Disparity in recrystallization of α- & γ-fibers and its impact on cube texture formation in non-oriented electrical steel

An investigation into the recovery and recrystallization of the two major texture fibres during annealing, namely α and γ, yielded subtle differences between the two. It is reported that with thermal activation static recovery occurs, where dislocation free sub-grains are formed and tend to grow, coalesce, or bulge out. This can form new strain-free recrystallisation nuclei, with the coalesce or bulging phenomenon depending on stored energy and geometrically dislocation density (GND). Due to low lattice curvature or otherwise, it was found α-fiber has low stored energy and GND values which favours bulging into neighbouring deformed grains as opposed to subgrain coalescement. In contrast, γ-fiber tends to undergo rapid subgrain coalescement due to high lattice curvature, i.e., GND and stored energy. The newly formed grains from both texture fibers were also found to typically differ in size, as γ-fiber has a much higher nucleation rate with rapid subgrain coalescence. Furthermore, it was discovered that Cube texture component though nucleating in higher rates within α-fiber, nucleates in all regions of high dislocation densities but will only survive in regions with a low recovery and nucleation rates, typically as in α-fiber state condition. Moreover, Goss texture component was found to preferentially nucleate from γ-fiber.