Flow behavior and microstructure evolution of Ti175 alloy during hot deformation

• Ti175 alloy’s flow stress modeled accurately with strain-compensated Arrhenius equation. • Strain rate dominates DRX type; temperature controls grain morphology via β-phase. • Optimal thermo-mechanical processing at 940°C - 0.01s⁻¹ yields fine uniform microstructure. • Non-equilibrium α-phase stabilization occurs via kinetic or thermodynamic pathways. As a high-performance dual-phase titanium alloy, the thermomechanical processing behavior of Ti175 fundamentally determines the microstructure and properties of final components. Through hot compression experiments, this study systematically investigates the flow characteristics, microstructural evolution, and texture development of Ti175 alloy within the temperature range of 900-980°C and strain rate range of 0.001-1 s⁻¹. A strain-compensated Arrhenius constitutive model was established, accurately predicting the flow stress (R² = 0.9655, AARE = 11.17%). Microstructural analysis reveals that strain rate predominantly governs the extent of dynamic recrystallization, while deformation temperature influences the equiaxed nature and size of recrystallized grains by modulating the β-phase fraction. Under the optimal condition of 940°C and 0.01 s⁻¹, the thermomechanical coupling achieves an ideal balance, resulting in a homogeneous and fine fully recrystallized microstructure. The study further identifies a "deformation-induced α-phase stabilization" phenomenon and elucidates its dual mechanisms: At high strain rates (1 s⁻¹), it exhibits thermodynamic stabilization induced by the accumulation of stored energy, while at high temperatures (980°C), it demonstrates kinetic suppression due to the dissipation of stored energy. Both transformation pathways extend beyond the predictions of conventional equilibrium phase diagrams. This work delineates how thermomechanical parameters influence phase transformation pathways in a non-equilibrium manner, providing a theoretical foundation for precise microstructural control in Ti175 alloy.