This paper deals with the resistance spot weldability of steel to aluminum alloy sheets using an intermediate layer of aluminum clad steel. Five types of the clad sheets with various steel/aluminum thickness ratios were produced by hot rolling. The mechanical properties of the clad sheets changed with the thickness ratio and ranged between those of the steel and the aluminum sheets. The peel strength of the steel/aluminum interfaces was as high as more than 25 N/mm.
Materials used in spot welding were 0.8 mm thick EDDQ steel sheets, three types of 1.0 mm thick aluminum alloy sheets and the clad sheets mentioned above. Spot-weldability, including suitable welding current, nugget diameters, tensileshear strength and the thicknesses of the intermetallic compound layers formed at the interfaces of the clad sheets, changed with the thickness ratio of the clad sheets. From these results, it was concluded that spot weldability was affected by the thickness ratio of the clad sheets.
Spot weldability was also affected by the alloying elements of aluminum alloy sheets. The tensile shear strength and the nugget diameters varied by using various types of aluminum alloy sheets.
