| 摘要 |
PURPOSE:To stably manufacture a grain-oriented silicon steel sheet with superlow iron loss, by subjecting a silicon-containing steel sheet to secondary recrystallization while applying temp. difference to the direction perpendicular to a rolling direction, by forming a high-tensile film by a CCD method, and by applying purification annealing to the above. CONSTITUTION:A continuously cast slab of silicon-containing steel is heated to about 1,390 deg.C, hot-rolled, and subjected to a single cold rolling or cold-rolled twice while process-annealed between the cold rolling stages. Subsequently, the cold-rolled sheet is subjected to primary recrystallization annealing which doubles as decarburization at about 850 deg.C. The annealed steel is wound up in a loose coil in which respective sheet surfaces are mutually separated, and then, secondary recrystallization is applied to the above in a furnace with temp. gradient while applying temp. difference to the width direction of the coil, and simultaneously, an extra thin high-tensile film is formed on the above by a CVD method. As the above film, the one consisting of one or more kinds among the nitrides and/or carbides of Ti, Zr, Hf, V, Nb, Ta, Mn, Cr, Mo, W, Co, Ni, Al, B, and Si and the oxides of Al, Ni, Cu, W, Si, Ti and Zn is suitably used. The steel sheet after film formation is heated in H2 and subjected to purification annealing so as to be formed into a product of silicon steel sheet.
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