Isothermal compression behavior and constitutive modeling of Ti-5Al-5Mo-5V-1Cr-1Fe alloy

Hot compression behavior of Ti-5Al-5Mo-5V-1Cr-1Fe alloy with an equiaxed (alpha+beta) starting microstructure was investigated by isothermal compression test and optical microscopy. Based on the true strain-stress data with temperature correction, constitutive models with a high accuracy were developed and processing maps were established. Strain inhomogeneity at different locations in the compressed sample is reduced by raising temperature, leading to a uniform distribution of a phases. For the temperature range of 800-840 degrees C with a strain rate of 10 s(-1), the transformed volume fraction of a phase increases and the average grain size of a phase decreases slightly with increasing the temperature, indicating co-existence of dynamic recovery and dynamic recrystallization. Flow localization and faint beta grain boundaries are observed at the strain rate of 10 s(-1) in the temperature range of 860-900 degrees C. The processing map analysis shows that hot working of Ti-5Al-5Mo-5V-1Cr-1Fe alloy should be conducted with the strain rate lower than 0.01 s(-1) to extend its workability.