The effects of the welding current on heat input, nugget geometry, and the mechanical and fractural properties of resistance spot welding on Mg/Al dissimilar materials

Investigating the joining capability of magnesium AZ31 alloy sheets and aluminium 1350 alloy sheets with the application of resistance spot welding was the objective of this study. The weld current values used in the welding process of Al–Mg sheets were 22, 23, 25, 27, 29, 31, and 33 kA. The studies examined the nugget geometries of joined specimens, recorded the scanning electron microscopy (SEM) images of the welded zone and the fracture surface, and recorded the energy-dispersive spectroscopy (EDS, semi-quantitative) analyses. The results of the experiment confirmed that nugget geometry was different for the Al and Mg sides. Tensile shear tests carried out on the welded joints determined their strength and failure mode. The increase in the weld current and duration resulted in an increase in the nugget size and the weld strength. According to observations, the tensile load bearing capacity (TLBC) increased up to 29 kA of the weld current value. It was also found that tearing during fracture occurred in two different ways.