Hot Deformation Behavior and Constitutive Relations of Titanium Alloy Ti-6Al-4V and Modified by Multinomial Coupling

The flow stress behavior of Ti-6Al-4V in the temperture range of 850~1100 ℃ and the strain rate range of 0.001~0.1 s⁻¹ was investigated through the high temperature compression test using a thermal simulation tester.The results show that the titanium alloy Ti-6Al-4V has strain rate and temperature sensitivity. As the temperature increases and the strain rate decreases, the flow stress gradually decreases, and the work hardening rate and the dynamic softening rate reach a dynamic balance. By analyzing the influence of process parameters on material parameters, it is found that the material parameters (N, A, Q) of the alloy are not constants, but change with the change of deformation conditions. Based on the traditional hyperbolic sine function Arrhenius equation, a hyperbolic sine constitutive equation considering the coupling correction of strain rate, temperature and strain is proposed. The accuracy of the established constitutive model is evaluated by the correlation coefficient R and the average relative error (AARE). The quantitative results show that the modified constitutive equation can predict the flow stress of titanium alloy Ti-6Al-4V more accurately.