Investigation on friction stir welding of hybrid composites fabricated on Al-Zn-Mg-Cu alloy through friction stir processing

This study presents microstructural and mechanical investigation on friction stir welding of composites fabricated through friction stir processing on a high strength Al-Zn-Mg-Cu alloy by utilizing hybrid reinforcement. Surface composites (SCs) were fabricated via FSP, sliced to the processed thickness and cut-apart through the longitudinal axis of the SCs. They were subsequently; friction stir butt welded by employing varied tool rpm (560-900 rpm). The mechanical properties, microstructural analysis and micro-hardness profile was obtained for the welds. Results of investigation revealed that in comparison to SC samples the reinforcement particle distribution of the welded samples became more homogeneous due to the weld pass. In comparison to SCed sampled the micro-hardness was found to be enhanced and more evenly distributed in the welded samples. The microstructural examination indicated that minute tunneling defect was introduced in samples welded at 560 and 900 rpm whereas incomplete root penetration (IRP) defect was observed in all welded samples. The ultimate tensile strength (UTS) of welded samples were found lower than base metal which was attributed to the presence of tunnel and IRP. (C) 2019 The Authors. Published by Elsevier B.V.