Mechanical and high-temperature deformation properties of Ti–43.5Al–3V–2Nb alloy

We studied mechanical properties and deformation behavior of Ti–43.5Al–3V–2Nb alloy at high-temperatures. Stress–strain curves demonstrated standard work-hardening and flow-softening characteristics,and the data obtained from these curves were used to obtain a corresponding formula to calculate activation energy (which was qual to 565 kJ mol⁻¹). Dynamic materials modeling was used to develop a processing map with a true strain equal to 0.6. Ti–43.5Al–3V–2Nb alloy with an equiaxed structure has a wide processing window. Instability zones were in the 1000 °C–1050 °C and >0.5 s⁻¹. Flow-soft mechanism in the unstable region is related to stress-relaxation due to the incompatible deformation of each phase. Flow-soft mechanism in the safe region is related to the dynamic recrystallization and dynamic recovery of γ, α and β polymorphic modifications. Heat treatment at 1235 °C for 60 min/AC + 900 °C/6 h/FC improved room-temperature tensile properties of the forged alloy significantly: tensile strength was 920MPa and tensile ductility was 2.5%. Thus, the alloy demonstrated excellent combination of high strength and ductility after this heat-treatment. Heat-treated Ti–43.5Al–3V–2Nb alloy also maintained tensile strength higher >820 MPa up to 750 °C. (paper)