Modeling of grain refinement by cellular automata

Abstract

Prediction of microstructure evolution and properties of ultrafine-grained materials is one of the most significant problems in materials science. Cellular automata (CA) method is able for proper simulation of the microstructure evolution and can be used for evaluation of mechanical properties. The paper presents a new original application of cellular automata for modeling of grain refinement. CA take into account deformation, evolution of dislocation density and dislocation structures; and simulate microstructure evolution as grain refinement. Deformation of grains in polycrystalline materials depends on their crystallographic orientation, which is unique for every grain. It causes anisotropy of deformation in micro-scale. Joining CA with other methods (finite element, discrete element, crystal plasticity, etc.) improves accuracy of coupled phenomena modeling in micro- and macro-scale. Finite element method and crystal plasticity theory provide information for CA calculations. Grain refinement occurs in two stages: a creation of low-angle boundaries and their evolution into high-angle boundaries. Three CA models of low-angle boundaries creation were developed. They are described and discussed in the paper. Developed models can be used for study of processes of grain refinement, as well as can be a part of the system for modeling of microstructure evolution in the processes of solidification, hot and cold deformation and phase transformation. Examples presented in the paper are model application for processes with severe plastic deformation (SPD). Results of simulations of grain refinement during the accumulative roll-bonding (ARB) process and MAXStrain® technology are presented in the paper.