Effect of T6I4 and T616 on the machinability of 7075 aluminum alloy and tool wear mechanism

The effect of T6I4 and T6I6 interrupted aging processes on the machinability of 7075 aluminum alloy is investigated. The cutting force, cutting temperature, surface roughness, and tool wear variations of the alloy in T6I4 and T6I6 states are identified at the macroscopic and microscopic scales with the help of a dynomometer, a roughness tester, an optical microscope, a scanning electron microscope, and ABAQUS 6.14 and through experiment and simulation. The results show that compared with T6 peak-aging, T6I4 and T6I6 greatly improve the machinability of 7075 aluminum alloy; under the same cutting parameters, 7075-T6I4 and 7075-T6I6 alloys have smaller cutting force, cutting temperature, and surface roughness, with 7075-T6I4 displaying the best performance. Increasing cutting speed and reducing feed rate, together, effectively improve the workpiece surface finish. The tool wear is also better and mainly comprises tool chipping and adhesive wear. XRD analysis indicates that during cutting, the precipitates of 7075 aluminum alloy are primarily & eta;-phases; the Al peak of 7075-T6I4 alloy is significantly higher than that of the other two heat treatment states. Its grain size is smaller, too.