Patents by Inventor Mitsumasa Kurosawa
Mitsumasa Kurosawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
-
Patent number: 7371291Abstract: A grain oriented electromagnetic steel sheet is free from an undercoating mainly composed of forsterite (Mg2SiO4), excellent in processability and magnetic properties and useful to production cost, and has a composition containing, by % by mass, 2.0 to 8.0% of Si, wherein secondary recrystallized grains contains fine crystal grains having a grain diameter of 0.15 mm to 0.50 mm at a rate of 2 grains/cm2 or more. In the process of producing the steel sheet, inhibitors are not utilized, and the fine crystal grains are achieved by high purification and low temperature final annealing.Type: GrantFiled: June 6, 2005Date of Patent: May 13, 2008Assignee: JFE Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Seiji Okabe, Takeshi Imamura
-
Publication number: 20050224142Abstract: A grain oriented electromagnetic steel sheet is free from an undercoating mainly composed of forsterite (Mg2SiO4), excellent in processability and magnetic properties and useful to production cost, and has a composition containing, by % by mass, 2.0 to 8.0% of Si, wherein secondary recrystallized grains contains fine crystal grains having a grain diameter of 0.15 mm to 0.50 mm at a rate of 2 grains/cm2 or more. In the process of producing the steel sheet, inhibitors are not utilized, and the fine crystal grains are achieved by high purification and low temperature final annealing.Type: ApplicationFiled: June 6, 2005Publication date: October 13, 2005Applicant: JFE Steel Corporation, a corporation of JapanInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Seiji Okabe, Takeshi Imamura
-
Patent number: 6942740Abstract: A grain oriented electromagnetic steel sheet is free from an undercoating mainly composed of forsterite (Mg2SiO4), excellent in processability and magnetic properties and useful to production cost, and has a composition containing, by % by mass, 2.0 to 8.0% of Si, wherein secondary recrystallized grains contains fine crystal grains having a grain diameter of 0.15 mm to 0.50 mm at a rate of 2 grains/cm2 or more. In the process of producing the steel sheet, inhibitors are not utilized, and the fine crystal grains are achieved by high purification and low temperature final annealing.Type: GrantFiled: January 17, 2002Date of Patent: September 13, 2005Assignee: JFE Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Seiji Okabe, Takeshi Imamura
-
Patent number: 6811619Abstract: A method of manufacturing a grain-oriented steel sheet including hot-rolling a slab prepared using molten steel containing, by mass %, C of not more than about 0.08%, Si of about 2.0 to about 8.0% and Mn of about 0.005 to about 3.0%; optionally annealing the hot-rolled steel sheet; performing cold rolling once, or twice or more with intermediate annealing therebetween; performing primary recrystallization annealing in a low- or non-oxidizative atmosphere and adjusting the C content in the steel sheet after primary recrystallization annealing to be held in the range of about 0.005 to about 0.025 mass %; performing secondary recrystallization annealing; decarburization annealing; and, preferably, performing additional high-temperature continuous or batch annealing. A grain-oriented electrical steel sheet having a sufficiently high magnetic flux density and a low iron loss can be advantageously obtained even when it is manufactured without using an inhibitor.Type: GrantFiled: July 23, 2002Date of Patent: November 2, 2004Assignee: JFE Steel CorporationInventors: Yasuyuki Hayakawa, Hideo Yamagami, Seiji Okabe, Takeshi Imamura, Minoru Takashima, Mitsumasa Kurosawa
-
Patent number: 6758915Abstract: The invention is a grain-oriented magnetic steel sheet having extremely low iron loss, suitable for use as an iron core material for transformers and power generators, and a method for producing the same. The method includes forming a coating layer on a surface of a steel sheet having a thickness of 0.27 mm or less by vapor deposition in a low oxidizing atmosphere with an oxygen partial pressure (Po2) of less than 0.1 atm and a total pressure of 0.1 atm or more. The steel sheet has extremely low iron loss with a thickness of 0.27 mm or less and includes a coating layer formed by vapor deposition on a matrix surface.Type: GrantFiled: December 5, 2002Date of Patent: July 6, 2004Assignee: JFE Steel CorporationInventors: Minoru Takashima, Mineo Muraki, Hiroi Yamaguchi, Mitsumasa Kurosawa, Michiro Komatsubara
-
Publication number: 20040074565Abstract: A grain oriented electromagnetic steel sheet is free from an undercoating mainly composed of forsterite (Mg2SiO4), excellent in processability and magnetic properties and useful to production cost, and has a composition containing, by % by mass, 2.0 to 8.0% of Si, wherein secondary recrystallized grains contains fine crystal grains having a grain diameter of 0.15 mm to 0.50 mm at a rate of 2 grains/cm2 or more. In the process of producing the steel sheet, inhibitors are not utilized, and the fine crystal grains are achieved by high purification and low temperature final annealing.Type: ApplicationFiled: November 27, 2002Publication date: April 22, 2004Inventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Seiji Okabe, Takeshi Imamura
-
Patent number: 6676771Abstract: Manufacturing a grain-oriented electrical steel sheet, a secondary recrystallization step and a forsterite coating forming step are separated into first batch annealing for developing secondary recrystallization and second batch annealing for forming a forsterite coating, with continuous annealing performed between these two steps of batch annealing, to produce a grain-oriented electrical steel sheet that is superior in both magnetic characteristics and coating characteristics.Type: GrantFiled: July 30, 2002Date of Patent: January 13, 2004Assignee: JFE Steel CorporationInventors: Minoru Takashima, Tetsuo Toge, Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara
-
Patent number: 6602357Abstract: A grain oriented electrical steel sheet comprises metal part containing Si: about 2.5 to about 5.0 mass % and Cr: about 0.05 to about 1.0 mass %, and an insulation coating formed on a surface of the metal part. A tension imparted to the metal part in the rolling direction by the insulation coating is not smaller than about 3.0 MPa. Magnetic flux density B8 satisfies a specific relation formula. A plurality of linear strains or grooves are formed in a surface of the steel sheet and linearly extended at an angle of not larger than about 45° (in each direction) relative to a direction perpendicular to a rolling direction such that an interval D of the linear strains or grooves satisfies a specific relation formula depending on the Cr content. A grain oriented electrical steel sheet is thereby obtained which has lower iron loss after domain refining treatment than conventional values.Type: GrantFiled: January 24, 2002Date of Patent: August 5, 2003Assignee: Kawasaki Steel CorporationInventors: Kunihiro Senda, Toshito Takamiya, Tadashi Nakanishi, Mitsumasa Kurosawa, Hiroaki Toda
-
Publication number: 20030136470Abstract: The present invention relates to a grain-oriented magnetic steel sheet having extremely low iron loss, which is suitable for use as an iron core material for transformers and power generators, and to a method for producing the same. That is, in accordance with the present invention, a method for producing a grain-oriented magnetic steel sheet includes the step of forming a coating layer on a surface of the matrix of a steel sheet having a thickness of 0.27 mm or less by vapor deposition in a low oxidizing atmosphere with an oxygen partial pressure (Po2) of less than 0.1 atm and a total pressure of 0.1 atm or more. A grain-oriented magnetic steel sheet of the present invention having extremely low iron loss with a thickness of 0.27 mm or less includes a coating layer formed by vapor deposition on a matrix surface.Type: ApplicationFiled: December 5, 2002Publication date: July 24, 2003Inventors: Minoru Takashima, Mineo Muraki, Hiroi Kurosawa, Mitsumasa Kurosawa, Michiro Komatsubara
-
Publication number: 20030116236Abstract: A method of manufacturing a grain-oriented steel sheet including hot-rolling a slab prepared using molten steel containing, by mass %, C of not more than about 0.08%, Si of about 2.0 to about 8.0% and Mn of about 0.005 to about 3.0%; optionally annealing the hot-rolled steel sheet; performing cold rolling once, or twice or more with intermediate annealing therebetween; performing primary recrystallization annealing in a low- or non-oxidizative atmosphere and adjusting the C content in the steel sheet after primary recrystallization annealing to be held in the range of about 0.005 to about 0.025 mass %; performing secondary recrystallization annealing; decarburization annealing; and, preferably, performing additional high-temperature continuous or batch annealing. A grain-oriented electrical steel sheet having a sufficiently high magnetic flux density and a low iron loss can be advantageously obtained even when it is manufactured without using an inhibitor.Type: ApplicationFiled: July 23, 2002Publication date: June 26, 2003Applicant: KAWASAKI STEEL CORPORATIONInventors: Yasuyuki Hayakawa, Hideo Yamagami, Seiji Okabe, Takeshi Imamura, Minoru Takashima, Mitsumasa Kurosawa
-
Patent number: 6562473Abstract: Electrical steel sheets having superior magnetic properties, anti-noise properties, and workability, are ideal for use a compact iron core material in electric apparatuses, such as compact transformers, motors, and electric generators. A totally new electrical steel sheet and a manufacturing method therefor are proposed, in which the electrical steel sheet is not only most advantageous in magnetic properties but also advantageous from economic point of view. That is, the electrical steel sheet of the present invention is composed of from about 2.0 to 8.0 wt % Si, from about 0.005 to 3.0 wt % Mn, from about 0.0010 to 0.020 wt % Al, balance essentially iron. The magnetic flux density B50(L) in a rolling direction and the magnetic flux density B50(C) in the direction perpendicular thereto are 1.70 T or more, and the B50(L)/B50(C) is 1.005 to 1.100.Type: GrantFiled: November 27, 2000Date of Patent: May 13, 2003Assignee: Kawasaki Steel CorporationInventors: Seiji Okabe, Yasuyuki Hayakawa, Takeshi Imamura, Mitsumasa Kurosawa
-
Patent number: 6531001Abstract: Non-oriented magnetic steel sheets, which are mainly used as materials for iron cores for use in electric apparatuses, have a low iron loss and a high magnetic flux density at the same time. The non-oriented magnetic steel sheet comprises from about 1.5 to about 8.0 weight % Si, from about 0.005 to about 2.50 weight % Mn, and not more than about 50 ppm each of C, S, N, O, and B, in which a crystal orientation parameter <&Ggr;> is 0.200 or less. In addition, the average crystal grain diameter is preferably from about 50 to about 500 &mgr;m, and an areal ratio of crystal grains on a surface of the steel sheet is preferably 20% and less, in which crystal plane orientations of the crystal grains are within 15° from the <111> axis. In addition, the non-oriented magnetic steel sheet preferably contains small amounts of elements such as Al, Sb, Ni, Sn, Cu, P, and Cr. The manufacturing method for the non-oriented magnetic steel is also described.Type: GrantFiled: May 8, 2002Date of Patent: March 11, 2003Assignee: Kawasaki Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Masaki Kawano, Michiro Komatsubara, Yuka Komori, Kazuaki Tamura
-
Publication number: 20030034092Abstract: Manufacturing a grain-oriented electrical steel sheet, a secondary recrystallization step and a forsterite coating forming step are separated into first batch annealing for developing secondary recrystallization and second batch annealing for forming a forsterite coating, with continuous annealing performed between these two steps of batch annealing, to produce a grain-oriented electrical steel sheet that is superior in both magnetic characteristics and coating characteristics.Type: ApplicationFiled: July 30, 2002Publication date: February 20, 2003Applicant: KAWASAKI STEEL CORPORATIONInventors: Minoru Takashima, Tetsuo Toge, Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara
-
Publication number: 20030024606Abstract: Non-oriented magnetic steel sheets, which are mainly used as materials for iron cores for use in electric apparatuses, have a low iron loss and a high magnetic flux density at the same time. The non-oriented magnetic steel sheet comprises from about 1.5 to about 8.0 weight % Si, from about 0.005 to about 2.50 weight % Mn, and not more than about 50 ppm each of C, S, N, O, and B, in which a crystal orientation parameter <&Ggr;> is 0.200 or less. In addition, the average crystal grain diameter is preferably from about 50 to about 500 &mgr;m, and an areal ratio of crystal grains on a surface of the steel sheet is preferably 20% and less, in which crystal plane orientations of the crystal grains are within 15° from the <111> axis. In addition, the non-oriented magnetic steel sheet preferably contains small amounts of elements such as Al, Sb, Ni, Sn, Cu, P, and Cr. The manufacturing method for the non-oriented magnetic steel is also described.Type: ApplicationFiled: May 8, 2002Publication date: February 6, 2003Applicant: KAWASAKI STEEL CORPORATIONInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Masaki Kawano, Michiro Komatsubara, Yuka Komori, Kazuaki Tamura
-
Patent number: 6475304Abstract: Grain-oriented silicon steel sheet with Bi as an auxiliary inhibitor and a forsterite coating film having a Cr spinel oxide subscale of FeCr2O4 or FexMn1-xCr2O4 (0.6≦x≦1), made from a steel slab containing 0.005-0.20 wt % of Bi and 0.1-1.0 wt % of Cr.Type: GrantFiled: July 18, 2001Date of Patent: November 5, 2002Assignee: Kawasaki Steel CorporationInventors: Hiroaki Toda, Kunihiro Senda, Mitsumasa Kurosawa, Makoto Watanabe, Atsuhito Honda
-
Publication number: 20020157734Abstract: A grain oriented electrical steel sheet comprises metal part containing Si: about 2.5 to about 5.0 mass % and Cr: about 0.05 to about 1.0 mass %, and an insulation coating formed on a surface of the metal part. A tension imparted to the metal part in the rolling direction by the insulation coating is not smaller than about 3.0 MPa. Magnetic flux density B8 satisfies a specific relation formula. A plurality of linear strains or grooves are formed in a surface of the steel sheet and linearly extended at an angle of not larger than about 45° (in each direction) relative to a direction perpendicular to a rolling direction such that an interval D of the linear strains or grooves satisfies a specific relation formula depending on the Cr content. A grain oriented electrical steel sheet is thereby obtained which has lower iron loss after domain refining treatment than conventional values.Type: ApplicationFiled: January 24, 2002Publication date: October 31, 2002Inventors: Kunihiro Senda, Toshito Takamiya, Tadashi Nakanishi, Mitsumasa Kurosawa, Hiroaki Toda
-
Patent number: 6444051Abstract: A method of making a grain-oriented electromagnetic steel sheet having a low iron loss and a high magnetic flux density, from a steel slab with 0.03 to 0.095 wt % carbon, about 1.5 to 7.0 wt % Si, about 0.03 to 2.50 wt % manganese, about 0.003 to 0.040 wt % sulfur and/or selenium, about 0.0010 to 0.0070 wt % borbon, about 30 to 120 wtppm nitrogen, about 0.015 wt % or less aluminum, and about 0.010 wt % or less vanadium by subjecting the steel slab to reheating, hot rolling, rapid cooling, cold rolling, primary recrystallization annealing, coating with an annealing separator, final annealing, secondary recrystallization, and coiling.Type: GrantFiled: August 9, 2001Date of Patent: September 3, 2002Assignee: Kawasaki Steel CorporationInventors: Michiro Komatsubara, Kazuaki Tamura, Mitsumasa Kurosawa
-
Patent number: 6436199Abstract: Non-oriented magnetic steel sheets, which are mainly used as materials for iron cores for use in electric apparatuses, have a low iron loss and a high magnetic flux density at the same time. The non-oriented magnetic steel sheet comprises from about 1.5 to about 8.0 weight % Si, from about 0.005 to about 2.50 weight % Mn, and not more than about 50 ppm each of C, S, N, O, and B, in which a crystal orientation parameter <&Ggr;> is 0.200 or less. In addition, the average crystal grain diameter is preferably from about 50 to about 500 &mgr;m, and an areal ratio of crystal grains on a surface of the steel sheet is preferably 20% and less, in which crystal plane orientations of the crystal grains are within 15° from the <111> axis. In addition, the non-oriented magnetic steel sheet preferably contains small amounts of elements such as Al, Sb, Ni, Sn, Cu, P, and Cr. The manufacturing method for the non-oriented magnetic steel is also described.Type: GrantFiled: August 29, 2000Date of Patent: August 20, 2002Assignee: Kawasaki Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Masaki Kawano, Michiro Komatsubara, Yuka Komori, Kazuaki Tamura
-
Patent number: 6432227Abstract: Electromagnetic steel sheet from a high-purity steel slab, composed essentially of Si 2.0 to 8.0 wt %, Mn 0.005 to 3.0 wt % and Al 0.0010 to 0.012 wt % with each of Se, S, N and O each not more than 30 ppm.Type: GrantFiled: October 3, 2001Date of Patent: August 13, 2002Assignee: Kawasaki Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara
-
Patent number: RE39482Abstract: Grain-oriented magnetic steel sheet made by the method-including hot rolling and final finish annealing, wherein (1) the O content in the steel slab is limited to up to about 30 ppm; (2) for the entire steel sheet having final thickness including an oxide film before final finish annealing, from among impurities, the Al content is limited to up to about 100 wtppm, and the respective contents of B, V, Nb, Se, S, P, and N, to up to about 50 wtppm each; and (3) during final finish annealing, the N content in the steel is, at least in the temperature region of from about 850 to 950° C., limited within the range of from about 6 to 80 wtppm.Type: GrantFiled: October 3, 2002Date of Patent: February 6, 2007Assignee: JFE Steel CorporationInventors: Yasuyuki Hayakawa, Mitsumasa Kurosawa, Michiro Komatsubara