High-Velocity Impact Response of Directly Recycled Aluminium Alloy AA6061 Plates

Recent research has shown that optimizing recycling process parameters enhances the mechanical properties of recycled aluminium alloys via hot press forging. However, there is limited data on damage characteristics, particularly impact resistance, for recycled AA6061. Therefore, this study utilizes plates made from recycled AA6061 using direct hot press forging, subjecting them to high-velocity impact tests to explore its impact response. Plates of 3 mm, 5 mm, and 7 mm thickness undergo systematic testing with 6 mm and 9 mm spherical stainless-steel bullets at velocities ranging from 92 m/s to 335 m/s. Perforation behaviour is analyzed, revealing ductile features like bulge, petal, plug, and radial crack formations, as well as brittle features such as cone-shaped fractures and material fragmentation. Metallurgical analysis of plate surfaces and craters show cracks, voids, dimples, and ridges. The impact deformation profile, evolving with plate thickness, velocity, and bullet size, is accurately presented. Critical perforation velocity ranges are determined for each plate thickness, and energy absorption analysis investigates changes in energy absorption behaviour. Generally, recycled AA6061 plates exhibit a mild ductile behaviour when impacted by spherical-shaped bullets, which further deteriorates towards a brittle behaviour post-full penetration.