Multi-objective optimization of FSW variables on joint properties of AA5754 aluminum alloy using Taguchi approach and grey relational analysis

Friction stir welding (FSW) processing of the joint is a technique to improve the quality of the weld. The present research employed the friction stir welding technique to butt-weld AA5754 plates, whereby the joints of every weld case were identified based on their tensile strength, hardness, and impact toughness. The plates were joined by varying the rotational speeds, welding speeds, and tool tilt angles. A multi-objective optimization Taguchi’s design of experiments approach and grey relational analysis (GRA) were used in this study to assess the combined effects of the process variables. The developed models are evaluated for sufficiency, and then the most significant parameters are determined using the analysis of variance (ANOVA). The results of the ANOVA showed that the rotational speed has a maximum contribution of 55.24%, 59%, and 46.27% in obtaining the optimal values of tensile strength, hardness, and impact toughness, respectively. It was found that formability and mechanical behaviors increased with increasing tilt angle for the tilt angle range examined in the current study. The two methods provide the same results, and the optimal conditions are a rotational speed of 1000 rpm, a welding speed of 60 mm/min, and a tilt angle of 2.5°. The optimal values for tensile strength, hardness, and impact toughness, respectively, were found to be 136 MPa, 85.25 HV, and 13 J. Significant implications for the welding industry may arise from the highly favorable outcomes in terms of microstructure and mechanical attributes.