Underwater Friction Stir Welded Armour Grade AA5083 Aluminum Alloys: Experimental Ballistic Performance and Corrosion Investigation

Lightweight combat units, assault warplanes, and destroyers are being developed to increase agility and resource efficiency. This is realized using lightweight frames composed of aluminum and magnesium alloys, which decrease weight, enhance cargo-carrying capacity, and improve vehicular efficiency. This research used 18.5 mm Armour Piercing Projectiles at a target velocity of 200 m/sec to test the ballistic performance of AA5083 Base Metal and underwater friction-stir welded (UWFSW) target welded plates. The Al’s joints were fabricated utilizing the UWFSW process at tool rotational speed (TRS), tool welding speed (TWS), and tool tilt angle (TTA), as well as variable tool pin shapes, cylindrical threaded, straight hexagonal, and straight cylindrical. With a TRS of 1200 rpm, TWS of 40 mm/min, TTA of 1°, and straight hexagonal tool pin shape, defect-free welds with improved tensile and impact qualities were attained. The macro hardness and microstructure of the UWFSW joints were examined. The fine grain structure has the highest hardness (135 HV). Adiabatic Shear Bands (ASBs) were confirmed by scanning electron microscopy of a projectile-pierced channel. Because of the increased amount of ASB lines on the ballistic hit UWFSW surface, there were more macro cracks. There was no fragmentation loss, reduced fissures, and lesser ASB lines in the hexagonal pin joints, all of which increased ballistic performance. In order to protect against the corrosion of UWFSWed 5083 Al alloy in seawater, electrochemical tests and nitric acid mass loss tests were conducted.