Surface integrity of recycled aluminum alloys after turning

The use of recycled aluminum alloys is increasing, driven by sustainability goals, as they require less energy than primary alloys while maintaining comparable mechanical properties. While significant research has focused on the mechanical properties of recycled parts, research on their machinability is relatively limited. This study investigates the machinability of primary and recycled (secondary) aluminum alloys, focusing on surface finish and integrity after machining. The alloys were analyzed using optical and scanning electron microscopy to characterize intermetallic particles, influencing machinability. Turning trials were then conducted at varying feeds under conventional lubrication. The surface finish was evaluated through roughness and defect analysis, while surface integrity was assessed by examining the severe plastic deformation layer caused by cutting. Results show that the primary alloy produced higher cutting forces and rougher surfaces compared to the secondary alloy. Tearing was the predominant surface defect observed in all alloys, but it was most severe in the primary alloy. This study underscores the potential of secondary aluminum alloys to deliver competitive machining performance while advancing sustainable manufacturing practices.