Effect of Milling Process Parameters on Machined Surface Integrity of Ti65 High Temperature Titanium Alloy

The Ti65 high temperature titanium alloy was subjected to the milling orthogonal test. The effects of single tooth feed （0.01, 0.04, 0.07, 0.10 mm·z⁻¹）, milling speed （30, 60, 90, 120 m·min⁻¹）, milling width （2, 4, 6, 8 mm） and milling depth （0.5, 1.0, 1.5, 2.0 mm） on the machined surface roughness, residual stress and hardness were studied. The results show that the factors influencing surface roughness, ranked by degree of impact from largest to smallest, were single tooth feed, milling depth, milling width and milling speed. With increasing single tooth feed or milling depth, the surface roughness increased. With increasing milling speed or decreasing milling width, the surface roughness slightly decreased but the change was not significant. The effect of single tooth feed and milling speed on surface residual stress was significant, while the effect of milling width and milling depth was small. With increasing single tooth feed increased or decreasing milling speed, the surface residual compressive stress decreased. With increasing milling width or increasing milling depth, the surface residual compressive stress showed no significant change. The milling depth had the greatest effect on surface hardness, followed by single tooth feed and milling speed, and the milling width had the least effect. With the increase of milling depth, single tooth feed, milling speed or milling width, the surface hardness increased.