Surface modification layer of Ti–6Al–4V produced by surface rolling and thermal oxidation

A surface-modified layer (oxide layer and oxygen diffusion region) was produced on a Ti–6Al–4V alloy substrate by the combination of multipass surface rolling and thermal oxidation. The effects of different oxidation temperatures (700, 750 800 and 850°C) on the microstructure and mechanical properties of surface-modified layers of the samples before and after multipass surface rolling were investigated. Scanning electron microscopy, X-ray diffraction and energy-dispersive spectroscopy were used to analyze the change in microstructure and composition phase. Surface roughness, microhardness, friction and wear properties and corrosion resistance of surface modification layers obtained by the surface-rolled sample after oxidation (SSAO) and sample treated only by oxidizing (STBO) were measured. It is found that SSAO shows better internal structure and properties of the surface modification layer compared with STBO. Surface roughness and microhardness have no obvious difference. But the friction, wear and corrosion resistance of SSAO were also significantly improved compared to those of STBO. The minimum wear rate was obtained by surface-rolled sample oxidized at 850°C.