ELECTRICAL STEEL SHEET WITH ORIENTED GRAIN STRUCTURE, AND ITS MANUFACTURING METHOD Russian patent published in 2013 - IPC C23C26/00 C21D1/78 

FIELD: metallurgy.

SUBSTANCE: sheet includes an aggregated section of a glassy covering film, the thickness of which continuously exceeds the average thickness of the glassy covering film by two or more times, and the size of which is 3 mcm or more in the direction that is parallel to the steel sheet surface. Ratio of total length of aggregated sections crossed with a piece with length of 500 mcm or more, which is parallel to the steel sheet surface, to the length of that piece is 0.15 or less. In order to implement the manufacturing method of the above sheet, nitration of the steel sheet is performed, the agent, the main component of which is MgO, is applied, annealing is performed for formation of a glassy covering film based on forsterite with aggregated section of glassy covering film. Annealing is performed by heating from the first temperature of 850°C or less to the second temperature of 1000°C or more and 1100°C or less in a mixed gas atmosphere containing gaseous H₂ and gaseous N₂; at that, fraction of gaseous N₂ is 20 vol % or more. Then, the atmosphere is changed over to atmosphere of gaseous H₂ at the above second temperature; at that, oxygen potential P(H₂O)/P(H₂) is provided, which comprises 0.05 to 0.3 when temperature is 850°C or less during heating in mixed gas atmosphere.

EFFECT: obtaining electrical steel with oriented grain structure without any defects in a glassy covering film.

9 cl, 8 dwg, 3 tbl, 2 ex