Research on surface integrity of turning titanium alloy TB6

Abstract

In this paper, machined surface integrity during orthogonal turning titanium alloy TB6 was systematic researched. The effects of cutting parameters and process system vibration on the machined surface roughness and defects were studied. Surface residual stress introduced by machining was explored by measurement combined with simulation technology. Micro-hardness and microstructure of the machined surface were also discussed. The results showed that it was not the cutting speed, but feed rate had obviously significant impacts on the surface roughness, residual stress and micro-hardness. The roughness Ra increased from 0.2 to 0.4 μm, the residual compressive stress also increased by 10% and the location depth of the peak increased from 50 to 70 μm, when the feed rate varied from 0.05 to 0.1 mm/rev. work-hardening phenomenon was obvious at the feed rate of 0.1 mm/rev. In addition, the vibration frequency of the processing system was found to be similar with that of the roughness profile, which meant process system vibration was one of the most important factor to limit the surface quality when finishing. Moreover, residual stress on surface was large compressive stress and the state alternated within the depth of 250 μm. Under the matching cutting conditions, there was no visible physical and chemical properties transition on the machined surface and subsurface. No change of grain size, plastic deformation, cracks and white layer was observed.