MANUFACTURE OF GRAIN-ORIENTED ELECTRICAL STEEL SHEET WITH LOW IRON LOSS EXCELLENT IN ADHESIVE STRENGTH OF FILM

Japanese Patent JPH01191743

A

PURPOSE:To manufacture a grain-oriented electrical sheet sheet with low iron loss causing no deterioration in iron-loss value even if subjected to stress-relief annealing and excellent also in adhesive strength of film by forming linear oxide film of specific width and depth or dotlike oxide film linearly formed at specific spaces from above a glass film on the surface of a magnetic steel sheet through this glass film. CONSTITUTION:A slab of a silicon steel with <4% Si content is hot-rolled into a metal plate and, after surface is subjected to pickling treatment, the above plate is cold-rolled, while process-annealed between the cold rolling stages, so as to be formed into a steel sheet of the final thickness, which is further subjected to decarburizing annealing. Subsequently, a separation agent at annealing is applied to the above sheet to carry out secondary recrystallization annealing, and a glass film with electric insulating property is further applied to the above. Successively, by utilizing the porous characteristic of the glass film, a linear oxide film of 0.05-0.5mm width and 0.005-0.06mm depth or a dotlike oxide film linearly formed at a space of <=0.7mm is optically, electrically, thermally, or chemically formed with the space of 2.5-10mm in the rolling direction of the steel sheet on the surface of the steel- sheet matrix so that the direction of the oxidation zone forms an angle of 90-45 deg. with the rolling direction of the steel sheet in the plane of the steel sheet.

KOBAYASHI TAKASHI
TANAKA OSAMU

JP1361488A

August 01, 1989

January 26, 1988

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NIPPON STEEL CORP

C21D8/12; (IPC1-7): C21D8/12

Tachio Chanogi

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