Anisotropic Mechanical Behavior and Plastic Deformation Mechanisms of Commercially Pure Titanium with Different Initial Orientations

Abstract:

The anisotropic mechanical behaviors of TA1 commercially pure titanium (CP-Ti) rolled plates with two different initial orientations (bimodal texture and dispersed texture) under uniaxial loading, including stress-strain curves, tension-compression yield asymmetry, strain hardening, plastic strain ratio (r-value), and texture evolution were investigated using macroscopic mechanical property testing, microstructural characterization, and crystal plasticity modeling. The simulation results based on the VPSC-PTR model are well agreement with the experimental data. Compared to the plate with dispersed texture, the plate with bimodal texture presents more prominent anisotropy and tension-compression asymmetry, accompanied by more significant changes in the r-value and more intense texture evolution during deformation. Combining with the Schmid factor distribution, the relative activity of slip/twinning system, and critical resolved shear stress, the effect of initial texture on competition between slip and twinning during the deformation is clarified, revealing the influence mechanism of the initial orientation on the anisotropy of the rolled CP-Ti plates. The prismatic slip is the dominant mechanism of plastic deformation in CP-Ti. And extension twinning is more easily activated in plate with bimodal texture, while basal slip and pyramidal slip are more active in plate with dispersed texture, leading to different anisotropic characteristics. Moreover, the r-value of plate with bimodal texture is higher than that with dispersed texture during deformation, which is related to the decrease in activity of prismatic slip and the increase in activity of extension twinning.