Research on dynamics of molten pool of laser-MIG hybrid welding

Different laser powers and arc currents were used to conduct experimental studies on 4 mm thick stainless-steel plates in order to investigate the effects of welding process parameters on the formation of 304 stainless steel laser-MIG composite welds. To determine the ideal parameters for the weld seam formation and to create the appropriate numerical model, theoretical analysis and experimental verification of the weld seam were performed. The influence mechanism of the melt pool velocity field and fluid flow behavior is analyzed, as well as the influence of heat, mass, and momentum on the melt pool caused by the melt drop transition. The simulation results show that as the laser power is increasing, the weld depth of fusion increased, with P = 2.5kW for 4mm 304 stainless steel melting past the critical threshold. The mass, energy, and momentum caused by the melt droplet's transition behavior change the temperature and flow fields of the melt pool, and the melt droplet falling on part of the melt pool during the composite welding process would then cause extrusion on the wall of the small hole, affecting laser energy absorption by the melt pool and leading to unstable small hole depth.