With Special Compositions Patents (Class 148/113)
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Patent number: 7198682Abstract: A process for the production of electrical steel strips, in which a strip is directly cast from molten steel and contains alloy elements apt to generate a precipitation of sulphides and/or nitrides apt to inhibit the grain growth. The strip is hot rolled in-line with the casting operation at a temperature between 1250 and 1000° C., and in which the strip is coiled after hot rolling at a temperature of less than 780° C. if sulphides are utilized, or at a temperature of less than 600° C. if nitrides, or nitrides plus sulphides, are utilized.Type: GrantFiled: December 17, 2001Date of Patent: April 3, 2007Assignee: Thyssenkrupp Acciai Speciali Terni S.p.A.Inventors: Stefano Cicale′, Stefano Fortunati, Giuseppe Abbruzzese
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Patent number: 7192492Abstract: In the production of electrical steel strips, a special islab-reheating treatment before hot rolling is carried out so that the maximum temperature within the furnace is reached by the slab well before its extraction from the furnace. During the heating stage and performance at the highest temperatures of the thermal cycle, second phase particles are dissolved and segregated elements are distributed in the metallic matrix, while during cooling and temperature equalising steps of the slab in the furnace a controlled amount of small second phases particles are more homogeneously re-precipitated from the metallic matrix. Differently from all the conventional processes for the production of electrical steels, the slab reheating furnace become a site in which it is performed the precipitation of a controlled amount of second phases particles for the necessary grain growth control during the successive process steps.Type: GrantFiled: August 8, 2001Date of Patent: March 20, 2007Assignee: Thyssenkrupp Acciai Speciali Terni S.p.A.Inventors: Stefano Fortunati, Stefano Cicale′, Claudia Rocchi, Giuseppe Abbruzzese
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Patent number: 7077919Abstract: Disclosed herein is an insulating material between adjacent metal layers of a soft magnetic core, and a process for forming this insulating material. The insulating material is composed of the native metal oxides of the metallic core material.Type: GrantFiled: June 5, 2003Date of Patent: July 18, 2006Assignee: Magnetic Metals CorporationInventors: Richard Wood, Richard Lathlaen, William C. Beckham
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Patent number: 7045025Abstract: A low core loss grain-oriented electrical steel sheet that does not have a significant deterioration in a magnetic flux density and a decrease of a space factor, and which may withstand stress-relieving annealing is provided. Melted and re-solidified layers can be formed on either or both of the surfaces of the grain-oriented electrical steel sheet that extend in a direction that is perpendicular to the rolling direction (e.g., in the direction of the width thereof), at a cyclic interval of not less than approximately 2 mm to less than approximately 5 mm in the rolling direction. The melted and re-solidified layers may be provided on each surface of the grain-oriented electrical steel sheet, and can have an aspect ratio that is a ratio of the depth to the width of the melted and re-solidified layer of not less than approximately 0.20 and a depth of not less than approximately 15 ?m. In addition, the melted and re-solidified layers can be formed by using a laser.Type: GrantFiled: May 30, 2003Date of Patent: May 16, 2006Assignee: Nippon Steel CorporationInventors: Hideyuki Hamamura, Tatsuhiko Sakai, Naoya Hamada
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Patent number: 6936792Abstract: Furnace cart assembly for loading high temperature vacuum furnaces for treating target material, for example, metal parts, under extreme temperature and vacuum environments. The furnace cart includes electrical heating elements as an integral part of the cart, which elements are adapted for releasable connection to the furnace electrical supply. When so connected the furnace cart heating elements can form a part of the heating system of the furnace. The lower part of the furnace cart assembly, including a frame above and supported on wheels, the frame having heat reflection means on at least Its upper surfaces providing some protection from heat is preferably also protected from heat during furnace operation by insulating material above the frame (the material desirably supported by the frame but separated therefrom).Type: GrantFiled: May 22, 2002Date of Patent: August 30, 2005Inventor: William R. Jones
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Patent number: 6929704Abstract: A grain-oriented electromagnetic steel sheet having a multiplicity of fine grains having a diameter of about 3 mm or less on the surface of the steel sheet, in a numerical ratio of about 65% or more and of about 98% or less relative to the constituting grains that penetrate the sheet along the direction parallel to its thickness, and a method for producing the same. The fine grains are artificially created and regularly disposed with a random orientation in the steel sheet, and contribute to decreasing the strain susceptibility of the steel. More preferably, a treatment for finely dividing magnetic domains is applied on the surface of the steel sheet. Transformers based upon the steel sheet have excellent magnetic characteristics (iron loss and magnetic flux density) together with strain resistance, and the steel sheet has good practical device characteristics (building factor) after being assembled into a transformer.Type: GrantFiled: June 6, 2002Date of Patent: August 16, 2005Assignee: JFE Steel CorporationInventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda
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Patent number: 6899768Abstract: The present invention is related to a magnesium oxide particle aggregate with the requirement of a first inflection point diameter is more than 0.30×10?6 to 0.60×10?6 m, a particle void volume is 0.50×10?3 to 0.90×10?3 m3·kg?1, and a micropore volume is 0.04×10?3 to 0.11×10?3 m3·kg?1 in the cumulative intrusion volume curve of said particle by having controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled.Type: GrantFiled: October 25, 2001Date of Patent: May 31, 2005Assignee: Tateho Chemical Industries Co., Ltd.Inventors: Atsuo Toutsuka, Yutaka Hiratsu
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Patent number: 6835250Abstract: An object of the present invention is to provide a magnesium oxide particle aggregate having a controlled particle aggregation structure so that the solid phase-solid phase reaction between magnesium oxide and the SiO2 film on the surface can be appropriately controlled. The object can be achieved by a magnesium oxide particle aggregate characterized in that a first inflection point diameter is 0.30×10−6 m or less, an interparticle void volume is 1.40×10−3 to 2.20×10−3 m3/kg and a particle void volume is 0.55×10−3 to 0.80×10−3 m3/kg in a cumulative intrusion volume curve of the particle aggregate.Type: GrantFiled: October 29, 2002Date of Patent: December 28, 2004Assignee: Tateho Chemical Industries Co., Ltd.Inventors: Yutaka Hiratsu, Toshio Kiyokawa, Atsuo Toutsuka
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Patent number: 6811900Abstract: When plural-layer ceramic coatings are formed on a surface of an grain-oriented silicon steel sheet after finish annealing according to the invention, TiNO coating is formed as a first coating layer by a hollow cathode process under an application of a high bias voltage to the steel sheet, whereby ceramic tension coatings having excellent coating adhesion property and hence tension applying effect can be formed. As a result, ultra-low iron loss grain-oriented silicon steel sheets having an excellent iron loss property even after stress relief annealing at high temperatures for a long time can be stably obtained.Type: GrantFiled: January 28, 2003Date of Patent: November 2, 2004Assignee: JFE Steel CorporationInventor: Yukio Inokuti
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Patent number: 6758915Abstract: The invention is a grain-oriented magnetic steel sheet having extremely low iron loss, suitable for use as an iron core material for transformers and power generators, and a method for producing the same. The method includes forming a coating layer on a surface of a steel sheet having a thickness of 0.27 mm or less by vapor deposition in a low oxidizing atmosphere with an oxygen partial pressure (Po2) of less than 0.1 atm and a total pressure of 0.1 atm or more. The steel sheet has extremely low iron loss with a thickness of 0.27 mm or less and includes a coating layer formed by vapor deposition on a matrix surface.Type: GrantFiled: December 5, 2002Date of Patent: July 6, 2004Assignee: JFE Steel CorporationInventors: Minoru Takashima, Mineo Muraki, Hiroi Yamaguchi, Mitsumasa Kurosawa, Michiro Komatsubara
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Patent number: 6733599Abstract: The present invention provides a method for producing a grain-oriented silicon steel sheet not having inorganic mineral films by using an annealing separator capable of preventing the inorganic mineral films composed of forsterite (Mg2SiO4), and so on, from forming during final annealing, comprising the steps of decarburization annealing followed by coating of annealing separator and final annealing, wherein alumina powder calcined at a calcination temperature of 900 to 1,400° C., or further having a BET specific surface area of 1 to 100 m2/g, an oil absorption of 1 to 70 ml/100 g, and/or having a gamma ratio of 0.001 to 2.0, is used as the annealing separator. Magnesia having a BET specific surface area of 0.5 to 5 m2/g may be added to said alumina powder.Type: GrantFiled: December 20, 2002Date of Patent: May 11, 2004Assignee: Nippon Steel CorporationInventors: Hiroyasu Fujii, Yoshiyuki Ushigami, Shuichi Nakamura, Kenichi Murakami, Norihiro Yamamoto, Kiyoshi Sawano, Shuichi Yamazaki
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Publication number: 20040074566Abstract: A ferromagnetic resonator for use in a marker in a magnetomechanical electronic article surveillance system is manufactured at reduced cost by being continuously annealed with a tensile stress applied along the ribbon axis and by providing an amorphous magnetic alloy containing iron, cobalt and nickel and in which the portion of cobalt is less than about 4 at %.Type: ApplicationFiled: October 8, 2003Publication date: April 22, 2004Applicant: Vacuumschmelze GmbH & Sensormatic Electronics CorpInventors: Giselher Herzer, Nen-Chin Liu
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Patent number: 6613160Abstract: The present invention, in a method to produce a grain-oriented electrical steel sheet, proposes conditions for stable production by clarifying the causes by which secondary recrystallization is rendered unstable when primary recrystallization is controlled by raising the heating rate of decarburization annealing. The primary recrystallization structure is controlled by changing the heating rate and the oxide layer of a steel sheet is controlled by changing the conditions of soaking annealing in the decarburization annealing. The composition of the (Al, Si)N inhibitor is also controlled in the nitriding treatment thereafter.Type: GrantFiled: August 7, 2001Date of Patent: September 2, 2003Assignee: Nippon Steel CorporationInventors: Yoshiyuki Ushigami, Shuichi Nakamura, Kenichi Murakami, Hiroyasu Fujii, Norihiro Yamamoto
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Publication number: 20030136470Abstract: The present invention relates to a grain-oriented magnetic steel sheet having extremely low iron loss, which is suitable for use as an iron core material for transformers and power generators, and to a method for producing the same. That is, in accordance with the present invention, a method for producing a grain-oriented magnetic steel sheet includes the step of forming a coating layer on a surface of the matrix of a steel sheet having a thickness of 0.27 mm or less by vapor deposition in a low oxidizing atmosphere with an oxygen partial pressure (Po2) of less than 0.1 atm and a total pressure of 0.1 atm or more. A grain-oriented magnetic steel sheet of the present invention having extremely low iron loss with a thickness of 0.27 mm or less includes a coating layer formed by vapor deposition on a matrix surface.Type: ApplicationFiled: December 5, 2002Publication date: July 24, 2003Inventors: Minoru Takashima, Mineo Muraki, Hiroi Kurosawa, Mitsumasa Kurosawa, Michiro Komatsubara
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Patent number: 6580348Abstract: A toroidal tape core is produced from magnetic sheets (1) which may have slits (4). In order to improve the behavior of the toroidal cores (3) at high frequencies, the magnetic sheets (1) have a high surface roughness. The surface roughness of each magnetic sheet (1) is at least equal to the skin penetration depth at the frequency being used.Type: GrantFiled: December 10, 2001Date of Patent: June 17, 2003Assignee: Vacuumschmelze GmbHInventors: Harald Hundt, Johannes Beichler
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Patent number: 6558479Abstract: The object of the present invention is to provide a low iron loss and low noise grain-oriented electrical steel sheet for securing both low core loss and low noise of a transformer at the same time. The present invention relates to a grain-oriented electrical steel sheet containing Si: 1.0-4.0 wt % produced by controlling, with regard to &egr;O, which is defined as a 0-p value when a grain-oriented electrical steel sheet is magnetized up to a saturated magnetic flux density, and &egr;17, which is defined as the value obtained by subtracting a 0-p value at the magnetization magnetic flux density of 1.7 T from a 0-p value at a saturated magnetic flux density, &egr;OC and &egr;17L, which are absolute values deviated by forming a tension film and a forsterite film, and &egr;OL and &egr;17L, which are absolute values deviated by irradiating laser after the film formation, in adequate ranges respectively, and further controlling &lgr;17, which is a 0-p value at the magnetization magnetic flux density of 1.Type: GrantFiled: May 11, 2001Date of Patent: May 6, 2003Assignee: Nippon Steel CorporationInventors: Masahiro Fujikura, Satoshi Arai, Masato Mizokami, Hisashi Mogi, Takeshi Kubota
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Patent number: 6527876Abstract: A silicon steel sheet having low iron loss of high frequency has a surface layer of the steel sheet which has Si concentration higher than Si concentration of a center portion of the steel sheet. Si concentration of sheet thickness center is 3.4 wt. % or more and Si concentration of the surface layer of the steel sheet is 5 wt. % or more. Si concentration in a surface layer portion is 5 to 8 wt. %. The production method comprises siliconizing treatment and diffusing treatment. Velocity of siliconizing and diffusing are controlled, and Si concentration distribution in the sheet thickness direction of the steel sheet is controlled.Type: GrantFiled: January 24, 2000Date of Patent: March 4, 2003Assignee: NKK CorporationInventors: Misao Namikawa, Yoshikazu Takada, Shoji Kasai, Hironori Ninomiya, Tsunehiro Yamaji, Tatsuhiko Hiratani
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Patent number: 6524400Abstract: A process for the production of grain-oriented electric quality sheet by melting a silicon steel and casting the melt continuously into a strand having a thickness of 25-100 mm. During solidification the strand is cooled to a temperature above 700° C. and divided into thin slabs. The thin slabs then pass through an equalization furnace standing in line where they are reheated to a temperature ≦1170° C. and continuously rolled in a multi-stand hot rolling mill to give hot strip having a thickness of ≦3.0 mm. The first shaping pass is performed at a temperature in the rolling stock up to 1150° C. The reduction in thickness is at least 20%. The hot strip is cold rolled in one or more stages with recrystallizing intermediate annealing to a final thickness in the range of 0.15-0.50 mm. The cold strip is then annealed with recrystallization and decarburization, furnished with a predominantly MgO-containing annealing separator and given a final annealing for imprinting a Goss texture.Type: GrantFiled: June 6, 2000Date of Patent: February 25, 2003Assignee: Thyssen Krupp Stahl AGInventors: Hans Pircher, Rudolf Kawalla, Manfred Espenhahn, Andreas Böttcher, Klaus Günther, Hans Huneus, Carl-Dieter Wuppermann
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Patent number: 6471787Abstract: A process for the production of oriented-grain electrical steel sheet with high magnetic characteristics, and more precisely a process in which the slab obtained from continuous casting is continuously nitrided by a reaction between aluminium and nitrogen is described. Amount, size and distribution of precipitates are controlled, enabling a high-temperature continuous heat treatment during which the primary-recrystallization and a high-temperature nitriding are realized.Type: GrantFiled: June 22, 1999Date of Patent: October 29, 2002Assignee: Acciai Speciali Terni S.p.A.Inventors: Stefano Cicale', Stefano Fortunati, Giuseppe Abbruzzese
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Publication number: 20020134466Abstract: A silicon steel sheet having low iron loss of high frequency has a surface layer of the steel sheet which has Si concentration higher than Si concentration of a center portion of the steel sheet. Si concentration of sheet thickness center is 3.4 wt. % or more and Si concentration of the surface layer of the steel sheet is 5 wt. % or more. Si concentration in a surface layer portion is 5 to 8 wt. %. The production method comprises siliconizing treatment and diffusing treatment. Velocity of siliconizing and diffusing are controlled, and Si concentration distribution in the sheet thickness direction of the steel sheet is controlled.Type: ApplicationFiled: January 24, 2000Publication date: September 26, 2002Inventors: MISAO NAMIKAWA, YOSHIKAZU TAKADA, SHOJI KASAI, HIRONORI NINOMIYA, TSUNEHIRO YAMAJI, TATSUHIKO HIRATANI
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Patent number: 6451128Abstract: A method for manufacturing a high magnetic flux density grain oriented electrical steel sheet is disclosed. A silicon steel slab is heated and hot-rolled, and the steel sheet is annealed and cold-rolled and decarburized. An annealing separator is spread on the steel sheet, and a final high temperature annealing is carried out. The silicon steel contains in weight % 0.02-0.045% of C, 2.90-3.30% of Si, 0.05-0.30% of Mn, 0.005-0.019% of Al, 0.003-0.008% of N, 0.006% or less of S (the above being main ingredients), 0.001-0.012% of B, and a balance of Fe and unavoidable impurities; or the above main ingredients plus 0.30-0.70% of Cu, 0.03-0.07% of Ni, 0.03-0.07% of Cr, and a balance of Fe and unavoidable impurities; or the above main ingredients plus 0.001-0.012% of B, 0.30-0.70% of Cu, 0.03-0.07% of Ni, 0.03-0.07% of Cr, and a balance of Fe and unavoidable impurities.Type: GrantFiled: February 25, 1999Date of Patent: September 17, 2002Assignee: Pohang Iron & Steel Co., Ltd.Inventors: Chung San Lee, Chan Hye Han, Jong Soo Woo, Gyu Seung Choi, Jae Kwan Kim, Byung Deuk Hong, Kyu Seok Han
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Patent number: 6444050Abstract: A grain-oriented electromagnetic steel sheet having a multiplicity of fine grains having a diameter of about 3 mm or less on the surface of the steel sheet, in a numerical ratio of about 65% or more and of about 98% or less relative to the constituting grains that penetrate the sheet along the direction parallel to its thickness, and a method for producing the same. The fine grains are artificially created and regularly disposed with a random orientation in the steel sheet, and contribute to decreasing the strain susceptibility of the steel. More preferably, a treatment for finely dividing magnetic domains is applied on the surface of the steel sheet. Transformers based upon the steel sheet have excellent magnetic characteristics (iron loss and magnetic flux density) together with strain resistance, and the steel sheet has good practical device characteristics (building factor) after being assembled into a transformer.Type: GrantFiled: April 24, 2000Date of Patent: September 3, 2002Assignee: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda
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Patent number: 6444051Abstract: A method of making a grain-oriented electromagnetic steel sheet having a low iron loss and a high magnetic flux density, from a steel slab with 0.03 to 0.095 wt % carbon, about 1.5 to 7.0 wt % Si, about 0.03 to 2.50 wt % manganese, about 0.003 to 0.040 wt % sulfur and/or selenium, about 0.0010 to 0.0070 wt % borbon, about 30 to 120 wtppm nitrogen, about 0.015 wt % or less aluminum, and about 0.010 wt % or less vanadium by subjecting the steel slab to reheating, hot rolling, rapid cooling, cold rolling, primary recrystallization annealing, coating with an annealing separator, final annealing, secondary recrystallization, and coiling.Type: GrantFiled: August 9, 2001Date of Patent: September 3, 2002Assignee: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Kazuaki Tamura, Mitsumasa Kurosawa
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Patent number: 6432222Abstract: A method for producing a grain-oriented electrical steel sheet excellent in magnetic property, comprising the steps of; heating a slab containing a prescribed amount of Al to a temperature of 1,200° C. or higher, hot-rolling the slab into a hot-rolled strip, annealing the strip as required, cold-rolling it once or twice or more with intermediate annealing(s), and decarburization annealing the cold rolled sheet, and final box annealing after the application of an annealing separator to prevent strip sticking during the annealing, characterized by heating the slab to a temperature (slab heating temperature Ts (° C.)) higher than the complete solution temperature of substances having intensities as inhibitors and nitriding treating the decarburization annealed steel sheet before the commencement of secondary recrystallization during the final box annealing.Type: GrantFiled: June 4, 2001Date of Patent: August 13, 2002Assignee: Nippon Steel CorporationInventors: Yoshifumi Ohata, Tomoji Kumano, Norikazu Fujii, Hisashi Mogi, Hitoshi Yokouchi, Norihiro Yamamoto
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Patent number: 6423156Abstract: The invention relates to a process for the coating of electric steel strips with an oxide powder as annealing separator by the application of an aqueous solution which contains mainly MgO and also at least one additive, including a chlorine-containing compound. The characterizing feature of the invention is that the additive added to the aqueous solution is ammonium chloride (NH4Cl or NH4Cl.nH2O).Type: GrantFiled: June 6, 2000Date of Patent: July 23, 2002Assignee: EBG Gesellschaft für Elektromagnetische Werkstoffe mbHInventors: Klaus Günther, Heiner Schrapers
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Patent number: 6416591Abstract: A finish annealed non-oriented electromagnetic steel sheet includes about 0.01 wt % or less of C, greater than about 1.0 wt % and at most about 3.5 wt % of Si, at least about 0.6 wt % and at most about 3.0 wt % of Al, at least about 0.1 wt % and at most about 2.0 wt % of Mn, at least about 2 ppm and at most about 80 ppm of one or more rare earth metals (REM), a maximum content of Ti and Zr being about 15 ppm and 80 ppm, respectively, wherein oxygen on the surface layer of the steel sheet is 1.0 g/e2 or less. Since the non-oriented electromagnetic steel sheet has desirable mechanical properties resulting from the increased amounts of Si and Al, a high magnetic flux density can be maintained without sacrificing a punching property as well as very low iron loss can be obtained even after stress relief annealing.Type: GrantFiled: August 3, 2001Date of Patent: July 9, 2002Assignee: Kawasaki Steel CorporationInventors: Masaki Kawano, Yoshihiro Ozaki, Atsuhito Honda
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Patent number: 6395104Abstract: A process for producing a grain-oriented electrical steel sheet wherein during the decarburization annealing step, the steel sheet is first rapidly heated in a rapid heating chamber and the PH2O/PH2 ratio in the rapid heating chamber is more than the PH2O/PH2 ratio in the decarburization annealing furnace so as to provide improved oxide film adhesion.Type: GrantFiled: December 15, 1998Date of Patent: May 28, 2002Assignee: Nippon Steel CorporationInventors: Kenji Kosuge, Kishio Mochinaga, Eiichi Nanba, Nobuo Tachibana, Shinya Ishii, Naoki Yagi
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Patent number: 6387522Abstract: The present invention provides a grain-oriented electrical steel sheet, for a low noise transformer, capable of reducing higher harmonics which are highly audible and lowering noise effectively, and relates to a grain-oriented electrical steel sheet for a low noise transformer, characterized by imposing a film tension of 0.5 to 6.0 MPa on the surface by coating or a method corresponding thereto, without forming a glass film on the grain-oriented electrical steel sheet or, if a glass film is formed, after removing the glass film by an arbitrary method.Type: GrantFiled: May 30, 2001Date of Patent: May 14, 2002Assignee: Nippon Steel CorporationInventors: Hisashi Mogi, Akira Sakaida, Masahiro Fujikura, Masato Mizokami
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Patent number: 6375761Abstract: A magnetoresistive material with two metallic magnetic phases. The material exhibits the giant magnetoresistance effect (GMR). A first phase of the material includes a matrix of an electrically conductive ferromagnetic transition metal or an alloy thereof. A second precipitate phase exhibits ferromagnetic behavior when precipitated into the matrix and is antiferromagnetically exchange coupled to the first phase. The second precipitate phase can be electrically conductive rare earth pnictide or can be a Heusler alloy. A method of manufacturing magnetoresistive materials according to the present invention employs facing targets magnetron sputtering.Type: GrantFiled: April 30, 2001Date of Patent: April 23, 2002Assignee: The Research Foundation of State University of New YorkInventors: Richard J. Gambino, Taewan Kim
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Patent number: 6368424Abstract: A grain-oriented electrical steel sheet with improved magnetic properties is achieved by a reduced 180° C. magnetic wall spacing with pulse laser light irradiation. The rolling direction width of the periodic closure domain generated by laser irradiation is no greater than 150 &mgr;m. The depth of the periodic closure domain in the direction of the steel sheet thickness is at least 30 &mgr;m. The product of the length of the periodic closure domain in the rolling direction width direction multiplied by the length of the depth of the periodic closure domain in the direction of the steel sheet thickness is at least 4500 &mgr;m2. The magnetostriction with materials of 0.23 mm sheet thickness (&lgr;19 p-p compression) is no greater than 0.9×10−6, and magnetostriction with materials of 0.27 mm sheet thickness (&lgr;19 p-p compression) is no greater than 1.3×10−6.Type: GrantFiled: August 20, 1998Date of Patent: April 9, 2002Assignee: Nippon Steel CorporationInventors: Tatsuhiko Sakai, Naoya Hamada, Katsuhiro Minamida, Kimihiko Sugiyama, Akira Sakaida, Hisashi Mogi
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Publication number: 20020038678Abstract: The present invention, in a method to produce a grain-oriented electrical steel sheet, proposes conditions for stable production by clarifying the causes by which secondary recrystallization is rendered unstable when primary recrystallization is controlled by raising the heating rate of decarburization annealing.Type: ApplicationFiled: August 7, 2001Publication date: April 4, 2002Inventors: Yoshiyuki Ushigami, Shuichi Nakamura, Kenichi Murakami, Hiroyasu Fujii, Norihiro Yamamoto
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Patent number: 6364963Abstract: In a grain oriented electrical steel sheet used for cores of transformers and generators, a high alignment degree of grain orientations reduces iron loss, by precipitating very fine AlN or/and BN and providing strong inhibiting effect against the growth of the primary recrystallized grains, providing radically improved texture and grain structure in the steel.Type: GrantFiled: April 11, 2000Date of Patent: April 2, 2002Assignee: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda
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Patent number: 6361621Abstract: The production of grain-oriented electrical steel sheets is disclosed wherein grain growth in the steel is inhibited by a method comprising the regulation of the content of sulfur and manganese in the steel strp and the cold rolled strip is continuously nitrided at high temperature.Type: GrantFiled: December 9, 1999Date of Patent: March 26, 2002Assignee: Acciai Speciali Terni S.p.A.Inventors: Stefano Fortunati, Stefano Cicale', Giuseppe Abbruzzese
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Patent number: 6361620Abstract: In the production of grain-oriented electrical steel strip, the grain growth inhibition is controlled by balancing the copper, aluminum and carbonium content in order to control the type and quantity of precipitated second phases and obtain optimum grain dimensions during the decarburization annealing. This is done by using a continuous high-temperature thermal treatment in which nitrogen is diffused into the steel strip and aluminum is directly precipitated as aluminum nitride which controls the grain orientation of the final product.Type: GrantFiled: December 9, 1999Date of Patent: March 26, 2002Assignee: Acciai Speciali Terni S.p.A.Inventors: Stefano Cicale′, Stefano Fortunati, Giuseppe Abbruzzese
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Publication number: 20020011278Abstract: An electromagnetic steel sheet having a low iron loss and a high magnetic flux density, with silicon, nitrogen and an added element bismuth or germanium prior to secondary recrystallization, to accelerate precipitation of fine BN and silicon nitride, improving the texture of the primary recrystallized grains of the steel sheet immediately before subjecting it to secondary recrystallization annealing, and combining the primary recrystallization annealing, cold rolling and further the texture improving treatment. Addition of bismuth or germanium or both to the steel prior to secondary recrystallization is combined with primary recrystallization annealing and warm rolling in the presence of limited aluminum and vanadium impurities limited to 0.002 wt % Al or less and 0.010 wt % V or less.Type: ApplicationFiled: August 9, 2001Publication date: January 31, 2002Applicant: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Kazuaki Tamura, Mitsumasa Kurosawa
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Publication number: 20020000265Abstract: Grain-oriented silicon steel sheet with Bi as an auxiliary inhibitor and a forsterite coating film having a Cr spinel oxide subscale of FeCr2O4 or FexMn1−xCr2O4 (0.6≦x≦1), made from a steel slab containing 0.005-0.20 wt % of Bi and 0.1-1.0 wt % of Cr.Type: ApplicationFiled: July 18, 2001Publication date: January 3, 2002Applicant: Kawasaki Steel CorporationInventors: Hiroaki Toda, Kunihiro Senda, Mitsumasa Kurosawa, Makoto Watanabe, Atsuhito Honda
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Patent number: 6331215Abstract: A grain-oriented electromagnetic steel sheet is provided which has a low ratio of iron loss in a weaker magnetic field to that in a stronger magnetic field and has special advantage in EI cores and the like. Also provided is a process for producing that steel sheet. The grain-oriented electromagnetic steel sheet is characterized in that its crystal grains of important components are specified in terms of their proportions in number, and the contents of Al, Ti and B, with a forsterite film formed on a surface of the steel sheet. In the process a low-Al silicon slab is heated at below 1,250° C. before hot rolling and the hot-rolled sheet is annealed with a temperature rise in the range of from 5 to 25° C./sec and at a temperature of from about 800 to 1,000 for a period of time of shorter than about 100 seconds.Type: GrantFiled: January 28, 2000Date of Patent: December 18, 2001Assignee: Kawasaki Steel CorporationInventors: Tetsuo Toge, Michiro Komatsubara, Atsuhito Honda, Kenichi Sadahiro, Kunihiro Senda
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Patent number: 6325866Abstract: A process for the production of grain oriented silicon steel sheet which provides an optimization of the production of conventional, grain oriented silicon steel strips, by the use of an appropriate synergistic combination of the composition levels of some elements and appropriate treatments which result in the control of the presence and type of inhibitors, and by so doing, controlling the primary-recrystallization grain size.Type: GrantFiled: June 22, 1999Date of Patent: December 4, 2001Assignee: Acciai Speciali Terni S.p.A.Inventors: Stefano Fortunati, Stefano Cicale′, Giuseppe Abbruzzese
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Patent number: 6322635Abstract: Electromagnetic steel sheet from a high-purity steel slab, composed essentially of Si 2.0 to 8.0 wt %, Mn 0.005 to 3.0 wt % and Al 0.0010 to 0.012 wt % with each of Se, S, N and O each not more than 30 ppm.Type: GrantFiled: October 26, 1999Date of Patent: November 27, 2001Assignee: Kawasaki Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara
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Patent number: 6287392Abstract: Grain-oriented silicon steel sheet with Bi as an auxiliary inhibitor and a forsterite coating film having a Cr spinel oxide subscale of FeCr2O4 or FexMn1−xCr2O4 (0.6≦x≦1), made from a steel slab containing 0.005-0.20 wt % of Bi and 0.1-1.0 wt % of Cr.Type: GrantFiled: September 17, 1999Date of Patent: September 11, 2001Assignee: Kawasaki Steel CorporationInventors: Hiroaki Toda, Kunihiro Senda, Mitsumasa Kurosawa, Makoto Watanabe, Atsuhito Honda
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Patent number: 6284388Abstract: The present invention is directed to a method of forming an electrically insulating layer on a steel article such as a stack of electrical steel laminations or an individual, unstacked electrical steel lamination, comprising exposing the article to an oxidation atmosphere, and to a temperature (such as at least about 800° F.) for a time sufficient to form on the article an electrically insulating layer comprising hematite. The hematite layer is effective to provide the article with a surface resistivity characterized by an F-amp value of not greater than about 0.85 at a test pressure of 50 psi and a transfer surface roughness of about 10 microinches (Ra). Also featured is a steel article having the electrically insulating layer formed thereon.Type: GrantFiled: August 23, 2000Date of Patent: September 4, 2001Assignee: LTV Steel Company, Inc.Inventors: Richard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
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Patent number: 6280862Abstract: Ultra-low iron grain-oriented silicon steel sheet which is made by forming a ceramic tensile coating including at least inner and outer portions of a nitride and/or a carbide, the outer portion having a coefficient of thermal expansion that is lower than that of the inner portion, and wherein the outermost portion has an insulating property.Type: GrantFiled: November 23, 1998Date of Patent: August 28, 2001Assignee: Kawasaki Steel CorporationInventor: Yukio Inokuti
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Patent number: 6280534Abstract: Method of making a grain oriented electromagnetic steel sheet having excellent magnetic properties, by a series of steps ranging from hot rolling to final finishing annealing for a silicon steel slab containing from about 0.001 to 0.07 wt % bismuth, wherein the average cooling rate for about five seconds measured immediately after the end of hot rolling is controlled within a range of from about 30 to 120° C./second; the value of the ratio PH2O/PH2 of the atmosphere for the soaking step in decarburization annealing is adjusted within a range of from about 0.45 to 0.70; and a treatment is provided for inhibiting decomposition of the surface inhibitor during final finishing annealing.Type: GrantFiled: May 10, 1999Date of Patent: August 28, 2001Assignee: Kawasaki Steel CorporationInventors: Kunihiro Senda, Toshito Takamiya, Makoto Watanabe, Mitsumasa Kurosawa
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Patent number: 6228182Abstract: A method and a low iron loss grain-oriented electromagnetic steel sheet are disclosed. The method comprises the steps of: hot-rolling a grain-oriented electromagnetic steel sheet; cold-rolling the hot-rolled steel sheet once or twice intervened by intermediate annealing, so as to achieve the sheet thickness of a final product; annealing the cold-rolled steel sheet for decarburization; finish-annealing the decarburized steel sheet; forming linear grooves on the steel sheet substantially perpendicularly to the rolling direction, after the final cold-rolling step and before the finish-annealing step, by, for example, electrolytic etching or acid dipping; and filling the linear grooves with an element selected from the group consisting of Sn, B and Sb, or an oxide or a sulfate of an element selected therefrom.Type: GrantFiled: December 28, 1994Date of Patent: May 8, 2001Assignee: Kawasaki Steel CorporationInventors: Koh Nakano, Atsuhito Honda, Keiji Sato
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Patent number: 6221501Abstract: The present invention is directed to a method of forming an electrically insulating layer on a steel article such as a stack of electrical steel laminations or an individual, unstacked electrical steel lamination, comprising exposing the article to an oxidation atmosphere, and to a temperature (such as at least about 800° F.) for a time sufficient to form on the article an electrically insulating layer comprising hematite. The hematite layer is effective to provide the article with a surface resistivity characterized by an F-amp value of not greater than about 0.85 at a test pressure of 50 psi and a transfer surface roughness of about 10 micro inches (Ra). Also featured is a steel article having the electrically insulating layer formed thereon.Type: GrantFiled: August 17, 1999Date of Patent: April 24, 2001Assignee: LTV Steel Company, Inc.Inventors: Richard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
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Patent number: 6159309Abstract: The present invention provides a grain-oriented electrical steel sheet having magnetic properties equal to, or higher than, those of conventional steel sheets can be produced economically with high productivity, and a method for producing such a steel sheet. The producing method comprises the steps of using, as a starting material, a coil obtained by heating a slab having a composition comprising, in terms of percent by weight, 0.02 to 0.15% of C, 2.5 to 4.0% of Si, 0.02 to 0.20% of Mn, 0.015 to 0.065% of Sol. Al, 0.0030 to 0.0150% of N, 0.005 to 0.040% as the sum of at least one of S and Se and the balance substantially consisting of Fe and hot rolling the slab to a coil, or a coil directly cast from a molten steel having the same components as the slab, conducting hot rolled sheet annealing at 900 to 1,100.degree. C.Type: GrantFiled: November 2, 1998Date of Patent: December 12, 2000Assignee: Nippon Steel CorporationInventors: Yousuke Kurosaki, Norito Abe, Nobuo Tachibana, Kentaro Chikuma, Kiyokazu Ichimura, Sadanobu Hirokami, Masayuki Yamashita
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Patent number: 6153019Abstract: A process for producing a grain-oriented magnetic steel sheet in which a slab, made from a steel containing (in mass %) more than 0.005 to 0.10% C, 2.5 to 4.5% Si, 0.03 to 0.15% Mn, more than 0.01 to 0.05% S, 0.01 to 0.035% Al, 0.0045 to 0.012% N, 0.02 to 0.3% Cu, the remainder being Fe, including unavoidable impurities, is heated through and hot rolled to a final thickness between 1.5 and 7.0 mm. The hot strip is annealed and immediately cooled and cold rolled in one or several cold-rolling steps to the final thickness of the cold strip. The cold strip is subjected to a recrystallizing annealing process in a humid atmosphere containing hydrogen and nitrogen, with synchronous decarburization. A non-stick layer, essentially containing MgO, is applied to the surface of the decarburized cold strip which is then subjected to final annealing. The cold strip is then rolled into coils.Type: GrantFiled: October 26, 1998Date of Patent: November 28, 2000Assignee: Thyssen Stahl AGInventors: Manfred Espenhahn, Andreas Bottcher, Klaus Gunther
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Patent number: 6068708Abstract: A method of making electrical steel strip characterized by low core loss, high permeability and good cleanliness includes producing a slab having a composition consisting essentially of (% by weight): up to 0.02 C, 0.20-1.35 Si, 0.10-0.45 Al, 0.10-1.0 Mn, up to 0.015 S, up to 0.006 N, up to 0.07 Sb, up to 0.12 Sn, and the balance being substantially iron. The slab is hot rolled into a strip with a finishing temperature in the ferrite region. The strip is coiled at a temperature less than 1200.degree. F. and, preferably, less than 1000.degree. F. The strip which has not been subjected to an annealing operation after the coiling is subjected to cold rolling. The strip is then batch annealed and temper rolled.Type: GrantFiled: March 10, 1998Date of Patent: May 30, 2000Assignee: LTV Steel Company, Inc.Inventors: Barry A. Lauer, Gerald F. Beatty, Jeffrey P. Anderson
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Patent number: 6045627Abstract: A silicon steel sheet contains 0.01 wt. % or less C, 4 to 10 wt. % Si, 0.5 wt. % or less Mn, 0.01 wt. % or less P, 0.01 wt. % or less S, 0.2 wt. % or less sol. Al, 0.01 wt. % or less N, 0.02 wt. % or less O and the balance being Fe. The silicon steel sheet has grain boundaries and carbides which are precipitated on the grain boundaries. The carbides have an area of 20% or less to an area of the grain boundaries. The steel sheet is cooled at a cooling speed of 5.degree. C./sec. or more in a temperature range of from 300 to 700.degree. C.Type: GrantFiled: June 4, 1998Date of Patent: April 4, 2000Assignee: NKK CorporationInventors: Koichiro Fujita, Yasushi Tanaka, Hironori Ninomiya, Tatsuhiko Hiratani, Shoji Kasai
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Patent number: RE36423Abstract: A method of manufacturing a grain-oriented silicon steel sheet exhibiting excellent magnetic characteristics over the entire length of a coil thereof, which involves hot rolling a silicon steel slab containing aluminum and suitable for making a grain-oriented silicon steel sheet; annealing the steel sheet, as the need arises; cold rolling the steel sheet to a final thickness, the cold rolling including an intermediate annealing process; performing a heat effect treatment before, during or after the cold rolling; performing a decarburizing annealing; and performing a final annealing process. The method inhibits oxidation of the surfaces of the steel sheet during the cold rolling.Type: GrantFiled: January 26, 1998Date of Patent: December 7, 1999Assignee: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Kazuaki Tamura, Masako Hisata, Masaki Kawano