Isothermal tensile deformation behaviors and fracture mechanism of Ti-5Al-5Mo-5V-1Cr-1Fe alloy in β phase field

The isothermal tensile deformation behaviors of Ti-5Al-5Mo-5V-1Cr-1Fe alloy in beta phase field are studied at the wide ranges of temperature and strain rate. The experimental results indicate that the processing parameters dramatically influence the isothermal tensile deformation characteristics of the studied alloy. Raising the deformation temperature or decreasing strain rate conspicuously decreases the flow stress. With the proceed of deformation process, the flow stress immediately approaches its peak value and then gradually decreases because of the dynamic softening induced by dynamic recrystallization and recovery. Meanwhile, the discontinuous yield phenomena can be found, especially at the higher deformation temperatures and lower strain rates. In the later tensile deformation stage, the flow stress sharply decreases due to the localized necking and microvoids coalescence, which leads to the final ductile fracture. A strain-compensated Arrhenius and Cingara constitutive equations are established to predict the tensile deformation characteristics of the studied alloy. A comparative study of the established constitutive equations is carried out, which reveals that the strain-compensated Arrhenius constitutive equation possesses the better capability to forecast the flow stress.