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 A degrees C with an interval of 25 A degrees 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 alpha-phase becomes equiaxed, while the secondary alpha-phase and the lamellar beta-phase are curved until crushed, indicating that the deformation occurred mainly in the secondary alpha-phase and the lamellar beta-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 A degrees 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.