The role of grain colony on secondary recrystallization in grain-oriented electrical steel: New insights from an original tracking experiment

Abstract

Secondary recrystallization is responsible for the sharp Goss texture ({110}<001>) of grain-oriented electrical steels. Many investigations have focused on establishing the relations between the sharpness of final Goss textures and primary recrystallization textures measured by the X-ray diffraction. However, the contributions of micro-texture characteristics to secondary recrystallization have not yet been well understood. Here, we report that the grain colonies composed of grains with similar orientations in the primary recrystallization matrix had a particular role on the development of secondary recrystallization via an original tracking experiment. We observe that the γ-grain (<111>//normal direction, ND) colonies facilitate the retention of primary recrystallization matrix grains (≤25µm) having 20-45° disorientation with {110}<001> and relatively large difference in the associated frequency with precise Goss orientation and that having deviation angle of 15°, promoting the abnormal growth of low-deviation-angle Goss grains especially after the onset of secondary recrystallization and leading to sharp final Goss texture. By contrast, the abnormal growth of high-deviation-angle Goss grains may be also promoted after the initiation of secondary recrystallization in case of randomly-distributed γ-grains in primary recrystallization matrix and thus resulted in deteriorated magnetic properties. In this way, we reveal the role of grain colony on secondary recrystallization and the underlying mechanism for the effect of primary recrystallization textures on the sharpness of final Goss texture. We also observe that the formation of grain colonies is mainly related to the initial solidification microstructure, processing route as well as the deformation and recrystallization features of γ-grains.