2605 結晶粒方位差に基づく転位パターニングに関する転位-結晶塑性シミュレーション(S18-1 組織変化と強度,S18 材料の強度と組織)

抄録

A multiscale model on dislocation patterning of cell structure and subgrain for polycrystal is newly developed on the basis of reaction-diffusion theory. We introduce a threshold value of slip for stage transition corresponding to the initial crystal orientation into a dislocation mean free path model so as to express the dependence of three-stage hardening on the initial crystal orientation of each grain. A FD simulation for dislocation patterning and a FE one for crystal deformation are simultaneously carried out for a FCC polycrystal under severe strain condition. 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. Moreover, the formation of GN boundaries with large misorientation angle is observed along subgrain walls due to large deformation.