Toshito Takamiya

Control of inhibitor precipitation for producing grain-oriented silicon steel

Grain-oriented electrical steels have been widely used for various products, and hence, improving their properties is greatly desired to thus save electricity. Magnetic properties of grain-oriented 3% Si steels have been steadily improved since Goss invented this steel. The authors are convinced that the possibility of further improvement still exists. An important metallurgical basis for producing grain-oriented Si steel is controlling the primary recrystallization texture and the dispersion of inhibitors. Mechanisms of secondary recrystallization and the influence of primary texture on it have been discussed by Harase et al. It is well known that the inhibitor plays its role at the secondary recrystallization stage. Three important metallurgical factors related to the inhibitor exist in the process: dissolution, precipitation, and Ostwald ripening. The most important of these processes is precipitation, which is achieved primarily during hot rolling and comprises a cooling process and a deformation process. The purpose of this article is to clarify the metallurgical sequence of precipitation during hot rolling and then to improve the process by the application of this information to obtain improved magnetic properties.

Influence of heat treatment before secondary recrystallization on magnetic properties of 3% Si grain-oriented steel containing Sb

Abstract The secondary recrystallization of 3% Si grain-oriented steel containing Sb has been investigated. The mechanism of the improvement of the magnetic properties under the conditions of Sb addition and a constant temperature treatment during secondary recrystallization has been clarified by three experiments. It has been found that (1) Sb segregation in grain boundaries during decarburization annealing retards decarburization and grain growth, so that the {110} intensity increases and the grain size decreases with increasing Sb; (2) the constant temperature treatment for final annealing enhances the Sb segregation in grain boundaries, and therefore maintains the {110} intensity in the specimen with the addition of Sb; and (3) the addition of Sb increases the inhibiting force. These three effects enable secondary recrystallization such that many (110)[001] nuclei grow rapidly, surrounded by small primary grains, leading to high B 8 values.