Application of hot forming quenching on patchwork blank using two-stage refilled friction stir spot welding

The purpose of this study is to apply Hot Forming Quenching (HFQ) on Patchwork Blank of AA6061 using Two-stage refilled Friction Stir Spot Welding (TFSSW). TFSSW is a developed joining method to improve joint strength of conventional Friction Stir Spot Welding (FSSW) and it consists of two stages. The first stage is a conventional FSSW process and second stage is a refilling process for refilling keyhole. The Design of Experiment (DOE) was used to optimize the TFSSW process parameters. A hat shape forming test was performed using a patchwork blank manufactured with the optimal process parameters to investigate validity of applying HFQ. Formed hat shape part was sequentially heat treated with artificial aging (T6) condition. The hardness of the weld zone was measured to confirm a drop of mechanical property in comparison with the conventional cold forming, which shows the validity of HFQ application to patchwork blank using TFSSW.