Dissimilar Friction Stir Butt Welding of AA6061-T6 and AA6061/SiCp Composite: Microstructural Characteristics, Impact Toughness, Hardness, Strength Under Transverse Impact

Impact response of dissimilar friction stir welded (FSWed) joints between a monolithic alloy and metal matrix composite has not been yet reported and thus requires a detailed investigation. Therefore, an exhaustive research on the microstructure, microhardness, tensile properties, fracture toughness and failure response under transverse impact of the FSWed AA6061-T6/AA6061 + SiCp joint was conducted within the study. The plates of size 300 × 120 × 3.2 mm3 were friction stir butt welded using a tool rotational speed of 1000 rpm, welding speed of 80 mm/min, tilt angle of 1° and a penetration depth of 0.2 mm into the upper surface of the workpieces. The obtained results indicated that there is no defect in the weld zone of the FSWed dissimilar joint. Microhardness distribution across the mid-thickness of the joint demonstrated superior Vickers hardness within the nugget zone compared to that of AA6061-T6. In addition, tensile rupture took place away from the weld region on the advancing side in the joint for all transverse tensile test specimens. It was also demonstrated that the FSW process resulted in a significant enhancement in fracture toughness compared to those of the base materials. Furthermore, weld nugget of the joint withstood the applied transverse impact energies ranging between 2.5 and 7.5 J.