Effect Of Micro-nano Structure Induced By Deep Rolling On The Oxidation Resistance Of Pure Titanium

In an effort to study the effect of surface strengthening on the oxidation resistance of pure titanium, rolling treatment is used in pure titanium to prepare a ultrafine grained surface layer. Then the thermal oxidation is carried out on Pure Titanium at600and700℃for different hours in an air atmosphere. Specimens for surface analysis and cross-sectional analyses are prepared, respectively.The surface oxide phase, morphology and the cross section morphology of the samples are analyzed by X-ray diffraction, optical microscopes and scanning electron microscopy methods.The growth kinetics of oxide layer and oxygen diffusion layer before and after rolling treatment are characterized by measuring their thickness. The growth of the oxide layer agrees with liner law at earlier stage. But over time, the dynamic curve of oxidation layer is of transforming from liner law to parabola. However, the changing points between unrolling and rolling samples are different, showing the changing time is shorter and shorter with the rolling depth increasing. The oxygen diffusion layer follows the same trends as the oxide layer, however, the parabolic law is not obvious. Moreover, obvious differences of oxygen diffusion layer thickness exist between unrolling and rolling samples. The oxygen diffusion layer thickness increases apparently after rolling treatment. But rolling treatment has little effect on the oxygen diffusion comparing with different rolling depth.