| 摘要 |
PURPOSE: To produce a grain oriented silicon steel sheet used for iron core for transformer, etc., and excellent in magnetic properties. CONSTITUTION: This grain oriented silicon steel sheet is produced by using a slab having a composition containing <=0.075% C, 2.2-4.S% Si, 0.010-0.060% acid-soluble Al, <=0.025% S or Se independently or in combination, and other components and subjecting this slab to heating at <1280 deg.C, to hot rolling, to hot rolled plate annealing, if necessary, to cold rolling at >=80%, to decarburizing annealing, and to final finish annealing. At this time, heating is performed by means of an induction heating furnace or a direct electrification heating furnace through the temp. region of >= at least 1000 deg.C in the course of temp. rise at slab heating to regulate the average grain size of primary recrystallized grains after decarburizing annealing to 18-30μm, and also the difference in average grain size between the sheet thickness surface layer and the central layer is regulated to a value <=15% of the whole thickness average grain size, and further, nitriding treatment of >=10ppm is applied in the course between the completion of cold rolling and the starting of secondary recrystallization. |
