Nippon Steel Corporation

Kunihide Takashima

Osamu Tanaka

Fumio Matsumoto

Toshihiko Takata

Hiromichi Yasumoto

Toshiya Wada

Kenzo Iwayama

Shozaburo Nakashima

Hidehiko Sumitomo

Tsutomu Haratani

Toshio Kikuma

Satohiro Hayami

Jirou Harase

Isao Iwanaga

Norito Abe

Tsunehiro Shimizu

Jiro Harase

Hisanobu Nakayama

Yoshio Nakamura

Katuro Kuroki

Akira Amemura

Ryutarou Kawamata

Kuniyasu Honda

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

A method of producing permalloy cores comprising the steps of coating at least one surface of permalloy strip with a slurry consisting of water containing 1 to 5 percent by weight of magnesium hydroxide (Mg(OH).sub.2) powder and the addition of one or more selected from a binder, a thickening agent and a defoaming agent and drying said coating, slitting the permalloy strip thus covered with a coating that when dry is 0.1 to 50 .mu.m thick, more preferably 0.5 to 10 .mu.m thick, and contains not less than 50 percent by weight Mg(OH).sub.2, and more preferably not less than 80 percent by weight Mg(OH).sub.2, as the main constituent, to a final width, or first to an intermediate width if necessary, winding or punching the final width strip to obtain wound or laminated punched cores, and subjecting the core materials to magnetization annealing.

Method of producing permalloy cores

The adhesiveness of a glass film and watt loss of a grain-oriented electrical steel sheet is improved by partially protruding the glass film into the steel sheet part thereof. To attain the partial protrusion, the steel sheet is subjected, prior or subsequent to decarburization annealing, to a treatment of the surface thereof to form unevennesses, by a mechanical device, e.g., brush rolling, buff polishing, marking-off, sand papering, and grinding.

Grain oriented electrical steel sheet having improved glass film

The adhesiveness of a glass film and watt loss of a grain-oriented electrical steel sheet is improved by partially protruding the glass film into the steel sheet part thereof. To attain the partial protrusion, the steel sheet is subjected, prior or subsequent to decarburization annealing, to a treatment of the surface thereof to form unevenness, by a mechanical device, e.g., brush rolling, buff polishing, marking-off, sand papering, and grinding.

Grain-oriented electrical steel sheet having improved glass film

In a process for producing a grain-oriented silicon steel strip, comprising the steps of: hot rolling, annealing, if necessary; heavy cold rolling; decarburization-annealing, and; final annealing, an improvement which comprises controlling a coiling temperature after the finish rolling of the hot rolling step within a range of from 700.degree. to 1000.degree. C. As a result of the coiling temperature control, the annealing of the hot rolled strip can be simplified or omitted, while the behavior of a grain-growth inhibitor is equivalent to that in the conventional process including the annealing step. The magnetic flux density of the material produced by the process of the present invention is excellent, notwithstanding the simplification or omission of the annealing.

Process for producing grain-oriented silicon steel strip

In a process for the production of a grain-oriented silicon steel strip, a slab is heated, hot-rolled, cold-rolled, and subjected to a decarburization annealing and secondary recrystallization annealing steps. Grain coarsening is likely to occur during the high temperature heating and remain in the final product as streaks. The secondary recrystallization is, therefore, incomplete due to the streaks. In the hot rolling, an asymmetric flow, is applied to the steel, so as to eliminate the streaks and, hence, to obtain excellent magnetic properties.

Process for producing a grain-oriented silicon steel sheet from silicon steel slabs, particularly from continuously cast steel slabs, comprising at least one recrystallization rolling at high reduction rate in a temperature range from 1190.degree. C. to 960.degree. C. in the hot rolling step. The process of the present invention is very effective in preventing the streaks of smaller, poorly oriented grains very often seen in the final product produced from silicon steel slabs.

Process for producing a grain-oriented silicon steel sheet

A cold rolling method for producing a high magnetic flux density grain oriented electrical steel sheet or strip having remarkably excellent B.sub.8 characteristics, comprising subjecting a hot rolled steel sheet or strip a combination of heavy cold rolling with annealing during which the steel sheet or strip is held at a temperature between 100.degree. and 350.degree.C at an interim sheet thickness stage during the heavy cold rolling.

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Kitakyushu, Japan

Kunihide Takashima