A novel phenomenological constitutive model for Ti-6AI-4V at high temperature conditions and quasi-static strain rates

摘要

Phenomenological constitutive modeling of Ti-6Al-4V at temperatures between 923 and 1023 K under 0.0005-0.05 s(-1) quasi-static rates is studied based on a phenomenological approach. For this purpose, the Johnson-Cook constitutive model is revisited. At low temperature conditions under moderate to high strain rates, the material's stress-strain curves are the most similar to power-law function. Contrary to this, at high temperature conditions under low to moderate strain rates, the saturation-type function well describes the stress-strain curves. On the other hand, it is illustrated that the Johnson-Cook constitutive model is feeble to predict the material's behavior correctly. Accordingly, in this study, a viscoplastic temperature-dependent constitutive model is developed. The strain rate hardening as well as thermal softening of the developed model is the same as the Johnson-Cook model. But a temperature-dependent strain hardening function is proposed in which both the saturation-type and power-law hardening behaviors of the material are implemented. In comparison with the Johnson-Cook model, the new constitutive model's fidelity in capturing the titanium behavior is depicted. At last, by considering an Arrhenius-type phenomenological constitutive model, it is noted that the developed constitutive model has the best correctness in predicting the Ti-6Al-4V stress-strain behavior at high temperature conditions under quasi-static rates.