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

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 B8 values.