Dynamic behaviour of Ti-17 alloy under high strain rates at elevated temperatures

The dynamic mechanical behaviour of Ti-17 alloy deformed at high strain rates ranging from 6,000 to 12,000 s(-1) and temperatures between 473K and 1,073K is studied using the Split Hopkinson Pressure Bar. The stress-strain curves of material under temperature-strain rate coupling actions are obtained. The mechanism of effect of temperature and strain rate on the plastic flow stress of Ti-17 alloy is discussed. The results show that the Ti-17 alloy has an evident heat softening effect, strain rate strengthening effect and strain hardening effect, and flow stress decreases with the temperature increase. But under different strain rates at a given temperature, the flow stress shows an obvious work softening phenomenon, this is a result of a competition between thermal softening and work hardening when the dynamic softening effect is sufficient to counteract the work-hardening effect under high strain rates.