High-temperature deformation behavior of a beta Ti–3.0Al–3.5Cr–2.0Fe–0.1B alloy

Abstract

The high-temperature deformation behavior of a beta Ti–3.0Al–3.5Cr–2.0Fe–0.1B alloy was investigated by a Gleeble-1500D thermal simulator. The height reduction was 50%, corresponding to a true strain of 0.693. The strain rate ranging from 0.01 to 10.00 s−1 and the deformation temperature ranging from 800 to 950 °C were considered. The flow stress and the apparent activation energy for deformation, along with the constitutive equation, were used to analyze the behavior of the Ti–3.0Al–3.5Cr–2.0Fe–0.1B alloy. The processing map was established. The effect of strain rate on the microstructure at 850 °C was evaluated. The flow stress–strain curves indicated that the peak flow stresses increased along with an increase in the strain rate and decreased as the deformation temperature increased. Based on the true stress–true strain curves, the constitutive equation was established and followed as the $$\dot{\varepsilon } = 6.58 \times 10^{10} \left[ {{ \sinh }\left( {0.0113\sigma } \right)} \right]^{3.44} { \exp }\left( { - 245481.3/RT} \right)$$ . The processing map exhibited the “unsafe” region at the strain rate of 10 s−1 and the temperature of 850 °C, and the rest region was “safe”. The deformation microstructure demonstrated that both dynamic recovery (DRV) and dynamic recrystallization (DRX) existed during deformation. At the lower strain rate of 0.01 s−1, the main deformation mechanism was the DRV, and the DRX was the dominant deformation mechanism at the higher strain rate of 1.00 s−1.