| 摘要 |
PROBLEM TO BE SOLVED: To attain extremely high magnetic flux density B8 and further to effectively solve the defect of film characteristics substantially inherent in Bi- containing steel, at the time of producing a grain oriented silicon steel sheet, by solving the instability of secondary recrystallization which has been feared in the case Bi is utilized as an inhibitor. SOLUTION: In the process of producing a grain oriented silicon steel sheet, particularly, at the time of hot rolling, before the start of rough rolling, heating treatment at 1,125 deg.C for 1 to 10 hr is performed in an atmosphere with the average oxygen concentration of 100 to 50,000 ppm, also the time from the start of rough rolling to the end of finish rolling is controlled to 30 to 300 sec, and further, in the process of the above rolling, the surface temperature of the rolling stock is held to a state always lower than the central temperature of the sheet thickness.
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