Prediction of anisotropic deformation behavior of TA32 titanium alloy sheet during hot tension by crystal plasticity finite element model

Abstract

An in-depth understanding of the anisotropic deformation behavior of titanium alloy sheet during hot deformation has important significance to fully exert the forming performance of the materials. In this work, a crystal plasticity finite element model (CPFEM) was established to accurately predict the anisotropic deformation behavior of TA32 titanium alloy rolled sheet during hot tension. An additional constitutive relationship was introduced into CPFEM to define the grain boundary sliding (GBS) mechanism. Meanwhile, the cellular automata (CA) model was embedded into CPFEM to simulate the dynamic recrystallization (DRX) behavior which has a significant effect on anisotropy during hot deformation. The results showed that the proposed model accurately predicts the stress-strain responses, r-values and DRX-acted microstructure evolution of TA32 alloy during hot tension along roll direction (RD) and transverse direction (TD). The transverse texture of the initial sheet results in the r-value of TA32 alloy for TD tension is higher than that for RD tension. Additionally, the higher dislocation density, especially geometrically necessary dislocation (GND) density, caused by more inhomogeneous plastic deformation during TD tension is the main reason for the larger flow stress of the material. Meanwhile, more dislocation density makes the volume fraction of DRX for TD tension higher than that for RD tension. The occurrence of DRX weakens the deformation anisotropy of TA32 alloy, which is mainly due to the fact that DRX enhances the effect of GBS and promotes the compatible deformation between grains, and the generation of substantial DRX grains with random orientation reduces the intensity of texture.