Influence of Different Welding Speeds on Droplet and Molten Pool in Laser-arc Hybrid Welding AH36 Steel

This study investigated the effects of laser-MIG hybrid welding on 4mm-thick AH36 steel at different welding speeds through numerical simulation and high-speed photography. The research revealed that: At 20 mm/s, the process was dominated by unstable short-circuit transfer; At 30 mm/s, a mixed transfer mode of jet and globular transitions emerged with improved stability; At 40 mm/s, stable jet transfer became predominant. Under low welding speed (20 mm/s), the fluid temperature fluctuated between 1425 K and 1800 K with significant temperature gradient variations, accompanied by molten pool fluctuations and vortex flow velocities of 3.75-5.0 m/min. Conversely, at high welding speed (40 mm/s), the fluid temperature stabilized at 1750 K with reduced vortex flow velocities of 1.25-2.5 m/min, and the molten pool exhibited enhanced stability under surface tension effects.