Optimization of Welding Parameters for Resistance Spot Welding of AA3003 to Galvanized DP780 Steel Using Response Surface Methodology

In this study, the strength prediction model for dissimilar joint between aluminum alloy (AA3003) and steel (GI DP780) in resistance spot welding (RSW) was proposed using response surface methodology (RSM). The welding was carried out using pedestal type with medium frequency DC electric power and hydraulic cylinder type spot welding machine. The welding conditions were designed with DOE of the central composite design (CCD) method. The welding time and the welding current were considered as input parameters and the tensile shear load (TSL) was the output. The effect of the welding current is higher than the welding time in order to increase the TSL. The TSL was high at high heat input conditions due to the influences on the effective joint length and the intermetallic compound (IMC) layer. The maximum TSL of 5.14 kN obtained at the optimum welding conditions of welding time 300 ms and welding current 20 kA. As a result of the verification of the regression model for the optimum welding condition, the spot welding experimental results with a maximum TSL was about 5.40 kN. The results showed that the proposed model of the spot weld strength can be estimated in accuracy of 5.5%.