| 摘要 |
PROBLEM TO BE SOLVED: To impart excellent magnetic properties by applying the slurry of a separation agent for annealing obtd. by adding MgO in which grain size and citric acid activity(CAA) are specified with a water soluble S compd. by a specified ratio on a nitriding annealed sheet obtd. by subjecting a slab to nitriding treatment, drying it at a steel sheet temp. equal to or below the specified temp. and thereafter executing finish annealing. SOLUTION: MgO in which the content of particles having grain size of <1 μm is >=10%, CAA40% value is 100 to 250 sec, and CAA70% value/CAA40% value is 2 to 10 is used as a separation agent for annealing. The slurry of a separation agent for annealing obtd. by adding 100 pts.wt. MgO with a water soluble S compd. by 0.02 to 0.5 pts.wt. as S is applied on a slab subjected to nitriding treatment, which is dried at <=300 deg.C steel sheet temp. and is subjected to finish annealing. The slab contg., by weight, 0.021 to 0.075% C, 2.5 to 4.0% Si, 0.05 to 0.45% Mn, <=0.014% S, 0.010 to 0.040% acid soluble Al, 0.0030 to 0.0130% N, 0.03 to 0.50% Sn, and the balance Fe with inevitable impurities is heated at <1,280 deg.C an is subjected to process annealing, cold rolling, decarburizing annealing and nitriding treatment. |
