Microstructure-based constitutive modeling of flow stress behavior of Ti-6Al-2Zr-2Sn-3Mo-1.5Cr-2Nb alloy at thermo-mechanical processing conditions

Abstract

The response of a Ti-6Al-2Zr-2Sn-3Mo-1.5Cr-2Nb alloy to the flow stress behavior was satisfactorily represented by a microstructure-based constitutive model. True stress-strain curves obtained by isothermal uniaxial compression tests under various thermo-mechanical processing conditions (temperature– 890, 920, 950, 980, 1010 °C, strain rate– 0.001, 0.01, 0.1, 1 s^− 1) were used for constitutive modeling. A new model was developed, mainly on the basis of the dislocation density theory and dynamic restoration mechanism. The Zener-Hollomon parameter was calculated through the development of Arrhenius type model on peak stresses. Also, a work hardening and dynamic recovery model and a dynamic recrystallization model were developed. The determination coefficient and the average absolute relative error of the developed constitutive model are 0.9955 and 2.95%. And the mean absolute error and root mean square error are also calculated and they are 1.8 MPa and 2.7 MPa. The comparison between measured and predicted flow stresses shows that the established constitutive model has the better accuracy than the constitutive models reported in literatures. In consequence of all, it was come to the conclusion that the developed microstructure-based constitutive model is wonderfully suitable to the numerical simulation of a Ti-6Al-2Zr-2Sn-3Mo-1.5Cr-2Nb alloy.