Hot deformation behavior and constitutive equation of TB8 titanium alloy with a lamellar structure of α phase

The hot deformation behavior of TB8 titanium alloy with a lamellar a structure in the alpha + beta dulex phase region was investigated. The results show that at the strain rate of 1 s(-1), a continuous flow softening phenomenon is observed in the curve of the samples deformed at 650 degrees C, while a discontinuous yield phenomenon is visual in the curve of the samples when the deformation temperature is higher than 650 degrees C. The discontinuous yield phenomenon is gradually disappeared with increasing deformation temperature and strain rate. When the strain rate is 0.001 s(-1) and the deformation temperature is 750 degrees C as well as 800 degrees C, typical characteristics of dynamic recrystallization is presented in the curve of the samples. The relationship among peak stress sigma(p) temperature T and strain rate (epsilon)over dot and is characterized by Arrhenius-type constitutive equation. The equation between the material constants (alpha, Q, n and lnA) and strain is constructed. The effect of strain on the material constants (alpha, Q, n and lnA) of the Arrhenius-type constitutive equation is analyzed. The value of alpha is increased with true strain, while the values of Q, n and lnA are gradually decreased. The correlation coefficient (R-2) and the AARE value between the experimental and the predicted stress are 0.945 and 9.08%, respectively. This indicates that the strain-compensates Arrhenius type constitutive equation can better predict the flow stress value under different deformation conditions for the TB8 titanium alloy with a lamellar alpha structure deformed in the alpha+ beta dulex phase region.