Effect of heat treatment process on the micro machinability of 7075 aluminum alloy

Abstract

This work aims to investigate the effect of heat treatment process on the micro machinability of 7075 aluminum alloy,7075 aluminum alloy was treated with T6, T73 and RRA.T6 single-stage aging process is 120 °C × 24 h; T73 two-stage aging process is 140 °C × 8 h + 180 × 12 h; retrogression and reaging (RRA) process is 120 °C × 16 h + 190 °C × 10min + 160 °C × 30 h. Finite element simulation and single-factor testing are used to examine how different heat treatment processes and different cutting parameters affect the cutting force, surface roughness, surface quality, and residual stress of 7075 aluminum alloy during micro machining.Under all three heat treatment processes, the cutting force of 7075 aluminum alloy increases with increasing cutting speed and cutting depth, but it is less affected by feed rate. Under the same cutting parameters, the cutting force of 7075 aluminum alloy under the three heat treatment processes is T73 > T6 > RRA. Under all three heat treatment processes, the surface roughness of 7075 aluminum alloy is negatively correlated with cutting speed and cutting depth, but positively correlated with feed rate. In the meantime, the micro-machined surface quality of 7075-RRA aluminum alloy is worse than that of 7075-T73 and 7075-T6 aluminum alloy. As cutting speed and cutting depth increase, the residual stress of 7075 aluminum alloy displays a typical “ladle” profile under all three heat treatment processes. When cutting speed changes, the machined surface residual tensile stress of 7075 aluminum alloy changes in much the same way under all three heat treatment processes. When cutting depth changes, the residual tensile stress of 7075 aluminum alloy under the three heat treatment processes is T73 > RRA > T6.