[SY-F1] Image-based crystal plasticity analysis on the activities of slip systems in polycrystal alpha-Ti
It has been pointed out that the activation of basal slip systems in alpha-Ti leads to fatigue failure under fatigue loading. Thus, it is important to quantitatively evaluate the activity of basal slip systems in alpha -Ti for ensuring the safety and reliability and predicting the fatigue lifetime with higher accuracy. However, the deformation mechanisms are still incompletely understood, and the activity of basal slip systems under the deformation is also not clarified.
When forced displacement is applied to polycrystal alpha-Ti, decreases in the amount of deformation in crystal grains would lead to those of increases in the other crystal grains because the reduction of the deformation in a crystal grain must be compensated by increases in those in the other crystal grains. That is, there is a possibility that changes in the activity of slip systems of crystal grains influence those of the basal slip systems of the other crystal grains.
In this study, a crystal orientation map obtained by Electron Back Scatter Diffraction (EBSD) patterns of a pure titanium (alpha-Ti) specimen was converted into a geometric model for finite element method using an interface developed by authors, and Crystal Plasticity Finite Element (CPFE) analysis was conducted. The crystal orientations in the specimen showed that (0001) planes of almost crystal grains declined in the direction from ND to RD, and the microstructure has a texture so-called RD-Split. A dislocation density dependent constitutive equation was employed and unidirectional tensile loading was applied to the geometric model by the forced displacement. Several sets of initial Critical Resolved Shear Stress (CRSS) were employed for the simulation. The relationship between the initial CRSS of each slip system and the activity of basal slip systems was investigated.
When forced displacement is applied to polycrystal alpha-Ti, decreases in the amount of deformation in crystal grains would lead to those of increases in the other crystal grains because the reduction of the deformation in a crystal grain must be compensated by increases in those in the other crystal grains. That is, there is a possibility that changes in the activity of slip systems of crystal grains influence those of the basal slip systems of the other crystal grains.
In this study, a crystal orientation map obtained by Electron Back Scatter Diffraction (EBSD) patterns of a pure titanium (alpha-Ti) specimen was converted into a geometric model for finite element method using an interface developed by authors, and Crystal Plasticity Finite Element (CPFE) analysis was conducted. The crystal orientations in the specimen showed that (0001) planes of almost crystal grains declined in the direction from ND to RD, and the microstructure has a texture so-called RD-Split. A dislocation density dependent constitutive equation was employed and unidirectional tensile loading was applied to the geometric model by the forced displacement. Several sets of initial Critical Resolved Shear Stress (CRSS) were employed for the simulation. The relationship between the initial CRSS of each slip system and the activity of basal slip systems was investigated.