BCC 전기강에 대한 전위 밀도 기반 결정 소성 모델의 수치 적분 기법

Abstract

Electrical steel sheets based on bcc single crystal structure are manufactured by cold rolling process, however, cracks or fractures occur largely depending on the reduction rate. Therefore, it is necessary to predict the plastic anisotropy deformation of electrical steel. In this research, constitutive crystal framework for bcc single crystal and polycrystalline material will be verified. Particularly in this model, equation of screw dislocation velocity equation will be used, including the dislocation evolution as well as the phenomenon that minimizes the energy corresponding to dislocation length which is called kink mechanism due to non-Schmid behavior. In addition, a monolithic time integration algorithm which simultaneously solves nonlinear equations based on Euler backward time discretization will be developed. The developed crystal plasticity model was carried out by the user subroutine UMAT of ABAQUS. The verification of single crystal constitutive framework will be made by comparing with the behavior of stress-strain curves according to temperature(143K, 195K, 250K, 295K) and orientations implemented by A.S.Keh. (1970). In addition, an anisotropic deformation behavior with plane strain compression, uniaxial tensile and compression will be predicted through a verified single-crystal plasticity model and comparisons have been made against pole figures obtained from experiments for previously mentioned deformation modes. The pole figure was implemented using MATLAB MTEX.