Modeling and Optimization of Process Parameters of Submerged Friction Stir Processing on AZ31B Alloys

Despite much investigation, submerged friction stir processing (SFSP) is still a developing method. In this work, a hot-rolled AZ31B magnesium alloy plate with a thickness of 6 mm is exposed to an FSP in submerged conditions. Rotational speed (RS), traverse feed (TF), tool pin profile of cylindrical (CL), stepped cylindrical (SCL), and stepped square (SSQ) are the FSP process parameters that are evaluated. The SFSP settings were optimized to maximize the stir zone's tensile strength and hardness. Response surface plots are used to ascertain the optimal values when using the Response Surface Method (RSM) for mathematical modeling. The regression models of tensile strength and hardness are developed with higher significance. At a rotational speed of 1000 rpm and a traverse feed of 60 mm/min, the maximum tensile strength and hardness of 238.96 MPa and 108 Hv can be obtained while optimizing the parameters. The microstructure of the SFSP-ed samples with varied tool pin profiles was compared using the technique of SEM. The SFSP of stepped square tool pin geometry was attained, having an ultra-fine grain size with an average of 1.92 µm.