The constitutive responses of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy at high strain rates and elevated temperatures

The effects of strain rate and temperature on the uniaxial tension responses of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy are systematically investigated over a wide range of strain rates, 0.001-1150 s(-1), and initial temperatures, 293-573 K. Dynamic tension and recovery tests are conducted using a split-Hopkinson tension bar to obtain the adiabatic and isothermal stress-strain responses of the alloy at high strain rates. The experiments reveal that the tension behavior of the alloy is dependent on the strain rate and temperature. The value of initial yield stress increases with increasing strain rate and decreasing temperature, whereas the isothermal strain-hardening behavior changes little with strain rate and temperature over the full ranges explored. The adiabatic temperature rise is the main reason for the reduction of strain hardening rate during the high-rate deformation process. SEM observations indicate that the tension specimen is broken in a manner of ductile fracture. The phenomenologically based constitutive model, Johnson-Cook model, is suitably modified to describe the rate-temperature dependent deformation behavior of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy. The model correlations are in good agreement with the experimental data within the investigated range of strain rates and temperatures. (C) 2015 Elsevier B.V. All rights reserved.