| 摘要 |
PROBLEM TO BE SOLVED: To accelerate nitrogen purification at the time of finish annealing of a grain oriented silicon steel sheet, to shorten annealing time or reduce purification temp., and to attain reduction of inferior shape and shortening of treatment time. SOLUTION: A cold rolled sheet, containing, by weight, 0.01-0.06% acid soluble Al and 0.005-0.0130% N, is subjected to primary recrystallization annealing. Successively, the sheet is subjected or not subjected to nitriding treatment and, after the completion of secondary recrystallization, the sheet is annealed in an atmosphere containing gaseous hydrogen. In this purification annealing for a grain oriented silicon steel sheet, annealing is carried out at 1000-1250 deg.C while regulating the partial pressure of nitrogen in the atmosphere with which the surface of the steel sheet is brought into contact to <=0.10 atm. |
