Effect of Heat Treatment Process on the Surface Integrity of 7A04 Aluminum Alloy

Abstract

This study aims to investigate the impact of heat treatment processes on the machinability of 7A04 aluminum alloy. The heat-treated samples underwent high-speed cutting tests to analyze the influence of cutting speed on three-dimensional cutting forces, surface roughness, work hardening, and residual stress of the alloy. The findings indicate that cutting forces, surface roughness, and work hardening exhibit similar trends with increasing cutting speed. As the cutting speed rises, the cutting forces, surface roughness, work hardening, and depth of the work-hardened layer also increase. When considering the same cutting speed, an increase in solution temperature initially leads to an increase in cutting forces followed by a reduction. Additionally, the machined surface roughness gradually decreases, while work hardening first increases and then decreases. Residual stress on the machined surface varies with different heat treatment processes and resembles a ladle shape. Higher cutting speeds result in greater surface residual compressive stress and depth of the residual compressive stress layer. When comparing the same cutting speed, the combination of solution treatment at 490°C for 20 min and solution treatment at 480°C for 20 min yields higher surface residual compressive stress and greater depth of the residual compressive stress layer than the combination of solution treatment at 480°C for 20 min. Thus, 7A04 aluminum alloy demonstrates satisfactory machinability at a cutting speed of 1550 m/mm when subjected to solution treatment at 490°C for 20 min.