Strain-Rate-Dependent Tensile Response of Ti⁻5Al⁻2.5Sn Alloy

This study is an experimental investigation on the tensile responses of Ti⁻5Al⁻2.5Sn alloy over a wide range of strain rates. Uniaxial tension tests within the rate range of 10^-3⁻10¹ s^-1 are performed using a hydraulic driven MTS810 machine and a moderate strain-rate testing system. The high-rate uniaxial tension and tension recovery tests are conducted using a split-Hopkinson tension bar to obtain the adiabatic and isothermal stress⁻strain responses of the alloy under dynamic loading conditions. The experimental results show that the value of the initial yield stress increases with the increasing strain rate, while the strain rate sensitivity is greater at high strain rates. The isothermal strain-hardening behavior changes little with the strain rate, and the adiabatic temperature rise is the main reason for the reduction of the strain-hardening rate during high strain-rate tension. The electron backscatter diffraction (EBSD) analysis of the post-deformed samples indicates that there are deformation twins under quasi-static and high-rate tensile loadings. Scanning electron microscope (SEM) micrographs of the fracture surfaces of the post-deformed samples show dimple-like features. The Zerilli⁻Armstrong model is modified to incorporate the thermal-softening effect of the adiabatic temperature rise at high strain rates and describe the tension responses of Ti⁻5Al⁻2.5Sn alloy over strain rates from quasi-static to 1050 s^-1.