Microstructural changes associated with high temperature deformation of Ti-3Al-4V alloy at 750°c

Superplastic behaviour of ti-3al-4v alloy was studied at 750°c by using the method of crosshead speed cycling in the strain rate range 2 × 10-5 /sec to 3 × 10-3 /sec. strain rate sensitivity values higher than 0.4 were observed from the flow stress-strain rate data. also,the microstructural studies showed a transformation of a banded microstructure of the alloy into an equiaxed one during the deformation at this temperature. both high strain rate sensitivity values and a small equiaxed two phase grain structure are usually indicative of superplasticity in a material. however,large neck free elongation was not obtained which leads to the conclusion that ti-3al-4v alloy exhibits limited superplasticity at this temperature in the strain rate range used.