Study on hot deformation and process parameters optimization of Ti-10.2Mo-4.9Zr-5.5Sn alloy

The isothermal constant strain rate compression test of Ti-10.2Mo-4.9Zr-5.55n alloy was carried out by Gleeble-3500 thermomechanical simulator. The hot deformation behavior at temperature of 670-820 degrees C and strain rate of 0.001-10s(-1) was studied, and the activation energy of hot deformation was calculated. The results show that the flow stress of the alloy is more sensitive to the deformation temperature and strain rate, and is reduced by the increase of the deformation temperature and the decrease of the strain rate; the activation energy of the hot deformation of the alloy is higher than the self-diffusion activation energy of pure alpha titanium and pure beta titanium alloy. According to the error calculation, the correlation coefficient and the average relative error of the constitutive model of Ti-10.2Mo-4.9Zr-5.5Sn alloy established by strain compensation are 0.9716 and 6.24%, and they own good precision. Based on the hot processing map of the Ti-10.2Mo-4.9Zr-5.5Sn alloy set up by the dynamic material model, instability zone's unstable form is mainly local flow and stable zone's deformation mechanism is mainly dynamic recovery and dynamic recrystallization through analyzing stable and unstable zones' microstructure; and it is found that the suitable deformation parameters of Ti-10.2Mo-4.9Zr-5.5Sn alloy are as follows: deformation temperature 670-700 degrees C, strain rate 0.001-0.003s(-1), deformation temperature 790-820 degrees C, and strain rate 0.001-0.1s(-1) through the processing map and microstructure observation. (C) 2018 Elsevier B.V. All rights reserved.