Welding 6061 t6 aluminum alloy with friction stir spot welding, investigating mechanical and microstructural features

In this study, welding 6061 T6 aluminum alloys used in aviation, military defence, automotive etc. sectors with refill friction stir spot welding (RFSSW) , which is one of the solid state methods, is investigated due to superior features such as having good machinability, high mechanical feature, high heat conductivity and corosion resistance. Two 6061 T6 aluminum alloys whose measures are 100×28×4 mm are investigated. 28 mm square overlap areas are made in overlapped specimens measured as 172×28×4 mm and welded in mid-point. 12 of 24 specimens, after they are welded, are used for shear-tensile test, others are used for investigating microstuctural features. Three different parameters which are tool rotational speed (2000-2500 rpm), welding time (1-1,5 s), plunge depth (1,7-2,0-2,5 mm) are used in welding process. Four different zone which are stir zone (SZ), heat affected zone (HAZ), thermo-mechanically affected zone (TMAZ) and base material is determined as a result of microstructural investigation. The plunge depth parameter is determined as most effective parameter for RFSSW method as a result of mechanical investigation. Keywords: Friction Stir Spot Welding, Aluminum Alloy, Refill