Ultrafine grained titanium sheets with high strength and high corrosion resistance

The pure titanium sheets with ultrafine grained (UFG) microstructures were produced by high-ratio differential speed rolling (HRDSR) at different roll speed ratios and different roll temperatures. Significant strengthening was achieved after HRDSR and the sample processed at a higher speed ratio or a lower processing temperature yielded a higher strength. The strengthening mechanism in the HRDSR processed Ti was examined in terms of the models based on the critical stress for activating the Frank–Read source and the grain-size strengthening. The UFG Ti exhibited high corrosion resistance in H2SO4 and HCl solutions. The corrosion rate decreased linearly with the inverse square root of the grain size. The Ti with the smallest grain size, which was HRDSR processed at room temperature, revealed the best combination of high strength and high corrosion rate.