Mechanical and microstructural characterization of the effect of increasing the tool rotational speed on submerged friction stir welded dissimilar Al-Mg alloy

Abstract This research article aims to determine the effect of increasing the tool rotational speed on the submerged friction stir welding of dissimilar alloys. The variable tool rotational speeds of 1500 rpm, 1600 rpm, 1700 rpm, and 1800 rpm, with a welding speed of 30 mm min −1 , were chosen based on the trial welding. Results reveal that macrostructural examination of the defect-free sound welded joint produced when the tool rotational speed increased constantly due to the material undergoing dynamic recrystallization. The EBSD measured grain size values of 6.12 μm, 5.29 μm, 2.93 μm, and 2.12 μm for the corresponding tool rotational speeds of 1500 rpm, 1600 rpm, 1700 rpm, and 1800 rpm. The XRD analysis reveals that the intermetallic compounds of Al 3 Mg 2 and Al 12 Mg 17 formations were observed at the stir zone of 1500 rpm, 1600 rpm, and 1700 rpm parameters, proving the brittle fracture. The tool rotational speed of 1700 rpm achieved a higher tensile strength value of 146 MPa.