Effects of welding parameters optimization on the tensile performance of friction stir welded AA3103 Al alloy

Friction Stir Welding (FSW) is a reliable solid-state joining technique for aluminium alloys, where conventional fusion welding often causes porosity, solidification cracking, and excessive heat-affected softening. The present study investigates the influence of tool pin geometry, shoulder-to-pin diameter ratio, rotational speed, and welding speed on the mechanical performance of friction stir welded AA3103 aluminium alloy. Twenty-seven experimental trials were conducted using a Taguchi L9 orthogonal array, repeated for three tool pin profiles: circular, square, and triangular. Three shoulder-to-pin diameter ratios (D/d = 3, 4, 5), rotational speeds (355, 710, and 1400 RPM), and welding speeds (20, 40, and 80 mm/min) were considered. Mechanical testing was performed according to ASTM E8 to determine yield strength, ultimate tensile strength (UTS), and percentage elongation. Statistical evaluation using Signal-to-Noise ratio and General Linear Model based ANOVA revealed that the shoulder-to-pin diameter ratio significantly influences UTS and YS at a 95% confidence level ( p < 0.05). The maximum UTS of 174.37 MPa was achieved using a square pin at D/d = 3, 355 RPM, and 20 mm/min, while maximum elongation of 26% was obtained with a triangular pin at higher rotational speed. Regression models showed acceptable predictive accuracy for process optimization.