Strain rate sensitivity, temperature sensitivity, and strain hardening during the isothermal compression of BT25y alloy

The high-temperature flow behavior and flow stress sensitivity of BT25y alloy were investigated. Results show that hot deformation is accompanied by the dynamic competition between work hardening and flow softening. The strain rate sensitivity exponentmtends to decrease with the strain rate after a first rise, and reaches the maximum at strain rate of 0.1 s−1. There is a large temperature range exhibitingmvalues above 0.2 at strain rates of 0.01–0.1 s−1. The temperature sensitivity exponentsshows an overall dropping trend with elevated temperature. The strain hardening exponentnfirst decreases and then increases with the strain at strain rate of 0.01 s−1. Large positivenvalues lie in areas with high strain rate, and small negativenvalues are located in areas with lower temperature and small strain rate. Secondary lamellar α appears near the phase transition temperature. The microstructure presents elongated characteristics at high strain rate.