Study on the Surface Integrity of 7050 Aluminum Alloy with Different Crystal Orientations During High-Speed Machining

Abstract

This paper investigates the effect of crystal orientations and machining parameters on the surface integrity of 7050 aluminum alloy in high-speed machining. Three groups of pre-compression deformations (10%, 15%, and 20%) are performed on the aluminum alloy to fabricate specimens with different crystal orientations. A single-factor dry cutting experiment was designed, and the surface roughness, surface morphology and defects, work hardening, and X-ray diffraction (XRD) were tested. The results show that the 15% pre-deformed 7050 aluminum alloy specimen had lower surface roughness and the best surface quality under the same cutting parameters. The surface roughness of 7050 aluminum alloy with different crystal orientations tended to first increase and then decrease with the increase of the cutting speed, and the surface roughness was positively correlated with the cutting depth and feed rate. Under different cutting parameters, the machined surfaces of 7050 aluminum alloy specimens with different crystal orientations exhibited different degrees of plowings, apophysis, sticky chips and pits. Moreover, the degree of work hardening of the 15% pre-deformed 7050 aluminum alloy specimen was small, while that of the 20% pre-deformed specimen was more serious. XRD analysis demonstrated that the diffraction peak width of the 10% pre-deformed 7050 aluminum alloy specimen slightly increased with the increase of the cutting depth. Moreover, the (111) and (200) diffraction peak intensities of the 15% pre-deformed 7050 aluminum alloy specimen increased with the increase of the cutting speed, and there was no obvious Al 2 CuMg phase on the machined surface of the 20% pre-deformed specimen.