| Abnormal grain growth in subgrain structures was investigated using computer simulation. The results showed that a theory of abnormal grain growth in subgrain structures determined for 2D microstructures is found to also apply to 3D subgrain structures. 3D Monte Carlo simulation results suggest that the probability of abnormal (sub-)grain growth is a function of orientation spread within a grain (measured by grain reference orientation deviation, GROD), which is closely related to the mean misorientation of 3D digital microstructures. When a high angle boundary exists between two subgrain structures, Strain Induced Boundary Migration can occur, leading to inter-granular nucleation, which is most evident for low values of mean misorientation. Using Hughes's empirical relation that quantifies the monotonic increase of mean misorientation with strain, 3D digital microstructures with different GROD values are analogous to microstructures at various strains. Therefore, the mean misorientation is used to estimate the recrystallization nucleus density by extending the probability of abnormal subgrain growth to recrystallization nucleation. Good agreement between the predicted density of new grains by our model and experimental data suggests that a combination of subgrain abnormal growth theory, subgrain size (as a function of stress) and the known monotonic increase in mean misorientation with strain leads to a quantitative prediction of recrystallized grain size. In addition, this work has provided reasonable evidence to help us understand under what circumstances we can expect to observe inter-granular versus intra-granular nucleation of recrystallization.;This work is supported by National Science Foundation under contract DMR-0503049. Computing facilities provided by the Intel Corporation were used for some of the computations. |
