Process stability in laser–MIG hybrid welding of aluminum alloys with various laser and arc distances

During laser–MIG hybrid welding process of aluminum alloys, the distance between laser and arc heat source (D LA ) is one of the key factors which affect the welding process stability. Weld formation exhibited various penetration depths, since the interaction between laser and arc changed. Hybrid plasma morphology fluctuated significantly at D LA of 0 mm and hybrid plasma height decreased with the increase of D LA . Violent evaporation of droplet and spatters were generated at D LA of 0 mm. Moreover, keyhole fluctuated violently and significant downward flow of liquid metal was induced at the bottom zone of molten pool due to the impact action of droplet. Keyhole fluctuation was suppressed and molten pool stability was improved at D LA of 2 mm.