A multi-objective optimization of the friction stir welding process using RSM-based-desirability function approach for joining aluminum alloy 6063-T6 pipes

In this study, a multi-objective optimization technique involving response surface methodology (RSM)-based desirability function approach is used in optimizing the process parameters for friction stir welding of AA6063-T6 pipes. Two process parameters, namely, tool rotational speed and weld speed, are optimized for achieving a weld joint having superior tensile properties, viz., maximum yield, and ultimate tensile strength and maximum % of elongation. A regression model, with a 95% confidence level, is developed using response surface methodology to predict the tensile strength of the weld joint. ANOVA technique is used to determine the adequacy of the developed model and identify the significant terms. The desirability function is used to analyze the responses and predict the optimal process parameters. It is found that tool rotational speed and weld speed have equal influence over the tensile strength of the pipe weld. Tool rotational speed 1986 rpm and weld speed 0.65 rpm have yielded a maximum ultimate tensile strength of 167 MPa, yield strength of 145 MPa, and % elongation of 8.3, under considered operating conditions. Microstructural attributes for superior weld properties are also discussed.