation and distribution of the temperature,deformation and residual stress field in laser welding of 409L stainless steel tube. We complete numerical simulation with a large-scale finite element analysis software Marc2005, measure the welding residual stress with cutting method, and verify the accuracy of the finite element model with the metallographic experiment of weld section.On the basis of a comprehensive analysis of deep penetration laser welding processs heat transfer behavior, we propose a heat source model of deep penetration laser welding in this paper: simulate the heat transfer of the keyhole with a limited depth cylinder heat and the depth of body heat decided by the critical power density, and simulate plasma cloud above the work piece with surface heat.We use the heat source model to build the finite element model of 409 L stainless steel tube temperature field in laser welding, consider the convection and radiation cooling,latent heat in phase change,thermophysical properties of materials with temperature changes and the spread of convective heat in the liquid metal in the model, simulate the temperature field in different welding parameters, and acquire the process parameters on the impact of temperature distribution.On the basis of the numerical simulation of the temperature field, we calculate the stress and strain field of 409 L stainless steel tube butt joints, consider the grid spacing transition and mechanical properties parameters of materials with temperature change in the calculation, and analyse the evolution process and distribution of stress and deformation of 409L stainless steel tube in laser welding process, compare residual stress and deformation with the result of experimental study in laser welding. The results lead to the following conclusions: The residual stress distribution of 409L stainless steel in laser welding and TIG welding is similar, however, the longitudinal residual stress distribution in laser welding is narrow, the residual stress in the vicinity of weld joint and bond line is similar. When the energy input of laser welding increases, the regional tension of longitudinal residual stress broadens, the peak stress reduces, however, the horizontal residual stress increases.