Development of constitutive relationship for the hot deformation of Ti-47Al-2Cr-2Nb-0.2W alloy

摘要

The high temperature deformation behaviors of Ti-47Al-2Cr-2Nb-0.2W alloy were investigated by isothermal compressive tests, performed at temperatures between 1000°C and 1150°C, strain rates between 0.001s~(-1) and 1s~(-1). The stress-strain curves of IM alloy exhibited an obvious work hardening peak followed by a broad flow softening at high strain rates(≥0.1s~(-1)) while work hardening could hardly be seen from the stress-strain curves at low strain rates(≤0.01s~(-1)). Also, the constitutive equation of the alloy had been established to describe the flow behavior. The apparent activation energy of hot deformation was calculated to be 351.61kJ/mol. The size of the recrystallized grain increased with increasing temperature and with decreasing strain rate, namely with decreasing the Zener-Hollomon parameter Z. It is necessary to select proper Z, that is, to strictly control the deformation parameters in order to obtain a homogeneous and fine microstructure.