Nippon Steel Corporation

Toshiya Wada

Osamu Tanaka

Toshihiko Takata

Katsuro Kuroki

Shozaburo Nakashima

Seizun Higuchi

Teruaki Izaki

Kunihide Takashima

Hiromichi Yasumoto

Takatoshi Egawa

Makoto Yoshida

Tadao Nozawa

Yoshitaka Hiromae

Jiro Harase

Hirotada Katoh

Kazuo Nakamura

Makato Yoshida

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

A grain-oriented electromagnetic steel sheet has an ultra low watt loss and heat resistant subdivided magnetic domains. The electromagnetic steel sheet has spaced apart regions of plastic strain and an insulating coating disposed thereon. Intruders are thermally intruded into the spaced apart regions of plastic strain causing the subdivided magnetic domains to be heat resistant and maintaining the subdivided magnetic domains after stress relief annealing. Preferred intruders include Sb and Sb containing materials.

Grain-oriented electrical steel sheet having a low watt loss

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 grain-oriented electromagnetic steel sheet which is produced by a process including a cold-rolling step(s), the final reduction ratio of the cold-rolling step(s) being high, a technical means for refining the secondary recrystallized grains is particularly important. One technical means is the incorporation of tin into silicon steel material. This, however, involves a problem because tin incorporated into silicon steel material deteriorates the surface coating which imparts tension to a grain-oriented electromagnetic steel sheet. The incorporation of copper into silicon steel material has been avoided since it causes secondary recrystallization to be unstable. The present invention is characterized by the combined incorporation of tin and copper into molten steel so as to simultaneously refine the secondary recrystallized grains and to form a good surface coating. The grain-oriented electromagnetic steel sheet of the present invention contains from 2.5% to less than 4.0% of silicon, from 0.03% to 0.15% of manganese, from 0.03% to 0.5% of tin, and from 0.02% to less than 0.3% of copper.

Grain-oriented electromagnetic steel sheet

Method for subdividing the magnetic domains of a grain-oriented electrical steel sheet is improved so that the watt loss can be further lessened and the watt-loss improving effect does not disappear during stress relief annealing. An intrudable means is formed on the finishing-annealed steel sheet on or in the vicinity of strain which promotes the intrusion of an intrudable means. Sb or Sb containing material is a preferred intrudable means and the laser irradiation is a preferred method for imparting the strain and also for attaining the removal of a surface coating.

Method for producing a grain-oriented electrical steel sheet having a

The present invention relates to an improvement in the precipitation annealing of a hot-rolled steel sheet or strip which is carried out immediately before cold-rolling in the production of a grain-oriented electromagnetic steel sheet or strip. Conventionally, precipitation annealing is carried out by heating a steel strip to a temperature of from 750.degree. to 1200.degree. C. and then quenching it. The present invention proposes to control the cooling rate during primary cooling, i.e. from a holding temperature (T.sub.1 temperature) of from 1080.degree. to 1200.degree. C. down to an intermediate temperature (T.sub.2 temperature) of from 900.degree. to 980.degree. C., and to control the staying time during primary cooling so that excellent magnetic properties can be obtained regardless of the unavoidable variation in the Al and Si content. The present invention also proposes to control the rate of temperature elevation between 800.degree. C. and the holding temperature as to obtain AlN particles having an optimum size.

Process for producing a grain-oriented electromagnetic steel sheet

Grain-oriented electromagnetic steel sheet and process for producing the

A coating composition including inorganic compounds dispersed in an organic material capable upon exposure to UV rays or electron beams of producing an adherent insulating film of high dielectric properties on the surfaces of electro-sheets of ferrous material. The coated electro-sheets are annealed after the forming, for example, cutting or punching operation in order to remove thereby imparted stresses without impairing the dielectric properties.

Insulating coating compositions applied on electrical steel sheets

An annealing separator for silicon steel sheets comprising not less than 90.00% by weight of an MgO and 0.01 to 2.0% by weight of B.sub.2 O.sub.3 in the form of nMgO.B.sub.2 O.sub.3 with the balance being unavoidable impurities.

Annealing separator for silicon steel sheets

A method for producing a grain-oriented electrical steel sheet showing super low watt loss, comprising making a silicon steel ingot containing 2.5 to 4.0% of Si, subjecting the ingot treatments including hot rolling, annealing and at least one cold rolling to obtain a final size, subjecting the steel to decarburization annealing and a finishing annealing which completes secondary recrystallization, subjecting the steel to remove surface product and then subjecting the steel to chemical polishing or electrolytic polishing to polish the steel surface to mirror condition.

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Kitakyushu, Japan

Toshiya Wada