Numerical simulation on backward deformation of MIG multi-layer and multi-pass welding of thick Invar alloy

Severe distortion often occurs during the production of thick Invar alloy mold using the multi-layer and multi-pass welding method. However, welding angular distortion and residual stress can be reduced greatly with the backward deformation method. The present paper is aimed at researching the appropriate backward deformation for thick Invar alloy welding, using commercial finite element software, MSC.Marc. The transition density grid meshing method was applied in this work. Besides, the double-ellipsoid distribution was employed as the heat source model. Welding process with different backward deformation was simulated. And the simulated angular distortion was compared with actual residual deformation. Both the simulated and experimental results indicated that the welding deformation of Invar alloy samples was efficiently controlled with reserved angle of two degrees. Furthermore, it was proven that the numerical simulation results were in good agreement with the experimental results.