Papers by Keyword: Dislocation Patterning

Abstract: In this study, we develop a multiscale crystal plasticity model that represents evolution of dislocation structure on formation process of ultrafine-grained metal based both on dislocation patterning and geometrically necessary dislocation accumulation. A computation on the processes of ultrafine-graining, i.e., generation of dislocation cell and subgrain patterns, evolution of dense dislocation walls, its transition to micro-bands and lamellar dislocation structure and formation of subdivision surrounded by high angle boundaries, is performed by use of the present model. Dislocation patterning depending on activity of slip systems is reproduced introducing slip rate of each slip system into reaction-diffusion equations governing self-organization of dislocation structure and increasing immobilizing rate of dislocation with activation of the secondary slip system. In addition, we investigate the effect of active slip systems to the processes of fine-graining by using the pseudo-three-dimensional model with twelve slip systems of FCC metal.

Abstract: A multiscale model on dislocation patterning of cell structure and subgrain for polycrystal is newly developed on the basis of reaction-diffusion theory. A FD simulation for dislocation patterning and a FE one for crystal deformation are simultaneously carried out for a FCC polycrystal at large strain. Reflecting stress value on stress-effect coefficients, it is numerically predicted that the evolution of dislocation pattern in a polycrystal is different in response to the stress condition of each grain.