Numerical simulation of thermo-mechanical coupling in laser-MIG hybrid welding utilizing dual volume heat sources

Laser-MIG hybrid welding is an energy-saving welding process. It is of great significance to quantitatively investigate the instantaneous evolution of temperature and stress in the process of hybrid welding to reveal the mechanism of hybrid welding and improve welding quality. Existing studies lack systematic analysis of temperature field and thermal stress field of laser-MIG hybrid welding of stainless steel, and there are relatively few literatures comparing traditional MIG welding and hybrid welding process. In this paper, the thermal mechanical coupling model of laser-MIG hybrid welding of SUS301L-HT stainless steel was established by numerical simulation. The temperature field, thermal stress field, and residual stress field distribution of the hybrid welding were quantitatively revealed, and compared with traditional MIG welding. The calculation results show that compared with the traditional single-heat source MIG welding, the center temperature of the laser-MIG hybrid welding pool is higher, and the peak temperature can reach 3386 K. Compared with the traditional MIG arc welding, the thermal stress distribution of laser-MIG hybrid welding is more uniform and the thermal stress value is lower at the same time. The distribution trend of residual stress in the two welding processes is similar. The overall residual stress in hybrid welding is relatively small, and the transverse residual stress and the thickness residual stress both have peak values in the heat affected zone. The research can provide theoretical reference and guidance for optimizing stainless steel hybrid welding process and improving welding quality and efficiency.