Investigation of similar welds of AA 6061 alloy using Il-FSSW process

Intermediate layer friction stir spot welding (IL-FSSW) was presented in this study as a new technology aimed to decrease Keyhole use related to traditional friction spot welding (FSSW). This technique would be used to weld similar 6061-T6 aluminum alloy sheets in this study. The mechanism of achieving spot welding in this process was different from that of the FSSW process in terms of introducing the Intermediate layer (IL) to solve the keyhole problem in addition to using a flat pinless, groove-less tool. In this study, the welding procedure was based on reducing the case of keyhole from the inception of welding Due to the effect addition of the IL part. Therefore, reducing the additional processes or post-treatments for the welds is unnecessary. Results showed a good joint appearance with shallow keyholes. Weld cross-section microstructure images indicated that the IL part represented the nugget zone (NZ) after welding and revealed its influence on the hooks fabrication. The failure load result from the lap shear tensile test was 6 kN which was then higher compared with the required strength value as stated by the American Welding Society. The failure surface confirmed a ductile fracture in the boundary of the IL. Whereas it was a mixed fracture outside of the IL boundary.