Nippon Steel Corporation

Isao Iwanaga

Kenzo Iwayama

Kenichi Miyazawa

Toshiaki Mizoguchi

Shozaburo Nakashima

Hidehiko Sumitomo

Kunihide Takashima

Norito Abe

Yoshio Nakamura

Ryutarou Kawamata

Very high magnetic flux density grain-oriented electrical steel slab containing 2.5 to 4.0 weight percent silicon as an essential component and having a very high magnetic flux density B.sub.8 of not less than 1.92 tesla, in which by area not less than 80 percent is accounted for by matrix secondary recrystallization grains having a diameter not larger than 100 mm and not smaller than 10 mm in a direction of cold rolling and not larger than 50 mm and not smaller than 5 mm in a direction perpendicular to the cold rolling direction, and in which, moreover, of the grains in said matrix, not fewer than 50 percent by ratio of number are fine secondary recrystallization grains having an average diameter not larger than 5 mm.

Grain-oriented electrical steel sheet and material having very high

Process for preparing rollable metal sheet from quenched solidified thin

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 cast strip having a thickness of 0.2 to 5 mm and directly obtained from the molten steel by the synchronous continuous casting machine, in which the speed of movement of the strand relative to the inner wall surface of the casting mold is the same, and by which the traditional hot rolling process can be omitted, 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 cast strip 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 of producing a grain oriented electrical steel sheet having a high magnetic flux density comprises the steps of continuously rapid quench solidifying a molten steel essentially consisting of 0.03 to 0.10% of C, 2.5 to 4.5% of Si, 0.02 to 0.15% of Mn, 0.01 to 0.04% of Al acid soluble by weight and the remainder substantially Fe, to obtain a thin strip, subjecting the thin strip to cold rolling one or two or more stages, with an annealing therebetween, decarburization annealing, and finishing annealing wherein the content of S in the molten steel is 0.01% or less the content of N in the molten steel is 0.003% or less, and sulfide and nitride are contained in the annealing separator for the finishing annealing.

Method of producing grain oriented electrical steel sheet having high

The present invention concerns a process for producing a grain-oriented electrical steel sheet by means of a rapid quench-solidification process, for example, a continuous casting by a twin roll strip caster. The feature of the present invention resides in quenching to solidify molten steels into a thin cast sheet of 0.7 to 3.0 mm thickness, at a cooling rate of greater than 50.degree. C./sec. in the central portion along the direction of thickness of the thin cast sheet, cooling the sheet at a cooling rate of greater than 10.degree. C./sec. in a temperature range between 1300.degree. to 900.degree. C. and then applying cold rolling for once or twice or more annealing the thin cast steel for a period between 30 seconds and 30 minutes in a temperature range between 950.degree. and 1,200.degree. C. and subsequently including intermediate annealing under a final cold rolling reduction rate of not less than 80%. In the present invention, precipitates that function as an inhibitor can finely be dispersed by adding 0.02 to 0.2% of Nb into the molten steel ingredients thereby to stably produce a grain-oriented electrical steel sheet of high magnetic flux density by means of a rapid quench-solidification process. Further, since a thin cast sheet of desired thickness within a range from 0.7 to 3.0 mm can be produced by the rapid quench-solidification process, the thin cast sheet can be cold rolled to a final thickness of less than 150 .mu.m by applying a cold rolling at a reduction rate optimum to magnetic properties, and an extremely thin grain-oriented electrical steel sheet of less than 150 .mu.m (0.15 mm) thickness can be produced in a simple production process and at a reduced cost, which so far has been remarkably difficult and expensive to produce.

Process for producing a grain-oriented electrical steel sheet by means

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Kitakyushu, Japan

Isao Iwanaga