Hot Workability and Microstructural Evolution of Ti-5.5Al-5Mo-5V-2Nb-1Fe-1Zr Titanium Alloy Based on the Different Phase Zones during Plastic Deformation at High Temperatures

Hot workability and microstructural evolution of Ti-5.5Al-5Mo-5V-2Nb-1Fe-1Zr titanium alloy, which is also called Ti555211 titanium alloy, are investigated during compressive deformation at different temperatures and strain rates. It can be found that Ti555211 samples deformed at 750 and 850 °C comprised α and β phases, while Ti555211 samples deformed at 950 and 1050 °C consist of single β phase. When Ti555211 sample undergoes compressive deformation in the α + β phase region, microstructures of β phase vary more substantially than those of α phase, which means that plastic deformation of Ti555211 sample is governed by β phase. The process parameters are optimized by establishing processing maps based on dynamic material model. Ti555211 alloy generally possesses the better hot workability in the β phase zone. In the β phase zone of Ti555211 alloy, the best hot process area involves temperature range from 925 to 1025 °C and a strain rate range of 0.005 to 0.03 s−1.