Flow Stress-Strain Rate Behavior of Ti-3Al-2.5V Alloy at Low Temperatures in the Superplastic Range

Flow stress-strain rate behavior of Ti-3Al-2.5V, an α + β titanium alloy was studied at 750 and 800 °C by using the method of crosshead speed cycling. The alloy was found to exhibit superplasticity at these temperatures on the basis of complete flow stress, strain rate and strain rate sensitivity data. Strain-induced softening was observed in the alloy to a small extent at 750 °C and was thought to be related to the grain refinement occurring in both α- and β-phases during the initial stages of deformation. However, at 800 °C the effect was seen only under increasing strain-rate conditions. Flow stress versus strain rate curves generally exhibited only region II which corresponded to low- and intermediate-strain rates and region III corresponding to high-strain rates.