Constitutive modeling of high temperature flow behavior in a Ti-45Al-8Nb-2Cr-2Mn-0.2Y alloy

Abstract

Abstract A constitutive equation based on the hyperbolic sinusoidal Arrhenius-type model has been developed to describe the hot deformation behavior of a β-γ Ti-Al alloy containing 8 at.% of Nb. Experimental true stress-true strain data were acquired from isothermal hot compression tests conducted across a wide range of temperatures (1273 K~1473 K) and strain rates (0.001 s −1 ~1 s −1 ), and the changes in the experimental conditions were reflected in the values of the Zener-Hollomon parameter. The impact of true strain was expressed through material constants ( A , α , n and Q ), and it was found that a 7th order polynomial is appropriate to express the relations between the true strain and these material constants. The average absolute relative error ( AARE ) and correlation coefficient ( R ) were used to evaluate the accuracy of the constitutive equation, and the values obtained were 6.009% and 0.9961, respectively. These results indicate that the type of constitutive equation developed here can predict the flow stress for this alloy with good accuracy over a wide range of experimental conditions. Thus, equations of this form could be applied more widely to analyses of hot deformation mechanism and microstructure evolution.