Effect of the magnitude of sub-boundary angles on the abnormal grain growth rate of Goss grains in Fe-3%Si steel

In spites of extensive studies, the selective abnormal grain growth (AGG) of Goss grains in Fe-3%Si steel remains still unclear. Here, the effect of the magnitude of sub-boundary angles on AGG behavior was investigated both by computer simulations and experiments. In 3-dimensional Monte Carlo simulations of grain growth based on the realistic grain boundary energy distribution data, the grains of Goss orientation, which are given the sub-boundaries, grew abnormally and smaller sub-boundary energies resulted in larger Goss grains. Additionally, a Fe-3%Si steel, after primary recrystallization, was heated to 1050 °C to induce AGG. Measurements of sub-boundary angles for three different sizes of abnormally growing Goss grains by synchrotron X-ray microdiffraction after the initial stage of secondary recrystallization showed that the misorientation of the sub-boundary angles was 0.41° for the small Goss grain of 734 μm. Moreover, the average misorientation of sub-boundary angles was 0.33° for the medium Goss grain of 1050 μm and 0.25° for the large Goss grain of 2978 μm. In contrast, the average misorientation angles of the sub-boundaries after the final stage of secondary recrystallization were only 0.05°. The results indicate that the sub-boundary angle is a determining parameter for the size of abnormally growing grains.