Dynamic mechanical behavior, microstructure evolution, and restoration mechanism of a β-Ti alloy during hot compression deformation

Abstract

Metastable β titanium alloys are promising materials for lightweight and energy-efficient applications due to their high strength and low density. Thermal–mechanical processing (TMP) is one of the most effective ways to improve the mechanical properties of such alloys. This paper describes a systematic TMP investigation on a new metastable β titanium alloy, including its dynamic mechanical behavior, and microstructure evolution, via isothermal compression tests and electron back-scattered diffraction characterizations. The results show that the compression stress increases with an increase in the strain rate and a decrease in the temperature. After yielding, the compression stress–strain pattern shows flow-softening behavior at a low temperature and a high strain rate, while sustaining a steady flow state at a high temperature and a low strain rate. The temperature-rise effect contributes to a large degree of flow softening at high strain rates. After the correction for temperature rise, the stress–strain constitutive relationships are established, showing that the compression behavior varies in different phase regions. Based on the microstructure characterizations, it is found that the dynamic recovery and dynamic recrystallization dominate the hot deformations in β phase region and at low strain rates, while the deformation band as an additional product is found in α + β phase region and at high strain rates. The results contribute to a better understanding of the TMP for the considered alloy and may also represent a useful database for β-Ti alloy applications in lightweight mechanical systems.