Enhancing the Mechanical Strength of Dissimilar Friction Stir Welded Joints Using Parametric Optimization

This study reports the enhancement of dissimilar alloys’ friction stir welded (FSW) joint strength by identifying the optimal parameters combination. Aluminum alloy 6061 (AA6061) is welded with magnesium alloy (AZ31) in a CNC vertical machining center using a cylindrical-headed tool made of H13 alloy. The experimental model using the Box-Behnken design (BBD) of response surface methodology (RSM) takes tool traverse speed (TTS), tool rotational speed (TRS), and plunge depth (PD) as inputs and micro-hardness (mH) and ultimate tensile strength (UTS) as responses. Observation reveals that as the PD increases, UTS and mH increases as higher material fusion takes place between the dissimilar alloys. Higher TRS produces higher heat generation, leading to a coarse grain structure that leads to lower strength, whereas moderate TRS generates better strength in weld. Higher TTS lowers the weldment strength, but it improves with lower TTS. Desirability analysis develops the optimum conditions that produce better UTS and mH compared to the experimental trials.