Optimization of Welding Parameters in Resistance Spot Welding of 980 MPa Grade GA Steel Sheet using Multi-Response Surface Methodology

In this study, the welding quality prediction model with high reliability was developed for the 980 MPa grade TRIP steel with minimum conditions in resistance spot welding process using response surface methodology. The welding time and welding current were selected as the important parameters. The welding quality was predicted by deriving four parameters including tensile shear strength, nugget size, expulsion, and button fracture. The experiment was carried out by using the central composite design. Then, the regression equation derived using the result data was analyzed and the effect of the independent variable on the objective function was analyzed by ANOVA. The welding time had a very small effect on tensile shear strength and nugget, but welding current had a dominant effect on the two properties. Also, the reliability of the derived regression mode l equation is verified by R correlation coefficient and experiments. Key words: Weldments, Resistance spot welding, Response surface methodology, GA steel, ANOVA