Mathematical modeling, optimization and prediction of friction stir spot welding parameters for dissimilar joining AA2024-T6 aluminium and AZ31B magnesium alloy in lap weld configuration

In this investigation, the dissimilar spot welds of AA2024-T6 Aluminium (Al) alloy and AZ31B Magnesium (Mg) alloy were fabricated using friction stir spot welding (FSSW) to counter over cracking, porosities, burning out issues, inferior joint strength and detrimental phase generation. The joint strength is a function of process parameters and can be maximized by the optimal process parametric selection. So, this study aims to enhance the tensile shear fracture load (TSFL) carrying capacity of Al/Mg spot joints by optimizing the FSSW parameters such as rate of tool plunging—RTP (mm/min), rotational speed of tool—RST (rpm), ratio of tool diameters—RTD and dwell time—DT (s). To achieve this objective, integrated statistical and computational approach of methodology of response surface (RSM) with design expert software was used. The regression based TSFL prediction equation was modeled by incorporating the FSSW parameters and its validity was assessed employing analysis of variance (ANOVA). The ANOVA analysis was also performed for determining the main influencing parameters of FSSW that control the TSFL of Al/Mg alloy joints. The optimization results displayed that the dissimilar Al/Mg alloy spot joints fabricated using the RTP of 16 mm/min, RST of 1000 rpm, RTD of 2.5 and DT of 5 s exhibited greater TSFL carrying capacity of 1.91 kN. The TSFL of dissimilar Al/Mg alloy spot joints was predicted accurately using regression based TSFL prediction model at a confidence level of 95