Method of producing grain oriented silicon steel sheets having magnetic properties
AssigneeKawasaki Steel Corporation
InventorsMitsumasa Kurosawa, Masayuki Sakaguchi, Katsuo Iwamoto, Yoshinori Kobayashi, Yoshiaki Iida
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Abstract
The magnetic properties, particularly magnetic flux density of a grain oriented silicon steel sheet are considerably improved by continuously and/or stepwise forming regions, wherein a temperature difference of a secondary recrystallization starting temperature in widthwise direction and/or longitudinal direction of the steel sheet is within a range of 10.degree. C. to 200.degree. C., in the steel sheet at a stage before the secondary recrystallization annealing step.
Claims11
A method of producing a grain oriented silicon steel sheet having excellent magnetic properties by a series of steps of hot rolling a slab of silicon containing steel, subjecting the hot rolled sheet to a heavy cold rolling step or to a combination of two cold rolling steps and an intermediate annealing between the two cold rolling steps to obtain a final sheet gauge, subjecting the cold rolled sheet to decarburization and primary recrystallization annealing, applying a slurry of an annealing separator to the surface of the steel sheet, and thereafter subjecting the steel sheet to a secondary recrystallization annealing and further to a purification annealing, characterized in that at a stage before the secondary recrystallization annealing step, treating the sheet to form a region having a gradient of starting temperature for secondary recrystallization (T.sub.SR) in widthwise and/or longitudinal directions of the sheet wherein said gradient is continuous and/or stepwise and wherein difference in T.sub.SR across the gradient is in a range of 10.degree. C. to 200.degree. C.
Dependencies are inferred from the claim text.