Formation of island grains in high-permeability grain-oriented silicon steel manufactured by the acquired inhibitor method

In high-permeability grain-oriented silicon steel, island grains are often observed in the final sheets. In this work, the formation of island grains was studied in high-permeability grain-oriented silicon steel manufactured by the acquired inhibitor method. It was found that the {210} < 001 > and {110} < 112 > orientations dominated in the island grains. To understand the formation mechanisms of island grains, the grain boundary characteristics were investigated. Abnormal growth of island grains occurs because their orientations have a higher frequency of high-energy boundaries in the primary recrystallization texture. The {210} < 001 > grains could be left behind as island grains because they had a low misorientation angle with a Goss orientation (about 20 degrees), whereas the {110} < 112 > island grains formed because of the size advantage of abnormally growing grains. The conclusions were also supported by the results of the interruption experiment. The {210} < 001 > grains were observed in the subsurface sheared area of the hot band and mainly nucleated at the subsurface layer during primary recrystallization. In addition, it was confirmed that the island grains (except for the exact {210} < 001 > orientation) had a negative influence on the magnetic properties because of the large deviation angle of the < 001 > axis from the rolling direction.