Flow stress and constitutive modeling of hydrogenated Ti-6Al-4V alloys

The mechanical behaviors of two kinds of hydrogenated Ti-6Al-4V alloy were investigated in quasi-static (material testing machine) and dynamic (split Hopkinson pressure bar) compression test. The stress-strain curves were obtained over the range of strain rates from 10^-3s^-1 to 1.5×10³ s^-1 and temperatures from 20°C (room temperature) to 700°C. The strain rate and temperature sensitivity of plastic flow stress are researched. The experimental results indicate that the influences of strain rate and strain-hardening are comparatively weaker than the effect of thermal-softening. At room temperature, the flow stress is more sensitive to strain rate than it is at higher temperature. Finally, the stress-strain curves are successfully modeled by Johnson-Cook (J-C) constitutive equation. The predicted flow stress and the experimental results are compared, attaining good agreements.