Constitutive model of Ti17 titanium alloy with lamellar-type initial microstructure during hot deformation based on orthogonal analysis

Abstract

Isothermal compression tests of Ti17 titanium alloy with the initial lamellar-type microstructure at the deformation temperatures and strain rate ranges of 780–860°C and 0.001–10.0s−1, respectively, were conducted on a Gleeble-1500 thermo-mechanical simulator. The flow stresses of all different conditions were obtained. The typical flow curves presented that softening at all the deformation conditions, even at low strain rate (0.001s−1), which have been considered that the flow softening results from lamellar globularization at low strain rates and adiabatic shear bands at high strain rates. According to orthogonal experiment and variance analysis on the significance of strain, strain rate, deformation temperature as well as interaction between strain rate and deformation temperature to the flow stress, the effect of interaction between strain rate and deformation temperature can be neglected in comparison with other factor. Thus, with consideration of strain, strain rate, and deformation temperature, a multivariate nonlinear regression model was established to predict the flow stress in isothermal compression of Ti17 titanium alloy in this paper. Predicted and experimental results show that the developed constitutive equation enables to predict the flow stress accurately throughout the entire domain of temperature and strain rate, excepting at high strain rate (10s−1), deformation temperature 780°C for Ti17 titanium alloy.