Parametric Optimization for Resistance Spot-Welded Thin-Sheet Aluminium Alloy 5052-H32

Resistance spot welding of 0.6-mm-thick AA 5052-H32 was performed within a selected range of parameters. The microstructure, nugget size and tensile shear strength (TSS) of the weldments were investigated. The TSS (ranging between 17 and 108 MPa) showed a positive dependency on the nugget diameter (ranging between 1.33 and 3.01 mm). The two weld qualities increased with increasing the welding current and decreasing electrode tip diameter. The nuggets exhibited hump-like shape which was caused by the variation in the heat generated at the two electrode terminals. Optimum parameters were found at electrode tip diameter of 4 mm, welding current of 8 kVA and welding time of 90 ms giving TSS of ~ 119 MPa. The optimal setting is suitable for aerospace applications because the corresponding nugget size met the AWS-D17.2 standard. Analysis of variance revealed that the weld current has the most significant effect on the tensile shear strength and nugget diameter with over 74% contribution.