Cellular automata simulation for high temperature austenite grain growth based on thermal activation theory and curvature-driven mechanism

Abstract

Based on the thermal activation theory and curvature-driven mechanism, a 2D cellular automaton model with different state transition rules was built. Validity of the model was proved by the shrinking of circular grains. Grain growth of high temperature austenite was simulated by this model; the morphology, grain size distribution, topological aspects, and local kinetics of austenite grain growth were analyzed under different simulation time. Among the grains with different sides, the 6-sided grains are the most common and 5-sided grains are the second most common. The grains with more than six sides will grow and grains with less than six sides will shrink, while the 6-sided grains will neither grow nor shrink. The kinetics of normal grain growth follows the Burke equation and the growth exponent at different temperatures and activation energies has been researched.

The Modeling and Simulation of Austenite Grain Growth in 25Cr2Ni4MoV Nuclear-Power Rotor Steel

“…The internal cause of grain growth is self-reducing grain boundary energy, while the external cause is physical factors that promote grain change, such as temperature and grain boundary curvature. Based on this, the CA method has developed different grain growth driving mechanisms, including the lowest energy principle, thermodynamic driving mechanism and curvature-driven mechanism, which have been widely used in isotropic grain growth [35][36][37][38]. In this paper, the above three types of grain growth mechanisms are extended to establish a CA model for grain growth considering anisotropic grain boundary energy, in which the von Neumann neighborhood with the nearest neighbor sites is adopted, and the periodic boundary condition is applied to simulate the infinite space.…”