Abstract: Based on wire-cut samples including cast slab, hot-rolled, normalized, cold-rolled and decarburized plates of 0.27 mm thickness high permeability grainoriented silicon steel by both Bi-bearing high-temperature and low-temperature slab reheating processes, the Bi particles were observed by BSE model of SEM and the semi quantitative analysis to the distribution of Bi was conducted by auger electron spectroscopy. The results showed that the undissolved Bi in molten steel would exist in the form of elemental particles as sphericity during the following different procedure processes, and both processes had the highest precipitate percentages of Bi after decarburizing anneal. In addition, both processes had the general same segregation regularity of Bi, each procedure process having obvious grain boundary segregation, and the Bi’s relative amount of grain boundary segregation up to the highest after decarburizing anneal.

Key words: high permeability grain-oriented silicon steel, Bi, grain boundary segregation