Enhanced mechanical properties of dissimilar Al and Mg alloys fabricated by pulse current assisted friction stir welding

The process window for conventional friction stir welding (FSW) of Al and Mg alloys is narrow and the maximum tensile strength and elongation are 162.2 MPa and 5.5%, respectively. The dissimilar Al and Mg alloys fabricated by pulse current assisted FSW was studied through a combination of microstructure analyses and mechanical properties to achieve the best performance. With increasing pulse current, the tensile strength and elongation increased to 215.7 MPa and 5.24%, respectively, and the fracture type has changed from brittle fracture to compound fracture. The process window was expanded via electrically assisted effect. And cracks, tunnels and other defects occurring in conventional FSW of Al and Mg were eliminated by pulse current, effectively inhibiting the thickness and quantity of the intermetallic compounds in the band structure zone and the Al-Mg interface and improving the joint efficiency.