OPTIMIZATION OF FRICTION STIR SPOT WELDING PARAMETERS FOR 7075 AND 6061 ALUMINUM ALLOYS USING TAGUCHI METHOD

Abstract

Friction stir welding is a solid-state welding process, where there is no melting taking place. In this study, a friction stir spot welding process was developed. The aim of this work was to optimize the process parameters of welding AA7075-T6 and AA6061-T6, separately. Rotational speed, pin profile, plunge depth, and shape of anvil were the main parameters studied. The experimental results showed that the optimal levels found to be 800 rpm, triangular pin, 1 mm, and convex anvil for AA7075-T6; and were 500 rpm, square pin, 1 mm, and convex anvil for AA6061-T6, respectively. The worst joint properties were observed for a rotational speed of 1250 rpm, and rounded pin profile and 1.5 mm plunge depth, with flat anvil for both alloys. ANOVA results revealed that the pin profile is the dominant parameter in the process, followed by the plunge depth, then the anvil shape and the last parameter was the rotational speed. The percentages of contribution were 54%, 21%, 14, and 11%, respectively, for the AA7075-T6 alloy. For the 6061-T6 alloy, it was found that the pin profile was most effective FSSW process parameter, followed by anvil shape, plunge depth and the rotational speed. The percentages of contribution were 51%, 35%, 8, and 6%, respectively