Multivariate nonlinear regression design of resistance spot welding for an advanced hot-formed steel

The effect of spot welding parameters on joint quality of advanced hot-formed steel was investigated using multivariate nonlinear regression orthogonal experiments. The shear strength of joint and the diameter of weld nugget were taken as the main indexes representing the quality of welded joint. With electrode pressure, welding current and welding time as the process parameters, their interactive correlation was analyzed. Nine experiments were designed by orthogonal theory. According to regression theory, a ternary quadratic non-linear regression equation was built and the residual standard deviation was calculated. The results show that the regression model could be used to predict the shear strength of joint and the diameter of weld nugget.