Weld Formation, Microstructure Evolution and Mechanical Property of Laser-Arc Hybrid Welded AZ31B Magnesium Alloy

Laser-arc hybrid welding of AZ31B magnesium alloy was carried out in this paper, and the effects of welding parameters (laser power, welding speed, welding current) on weld formation, microstructure evolution and mechanical property were studied. The results showed that laser-arc hybrid welding can inhibit the undercut defect during laser welding on the one hand, and enhance the arc stability on the other hand. The penetration depth and width showed no significant relation with the total heat input, but were linear related to the laser heat input and the arc heat input, respectively. The average grain size of the equiaxed grains was closely related to the heat input. The higher the heat input was, the larger the grains. The optimized welding parameters were laser power of 3.5 kW, welding speed of 1.8 m/min and welding current of 100 A. In this case, the weld was free of undercut and pores, and the tensile strength and elongation rate reached 190 MPa and 12%, respectively.