| 摘要 |
PROBLEM TO BE SOLVED: To obtain a grain oriented silicon steel sheet excellent in magnetic properties with energy saving by rapidly solidifying the molten steel of a specific composition by means of the surface of a moving cooling body and subjecting the resultant steel strip to cold rolling, nitriding treatment, and final finish annealing under respectively specified conditions. SOLUTION: A steel, having a composition consisting of, by weight ratio, 0.025-0.075% C, 2.5-4.0% Si, 0.020-0.040% acid soluble Al, 0.005-0.010% N, 0.005-0.015% of S and/or Se, 0.05-0.8% Mn, and the balance Fe with inevitable impurities, is used. A molten steel with this composition is rapidly solidified by means of the surface of a moving cooling body. The resultant steel strip is cold-rolled while process-annealed between cold rolling stages. Final cold draft is regulated to >=85%. After decarburizing annealing, nitriding treatment is performed in a gaseous mixture of hydrogen, nitrogen, and ammonia while allowing the strip to travel. After the application of a separation agent at annealing, composed essentially of MgO, final finish annealing is carried out. At this time, as to the alternative to the above method, the rapidly solidified steel strip is subjected to rolling reduction at 800-1000 deg.C at <=45% and then to final cold rolling reduction at >=80%. |
