文摘
A grade 2 commercially pure (CP) titanium was processed by high-pressure torsion (HPT) at pressures of 3.0 and 6.0?GPa in order to achieve improved strengths. The microhardness values for these Ti samples were plotted against the imposed strain, and the plots show that a higher saturation microhardness of 320?Hv is achieved for the sample processed at 6.0?GPa compared to a microhardness of 305?Hv when using a pressure of 3.0?GPa. The omega ω-phase has been reported in some earlier HPT investigations of pure titanium, but it was not detected in this investigation even after processing at 6.0?GPa. The absence of the ω-phase is attributed to the relatively high level of oxygen (0.25 wt%) in these CP titanium samples. The higher saturation hardness for the 6.0?GPa sample is consistent with the smaller average grain size of ~105?±?12?nm compared with the measured grain size of ~130?±?18?nm after processing with an imposed pressure of 3.0?GPa.