Production method of small grain-oriented electrical steel sheet excellent thick plate thickness of the glass coating of magnetic properties

摘要

PURPOSE: To obtain a grain-oriented silicon steel plate hardly having glass films by specifying the conditions of the cumulative draft of the final three passes in hot rolling, cold rolling conditions, primarily recrystallized grains till the start of final finish annealing, nitriding treatment or the like. ;CONSTITUTION: A slab constituted of, by weight, 0.021 to 0.075% C, 2.5 to 4.5% Si, 0.010 to 0.060% acid soluble Al, 0.0010 to 0.060% N, S+0.405Se;≤0.014% and 0.05 to 0.80% Mn, and the balance Fe with inevitable impurities is subjected to hot rolling. The finishing temp. in the hot rolling is regulated to 800 to 1100°C, and the cumulative draft of the final three passes is regulated to ≥40%. Successively, it is subjected to cold rolling at 60 to 79% draft. The temp. of the steel plate between the cold rolling passes is regulated to ≤250°C. Then, it is subjected to decarburizing annealing to regulate the average grain size of the primarily recrsytallized grains till the start of the final finish annealing into 18 to 30μm. Moreover, nitriding treatment is executed till the start of the secondary recrystallization in the final finish annealing. Furthermore, as for a separation agent for annealing, the one obtd. by adding MgO with the chloride, nitrate, sulfide or the like of Li, K, Na, Ba, Ca, Mg, Zn, Fe, etc., is used.;COPYRIGHT: (C)1994,JPO&Japio