The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 17, 1991
Filed:
Sep. 27, 1990
Nobuyuki Takahashi, Fukuoka, JP;
Katsuro Kuroki, Fukuoka, JP;
Yozo Suga, Fukuoka, JP;
Kiyoshi Ueno, Fukuoka, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
The present invention relates to a process for preparing a unidirectional silicon steel sheet having a high magnetic flux density which comprises heating a silicon steel slab comprising by weight 0.025 to 0.075% of carbon, 2.5 to 4.5% of silicon, 0.015% or less of sulfur, 0.010 to 0.050% of acid-soluble aluminum, 0.0010 to 0.012% of nitrogen, 0.050 to 0.45% of manganese and 0.01 to 0.10% of tin and optionally 0.0005 to 0.0080% of boron with the balance being iron and unavoidable impurities, at 1200.degree. C. or below; hot-rolling the slab; subjecting the slab to rolling once or two or more times wherein intermediate annealing is provided, thereby attaining a percentage final rolling of 80% or more; subjecting the resultant steel sheet to decarburizing annealing in a wet hydrogen atmosphere; coating the steel sheet with an annealing separator; conducting finishing annealing for secondary recrystallization and purification of the steel; and subjecting the steel sheet to a nitriding treatment between after the ignition for decarburizing annealing and before the initiation of the secondary recrystallization in the finishing annealing.