Nippon Steel Corporation

Kiyoshi Ueno

Yozo Suga

Katsuro Kuroki

Yoshiyuki Ushigami

Nobuyuki Takahashi

Shozaburo Nakashima

Fumio Matsumoto

Toyohiko Konno

Katuro Kuroki

Yasuhiro Shinkai

Mikio Itoh

Toshio Nishiyama

Kenichi Takimoto

Shouzou Oota

A method of producing an oriented electrical steel sheet having superior magnetic properties comprises the steps of, hot rolling a slab containing 0.8 to 6.8% of Si, 0.008% of Al acid soluble, the balance being Fe and accompanying impurities, by weight to form a strip, cold rolling the strip, primary-recrystallization annealing, coating the strip with an annealing separator, and finishing annealing, a nitriding treatment being effected after the primary recrystallization annealing but before the start of the secondary recrystallization of the finishing annealing. According to the present invention, with an atmosphere oxidizing degree (PH.sub.2 O/PH.sub.2): x in a soaking process in said primary recrystallization annealing an annealing is effected in an atmosphere which has an oxidizing degree (PH.sub.2 O/PH.sub.2): y in a range defined by the following inequality, at a temperature ranging from 650.degree. to 800.degree. C. in the heating process, for at least 5 secs. ##EQU1##

Method of producing oriented electrical steel sheet having superior

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.

Process for preparing unidirectional silicon steel sheet having high

Disclosed is a process for preparing a thin grain oriented electrical steel sheet having a final thickness of 0.05 to 0.25 mm from a silicon steel slab comprising 0.050 to 0.120% by weight of C, 2.8 to 4.0% by weight of Si and 0.05 to 0.25% by weight of Sn, wherein the starting silicon slab further comprises up to 0.035% by weight of S and 0.005 to 0.035% by weight of Se, with the proviso that the total amount of S and Se is in the range of 0.015 to 0.060% by weight, 0.050 to 0.090% by weight of Mn, with the proviso that the Mn content is in the range of {1.5.times.[content (% by weight) of S+content (% by weight) of Se[} to {4.5.times.[content (% by weight) of S+content (% by weight) of Se[} % by weight, 0.0050 to 0.0100% by weight of N, and {[27/14].times.content (% by weight) of N+0.0030} to {[27/14].times.content (% by weight) of N+0.0150} % by weight of acid-soluble Al.

Process for preparation of thin grain oriented electrical steel sheet

A method for producing high magnetic flux density grain oriented electrical steel sheets or strips having a B.sub.8 characteristic in the rolling direction of not less than 1.9 Wb/m.sup.2 by hot rolling, continuous annealing for precipitation of the AlN, cold rolling into the final thickness, decarburization annealing, and finishing annealing. The cold rolling includes a final rolling at a strong reduction between 81 and 95%.

Method for producing high magnetic flux density grain-oriented

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Kitakyushu, Japan

Kiyoshi Ueno