Numerical investigation on the molten pool and keyhole dynamic behaviors and weld microstructure in laser-induction hybrid welding of stainless steel

The laser-induction hybrid welding (LIHW) can inhibit the formation of welding defects and enhance the mechanical properties of welded joints, which improves the applicability of laser welding in different industries. In this paper, a macro-micro numerical model consisting of macroscopic heat transfer and fluid flow model coupled with magnetic field, transient solidification conditions (SCs) model and microscopic phase field model (PFM) is developed to investigate the LIHW of 304 stainless steel. The validity of the developed model is confirmed by comparing the simulation results with the experimental results. The effects of electromagnetic induction heating on the molten pool and keyhole dynamic behaviors and weld microstructure during LIHW are analyzed and discussed in detail. Compared with the single-laser welding (SLW), the depth and half width of the molten pool are increased and the stability of the keyhole has been improved during LIHW. Additionally, the primary dendrite arm spacing during SLW is smaller than that during LIHW. The results show that the proposed model is beneficial for understanding the molten pool and keyhole dynamic behaviors and microstructure evolution process during LIHW and hence improving the welding quality.