Microstructure and Properties of Joint between AZ31B Magnesium Alloy Thin Sheets Welded by Nd:YAG Laser

AZ31B magnesium alloy thin sheets were welded by one side welding both sides formation technology using Nd:YAG laser. The microstructure and properties of the joint were studied, and the tensile fracture morphology of the substrate and welded joint was analyzed. The results show that compared with the matrix, the grains of weld seam of the AZ31B magnesium alloy welded by laser welding were refined obviously; Compared with the substrate, the tensile strength of the joint reduced to 68.5%, the yield strength reduced to 83.68%, the maximum microhardness in weld seam zone increased about 31% comparing with the substrate. Both the tensile fracture of the substrate was mixed fracture which was mainly composed of quasi-cleavage fracture, and the weld joint had obvious ductile fracture characteristics.