Research on hot deformation behavior of Ti–5Al–5Mo–5V–1Cr–1Fe alloy

• The hot deformation constitutive equation of Ti–5Al–5Mo–5V–1Cr–1Fe alloy is derived.
• The critical strain of dynamic recrystallization and peak strain can be described as: εc/εp=0.64εc/εp=0.64.
• The softening mechanism of Ti–5Al–5Mo–5V–1Cr–1Fe alloy is analyzed by electron backscattered diffraction technique.
• The relationship between dynamic recrystallization and initial strain rate is discovered.
• The nucleation mechanisms of dynamic recrystallization are grain boundary bowing and sub-grain merge.

Ti–5Al–5Mo–5V–1Cr–1Fe is a near β-type Ti-alloy. It has been widely used in large loading-carry structures in aircrafts due to its excellent mechanical properties. For near-β titanium alloys, DRX (dynamic recrystallization) in hot deformation process can eliminate the bimodal microstructure and refine microstructure, which helps to improve the alloy performance. So, the hot deformation behavior of Ti–5Al–5Mo–5V–1Cr–1Fe alloy was characterized in the temperature range of 750–950 °C and the initial strain rate range of 0.01–10 s−1 by the constitutive model, the critical conditions of DRX and EBSD (Electron Backscattered Diffraction) technique. The constitutive model of Ti–5Al–5Mo–5V–1Cr–1Fe alloy during hot deformation can be well described by Arrhenius hyperbolic sine function. The calculation results show that the ratio of critical strain and peak strain is about 0.64. Under the experimental conditions in this research, Ti–5Al–5Mo–5V–1Cr–1Fe alloy exhibits two soften mechanisms of (DRV) dynamic recovery and DRX. The DRX phenomenon of Ti–5Al–5Mo–5V–1Cr–1Fe alloy exists in all of hot deformation conditions. Only the extents of DRX are different. There are several nucleation mechanisms of DRX in the process of hot deformation of Ti–5Al–5Mo–5V–1Cr–1Fe alloy in this study.