Simulation on Changes in Microstructure and Texture during Normal Grain Growth of Steel Sheet by Two-dimensional Local Curvature Multi-vertex Model

The two-dimensional local curvature multi-vertex model was applied to the normal grain growth of actual steel sheets for examination of the effect of the respective misorientation dependencies of grain boundary energy and mobility on grain growth and for comparison with experimental results. The simulation result revealed that the grain boundary energy had a major influence on the change in misorientation distribution with grain growth, whereas the grain boundary mobility did not have such a large influence. The simulation considering the misorientation dependency on grain boundary energy and mobility, in particular, accounting for Σ1 and high angle boundaries was constructed and was effective for reproducing the experimental results. Simulated microstructures were similar to the experimental ones; however, the detailed standard deviation of grain size distribution was smaller in the calculation than that in the experiment. The texture change with grain growth in the simulation was weaker than that in the actual steel sheets. As a whole, the developed model described the experimental grain growth well, and the difference in the results between the simulation and the experiment is probably attributable to the difference in dimension; i.e., two-dimension in simulation and three-dimension in experiment and the inaccuracy of the grain boundary conditions such as grain boundary energy and mobility in the model.