Dual-phase morphology distribution effects on mechanical behaviors of Ti6Al4V via pseudorandom crystal plasticity modeling

Abstract

As an important factor of dual-phase polycrystalline materials, dual-phase morphology distribution significantly affects its deformation mechanism due to the complex biphasic interactions. However, it was rarely investigated, especially for titanium alloy. Although crystal plasticity modeling has been regarded as an important method to study the deformation behaviors, the current models do not fully consider the actual grain scale information of dual-phase materials. In this paper, a pseudorandom dual-phase crystal plasticity finite element (CPFE) model is established, which fully considers the actual grain size and orientation information, volume fraction, and constitutive behaviors of the dual-phase grains. The model is calibrated by uniaxial tensile experiments, and validated from micro and macro levels respectively. Four situations are introduced to study the effects of dual-phase morphology distribution on mechanical behaviors of Ti6Al4V, including Model 1 (dual-phase grains are randomly distributed), Model 2 (dual-phase grains are homogeneously distributed), Model 3 (dual-phase grains are periodically distributed perpendicular to the tensile direction) and Model 4 (dual-phase grains are periodically distributed parallel to the tensile direction). The results show that Model 4 has significant advantages in the comprehensive performance on micro stress/strain homogeneity and macro tensile strength compared with the other three models. Model 2 has the highest tensile strength due to the full use of plugging effect of the phase boundaries on dislocations. The slip transmission between the dual phases is more difficult than that in the hard phase (α phase) due to the different crystal structure. The research results provide a reference for material metallurgy.

Keywords

• Dual-phase
• Pseudorandom
• CPFE
• Ti6Al4V
• Mechanical behaviors