Effect of Heating Rate on the Development of Annealing Texture in Nonoriented Electrical Steels

Abstract

The magnetic properties of nonoriented electrical steels are influenced by grain size and texture. During the final annealing process, heating rate, annealing temperature and time, and cooling rate are the main factors which can influence the formation of annealing texture. Among these parameters, heating rate is more effective in controlling texture development through changes in the recovery and recrystallization processes. Therefore, it can provide the means to decrease core loss and increase permeability. In nonoriented electrical steels with different initial grain sizes, the effect of heating rate on texture development during final annealing is examined, and the reasons for texture changes are discussed. The average grain size decreases with the increase in heating rate both in the coarse-grained and in the fine-grained specimens. In the coarse-grained specimen, the Goss texture is significantly strengthened but the {111}〈112〉 texture component is slightly weakened as heating rate increases. On the other hand, in the fine-grained specimen, the {111}〈112〉 intensity is greatly decreased but the Goss intensity is slightly increased as the heating rate increases. The heating rate up to the annealing temperature affects texture formation differently depending on the initial grain size prior to cold rolling. These differences are mainly related to the difference in the number of shear bands formed during cold rolling in grains having different sizes.