With Special Compositions Patents (Class 148/113)
  • Patent number: 6613160
    Abstract: 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: Grant
    Filed: August 7, 2001
    Date of Patent: September 2, 2003
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ushigami, Shuichi Nakamura, Kenichi Murakami, Hiroyasu Fujii, Norihiro Yamamoto
  • Publication number: 20030136470
    Abstract: 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: Application
    Filed: December 5, 2002
    Publication date: July 24, 2003
    Inventors: Minoru Takashima, Mineo Muraki, Hiroi Kurosawa, Mitsumasa Kurosawa, Michiro Komatsubara
  • Patent number: 6580348
    Abstract: 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: Grant
    Filed: December 10, 2001
    Date of Patent: June 17, 2003
    Assignee: Vacuumschmelze GmbH
    Inventors: Harald Hundt, Johannes Beichler
  • Patent number: 6558479
    Abstract: 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: Grant
    Filed: May 11, 2001
    Date of Patent: May 6, 2003
    Assignee: Nippon Steel Corporation
    Inventors: Masahiro Fujikura, Satoshi Arai, Masato Mizokami, Hisashi Mogi, Takeshi Kubota
  • Patent number: 6527876
    Abstract: 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: Grant
    Filed: January 24, 2000
    Date of Patent: March 4, 2003
    Assignee: NKK Corporation
    Inventors: Misao Namikawa, Yoshikazu Takada, Shoji Kasai, Hironori Ninomiya, Tsunehiro Yamaji, Tatsuhiko Hiratani
  • Patent number: 6524400
    Abstract: 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: Grant
    Filed: June 6, 2000
    Date of Patent: February 25, 2003
    Assignee: Thyssen Krupp Stahl AG
    Inventors: Hans Pircher, Rudolf Kawalla, Manfred Espenhahn, Andreas Böttcher, Klaus Günther, Hans Huneus, Carl-Dieter Wuppermann
  • Patent number: 6471787
    Abstract: 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: Grant
    Filed: June 22, 1999
    Date of Patent: October 29, 2002
    Assignee: Acciai Speciali Terni S.p.A.
    Inventors: Stefano Cicale', Stefano Fortunati, Giuseppe Abbruzzese
  • Publication number: 20020134466
    Abstract: 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: Application
    Filed: January 24, 2000
    Publication date: September 26, 2002
    Inventors: MISAO NAMIKAWA, YOSHIKAZU TAKADA, SHOJI KASAI, HIRONORI NINOMIYA, TSUNEHIRO YAMAJI, TATSUHIKO HIRATANI
  • Patent number: 6451128
    Abstract: 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: Grant
    Filed: February 25, 1999
    Date of Patent: September 17, 2002
    Assignee: 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
  • Patent number: 6444050
    Abstract: 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: Grant
    Filed: April 24, 2000
    Date of Patent: September 3, 2002
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda
  • Patent number: 6444051
    Abstract: 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: Grant
    Filed: August 9, 2001
    Date of Patent: September 3, 2002
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Kazuaki Tamura, Mitsumasa Kurosawa
  • Patent number: 6432222
    Abstract: 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: Grant
    Filed: June 4, 2001
    Date of Patent: August 13, 2002
    Assignee: Nippon Steel Corporation
    Inventors: Yoshifumi Ohata, Tomoji Kumano, Norikazu Fujii, Hisashi Mogi, Hitoshi Yokouchi, Norihiro Yamamoto
  • Patent number: 6423156
    Abstract: 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: Grant
    Filed: June 6, 2000
    Date of Patent: July 23, 2002
    Assignee: EBG Gesellschaft für Elektromagnetische Werkstoffe mbH
    Inventors: Klaus Günther, Heiner Schrapers
  • Patent number: 6416591
    Abstract: 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: Grant
    Filed: August 3, 2001
    Date of Patent: July 9, 2002
    Assignee: Kawasaki Steel Corporation
    Inventors: Masaki Kawano, Yoshihiro Ozaki, Atsuhito Honda
  • Patent number: 6395104
    Abstract: 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: Grant
    Filed: December 15, 1998
    Date of Patent: May 28, 2002
    Assignee: Nippon Steel Corporation
    Inventors: Kenji Kosuge, Kishio Mochinaga, Eiichi Nanba, Nobuo Tachibana, Shinya Ishii, Naoki Yagi
  • Patent number: 6387522
    Abstract: 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: Grant
    Filed: May 30, 2001
    Date of Patent: May 14, 2002
    Assignee: Nippon Steel Corporation
    Inventors: Hisashi Mogi, Akira Sakaida, Masahiro Fujikura, Masato Mizokami
  • Patent number: 6375761
    Abstract: 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: Grant
    Filed: April 30, 2001
    Date of Patent: April 23, 2002
    Assignee: The Research Foundation of State University of New York
    Inventors: Richard J. Gambino, Taewan Kim
  • Patent number: 6368424
    Abstract: 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: Grant
    Filed: August 20, 1998
    Date of Patent: April 9, 2002
    Assignee: Nippon Steel Corporation
    Inventors: Tatsuhiko Sakai, Naoya Hamada, Katsuhiro Minamida, Kimihiko Sugiyama, Akira Sakaida, Hisashi Mogi
  • Publication number: 20020038678
    Abstract: 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: Application
    Filed: August 7, 2001
    Publication date: April 4, 2002
    Inventors: Yoshiyuki Ushigami, Shuichi Nakamura, Kenichi Murakami, Hiroyasu Fujii, Norihiro Yamamoto
  • Patent number: 6364963
    Abstract: 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: Grant
    Filed: April 11, 2000
    Date of Patent: April 2, 2002
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda
  • Patent number: 6361621
    Abstract: 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: Grant
    Filed: December 9, 1999
    Date of Patent: March 26, 2002
    Assignee: Acciai Speciali Terni S.p.A.
    Inventors: Stefano Fortunati, Stefano Cicale', Giuseppe Abbruzzese
  • Patent number: 6361620
    Abstract: 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: Grant
    Filed: December 9, 1999
    Date of Patent: March 26, 2002
    Assignee: Acciai Speciali Terni S.p.A.
    Inventors: Stefano Cicale′, Stefano Fortunati, Giuseppe Abbruzzese
  • Publication number: 20020011278
    Abstract: 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: Application
    Filed: August 9, 2001
    Publication date: January 31, 2002
    Applicant: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Kazuaki Tamura, Mitsumasa Kurosawa
  • Publication number: 20020000265
    Abstract: 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: Application
    Filed: July 18, 2001
    Publication date: January 3, 2002
    Applicant: Kawasaki Steel Corporation
    Inventors: Hiroaki Toda, Kunihiro Senda, Mitsumasa Kurosawa, Makoto Watanabe, Atsuhito Honda
  • Patent number: 6331215
    Abstract: 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: Grant
    Filed: January 28, 2000
    Date of Patent: December 18, 2001
    Assignee: Kawasaki Steel Corporation
    Inventors: Tetsuo Toge, Michiro Komatsubara, Atsuhito Honda, Kenichi Sadahiro, Kunihiro Senda
  • Patent number: 6325866
    Abstract: 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: Grant
    Filed: June 22, 1999
    Date of Patent: December 4, 2001
    Assignee: Acciai Speciali Terni S.p.A.
    Inventors: Stefano Fortunati, Stefano Cicale′, Giuseppe Abbruzzese
  • Patent number: 6322635
    Abstract: 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: Grant
    Filed: October 26, 1999
    Date of Patent: November 27, 2001
    Assignee: Kawasaki Steel Corporation
    Inventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara
  • Patent number: 6287392
    Abstract: 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: Grant
    Filed: September 17, 1999
    Date of Patent: September 11, 2001
    Assignee: Kawasaki Steel Corporation
    Inventors: Hiroaki Toda, Kunihiro Senda, Mitsumasa Kurosawa, Makoto Watanabe, Atsuhito Honda
  • Patent number: 6284388
    Abstract: 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: Grant
    Filed: August 23, 2000
    Date of Patent: September 4, 2001
    Assignee: LTV Steel Company, Inc.
    Inventors: Richard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
  • Patent number: 6280862
    Abstract: 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: Grant
    Filed: November 23, 1998
    Date of Patent: August 28, 2001
    Assignee: Kawasaki Steel Corporation
    Inventor: Yukio Inokuti
  • Patent number: 6280534
    Abstract: 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: Grant
    Filed: May 10, 1999
    Date of Patent: August 28, 2001
    Assignee: Kawasaki Steel Corporation
    Inventors: Kunihiro Senda, Toshito Takamiya, Makoto Watanabe, Mitsumasa Kurosawa
  • Patent number: 6228182
    Abstract: 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: Grant
    Filed: December 28, 1994
    Date of Patent: May 8, 2001
    Assignee: Kawasaki Steel Corporation
    Inventors: Koh Nakano, Atsuhito Honda, Keiji Sato
  • Patent number: 6221501
    Abstract: 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: Grant
    Filed: August 17, 1999
    Date of Patent: April 24, 2001
    Assignee: LTV Steel Company, Inc.
    Inventors: Richard J. Blotzer, Jeffrey P. Anderson, Barry A. Lauer
  • Patent number: 6159309
    Abstract: 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: Grant
    Filed: November 2, 1998
    Date of Patent: December 12, 2000
    Assignee: Nippon Steel Corporation
    Inventors: Yousuke Kurosaki, Norito Abe, Nobuo Tachibana, Kentaro Chikuma, Kiyokazu Ichimura, Sadanobu Hirokami, Masayuki Yamashita
  • Patent number: 6153019
    Abstract: 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: Grant
    Filed: October 26, 1998
    Date of Patent: November 28, 2000
    Assignee: Thyssen Stahl AG
    Inventors: Manfred Espenhahn, Andreas Bottcher, Klaus Gunther
  • Patent number: 6068708
    Abstract: 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: Grant
    Filed: March 10, 1998
    Date of Patent: May 30, 2000
    Assignee: LTV Steel Company, Inc.
    Inventors: Barry A. Lauer, Gerald F. Beatty, Jeffrey P. Anderson
  • Patent number: 6045627
    Abstract: 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: Grant
    Filed: June 4, 1998
    Date of Patent: April 4, 2000
    Assignee: NKK Corporation
    Inventors: Koichiro Fujita, Yasushi Tanaka, Hironori Ninomiya, Tatsuhiko Hiratani, Shoji Kasai
  • Patent number: 5961744
    Abstract: Grain oriented silicon steel sheet on which is formed an insulating coating having a thickness that is not less than 2.5 .mu.m that imparts tension to the steel sheet which does not have an inorganic mineral layer formed during a final annealing step (glass film) and a method of forming on grain oriented silicon steel sheet an insulating coating that is not less than 2.5 .mu.m thick and which imparts tension to the steel sheet which does not have the inorganic mineral layer (glass film) that forms during finish annealing, and a method of forming a tensioning insulating coating on grain oriented silicon steel sheet which has been finish annealed and does not have an inorganic mineral surface layer (glass film), after first forming a layer of SiO.sub.2 not less than 0.001 .mu.m thick on the oriented silicon steel sheet.
    Type: Grant
    Filed: May 24, 1995
    Date of Patent: October 5, 1999
    Assignee: Nippon Steel Corporation
    Inventors: Shuichi Yamazaki, Hiroyasu Fujii, Takeo Nagashima, Yoshiyuki Ushigami, Osamu Tanaka, Katsurou Kuroki, Hiroaki Masui
  • Patent number: 5951788
    Abstract: A stainless steel alloy useful as a construction material in superconducting magnetic components, said alloy containing in weight percent 0.05-0.25% C, 0.1-1.5% Si, 3.5-7.5% Mn, 17-21% Cr, 6-10% Ni, 0.10-0.50% N, the remainder being Fe and normal impurities.
    Type: Grant
    Filed: August 1, 1997
    Date of Patent: September 14, 1999
    Assignee: Sandvik AB
    Inventor: H.ang.kan Holmberg
  • Patent number: 5902419
    Abstract: 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 0 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: Grant
    Filed: September 23, 1996
    Date of Patent: May 11, 1999
    Assignee: NKK Corporation
    Inventors: Koichiro Fujita, Yasushi Tanaka, Hironori Ninomiya, Tatsuhiko Hiratani, Shoji Kasai
  • Patent number: 5888314
    Abstract: In a process for the preparation of oriented electrical steel sheet having a high magnetic flux density a primary recrystallization annealed steel sheet is nitrided for a short period of time in a temperature range of 800.degree. C. or less whereby growth of crystal grains does not substantially occur. The nitrided sheet is held at a temperature range of 700.degree. C. to 800.degree. C. for at least four hours during temperature raising to final annealing temperature whereby nitride formed by the nitriding dissolves and re-precipitates allowing the nitride to transform to a thermally stable nitride containing aluminium.
    Type: Grant
    Filed: January 21, 1994
    Date of Patent: March 30, 1999
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ushigami, Fumio Kurosawa, Hajime Komatsu
  • Patent number: 5885371
    Abstract: A method of producing a grain-oriented magnetic steel sheet exhibiting a very low core loss and high magnetic flux density uses a slab of silicon steel containing Al, B, N, and S and/or Se. The method employs hot rolling conducted such that the rolling reduction falls within the range of from about 85 to 99%, and the hot-rolling finish temperature falls within the range of from 950.degree. to 1150.degree. C. and is based on the contents of Si, Al and B. The hot-rolled steel sheet is rapidly cooled at a cooling rate of about 20.degree. C./s and is coiled at a temperature of about 670.degree. C. or lower. Hot-rolled sheet annealing or intermediate annealing is executed by heating the hot-rolled steel sheet up to about 800.degree. C. at a heating rate of from 5.degree. to 25.degree. C./s and holding at a temperature of from about 800.degree. to 1125.degree. C. for a period not longer than about 150 seconds.
    Type: Grant
    Filed: October 9, 1997
    Date of Patent: March 23, 1999
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Toshito Takamiya, Kunihiro Senda, Mineo Muraki, Chizuko Goto, Mitsumasa Kurosawa, Kazuaki Tamura
  • Patent number: 5863356
    Abstract: The invention comprises a method for producing electric sheets, in particular grain-oriented electric sheets, with an evenly well-adhering glass film and with improved magnetic properties, in which the hot rolled strip which is produced at first and is optionally annealed is cold-rolled up to an end thickness in one or several steps, thereafter an annealing separator is applied to the strip which is rolled up to the end thickness, and is dried, and therafter the cold strip thus coated is subjected to high-temperature annealing, with an important component of the annealing separator being a hydrous magnesium oxide (MgO) dispersion and the annealing separator being additionally provided with at least one additive. The characterizing feature of the invention is that a finely dispersed water-soluble sodium phosphate compound is used as at least one additive.
    Type: Grant
    Filed: October 3, 1996
    Date of Patent: January 26, 1999
    Assignee: EBG Gesellschaft fur Elektromagnetische Werkstoffe mbH
    Inventors: Fritz Bolling, Brigitte Hammer, Thomas Dolle, Klaus Gehnen, Heiner Schrapers
  • Patent number: 5853499
    Abstract: Grain-oriented electrical steel sheet having a very low iron loss with controlled area ratio of fine grains, average grain size of coarse grains, obliquity of the grain boundary line of coarse grains, permeability under 1.0 T, and film tension.
    Type: Grant
    Filed: August 28, 1997
    Date of Patent: December 29, 1998
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Kunihiro Senda, Takafumi Suzuki, Hiroaki Toda, Hiroi Yamaguchi
  • Patent number: 5840131
    Abstract: A process for producing a grain-oriented electrical steel sheet excellent in the glass film and the magnetic properties by coating a steel sheet with an annealing separator, finish annealing the steel sheet, and baking an insulating coating agent, which comprises coating the steel sheet having been decarburization annealed with an annealing separator prepared by allowing 100 parts by weight of MgO to contain, in the course from the step of producing MgO to the stage of preparing a slurry in the step of coating the steel sheet with MgO, halogens selected from F, Cl, Br and I or compounds of the halogens in an amount of 0.015 to 0.120 part by weight in terms of F, Cl, Br and I, and finish annealing the steel sheet.
    Type: Grant
    Filed: May 17, 1997
    Date of Patent: November 24, 1998
    Assignee: Nippon Steel Corporation
    Inventors: Kenichi Yakashiro, Hotaka Honma, Maremizu Ishibashi, Akira Sakaida, Tomoji Kumano, Koji Yamasaki, Katsuro Kuroki, Osamu Tanaka
  • Patent number: 5833768
    Abstract: A method of producing a grain-oriented electrical steel sheet with a very low core loss comprises the steps of obtaining a rolled strip of final product thickness using as a starting material molten steel consisting of not more than 0.10 wt % C, 2.5-7.0 wt % Si, ordinary inhibitor components and the balance of iron and unavoidable impurities, heating the strip to a temperature range of not less than 700.degree. C. at a heating rate of not less than 80.degree. C./s and within 0.1 second after the maximum temperature has been reached cooling the strip at a cooling rate of not less than 50.degree. C./s, and subjecting the strip to decarburization annealing and final finish annealing.
    Type: Grant
    Filed: March 8, 1996
    Date of Patent: November 10, 1998
    Assignee: Nippon Steel Corporation
    Inventors: Kenji Kosuge, Mikio Itoh, Shinji Ueno, Haruo Hukazawa, Takashi Yoshimura
  • Patent number: 5807441
    Abstract: A method of effectively manufacturing silicon steel sheets with highly accumulated {100} orientations having excellent magnetic characteristics by a single tight-coil annealing or multi-layer annealing. The method can be widely used in the manufacture of magnetic steel sheets. The silicon steel sheet with excellent magnetic characteristics can be obtained by subjecting a cold-rolled silicon steel sheet containing, on a weight basis, not more than 1% of C, 0.2 to 6.5% of Si, and 0.05 to 5.0% of Mn to a tight-coil annealing or a multilayer annealing together with a substance which accelerates decarburization or with a combination of a substance which accelerates decarburization and a substance which accelerates demanganization, as separators in annealing.
    Type: Grant
    Filed: October 17, 1996
    Date of Patent: September 15, 1998
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Toshiro Tomida, Shigeo Uenoya
  • Patent number: 5803988
    Abstract: The annealing conditions of a cold rolled steel sheet are properly controlled so as to form a dense surface oxide layer, thereby improving the adherence strength of the insulating layer on non-oriented electrical steel sheet. The method includes the following steps. A steel slab is prepared which is composed of in weight %: 0.05% or less of C, 3.5% or less of Si, 1.5% or less of Mn, 0.15% or less of P, 0.015% or less of S, 1.0% or less of Al, one or more elements selected from a group consisting of 0.03-0.30% of Sn, 0.03-0.3% of Sb, 0.03-1.0% of Ni and 0.03-0.50% of Cu, the balance of Fe and unavoidable impurities. The steel slab is reheated, hot rolled, pickled after annealing or without annealing and cold-rolled. A low temperature annealing is carried out on the cold rolled steel sheet at a temperature of 750.degree.-850.degree. C. for 30 seconds to 5 minutes under a humid atmosphere having a dew point of 25.degree.-65.degree. C.
    Type: Grant
    Filed: August 18, 1997
    Date of Patent: September 8, 1998
    Assignee: Pohang Iron & Steel Co., Ltd.
    Inventors: Byung Keun Bae, Sam Kyu Chang, Jong Soo Woo, Wun Gul Lee
  • Patent number: 5800633
    Abstract: A method for producing a grain oriented electromagnetic steel sheet exhibiting excellent magnetic flux density and excellent iron loss, including preparing a slab from steel capable of being formed into an oriented electromagnetic steel sheet, the steel comprising about 2.5 to 4.0 weight percent of Si and about 0.005 to 0.06 weight percent of Al; hot rolling the slab to a hot-rolled plate; cold rolling the hot-rolled plate up to two times, including an intermediate annealing between cold rollings, to form a cold-rolled steel sheet; decarburization and primary recrystallization annealing the steel sheet, the decarburization and primary recrystallization annealing including a first half and a second half, the decarburization and primary recrystallization annealing comprising rapidly heating the cold-rolled steel sheet at a rate of about 10.degree. C./min or more from about 450.degree. C. to a predetermined constant temperature between about 800.degree. to 880.degree. C.
    Type: Grant
    Filed: May 16, 1997
    Date of Patent: September 1, 1998
    Assignee: Kawasaki Steel Corporation
    Inventor: Yukio Inokuti
  • Patent number: RE36423
    Abstract: 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: Grant
    Filed: January 26, 1998
    Date of Patent: December 7, 1999
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Kazuaki Tamura, Masako Hisata, Masaki Kawano