Modeling and simulation on ultrafine-graining based on multiscale crystal plasticity considering dislocation patterning

Aoyagi, Yoshiteru*; Kobayashi, Ryotaro*; Kaji, Yoshiyuki  ; Shizawa, Kazuyuki*

In this study, we derive reaction-diffusion equations for dislocation patterning of dislocation cell structures and subgrains. In order to express the generation of dislocation pattern responding to deformation progress, information of slip rate and stress and effect of interactions between slip systems on formation of cell structures are introduced into the reaction rate coefficients of reaction-diffusion equations. Moreover, we propose a multiscale crystal plasticity model based on dislocation patterning. Then we carry out pseudo-three-dimensional FE-FD hybrid simulation for severe compression of FCC polycrystal using the present model. Some processes of ultra fine-graining, i.e., generation of dislocation cell structures, subgrains, dense dislocation walls and lamella subdivisions with high angle boundaries are numerically reproduced, and we investigate the effect of dislocation behavior on the processes of ultrafine-graining.