| 摘要 |
PURPOSE:To manufacture a grain-oriented silicon steel sheet excellent in magnetic flux density and iron loss characteristics, by subjecting a silicon-steel slab to hot rolling and cold rolling to form a steel sheet and then by applying primary recrystallization annealing, which doubles as decarburization, secondary recrystallization annealing, and purification annealing to the above steel sheet under respectively specified conditions. CONSTITUTION:A silicon-steel slab is soaked to 1,400 deg.C, hot-rolled into a metal plate of 2.0mm thickness, and then subjected to single cold rolling or to two-time or more cold rollings, while process-annealed between the cold-rolling stages, so as to be worked into 0.22mm final sheet thickness. Subsequently, prior to decarburization and primary annealing, C content is changed continuously or in stages over the range from 0.002-0.05% extending over the width direction or longitudinal direction of the steel sheet so as to provide >=10 deg.C local difference to the initial temp. of the secondary recrystallization of the steel sheet, and further, if necessary, gradient annealing in which secondary recrystallization is started from the steel-sheet edge having high secondary recrystallization temp. under a temp. gradient of >=2 deg.C per unit length (cm) larger than the gradient of the initial temp. of the secondary recrystallization is applied.
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