Feasibility study of resistance spot welding of dissimilar Al/Mg combinations with Ni based interlayers

Microstructure and mechanical properties of the dissimilar aluminium–magnesium resistance spot welds made with gold coated and bare nickel interlayers are investigated. Welds were made with different welding currents in a range from 16 to 24 kA with a fixed welding time of five cycles. No joints were achieved with a bare nickel interlayer; after welding, specimens were separated without applying any force. Addition of gold coating on nickel surface greatly contributed to the metallurgical bonding at the interfaces and welds easily met requirements of AWS D17·2 standard. Average lap shear strength reached 90% of similar AZ-31B spot weld strength. Fusion nugget size, interfacial microstructure and fracture surface morphology of the welds were analysed.