Modified Friction Stir Clinching of AA5754-O to AA6061-T6: The role of shoulder feature on the metallurgical and mechanical properties

The dissimilar Modified Friction Stir Clinching (MFSC) process between AA6061-T6 and AA5754-O aluminum alloy sheets was examined. The effect of shoulder feature (scrolled and smooth pinless tools) on the material flow behavior within the weld region is investigated in this study. The results revealed that the scrolled pinless tool (Tool #1) played a significant role in influencing the interlocking mechanism of the joint and a better modification of the internal hooking line was achieved by Tool #1. The tensile/shear fracture of the MFSC spot welds revealed that the shoulder feature had a vital impact on the tensile/shear fracture load. It is found that the tensile/shear load of 5237 N is attained in the sample welded by Tool #1, which was higher than that of the weld made by Tool #2 (4513 N). Ductile failure mode was obtained irrespective of the shoulder feature. The more elongated dimple patterns for the scrolled tool sample confirm the appropriate dispersion of the strengthening precipitates via the intermixed mass flow at the weld bond area.