| 摘要 |
PURPOSE:To manufacture a grain-oriented silicon steel sheet excellent in magnetic flux density, by subjecting a silicon-steel slab to hot rolling, cold rolling, and primary recrystallization annealing which doubles as decarburization, by subjecting the above sheet to secondary recrystallization annealing after the application of a specific annealing and separation agent, and then by applying purification annealing to the above sheet. CONSTITUTION:A silicon-steel slab is formed into a silicon-steel sheet by means of hot and cold rollings, which is subjected to primary recrystallization annealing which doubles as decarburization in wet hydrogen. Subsequently, an annealing and separation agent composed principally of MgO and containing at least one kind selected from Se, S, and compounds thereof is applied so that a region where S and Se concentrations are changed by >=0.01% is formed continuously or in stages extending over the width or longitudinal direction of the steel sheet, by which secondary recrystallization annealing is carried out by providing a gradient or a difference in level to the initial temp. of secondary recrystallization. At this time, the above steel sheet is subjected to gradient annealing in which a temp. gradient of >=2 deg.C per cm is applied from the steel-sheet edge having high secondary recrystallization temp. and finally to purification annealing in a dry hydrogen atmosphere. |
