Effect of Temper Rolling Reduction and Annealing Time on Texture Formation during Final Annealing in Electrical Steels

The magnetic properties of semi-processed nonoriented electrical steels are significantly improved by strain induced boundary migration (SIBM) during final annealing. In order to investigate the possibility of texture control, temper rolling reduction was changed in the range of 2% to 8% and annealing time in the range of 10 minutes to 180 minutes. Furthermore, based on observed experimental data, a mechanism of grain growth during SIBM is suggested. Temper rolling reduction plays an important role in deciding the texture developed after strain induced boundary migration. In the specimen temper rolled by 2%, relatively strong {111} < 112 > texture develops, whereas in the specimens temper rolled by 4% through 8%, strong Goss texture develops as a result of strain induced boundary migration during final annealing. The latter case can be explained by the fact that the Goss grains have the lowest stored energy in temper rolled state, which is confirmed by average image quality value in EBSD measurements. However, for the Goss grains to grow preferentially, stored energy difference between two neighboring grains may have to be higher than a certain critical value. The grain growth by means of strain induced boundary migration happens earlier in the specimen temper rolled by higher reduction.