Jfe Steel Corporation

Kawasaki Steel Corporation

Toyo Seikan Group Holdings, Ltd.

Tokan Kogyo Co., Ltd.

Seiji Okabe

Hirotaka Inoue

Takeshi Omura

Shigehiro Takajo

Hiroi Yamaguchi

Takeshi Imamura

Yasuyuki Hayakawa

Kunihiro Senda

Mitsumasa Kurosawa

Masao Yukumoto

Kazuhiro Hanazawa

Minoru Takashima

Fumio Kogiku

Makoto Watanabe

Hiroaki Toda

Ryuichi Suehiro

Yasushi Kitani

Ichiro Kunihiro

Nobuo Shiga

Katsumi Yamada

Toshito Takamiya

Takashi Kawano

Michiro Komatsubara

Tadashi Nakanishi

Masahiro Ogawa

Kensuke Matsuki

Kenichi Takao

Souichiro Yoshizaki

Hiroshi Yamane

Hideo Yamagami

Masanao Midorikawa

Kenzo Ohsu

A grain-oriented electrical steel sheet for a wound transformer core. The steel sheet having a sheet thickness t, where t and an iron loss deterioration ratio obtained by subjecting the steel sheet under elliptic magnetization satisfy the following relations: (i) when t≤0.20 mm, the iron loss deterioration ratio is 60% or less; (ii) when 0.20 mm<t<0.27 mm, the iron loss deterioration ratio is 55% or less; and (iii) when 0.27 mm≤t, the iron loss deterioration ratio is 50% or less. The iron loss deterioration ratio is calculated from ((W−W)/W)×100, where Wis iron loss under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 0.6 T in a direction orthogonal to the rolling direction, and Wis iron loss under 50 Hz alternating magnetization of 1.7 T in the rolling direction.

Grain-oriented electrical steel sheet, wound transformer core using the same, and method for producing wound core

Vibration of an iron core is reduced to reduce transformer noise. An iron core for a transformer comprises a plurality of grain-oriented electrical steel sheets stacked together, wherein at least one of the plurality of grain-oriented electrical steel sheets: (1) has a region in which closure domains are formed in a direction crossing a rolling direction and a region in which no closure domains are formed; (2) has an area ratio Rof 0.10% to 3.0%, the area ratio Rbeing defined as a ratio of Sto S; and (3) has an area ratio Rof 50% or more, the area ratio Rbeing defined as a ratio of Sto S.

Iron core for transformer

Vibration of an iron core is reduced to reduce transformer noise. An iron core for a transformer comprises a plurality of grain-oriented electrical steel sheets stacked together, wherein at least one of the plurality of grain-oriented electrical steel sheets: (1) has a region in which closure domains are formed in a direction crossing a rolling direction and a region in which no closure domains are formed; and (2) has an area ratio R of 0.10% to 30%, the area ratio R being an area ratio, to the whole grain-oriented electrical steel sheet, of a region in which a shrinkage amount at a maximum displacement point when excited in the rolling direction at a maximum magnetic flux density of 1.7 T and a frequency of 50 Hz is at least 2×10less than a shrinkage amount in the region in which no closure domains are formed.

To reduce variations in iron loss among materials subjected to magnetic domain refining by electron beam irradiation and to stably obtain good iron loss properties, disclosed is a method of producing a grain-oriented electrical steel sheet including performing magnetic domain refining treatment by irradiating with an electron beam, in a pressure reduced area, a surface of a grain-oriented electrical steel sheet after subjection to final annealing, the method further including: before the irradiating with the electron beam, delivering the grain-oriented electrical steel sheet wound in a coil shape and heating the delivered grain-oriented electrical steel sheet to 50&#xb0; C. or higher; and then cooling the grain-oriented electrical steel sheet such that the grain-oriented electrical steel sheet has a temperature of lower than 50&#xb0; C. at the time of entering the pressure reduced area.

Method of producing grain-oriented electrical steel sheet and production line therefor

Provided is a method for manufacturing a grain-oriented electrical steel sheet. The method comprises: hot rolling a slab to obtain a hot rolled sheet; subjecting the hot rolled sheet to hot band annealing as necessary; subjecting the hot rolled sheet to cold rolling; subjecting the cold rolled sheet to decarburization annealing; applying an annealing separator having MgO as a main component onto a surface of the decarburization annealed sheet and subjecting the decarburization annealed sheet to final annealing to form the forsterite film; and applying an insulating coating treatment liquid onto the final annealed sheet and subjecting the final annealed sheet to flattening annealing to form a tension-applying insulating coating. A difference in total tensions between one and opposite surfaces of the sheet is less than 0.5 MPa. A difference in tensions between the forsterite films in one and opposite surfaces of the sheet is 0.5 MPa or more.

Method for manufacturing a grain-oriented electrical steel sheet

Provided is a grain-oriented electrical steel sheet having better transformer iron loss property than conventional grain-oriented electrical steel sheets. A grain-oriented electrical steel sheet comprises: a steel substrate; a forsterite film on a surface of the steel substrate; and a Cr-depleted layer at a boundary between the steel substrate and the forsterite film, the Cr-depleted layer having a Cr concentration that is 0.70 times to 0.90 times a Cr concentration of the steel substrate.

Grain-oriented electrical steel sheet and method for manufacturing same

A grain-oriented electrical steel sheet for a stacked transformer core. The steel sheet having a sheet thickness t, where t and an iron loss deterioration ratio obtained by subjecting the steel sheet under elliptic magnetization satisfy the following relations: (i) when t&#x2264;0.20 mm, the iron loss deterioration ratio is 85% or less; (ii) when 0.20 mm&#x3c;t&#x3c;0.27 mm, the iron loss deterioration ratio is 80% or less; and (iii) when 0.27 mm&#x2264;t, the iron loss deterioration ratio is 75% or less. The iron loss deterioration ratio is calculated from ((W&#x2212;W)/W)&#xd7;100, where Wis iron loss under 50 Hz elliptic magnetization of 1.7 T in a rolling direction and 1.0 T in a direction orthogonal to the rolling direction, and Wis iron loss under 50 Hz alternating magnetization of 1.7 T in the rolling direction.

Grain-oriented electrical steel sheet, stacked transformer core using the same, and method for producing stacked core

Iron core vibration and transformer noise can be reduced by using, as a transformer iron core, an iron core formed by a stack of at least two types of grain-oriented electrical steel sheets that differ in magnetostriction by 2&#xd7;10or more when excited from 0 T to 1.7 T.

Transformer iron core

This device scans a high-energy beam in a direction traversing a feed path of a grain-oriented electrical steel sheet having subjected to final annealing so as to irradiate a surface of the steel sheet being passed through with the high-energy beam to thereby perform magnetic domain refinement, the device including an irradiation mechanism for scanning the high-energy beam in a direction orthogonal to the feed direction of the steel sheet, in which the irradiation mechanism has a function of having the scanning direction of the high-energy beam oriented diagonally, relative to the orthogonal direction, toward the feed direction at an angle determined based on a sheet passing speed of the steel sheet on the feed path.

Device to improve iron loss properties of grain-oriented electrical steel sheet

There is provided an amorphous alloy thin strip having a chemical composition represented by a chemical formula: FeBSi(x: 78-83 at %, y: 8-15 at % and z: 6-13 at %) capable of stably attaining a low iron loss even when shaped into a wound core, wherein a generation density of air pockets on a face contacting with a cooling roll is not more than 8 per 1 mmand an arithmetic mean height Sa on portions other than the air pockets is not more than 0.3 &#x3bc;m.

Amorphous alloy thin strip

Further lower iron loss can be achieved in a grain-oriented electrical steel sheet including: a predetermined film mainly composed of forsterite on a front and back surfaces thereof; and a plurality of grooves on the front surface thereof, in which the plurality of grooves have an average depth of 6% or more of a thickness of the steel sheet and are spaced a distance of 1 mm to 15 mm from respective adjacent grooves, the steel sheet has a specific magnetic permeability &#x3bc;rof 35000 or more when subjected to alternating current magnetization at a frequency of 50 Hz and a maximum magnetic flux density of 1.5 T, and the steel sheet includes isolated parts having a presence frequency of 0.3/&#x3bc;m or less, the isolated parts being separated from a continuous part of the film in an interface between the steel sheet and the film in a cross section orthogonal to the rolling direction of the steel sheet.

Grain-oriented electrical steel sheet

A single roll type apparatus for manufacturing a metal thin strip by injecting a molten metal onto an outer peripheral face of a cooling roll rotating at a high speed and rapidly solidifying it to manufacture a metal thin strip, wherein an airflow blocking device for blocking the airflow along the surface of the cooling roll is provided at an upstream side of a molten metal injection nozzle for injecting the molten metal in a rotation direction of the cooling roll, and a carbon dioxide gas injection nozzle for forming a flow of carbon dioxide gas on an outer peripheral surface of the cooling roll between the airflow blocking device and the molten metal injection nozzle or forming a carbon dioxide atmosphere on the surface of the cooling roll between the airflow blocking device and the molten metal injection nozzle is disposed, and a foreign material removal device for removing foreign material attached to the surface of the cooling roll is disposed at an upstream side of the airflow blocking device in the rotation direction of the cooling roll, whereby a metal thin strip having a good surface quality can be manufactured stably even in the continuous operation for a long time.

Apparatus for manufacturing metal thin strip

A magnetic domain refining treatment is performed by dividing a surface of a steel sheet into a plurality of regions in a widthwise direction, disposing a laser irradiation apparatus or an electron beam irradiation apparatus in each of the regions, and forming beam-irradiated regions through beam irradiation, wherein beams are irradiated so that a nature of a juncture between beam-irradiated regions satisfies 0&#x2264;&#x3b1;&#x2264;0.3&#xd7;a and &#x2212;1.2&#xd7;a+0.02&#xd7;w&#x2212;0.5&#xd7;&#x3b1;&#x2212;6.5&#x2264;&#x3b2;&#x2264;&#x2212;0.13&#xd7;a&#x2212;200&#xd7;(1/w)+5.4 when TD spacing &#x3b2; at the juncture between the beam-irradiated regions is &#x2212;3 to 0 mm, whereby a grain oriented electrical steel sheet having an excellent iron loss property is produced in a good productivity.

Grain oriented electrical steel sheet and production method therefor

A method of manufacturing a grain oriented electrical steel sheet includes subjecting a steel slab to a rolling process including cold rolling to obtain a steel sheet with a final sheet thickness, the steel slab containing by mass % C: 0.01% to 0.20%, Si: 2.0% to 5.0%, Mn: 0.03% to 0.20%, sol. Al: 0.010% to 0.05%, N: 0.0010% to 0.020%, at least one element selected from S and Se in a total of 0.005% to 0.040%, and the balance including Fe and incidental impurities; forming, by a chemical process, a linear groove extending in a direction forming an angle of 45&#xb0; or less with a direction orthogonal to a rolling direction of the steel sheet; subjecting the steel sheet to decarburization annealing; applying an annealing separator thereon mainly composed of MgO; and subjecting the steel sheet to final annealing to manufacture a grain oriented electrical steel sheet.

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Tokyo, Japan

Seiji Okabe