Effect of Friction Stir Welding on Mechanical Properties and Formability of Aluminum Alloy-AA1100

This study investigates the influence of friction stir welding (FSW) on the mechanical properties and formability of thin aluminum alloy sheets for automotive applications. The feasibility of a novel technique, pinless FSW, for joining aluminum sheets was demonstrated. Defect-free welds were successfully achieved using parameter sets R1 (450 rpm, 80 mm/min, 8 mm), R4 (560 rpm, 160 mm/min, 8 mm), and R7 (710 rpm, 250 mm/min, 8 mm). The welded region exhibited an outward material flow due to the stirring action of the FSW tool. Microhardness measurements were conducted in the transverse direction of the weld and along the depth from the top to the bottom at the weld center. Hardness values exhibited variation from the weld zone centerline to the heat-affected zone (HAZ). Lower hardness values were observed at the center of the weld zone, whereas higher hardness values were recorded in the HAZ. The transverse and longitudinal tensile properties of the welds were evaluated at room temperature. The tensile tests revealed that the welded samples failed outside the weld region. To assess the ductility of the FSW welded samples, formability tests were performed, indicating an increase in ductility within the welded area.