Investigation of Softening Behavior on Residual Stress of Laser-MIG Hybrid Welding for Aluminum Alloy Based on Finite Element Method

Aluminum alloy is an important material of high-speed train, mainly used as load-bearing structure. The advantages of laser-MIG hybrid welding are high efficiency, low stress and small deformation, which is very suitable for the welding of aluminum alloy. In this paper, the welding residual stress of laser-MIG hybrid welding 6N01-T5 aluminum alloy is simulated based on the thermo-elasto-plastic method in ABAQUS software. A softening model is established to assign the corresponding softening yield strength to the softening zone of the welded joints, and the distributions of residual stress are analyzed. The results are compared with that obtained without considering the softening behavior. The comparisons show that the softening behavior of welded joints can reduce the welding residual stress in the softening zone, but has little effect on the residual stress far away from it. The softening behavior has a greater effect on the longitudinal residual stress in the softening zone, while a relatively smaller effect on the transverse direction. The results of the study show that it is necessary to consider the softening behavior of the welded joints to accurately predict the residual stress.