Establishing empirical relationships and process parameter optimization of tungsten inert gas welded butt joints of nickel-based alloy using statistical approach of regression analysis and response surface methodology

This investigation presents the process parameter optimisation of high-frequency concentrated arc TIG (HFCA-TIG) welded butt joints of nickel-based alloy 718 using response surface methodology to enhance the performance characteristics of joints. The polynomial regression equations of second order were formulated for predicting the performance characteristics of alloy 718 butt joints from the process parameters. Analysis of variance (ANOVA) was performed to determine the significant process parameters and to estimate the proficiency of empirical relationships. The experimental and predicted results were compared for validation of empirical relationships. It disclosed less than 4% error at 95% confidence level. The numerical and graphical optimisation complying the optimisation criteria was executed to find the optimum conditions of process parameters depending on the desirability function. The interaction effect of process parameters on performance characteristics of joints was analysed from three-dimensional response surface plots.