Crystal Plasticity Analysis of Development of Intragranular Misorientations due to Kinking in HCP Single Crystals Subjected to Uniaxial Compressive Loading

The mechanism and the effective factors for the development of intragranular misorientations due to kinking is studied by a crystal plasticity finite element method. A single crystal with hexagonal close-packed (HCP) structure in which only basal slip system is activated is used as a model material. To activate basal slip system, the initial crystal orientations are set to be the ones whose basal planes are slightly deviated from the compressive direction. The result shows that basal slip and the development of intragranular misorientations are sometimes localized near the center of the specimen depending on the initial deviation angle, strain hardening rate, and strain rate sensitivity. The mechanism is discussed in terms of the nonuniform stress distribution and lattice rotation. The effect of slight changes in the boundary conditions shows significant effect on the positions of slip localization. In summary, the present numerical results suggest that there are a number of effective factors for the development of the intragranular misorientations due to kinking including initial crystal orientation, material parameters, and boundary conditions.