Abstract:Hot compression behavior of Ti-5Al-5Mo-5V-1Cr-1Fe alloy with an equiaxed (α+β) 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 α phases. For the temperature range of 800-840 °C with a strain rate of 10 s^-1, the transformed volume fraction of α phase increases and the average grain size of α phase decreases slightly with increasing the temperature, indicating co-existence of dynamic recovery and dynamic recrystallization. Flow localization and faint β grain boundaries are observed at the strain rate of 10 s^-1 in the temperature range of 860-900 °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.

Key words: Ti-5Al-5Mo-5V-1Cr-1Fe alloy; isothermal compression; constitutive equations; processing map