Optimization of FSW parameters for enhancing dissimilar joint strength of AA7050 and AA6061 using Response Surface Methodology (RSM)

This study used a central composite design of RSM to friction stir welding (FSW) of two different Al-alloys, AA6061 and AA7050, by varying input parameters, including tool tilt angle (TTA), rotating tool speed (TRS), and welding speed (WS). Twenty experiments were performed, and output responses such as UTS, percent strain, and hardness were perceived. The FSW parameters were optimized using the desirability method. An analysis of variance was performed with a 95 percent confidence interval (CI) to assess the suitability of the produced model. This study found that the WS and TRS were the most crucial variables affecting the ultimate tensile strength (UTS) and hardness of the weldments. At a TRS of 1500 rpm, 150 mm/min, and a TTA of 2°, the highest UTS (255.83 MPa) and percent strain (21.02) were recorded. At a WS of 120 mm/min, a TTA of 2°, and a TRS of 1100 rpm, the lowest UTS (148.58 MPa) and hardness value (66.4HV) were noted. The results of the tensile test demonstrate the significance of the TRS and WS in affecting the UTS of the welded joint. A higher TRS causes more significant material consolidation behind the shoulder and improved mechanical properties.