With Special Compositions Patents (Class 148/113)
  • Patent number: 5782998
    Abstract: In order to provide a very low iron loss, it is necessary to render the surface of a steel sheet smooth (specular). In the present invention, this is effected in a finish annealing furnace to simultaneously attain a high magnetic flux density and a specular surface. Specifically, after the completion of decarburization annealing, a steel material is pickled to remove an oxide layer present on the surface of the steel sheet, coated with an annealing separator comprising a substance nonreactive or less reactive with SiO.sub.2 and then subjected to finish annealing to provide a grain oriented electrical steel sheet having a specular surface. Magnetic domain division and tension coating of the steel sheet can provide a low iron loss value. In the finish annealing, since no time is required for dehydration, the annealing time can be shortened.
    Type: Grant
    Filed: January 7, 1994
    Date of Patent: July 21, 1998
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ushigami, Takeo Nagashima, Shuichi Yamazaki, Hiroyasu Fujii, Yozo Suga, Tadashi Nakayama, Katsuro Kuroki, Yosuke Kurosaki
  • Patent number: 5753051
    Abstract: Low core loss oriented electrical steel sheet having a surface coating that has a Young's modulus that is not less than 100 GPa and a differential of thermal expansion coefficient relative to the sheet base metal that is not less than 2.times.10.sup.-6 /K and which contains not less than 10 percent, by weight, of crystallites with an average size of not less than 10 nm and an average crystal grain diameter that does not exceed 1000 nm, and a method of manufacturing same.
    Type: Grant
    Filed: January 28, 1997
    Date of Patent: May 19, 1998
    Assignee: Nippon Steel Corporation
    Inventors: Takao Kanai, Kei Tanemoto, Shuichi Yamazaki, Takeo Nagashima
  • Patent number: 5725681
    Abstract: Producing a grain oriented silicon steel sheet by controlling physical properties of the oxides layer, formed in decarburization annealing, in the surface layer of a steel sheet. A silicon compound is adhered to the surface of steel sheet before the decarburization annealing in an amount ranging from about 0.5 to 7.0 mg per square meter, expressed as Si, and the atmosphere of an earlier portion of the temperature holding process is adjusted to a ratio of steam partial pressure to the hydrogen partial pressure of less than about 0.7, and the atmosphere of the temperature rising process up to the temperature holding process is adjusted to an atmospheric composition lower than the atmospheric composition of the earlier portion of the temperature holding process, and the atmosphere of a later part of the temperature holding process is adjusted to an atmospheric composition lower than the atmospheric composition of the earlier part of the temperature holding process and in a range from about 0.005 to 0.2.
    Type: Grant
    Filed: September 3, 1996
    Date of Patent: March 10, 1998
    Assignee: Kawasaki Steel Corporation
    Inventors: Hirotake Ishitobi, Takafumi Suzuki, Michiro Komatsubara, Hiroi Yamaguchi
  • Patent number: 5702539
    Abstract: The present invention provides a method of producing grain oriented electrical steel having excellent mechanical and magnetic properties. A hot processed strip having a thickness of 1.5-4.0 mm thickness a composition consisting essentially of 2.5-4.5% silicon, 0.1-1.2% chromium, less than 0.050% carbon, less than 0.005% aluminum, up to 0.1% sulfur, up to 0.14% selenium, 0.01-1% manganese and balance being essentially iron and residual elements, all percentages by weight. The strip has a volume resistivity of at least 45 .mu..OMEGA.-cm, at least 0.010% carbon so that an austenite volume fraction (.gamma..sub.1150.degree. C.) of at least 2.5% is present in the hot processed strip and each surface of the strip has an isomorphic layer having a thickness of at least 10% of the total thickness of the hot processed strip. The strip is cold reduced to an intermediate thickness, annealed, cold reduced to a final thickness and decarburized to less than 0.003% carbon.
    Type: Grant
    Filed: February 28, 1997
    Date of Patent: December 30, 1997
    Assignee: Armco Inc.
    Inventors: Jerry W. Schoen, Norris A. Dahlstrom, Christopher G. Klapheke
  • Patent number: 5685920
    Abstract: Disclosed is an annealing separator for production for grain-oriented electrical steel sheet, containing one or more compound selected from the following general formula;?Mg.sub.1-x M.sup.3+.sub.x !O ?Mg.sub.1-x M.sup.2+.sub.x !O or ?Mg.sub.1-x M.sup.2+.sub.x1 M.sup.3+.sub.x2 !OwhereM.sup.2+ is at least one bivalent element selected from the group consisting of Be, Ca, Ba, Sr, Sn, Mn, Fe, Co, Ni, Cu, Zn;M.sup.3+ is at least one tervalent element selected from the group consisting of Al, Fe, Cr, Co, B, Ti, Sb;0.01.ltoreq.x.ltoreq.0.40; x=x1+x2This annealing separator having a lower melting point and higher degree of reactivity is applied on the decarburization annealed strip, and improves the properties of the glass film, especially uniform film appearance and good sealing effect, and magnetic properties.
    Type: Grant
    Filed: May 12, 1995
    Date of Patent: November 11, 1997
    Assignee: Nippon Steel Corporation
    Inventors: Osamu Tanaka, Maremizu Ishibashi, Tsuyoshi Hamaya, Tsutomu Haratani, Tomoji Kumano, Koji Yamasaki, Akira Sakaida, Chihiro Sakurai, Hotaka Honma
  • Patent number: 5679177
    Abstract: Low core loss oriented electrical steel sheet having a surface coating that has a Young's modulus that is not less than 100 GPa and a differential of thermal expansion coefficient relative to the sheet base metal that is not less than 2.times.10.sup.-6 /K and which contains not less than 10 percent, by weight, of crystallites with an average size of not less than 10 nm and an average crystal grain diameter that does not exceed 1000 nm, and a method of manufacturing same.
    Type: Grant
    Filed: January 30, 1995
    Date of Patent: October 21, 1997
    Assignee: Nippon Steel Corporation
    Inventors: Takao Kanai, Kei Tanemoto, Shuichi Yamazaki, Takeo Nagashima
  • Patent number: 5679178
    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: July 20, 1995
    Date of Patent: October 21, 1997
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Kazuaki Tamura, Masako Hisata, Masaki Kawano
  • Patent number: 5667598
    Abstract: Method for producing a grain oriented silicon steel sheet comprises heating a silicon steel slab containing about:C : 0.01 to 0.10 wt %, Si: 2.5 to 4.5 wt %,Mn: 0.02 to 0.12 wt %, Al: 0.005 to 0.10 wt %,N : 0.004 to 0,015 wt %,to about 1280.degree. C. or higher and then subjecting it to hot rolling to prepare a hot-rolled steel sheet, subjecting the steel sheet to hot-rolled sheet annealing according to necessity, then subjecting it to one cold-rolling step or two or more cold-rolling steps with interposed intermediate annealing steps to prepare a cold-rolled steel sheet, and subjecting the cold-rolled steel sheet to decarburization annealing and finishing annealing, wherein the finishing rolling terminating temperature of the hot-rolling step is controlled to a range of about 900.degree. to 1100.degree. C., and the rolled sheet is processed so that the steel sheet temperature T(t) (.degree. C.
    Type: Grant
    Filed: March 27, 1996
    Date of Patent: September 16, 1997
    Assignee: Kawasaki Steel Corporation
    Inventors: Yoshihiro Ozaki, Akio Fujita, Mineo Muraki
  • Patent number: 5653821
    Abstract: A method for manufacturing an oriented electrical steel sheet includes the step of preparing a steel slab composed of in weight %: 0.035-0.050% of C, 2.9-3.3% of Si, less than 0.016% of P, 0.011-0.017% of soluble Al, 0.0080-0.012% of N, less than 0.007% of S, 0.06-0.18% of Ni+Cr, less than 0.32% of Mn with an Mn/S ratio of 20 or more, less than 0.6% of Cu with a Cu/Mn ratio of 1.5 or more, and balance of Fe and other inevitable impurities. The steel slab is heated at a temperature of 1250.degree.-1320.degree. C., and then hot rolled. The hot rolled slab is then cold rolled in two stages to a final sheet thickness, with a decarburization annealing being carried out at an intermediate thickness. The decarburized cold rolled sheet is coated with an annealing separator containing MgO as the main ingredient and then a finish annealing treatment is conducted, thereby obtaining a magnetically superior oriented electrical steel sheet.
    Type: Grant
    Filed: July 7, 1995
    Date of Patent: August 5, 1997
    Assignees: Pohang Iron & Steel Co., Ltd., Research Institute of Industrial Science & Technology
    Inventors: Gyu Seung Choi, Chung San Lee, Jong Soo Woo, Byung Deug Hong
  • Patent number: 5643370
    Abstract: The present invention relates to the production of a grain oriented electrical steel composition having a volume resistivity of at least 50 micro-ohm-cm. The melt composition of the steel consists essentially of, in weight %, about 0.08% max carbon, about 0.015 to about 0.05% aluminum, 2.25 to 7% silicon, greater than about 0.5% manganese.sub.eq, about 0.001 to about 0.011% nitrogen, about 0.01% max sulfur, about 3% max chromium, about 1% max copper, about 2% max nickel and balance essentially iron. High levels of silicon are balanced with a manganese equivalent relationship which permits lower levels of carbon while still providing the desired levels of austenite during rolling and annealing. The processing also includes the addition of excess nitrogen to the steel prior to secondary grain growth which is subsequently removed during a purification treatment.
    Type: Grant
    Filed: May 16, 1995
    Date of Patent: July 1, 1997
    Assignee: Armco Inc.
    Inventor: Glenn Stuart Huppi
  • Patent number: 5620533
    Abstract: A method for producing a grain-oriented silicon steel sheet in the coil shape having high magnetic induction and including AlN and MnSe as principal inhibitors is disclosed. In a series of processes for producing a grain-oriented silicon steel sheet, the oxide content on the steel sheet surface is controlled within a range of about 0.02 to 0.10 g/m.sup.2 before the temperature elevation phase of a decarburization annealing process, and the ratio of the steam partial pressure to the hydrogen partial pressure is controlled within a range of about 0.2 to 0.65 at a steel sheet surface temperature ranging from about 500.degree. to 750.degree. C. during the temperature elevation phase in a decarburization annealing process. The method promotes stable secondary recrystallized grain formation even in different coils or at different places in the same coil, such that fluctuation of magnetic properties is depressed.
    Type: Grant
    Filed: September 26, 1995
    Date of Patent: April 15, 1997
    Assignee: Kawasaki Steel Corporation
    Inventors: Keisuke Kotani, Mitsumasa Kurosawa, Masaki Kawano, Hirotake Ishitobi, Masayuki Sakaguchi, Takafumi Suzuki, Ujihiro Nishiike
  • Patent number: 5571342
    Abstract: A decarburized steel sheet for a thin oriented silicon steel sheet having improved magnetic and coating characteristics and a method of producing the same. Silicon steel strip is hot-rolled, cold-rolled to a final thickness of about 0.28 mm or less, subjected to decarburization/primary-recrystallization annealing, coated with an annealing separator, and thereafter subjected to finishing annealing. In the decarburization/primary-recrystallization annealing step, a novel subscale is formed at the steel sheet surface having a fayalite-silica composition ratio in accordance with an infrared reflection absorbance ratio of about 0.5 to 5.5, and a marked oxygen amount of about 0.4 to 1.6 g/m.sup.2.
    Type: Grant
    Filed: December 14, 1993
    Date of Patent: November 5, 1996
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Yasuyuki Hayakawa, Katsuo Iwamoto, Makoto Watanabe
  • Patent number: 5565272
    Abstract: A grain oriented silicon steel sheet having excellent primary glass film property and magnetic property, comprising 2.0 to 5.0% by weight of Si, wherein a primary glass film formed during secondary recrystallization annealing is composed mainly of forsterite (Mg.sub.2 SiO.sub.4) and an oxide containing Al, mainly of spinel (MgAl.sub.2 O.sub.4), or Al and Si, mainly of cordierite (MgO.sub.2 Al.sub.4 Si.sub.5 O.sub.18) and/or sapphirine (Mg.sub.4 Al.sub.10 Si.sub.2 O.sub.23), and in an analysis of the surface of the steel sheet by glow discharge optical emission spectrometry analysis (GDS analysis), a peak derived from Al is separated from a peak derived from Mg, and, preferably, the peak derived from Al is separated from the peak derived from Mg and the distance (time) from the surface of the steel sheet at which the peak derived from Al is 1.2 times or more the distance from the surface of the steel sheet at which the peak derived from Mg appears.
    Type: Grant
    Filed: July 10, 1992
    Date of Patent: October 15, 1996
    Assignee: Nippon Steel Corporation
    Inventors: Hiroaki Masui, Morio Shiozaki, Nobuyuki Takahashi, Hisashi Kabayashi, Takeo Nagashima, Shuichi Yamazaki, Hiroyasu Fujii
  • Patent number: 5558724
    Abstract: A method for making a lamination insulated by iron-manganese phosphate comprises the following operations:1. The lamination is treated with an acid or basic medium to eliminate the surface layer of the lamination that contains excess silicon and aluminum.2. The lamination is rinsed.3. The lamination is brought into contact with a solution of phosphoric acid containing iron phosphate and manganese phosphate for sufficient time to obtain an insulative layer of the required thickness.
    Type: Grant
    Filed: September 11, 1995
    Date of Patent: September 24, 1996
    Assignee: GEC Alsthom Transport SA
    Inventor: Alain Roche
  • Patent number: 5547519
    Abstract: The present invention provides an annealing separator composition for coating grain oriented electrical steel prior to the final high temperature anneal for secondary grain growth. The magnesia based coating contains at least 20% silica on a water free basis. The large silica additions limit the interface between the coating and the base metal and results in a thick glass which is easily removed. The magnesia coating develops excellent magnetic properties and does not require the normal strong acid cleaning or special abrasive means to remove the glass film which forms. The bare electrical steel, which may be coated to enhance the punching properties, has improved the die life because the hard glass film has been substantially removed.
    Type: Grant
    Filed: June 5, 1995
    Date of Patent: August 20, 1996
    Assignee: Armco Inc.
    Inventor: Robin A. Murphy
  • Patent number: 5512110
    Abstract: In the present invention, grain oriented electrical steel sheets provided by heating a slab comprising, by weight percent, 0.025 to 0.075% of C, 3.4 to 5.0% of Si, 0.015 to 0.080% of sol. Al, 0.0030 to 0.013% of N, 0.014% or less of (S+0.405 Se) and 0.05 to 0.8% of Mn, sol. Al (%)/Si (%) being 0.0080 or more, the balance consisting of Fe and unavoidable impurities at a temperature below 1280.degree. C., hot-rolling the heated slab, subjecting the hot-rolled steel sheet to cold rolling, subjecting the cold-rolled steel sheet to decarbonization annealing with regulating the average diameter of primary recrystallized grains of the steel sheet subjected to decarbonization annealing to 18 to 35 .mu.
    Type: Grant
    Filed: June 6, 1995
    Date of Patent: April 30, 1996
    Assignee: Nippon Steel Corporation
    Inventors: Yasunari Yoshitomi, Katsuro Kuroki, Yukio Matsuo, Hiroaki Masui, Yoshio Nakamura, Maremizu Ishibashi, Tsuyoshi Kawano, Tsutomu Haratani, Yoshiyuki Ushigami
  • Patent number: 5509976
    Abstract: Disclosed is a method for producing a grain-oriented electrical steel sheet having mirror surface containing 0.8 to 4.8% of Si in the form of a strip which has been subjected to a conventional series of operations including hot rolling with or without annealing, cold rolling once or at least twice with intermediate annealing to obtain a final thickness, decarburization annealing with or without nitriding treatment, coating the steel sheet with an annealing separator mainly containing non-hydrating oxide and final annealing, the improvement comprising:satisfying the relationshipA!>0.2.times. O!where A! is the total concentration of alkali metal impurity in the annealing separator (weight %), andO! is the amount of oxygen contained in the steel sheet just prior to the final annealing (g/m.sup.2).
    Type: Grant
    Filed: July 17, 1995
    Date of Patent: April 23, 1996
    Assignee: Nippon Steel Corporation
    Inventors: Shuichi Yamazaki, Yoshiyuki Ushigami, Hiroyasu Fujii, Kenichi Murakami
  • Patent number: 5507883
    Abstract: A grain oriented electrical steel sheet having no significant glass film and having a high magnetic flux density and an excellent iron loss property, comprising, in terms of by weight, 2.5 to 4.5% of Si, the steel sheet having, as oxides on its surface, a glass film comprising 0.6 g/m.sup.2 or less in total of forsterite and spinel composed of MgO, SiO.sub.2 and Al.sub.2 O.sub.3 and an insulating coating having a thickness of 6 .mu.m or less, the face tension imparted on the surface of the steel sheet by the coating being in the range of from 0.5 to 2.0 kg/mm.sup.2. In the final box annealing of the steel sheet after primary recrystallization annealing, use is made of an annealing separator comprising 100 parts by weight of MgO and, added thereto, 2 to 30 parts by weight of at least one member selected from the group consisting of chlorides, carbonates, nitrates, sulfates and sulfides of Li, K, Bi, Na, Ba, Ca, Mg, Zn, Fe, Zr, Sr, Sn, Al, etc.
    Type: Grant
    Filed: June 9, 1994
    Date of Patent: April 16, 1996
    Assignee: Nippon Steel Corporation
    Inventors: Osamu Tanaka, Hiroaki Masui, Hotaka Honma, Katsuro Kuroki, Tsutomu Haratani, Yoichi Mishima, Maremizu Ishibashi, Yoshio Nakamura
  • Patent number: 5478410
    Abstract: A process for producing a grain-oriented electrical steel sheet having a low watt loss, in which a steel strip consisting, in wt %, of 0.8 to 4.8 Si, 0.012 to 0.050 acid-soluble Al, 0.01 or less N, and the balance consisting of Fe and unavoidable impurities is cold-rolled to a final thickness of 0.15 mm or less, primary-recrystallization annealed, applied with a annealing separator containing magnesia as a major component by electrostatic spray painting, and then final-texture annealed.
    Type: Grant
    Filed: March 15, 1995
    Date of Patent: December 26, 1995
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ushigami, Yozo Suga, Takeo Nagashima
  • Patent number: 5421911
    Abstract: The present invention provides a steel composition and method for producing a high quality regular grain oriented electrical steel having less than 0.005% aluminum using a single cold reduction step. A high austenite volume fraction, the use of an annealing separator coating with high sulfur or a sulfur bearing atmosphere to provide strong surface energy grain growth, a quench after initial annealing to provide the optimum microstructure having a small amount of martensite with a fine carbide dispersion and various chemistry changes are included in the method. Excess manganese in combination with tin, which has been found to act similarly to excess Mn, are maintained at a total level less than 0.03%. The use of chromium in an amount ranging from 0.11% to 1.2% provides outstanding control of stability for secondary grain growth.
    Type: Grant
    Filed: November 22, 1993
    Date of Patent: June 6, 1995
    Assignee: Armco Inc.
    Inventor: Jerry W. Schoen
  • Patent number: 5413639
    Abstract: A method of manufacturing a low-core-loss oriented electrical steel sheet. Thread-like grooves are formed in a cold-rolled grain oriented electrical steel sheet having a final thickness of about 0.27 mm or less in a direction within the range of about 30.degree. from the direction perpendicular to the rolling direction. The grooves and sheet satisfy the equationlog d.gtoreq.0.6 Ra+0.4where d is the groove depth (.mu.m), and Ra is the mean surface roughness of the steel sheet cold-rolled to final gauge. The steel sheet is thereafter decarburization annealed and final texture annealed.
    Type: Grant
    Filed: January 19, 1993
    Date of Patent: May 9, 1995
    Assignee: Kawasaki Steel Corporation
    Inventors: Keiji Sato, Bunjiro Fukuda
  • Patent number: 5411605
    Abstract: This invention is intended for providing a soft magnetic steel material having excellent DC magnetization properties and corrosion resistance, and capable of being manufactured at a low cost, and a method of manufacturing the same.The soft magnetic steel material of this invention contains 0.8 to 3.5% by weight of soluble aluminum, as well as limited amounts of C, total nitrogen, Si, Mn, P, S and total oxygen, and has an average ferrite crystal diameter of which the minimum has a specific relation to the thickness or diameter of the material. The material has a surface covered densely with aluminum oxide particles having a diameter of 0.01 to 5 microns. It exhibits a coercive force not exceeding 0.4 Oe in the absence of any strain and a magnetic flux density of 15,000 G or more at a magnetomotive force of 25 Oe. The aluminum oxide particles formed on the surface of the material are preferably formed with a density of 1.times.10.sup.12 to 1.times.10.sup.16 particles, or more preferably 1.times.10.sup.13 to 1.
    Type: Grant
    Filed: June 11, 1993
    Date of Patent: May 2, 1995
    Assignee: NKK Corporation
    Inventors: Toshimichi Omori, Haruo Suzuki, Tetsuya Sampei, Takahiro Kanero, Masayoshi Nakagawa, Masayoshi Kurihara
  • Patent number: 5397402
    Abstract: A grain oriented silicon steel strip and method are provided for producing the same wherein a chevron pattern of scribe lines mechanically refines the magnetic domain wall spacings. Multiple chevron patterns are formed to extend always transversely across the strip width.
    Type: Grant
    Filed: June 1, 1994
    Date of Patent: March 14, 1995
    Assignee: Allegheny Ludlum Corporation
    Inventor: James G. Benford
  • Patent number: 5370748
    Abstract: The present invention is a process for manufacturing a double oriented electrical steel sheet having a high magnetic flux density by carrying out a low temperature annealing for the secondary recrystallization by the use of AlN as inhibitor, characterized by hot-rolling a silicon steel slab comprising 1.8-4.8% by weight of Si, 0.008-0.048% by weight of acid soluble Al, 0.0028-0.0100% by weight of acid soluble Al, 0.0028-0.0100% by weight of total N, not more than 0.016% by weight of S and the balance being Fe and unavoidable impurities into a hot-rolled sheet, subjecting the sheet to cold-rolling at a reduction rate of 40-80%, subsequently subjecting the sheet to another cold-rolling at a reduction rate of 30-70% in the direction crossing the cold-rolled direction, annealing at 750.degree.-950.degree. C. in a wet hydrogen atmosphere for decarburization, and carrying out the final finishing annealing which comprises a stage for completing the secondary recrystallizing at a temperature of 920.degree.-1100.
    Type: Grant
    Filed: November 10, 1992
    Date of Patent: December 6, 1994
    Assignee: Nippon Steel Corporation
    Inventors: Yozo Suga, Yoshiyuki Ushigami
  • Patent number: 5352490
    Abstract: A reaction gas or a gas containing a reaction gas is blown through blowing nozzles onto a steel material in a chemical vapor deposition treating chamber at a velocity sufficient to forcibly remove reacted products from reacted surfaces of a steel material while suppressing irregular thickness of a deposited film.
    Type: Grant
    Filed: July 6, 1992
    Date of Patent: October 4, 1994
    Assignee: NKK Corporation
    Inventors: Masahiro Abe, Kazuhisa Okada, Shuzo Fukuda
  • Patent number: 5342454
    Abstract: A method of producing a grain oriented silicon steel sheet is adapted to lower the iron loss. A silicon steel slab, containing about 2.0 to 4.0 weight % of Si and an inhibitor-forming amount of S, or Se, or both, is hot rolled. After the hot rolled steel sheet is annealed when necessary, the steel sheet is cold rolled into a cold rolled steel sheet having a final thickness by performing cold rolling either one time or a plurality of times with intermediate annealing therebetween, the cold rolled steel sheet then being subjected to decarburization, coating of the surface of the steel sheet with an annealing separation agent mainly comprising MgO, secondary recrystallization annealing, and purification annealing. In the cold rolling step, an oxide layer exists on the surface of the steel sheet. Specifically, in the cold rolling step, rolling oil is supplied only at the entrance of the rolling mill used, and an oxide layer having a thickness of about 0.05 to 5 .mu.m is generated.
    Type: Grant
    Filed: August 18, 1992
    Date of Patent: August 30, 1994
    Assignee: Kawasaki Steel Corporation
    Inventors: Yasuyuki Hayakawa, Ujihiro Nishiike, Bunjiro Fukuda, Masataka Yamada, Yoshiaki Iida, Fumihiko Takeuchi, Michiro Komatsubara
  • Patent number: 5330586
    Abstract: A method of producing a grain oriented silicon steel thin sheet having excellent magnetic properties. A silicon steel slab containing Cu, Se and Sb as inhibitor-forming elements is hot rolled to form a hot-rolled sheet, followed by cold rolling at least twice including intermediate annealing to form a cold-rolled sheet having a final thickness of about 0.10 to 0.25 mm, decarburization and primary recrystallization annealing, and then final finish annealing. The temperature of the material to be rolled on the inlet side of the hot finish rolling mill is about 1000.degree. to 1150.degree. C. the surface temperature of the work rolls of the first stand of the hot finish rolling mill immediately before contact with the material to be rolled is about 100.degree. C. or less the total rolling reduction of the hot finish rolling is about 93 to 97%, the intermediate annealing is effected at a temperature of about 900.degree. to 1050.degree. C.
    Type: Grant
    Filed: June 29, 1992
    Date of Patent: July 19, 1994
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Yasuyuki Hayakawa, Katsuo Iwamoto, Makoto Watanabe, Toshito Takamiya
  • Patent number: 5318639
    Abstract: Method of manufacturing a grain oriented silicon steel sheet. An annealing separating agent mainly composed of MgO is coated on a surface of a decarburized silicon steel sheet. The silicon steel sheet is subjected to secondary recrystallization annealing and then purification annealing. The annealing separating agent contains Ti oxide or a Ti compound which can be oxidized by heating. The purification annealing is conducted in steps. A non-oxidizing atmosphere having a high nitrogen concentration is present in one step. A hydrogen atmosphere having a low nitrogen concentration is present in a subsequent step.
    Type: Grant
    Filed: September 24, 1992
    Date of Patent: June 7, 1994
    Assignee: Kawasaki Steel Corporation
    Inventors: Yasuyuki Hayakawa, Ujihiro Nishiike, Bunjiro Fukuda, Masataka Yamada, Tetsuya Oishi, Shigeru Yoshida, Yoh Shimizu
  • Patent number: 5308411
    Abstract: An ultrahigh silicon, grain-oriented electrical steel sheet having a magnetic flux density, B.sub.8, of 1.57 or more and a degree of azimuth orientation, R (B.sub.8 /B.sub.s) of 0.87 or more is provided by cold-rolling an ultrahigh silicon steel sheet comprising by weight 0.005 to 0.023% of C, 5 to 7.1% of Si, 0.014% or less of S, 0.013 to 0.055% of acid soluble Al and 0.0095% or less of total N with the balance consisting of Fe and unavoidable impurities at a temperature in the range of from 120.degree. to 380.degree. C. optionally after annealing at a temperature in the range of from 800.degree. to 1100.degree. C.
    Type: Grant
    Filed: February 20, 1992
    Date of Patent: May 3, 1994
    Assignee: Nippon Steel Corporation
    Inventors: Yozo Suga, Yoshiyuki Ushigami, Hodaka Honma, Nobuyuki Takahashi
  • Patent number: 5306353
    Abstract: In grain oriented silicon steel sheets containing MnSe as a main inhibitor, an iron loss is reduced by increasing the magnetic flux density and realizing the thinning of product thickness and fine division of crystal grains while utilizing the stability of secondary recrystallization as a merit of such a sheet. In this case, 0.02-0.30% of Cu is added to a slab of the above grain oriented silicon steel, and particularly the decarburization annealing and/or the final finish annealing are carried out under particular conditions.
    Type: Grant
    Filed: June 17, 1992
    Date of Patent: April 26, 1994
    Assignee: Kawasaki Steel Corporation
    Inventors: Yasuyuki Hayakawa, Michiro Komatsubara, Takahiro Kan, Hirotake Ishitobi, Katsuo Iwamoto
  • Patent number: 5296051
    Abstract: A method of producing a low iron loss grain oriented silicon steel sheet which generates improved magnetostrictive characteristics when used as a stacked iron core and low noise when used in a stacked transformer, as well as superior shape characteristics. A grain oriented finish-annealed silicon steel sheet is coated with an insulating film. The surface of the grain oriented silicon steel sheet is irradiated with an electron beam along a multiplicity of spaced paths so as to refine the magnetic domains. The irradiation with the electron beam is conducted continuously or intermittently along a waveform path on the surface of the grain oriented silicon steel, and the wave-form, such as a zigzag form, has a period length much smaller than the width of the grain oriented silicon steel sheet, and line interconnecting the centers of successive waves extends substantially perpendicularly to the direction of rolling of the grain oriented silicon steel sheet.
    Type: Grant
    Filed: February 11, 1993
    Date of Patent: March 22, 1994
    Assignee: Kawasaki Steel Corporation
    Inventors: Yukio Inokuti, Kazuhiro Suzuki
  • Patent number: 5288736
    Abstract: The present invention produces a regular grain oriented electrical steel using a single cold reduction step having excellent and highly uniform magnetic quality. The method includes the steps of providing an electrical steel band having Mn of 0.024% or less in excess of that needed to combine with S and/or Se. The band is provided with an anneal at a temperature of from 900.degree.-1125.degree. C. (1650.degree.-2050.degree. F.) for a time up to 10 minutes and slowly cooled to 480.degree.-650.degree. C. (900.degree.-1200.degree. F.) followed by rapid cooling to a temperature below 100.degree. C. (212.degree. F.). The annealed band must have a critical amount of austenite, .gamma..sub.1150.degree. C., of 7% or more. The annealed band is cold reduced in a single stage to the desired final thickness. The strip is decarburized and provided with an annealing separator coating on one or more surfaces of the strip.
    Type: Grant
    Filed: November 12, 1992
    Date of Patent: February 22, 1994
    Assignee: Armco Inc.
    Inventors: Jerry W. Schoen, Francesco Gaudino
  • Patent number: 5269853
    Abstract: A decarburized steel sheet for a thin oriented silicon steel sheet having improved magnetic and coating characteristics and a method of producing the same. Silicon steel strip is hot-rolled, cold-rolled to a final thickness of about 0.28 mm or less, subjected to decarburization/primary-recrystallization annealing, coated with an annealing separator, and thereafter subjected to finishing annealing. In the decarburization/primary-recrystallization annealing step, a novel subscale is formed at the steel sheet surface having a fayalite-silica composition ratio in accordance with an infrared reflection absorbance ratio of about 0.5 to 5.5, and a marked oxygen amount of about 0.4 to 1.6 g/m.sup.2.
    Type: Grant
    Filed: March 29, 1993
    Date of Patent: December 14, 1993
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Yasuyuki Hayakawa, Katsuo Iwamoto, Makoto Watanabe
  • Patent number: 5266129
    Abstract: A slab for an electrical steel sheet is heated at a temperature of 1280.degree. C. or below and then hot-rolled. The hot-rolled steel sheet or hot rolled and annealed steel sheet is then cold-rolled once or at least twice with intermediate annealing being performed between rollings. The cold-rolled sheet is decarburized and nitrided to form an inhibitor. The amount of nitrogen of in the steel sheet during the nitriding treatment subsequent to the decarburization annealing and the iron loss value after the withdrawal of the steel sheet from the furnace are measured to estimate the average diameter of a primary recrystallized grain, and next decarburization annealing is performed under conditions regulated in such a manner that the average diameter of the primary recrystallized grain of a product sheet falls within a proper range. The steel sheet subjected to the decarburization annealing is coated with an annealing separator composed mainly of MgO and then subjected to finish annealing.
    Type: Grant
    Filed: September 21, 1992
    Date of Patent: November 30, 1993
    Assignee: Nippon Steel Corporation
    Inventors: Masayoshi Minakuchi, Yasumitsu Kondo, Maremizu Ishibashi
  • Patent number: 5261972
    Abstract: The present invention discloses a process for producing a grain-oriented electrical steel strip having a high magnetic flux density. The process comprises hot-rolling a steel ingot comprising basic ingredients and, added thereto, 0.02 to 0.15% of Sn at a temperature of 1200.degree. C. or below, annealing the hot-rolled strip, cold-rolling the annealed strip with a final rolling reduction of 80% or more and subjecting the cold-rolled strip to decarburization annealing, a nitriding treatment and finish annealing, wherein the temperature, T.degree.C., of annealing of the hot-rolled strip is set so as to fall within the range 1240-2.1.times.Al.sub.R <T<1310-1.8.times.Al.sub.R (wherein Al.sub.R =acid soluble [Al]-27/14.times.[N]) and the strip is soaked for 180 sec or less, maintained at a temperature in the range of from 800.degree. to 950.degree. C. for 30 to 300 sec and then quenched.The grain-oriented electrical steel strip thus produced is not influenced by the variation in the [Al] and [N].
    Type: Grant
    Filed: October 22, 1992
    Date of Patent: November 16, 1993
    Assignee: Nippon Steel Corporation
    Inventors: Katsuro Kuroki, Yasunari Yoshitomi, Hiroaki Masui, Tsutomu Haratani
  • Patent number: 5250123
    Abstract: An oriented silicon steel sheet with a very low core loss and a process for producing it at a lower cost are disclosed. The steel sheet consists essentially of Si: 1.5-3.0%, Mn: 1.0-3.0%, sol. Al: 0.003-0.015%, with Si (%)-0.5.times.Mn (%).ltoreq.2.0 and the balance being Fe and incidental impurities, in which the amount of C and N as impurities is not more than 0.0020%, with S being not more than 0.01%. This steel sheet can be produced from a slab containing up to 0.01% C and 0.001-0.010% N through hot rolling, cold rolling, primary and secondary recrystallization, and then decarburization.
    Type: Grant
    Filed: March 13, 1992
    Date of Patent: October 5, 1993
    Assignee: Sumitomo Metal Industries, Ltd.
    Inventors: Hiroyoshi Yashiki, Teruo Kaneko
  • Patent number: 5203928
    Abstract: It is a technical subject to advantageously avoid the degradation of surface properties in a low iron loss grain oriented silicon steel sheet as a material for transformers, particularly if it is intended to thin the gauge to 0.1.about.0.25 mm. A low iron loss grain oriented silicon steel thin sheet can stably be produced without causing the degradation of performances through strain relief annealing by considering a chemical composition in steel, optimizing the rolling conditions, particularly cold rolling conditions, and further forming heterogeneous microareas onto the steel sheet surface.
    Type: Grant
    Filed: October 11, 1991
    Date of Patent: April 20, 1993
    Assignee: Kawasaki Steel Corporation
    Inventors: Yukio Inokuti, Yoh Ito
  • Patent number: 5200145
    Abstract: The present invention relates to a novel process for producing silicon and/or aluminum containing iron alloy product as well as the material produced from same in either sheet or bulk structure form for electromagnetic circuit application. The process entails modifying an iron feedstock containing less than about 2.5 wt % silicon, aluminum or a combination thereof. The process further consists of diffusion of silicon or silicon and aluminum or aluminum into an iron feedstock by a pack diffusion or a chemical vapor deposition method in which the iron feedstock is heated to a temperature at which diffusion occurs in the presence of a pack containing silicon and/or aluminum sources, a reducing agent, a catalyst, and a filler, or in the presence of a flowing gas stream containing a volatile silicon compound. The resulting iron alloy product, which has a silicon content in the range of 0.
    Type: Grant
    Filed: July 12, 1991
    Date of Patent: April 6, 1993
    Assignee: Exxon Research and Engineering Co.
    Inventors: Richard C. Krutenat, Robert S. Barnard, John P. Dismukes, Bernard H. Kear, Horst Witzke
  • Patent number: 5192373
    Abstract: Decarburized grain oriented silicon steel is provided with an annealing separator which forms a glass film after the final high temperature anneal. The magnesia used as the annealing separator has a total chlorine level of 0.01 to 0.20% by weight based on the weight of magnesia with at least 0.01% metal chloride selected from the group of Mg, Ca, Na and K. The chloride addition acts to seal the coating surface during the final anneal to control diffusion and stabilize the secondary grain growth. The glass film which forms during the anneal may be laser scribed for domain refinement without coating damage. The magnesia may also contain additions of phosphates, TiO.sub.2, SiO.sub.2, Cr and B. The temperature of the magnesia is maintained below 25.degree. C. to control hydration and eliminate the need for other additives in the magnesia slurry to control hydration.
    Type: Grant
    Filed: April 12, 1991
    Date of Patent: March 9, 1993
    Assignee: Armco, Inc.
    Inventors: Wade S. Wright, Robin A. Murphy
  • Patent number: 5190597
    Abstract: A process for producing a grain-oriented electrical steel sheet having improved magnetic and surface film properties, comprising: using an electrical silicon steel slab containins S in an extremely small amount of 0.012 wt % or less and Mn in a limited range of 0.08 to 0.45 wt %; heating the slab to a relatively low temperature of not higher than 1200.degree. C.; hot-rolling the slab to form a hot-rolled strip; cold-rolling the strip to a thickness of a final product sheet; decarburization-annealing the cold-rolled strip; nitriding the strip while it is travelling; applying an annealing separator to the strip; and final texture-annealing the strip by heating the strip to a first temperature of from 800.degree. to 850.degree. C. in an atmosphere of (N.sub.2 +Ar).gtoreq.30 vol % with 25 vol % or more N.sub.2 and the remainder H.sub.2 and subsequently heating from the first temperature to above 1200.degree. C. in a conventional atmosphere.
    Type: Grant
    Filed: November 5, 1991
    Date of Patent: March 2, 1993
    Assignee: Nippon Steel Corporation
    Inventors: Hisashi Kobayashi, Osamu Tanaka, Hiroyasu Fujii
  • Patent number: 5186762
    Abstract: A process for producing a grain-oriented electrical steel sheet having a high magnetic flux density, comprising the steps of: heating a steel slab comprising 1.8 to 4.8 wt % Si, 0.012 to 0.050 wt % acid-soluble A1, 0.010 wt % or less N, and the balance consisting of Fe and unavoidable impurities, to a temperature for hot rolling; hot-rolling the heated slab to form a hot-rolled strip; cold-rolling the hot-rolled strip to a final product sheet thickness at a final cold rolling reduction of 80% or more by a single step of cold rolling or by two or more steps of cold rolling with an intermediate annealing step inserted therebetween; primary-recrystallization-annealing the cold-rolled strip; final-annealing the primary-recrystallization-annealed strip so that secondary-recrystallized grains substantially completely grow up in a temperature region of from 1000.degree. to 1100.degree. C. and then purification is effected above 1100.degree. C.
    Type: Grant
    Filed: October 4, 1991
    Date of Patent: February 16, 1993
    Assignee: Nippon Steel Corporation
    Inventors: Yoshiyuki Ushigami, Tadashi Nakayama, Nobuyuki Takahashi
  • Patent number: 5185043
    Abstract: A grain oriented silicon steel sheet having a low iron loss and not causing degradation of properties even through strain relief annealing is produced by applying ultrasonic vibrations to the surface of the sheet after secondary recrystallization annealing.
    Type: Grant
    Filed: October 31, 1990
    Date of Patent: February 9, 1993
    Assignee: Kawasaki Steel Corporation
    Inventors: Ujihiro Nishike, Shigeko Sujita, Tsuneo Nagamine
  • Patent number: 5181972
    Abstract: The present invention realizes the stable production of grain oriented silicon steel sheets having excellent magnetic properties under high productivity through effectively combining aging treatment with tandem rolling, in which cold rolling is effected until a final thickness is attained. In the final cold rolling step of the production of the grain oriented silicon steel sheets, the tandem rolling is first effected, and then continuous heat treatment is effected, preferably under application of tension.
    Type: Grant
    Filed: January 9, 1991
    Date of Patent: January 26, 1993
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Mitsumasa Kurosawa, Yasuyuki Hayakawa, Yoshiaki Iida, Toshio Sadayori
  • Patent number: 5174833
    Abstract: A method for forming an insulating film on a grain-oriented silicon steel sheet by applying an insulating coating solution comprising100 parts by weight (calculated as the solid component) of a mixture of colloidal substances, composed of 50 to 98 weight % (calculated as the solid component SiO.sub.2) of colloidal silica having a partical diameter not larger than 50 nano m, and 2 to 50 weight % (calculated as the solid component) of at least one colloidal substance having a particle diameter randing from 80 to 3000 nano m, selected from the group consisting of oxides, carbides, nitrides, sulfides, borides, hydroxides, silicates, carbonates, borates, sulfates, nitrates and chlorides of Fe, Ca, Ba, Zn, Al, Ni, Sn Cu, Cr, Cd, Nd, Mn, Mo, Si, Ti, W, Bi, Sr, and V,130 to 250 parts by weight of at least one selected from the group consisting of phosphates of Al, Mg, Ca, and Zn, and10 to 40 parts by weight of at least one selected from the group consisting of chromic anhydride, chromate, and dichromate.
    Type: Grant
    Filed: July 2, 1990
    Date of Patent: December 29, 1992
    Assignee: Nippon Steel Corporation
    Inventors: Osamu Tanaka, Eisuke Minematsu, Norikazu Fujii, Kikuji Hirose
  • Patent number: 5173128
    Abstract: An oriented silicon steel sheet having a very high magnetic flux density is produced from an oriented silicon steel containing AlN as the main inhibitor and also containing Sb by a method adapted to prevent the loss of the inhibiting ability of the surface layer of the steel, and to improve cooling conditions in annealing before the final cold rolling. The steel is hot rolled, subjected to at least one time the combination of annealing and cold rolling wherein the final cold rolling is performed with a rolling reduction of about 80 to 95%, subjected to decarburization and primary recrystallization annealing, and subjected to, after coating an annealing separation agent, final finish annealing. Before annealing is performed before the final cold rolling, a nitriding promoter is applied to the surface of the steel sheet, and the partial-pressure ratio of N.sub.2 in the atmosphere for that annealing is adjusted to a value of not less than about 20%.
    Type: Grant
    Filed: October 28, 1991
    Date of Patent: December 22, 1992
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Toshio Sadayori, Katsuo Iwamoto, Yasuyuki Hayakawa, Takahiro Kan
  • Patent number: 5173129
    Abstract: A grain-oriented silicon steel sheet having a low iron loss free from deterioration due to the stress-relief annealing, can be obtained by forming on its surface a forsterite film locally having regions, which have a thickness different from that of the remaining regions in the film, or locally having filmless regions which do not coat the steel sheet surface.
    Type: Grant
    Filed: December 8, 1989
    Date of Patent: December 22, 1992
    Assignee: Kawasaki Steel Corporation
    Inventors: Ujihiro Nishiike, Michiro Komatsubara, Yoshiaki Iida, Isao Matoba
  • Patent number: 5145533
    Abstract: A process for producing a grain-oriented electrical steel sheet having an excellent magnetic characteristic, comprising the steps of: heating to a temperature lower than 1280.degree. C. a steel slab comprising 0.025 to 0.075 wt % C, 2.5 to 4.5 wt % Si, 0.010 to 0.060 wt % acid-soluble Al, 0.0030 to 0.0130 wt % N, 0.014 wt % or less (S+0.405 Se), 0.05 to 0.
    Type: Grant
    Filed: October 2, 1991
    Date of Patent: September 8, 1992
    Assignee: Nippon Steel Corporation
    Inventors: Yasunari Yoshitomi, Yozo Suga, Nobuyuki Takahashi, Yoshiyuki Ushigami, Tadashi Nakayama
  • Patent number: 5141573
    Abstract: An electrical steel sheet having a very small watt loss can be provided by improving the conventional magnetic domain-controlling treatment. Namely, a high-flux density, grain-oriented electrical steel sheet having a superior watt loss characteristic and a flux density of at least 1.88 T at a magnetizing force of 800 A/m, which comprises, as the steel sheet components, up to 0.0030% by weight of C, 2.8 to 4.5% by weight of Si, 0.045 to 0.100% by weight of Mn, up to 0.0050% by weight of one or two elements selected from the group consisting of S and Se, up to 0.0050% by weight of Al, up to 0.0030% by weight of N, 0.03 to 0.25% by weight of Sn, 0.35 to 2.0% by weight of Ni and if necessary, 0.03 to 0.
    Type: Grant
    Filed: October 26, 1990
    Date of Patent: August 25, 1992
    Assignee: Nippon Steel Corporation
    Inventor: Shozaburo Nakashima
  • Patent number: 5129965
    Abstract: A method of producing grain oriented silicon steel sheets each having a low watt loss, at an inexpensive cost and a high operational efficiency, wherein surfaces of each silicon steel sheet are given a mirror surface is disclosed. After completion of a finish annealing, forsterite films on the surface of each grain oriented silicon steel sheet are removed therefrom, and thereafter, the silicon steel sheet is annealed within the temperature range of 1000.degree. C. or higher in an atmosphere composed of a mixture gas comprising 20 to 80% by volume of hydrogen gas and 0 to 80% by volume of an inert gas, whereby surfaces of the silicon steel sheet are given a mirror surface. Subsequently, tensile stress additive films are formed on the surfaces of the silicon steel sheet, and consequently, the resultant silicon steel sheet exhibits a remarkably reduced watt loss.
    Type: Grant
    Filed: July 18, 1991
    Date of Patent: July 14, 1992
    Assignee: Nippon Steel Corporation
    Inventors: Hisashi Kobayashi, Yoshiyuki Ushigami, Hiroyasu Fujii
  • Patent number: 5127971
    Abstract: The production of grain oriented silicon steel sheets comprises a combination of hot rolling step, cold rolling step, decarburization and primary recrystallization annealing step, annealing separator applying step and secondary recrystallization annealing and purification annealing step. In this case, the cold rolled sheet is subjected to an electrolytic degreasing in a silicate bath containing an iron concentration of 50-5000 mg/l, and Cu is adhered to the surface(s) of the sheet after the decarburization and primary recrystallization annealing in an amount of 400-2000 mg/m.sup.2 per one-side surface.
    Type: Grant
    Filed: February 15, 1991
    Date of Patent: July 7, 1992
    Assignee: Kawasaki Steel Corporation
    Inventors: Michiro Komatsubara, Yasuyuki Hayakawa, Mitsumasa Kurosawa, Takahiro Kan, Toshio Sandayori