Hot deformation behavior and microstructural evolution of beta C titanium alloy in β phase field
(Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China)
Abstract: The hot deformation behavior of beta C titanium alloy in β phase field was investigated by isothermal compression tests on a Gleeble-3800 thermomechanical simulator. The constitutive equation describing the hot deformation behavior was obtained and a processing map was established at the true strain of 0.7. The microstructure was characterized by optical microscopy (OM), scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD) technique. The results show that the flow stress increases with increasing strain rates, and decreases with increasing experimental temperatures. The calculated apparent activation energy (167 kJ/mol) is close to that of self-diffusion in β titanium. The processing map and microstructure observation exhibit a dynamic recrystallization domain in the temperature range of 900-1000 °C and strain rate range of 0.1-1 s-1. An instability region exists when the strain rate is higher than 1.7 s-1. The microstructure of beta C titanium alloy can be optimized by proper heat treatments after the deformation in the dynamic recrystallization domain.
Key words: titanium alloy; hot deformation; dynamic recrystallization; processing map