Hot Tensile Behavior and Self-consistent Constitutive Modeling of TA15 Titanium Alloy Sheets

Hot tensile behavior of TA15 sheets with bimodal microstructure was studied through tensile tests from 750 to 850 °C with an interval of 25 °C and at strain rates of 0.001, 0.01, and 0.1 s⁻¹. Results of the tensile tests reveal that the flow stress reaches peak values at specific strains, and then softening or steady-state flow occurs. Metallographic examination of deformed specimens shows that the primary α-phase becomes equiaxed, while the secondary α-phase and the lamellar β-phase are curved until crushed, indicating that the deformation occurred mainly in the secondary α-phase and the lamellar β-phase. A self-consistent model was developed to predict the plastic flow behavior of the TA15 sheets. Model parameters were determined according to the composition contents of individual phases and the stress-strain curves. The stress-strain curves at 775 °C and at the strain rates of 0.001, 0.01, and 0.1 s⁻¹ were predicted by the proposed model, showing good agreement with the experimental results.