Patents by Inventor Nobusato Kojima

Nobusato Kojima 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: 10815553
    Abstract: Provided is a galvannealed steel sheet having high strength and excellent deep drawability, and being further excellent in slab cracking resistance and secondary working embrittlement resistance. A base metal steel sheet of the galvannealed steel sheet has a chemical composition containing, in mass %: C: 0.0080% or less; Si: 0.7% or less; Mn: 1.0 to 2.5%; P: more than 0.030 to 0.048%; S: 0.025% or less; Al: 0.005 to 0.20%; N: 0.010% or less; Ti: 0.005 to 0.040%; Nb: 0.005 to 0.060%; and B: 0.0005 to 0.0030%, with the balance being Fe and impurities, satisfying Formula (1) to (4). A galvannealed layer contains 7 to 15 mass % of Fe. 25×P+4×Si?3.6??(1) B?X1?0.0005??(2) C?(12/93)×Nb?X2??0.
    Type: Grant
    Filed: August 22, 2016
    Date of Patent: October 27, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Masaharu Oka, Nobusato Kojima, Tetsuya Okada
  • Patent number: 10718033
    Abstract: A heat-treated steel material is provided having strength of 2.000 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+51×[Si]+102×[Mn]+605>2000” is satisfied. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.2×1016 m?2.
    Type: Grant
    Filed: May 26, 2015
    Date of Patent: July 21, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima
  • Patent number: 10662494
    Abstract: A heat-treated steel material is provided having strength of 1.800 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+102×[Mn]+605?1800” is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.0×1015 m?2.
    Type: Grant
    Filed: May 26, 2015
    Date of Patent: May 26, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima
  • Patent number: 10603703
    Abstract: The present invention provides a method of manufacturing a press-formed product. The method includes: a first process of preparing a material that is long in a first direction, and when viewed in a cross-section perpendicular to the first direction, the cross-section is a hollow cross-section that is long in a second direction perpendicular to the first direction; and a second process of bending the material in a direction intersecting the second direction when viewed from the first direction, by pressing the material along the second direction.
    Type: Grant
    Filed: September 30, 2015
    Date of Patent: March 31, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Eiji Isogai, Nobusato Kojima, Riki Okamoto, Yutaka Mikazuki
  • Publication number: 20200048730
    Abstract: A steel sheet for a drawn can has a predetermined chemical composition and has a ferrite single-phase structure with a crystal grain size number of 11.0 or more, the sheet thickness is 0.15 to 0.50 mm, in an L direction of the steel sheet after an ageing treatment at 100° C. for one hour, an yield strength YP is 220 to 290 MPa, a tensile strength TS is 330 to 390 MPa, a total elongation EL is 32% or more, an yield point elongation YP-EL is 0%, an average plastic strain ratio rm is more than 1.35, and an in-plane anisotropy ?r is ?0.30 to +0.15.
    Type: Application
    Filed: April 19, 2018
    Publication date: February 13, 2020
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Masaharu OKA, Nobusato KOJIMA, Yuta DAIROKUNO, Michihiro NONO
  • Patent number: 10435761
    Abstract: A heat-treated steel material includes: a chemical composition expressed by, in mass %: C: 0.16% to 0.38%; Mn: 0.6% to 1.5%; Cr: 0.4% to 2.0%; Ti: 0.01% to 0.10%; B: 0.001% to 0.010%; Si: 0.20% or less; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ni: 0% to 2.0%; Cu: 0% to 1.0%; Mo: 0% to 1.0%; V: 0% to 1.0%; Al: 0% to 1.0%; Nb: 0% to 1.0%; REM: 0% to 0.1%; and the balance: Fe and impurities; and a structure expressed by: retained austenite: 1.5 volume % or less; and the balance: martensite.
    Type: Grant
    Filed: June 6, 2014
    Date of Patent: October 8, 2019
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima, Naomitsu Mizui
  • Publication number: 20190218637
    Abstract: A manufacturing method of a steel component includes: heating a steel sheet in a carburizing atmosphere to form a carburized layer on a surface of the steel sheet, the steel sheet having: a chemical composition represented by: in mass %, C: 0.0005 to 0.1%; Si: 0.01 to 2.0%; Mn: 0.05 to 3.0%; Al: 0.9% or less; P: 0.05% or less; S: 0.01% or less; Ti: 0.0 to 0.2%; Nb: 0.0 to 0.1%; Cr: 0 to 2%; Mo: 0.0 to 0.2%; B: 0.000 to 0.005%; and the balance: Fe and impurities; and a steel structure represented by ferrite with an area fraction of 70% or more; and forming the steel sheet by using metal dies, and performing quenching on the steel sheet in a state of housing the steel sheet in the metal dies to transform the carburized layer into martensite and make a part of the steel sheet on the further inside than the carburized layer to be a steel structure represented by ferrite with an area fraction of 50% or more.
    Type: Application
    Filed: October 31, 2016
    Publication date: July 18, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Riki OKAMOTO, Nobusato KOJIMA, Kazuo HIKIDA, Noriyuki MAEKAWA
  • Publication number: 20180258514
    Abstract: Provided is a galvannealed steel sheet having high strength and excellent deep drawability, and being further excellent in slab cracking resistance and secondary working embrittlement resistance. A base metal steel sheet of the galvannealed steel sheet has a chemical composition containing, in mass %: C: 0.0080% or less; Si: 0.7% or less; Mn: 1.0 to 2.5%; P: more than 0.030 to 0.048%; S: 0.025% or less; Al: 0.005 to 0.20%; N: 0.010% or less; Ti: 0.005 to 0.040%; Nb: 0.005 to 0.060%; and B: 0.0005 to 0.0030%, with the balance being Fe and impurities, satisfying Formula (1) to (4). A galvannealed layer contains 7 to 15 mass % of Fe. 25×P+4×Si?3.6??(1) B?X1?0.0005??(2) C?(12/93)×Nb?X2??0.
    Type: Application
    Filed: August 22, 2016
    Publication date: September 13, 2018
    Inventors: Masaharu OKA, Nobusato KOJIMA, Tetsuya OKADA
  • Patent number: 10060005
    Abstract: A high-strength hot-formed steel sheet member exhibiting both a consistent hardness and delayed-fracture resistance, and is characterized in that: the high-strength hot-formed steel sheet member has a prescribed chemical composition; the degree of Mn segregation ? (=[maximum Mn concentration (mass %) at the sheet center in the thickness direction]/[average Mn concentration (mass %) at a depth of ¼ of the total thickness of the sheet from the surface]) is less than or equal to 1.6; the steel purity value as defined in JIS G 0555 (2003) is less than or equal to 0.08%; the average grain size for prior ? grains is less than or equal to 10 ?m; and the number density of the residual carbides is less than or equal to 4×103 particles/mm2.
    Type: Grant
    Filed: March 26, 2015
    Date of Patent: August 28, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kazuo Hikida, Shinichiro Tabata, Nobusato Kojima, Takahiro Moriki
  • Publication number: 20170232492
    Abstract: The present invention provides a method of manufacturing a press-formed product. The method includes: a first process of preparing a material that is long in a first direction, and when viewed in a cross-section perpendicular to the first direction, the cross-section is a hollow cross-section that is long in a second direction perpendicular to the first direction; and a second process of bending the material in a direction intersecting the second direction when viewed from the first direction, by pressing the material along the second direction.
    Type: Application
    Filed: September 30, 2015
    Publication date: August 17, 2017
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Eiji ISOGAI, Nobusato KOJIMA, Riki OKAMOTO, Yutaka MIKAZUKI
  • Publication number: 20170096724
    Abstract: A high-strength hot-formed steel sheet member exhibiting both a consistent hardness and delayed-fracture resistance, and is characterized in that: the high-strength hot-formed steel sheet member has a prescribed chemical composition; the degree of Mn segregation ? (=[maximum Mn concentration (mass %) at the sheet center in the thickness direction]/[average Mn concentration (mass %) at a depth of ¼ of the total thickness of the sheet from the surface]) is less than or equal to 1.6; the steel purity value as defined in JIS G 0555 (2003) is less than or equal to 0.08%; the average grain size for prior ? grains is less than or equal to 10 ?m; and the number density of the residual carbides is less than or equal to 4×103 particles/mm2.
    Type: Application
    Filed: March 26, 2015
    Publication date: April 6, 2017
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kazuo HIKIDA, Shinichiro TABATA, Nobusato KOJIMA, Takahiro MORIKI
  • Publication number: 20170081742
    Abstract: The present invention provides a heat-treated steel material having strength of 2.000 GPa or more with obtaining excellent toughness and weldability. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+51×[Si]+102×[Mn]+605?2000” is satisfied where [C] denotes a C content, [Si] denotes a Si content, and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.2×1016 m?2.
    Type: Application
    Filed: May 26, 2015
    Publication date: March 23, 2017
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA
  • Publication number: 20170081741
    Abstract: The present invention provides a heat-treated steel material having strength of 1.800 GPa or more with obtaining excellent toughness and weldability. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+102×[Mn]+605?1800” is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.0×1015 m?2.
    Type: Application
    Filed: May 26, 2015
    Publication date: March 23, 2017
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA
  • Publication number: 20170073792
    Abstract: A hot-formed steel sheet member having a chemical composition includes, in terms of mass %, from 0.08 to 0.16% of C, 0.19% or less of Si, from 0.40 to 1.50% of Mn, 0.02% or less of P, 0.01% or less of S, from 0.01 to 1.0% of sol. Al, 0.01% or less of N, from 0.25 to 3.00% of Cr, from 0.01 to 0.05% of Ti, from 0.001 to 0.01% of B, and a reminder consisting of Fe and impurities, wherein a total volume fraction of martensite, tempered martensite, and bainite is 50% or more, and a volume fraction of ferrite is 3% or less, an average grain size of prior ? grains is 10 ?m or less, and a number density of residual carbides which are present is 4×103 per mm2 or less.
    Type: Application
    Filed: May 15, 2015
    Publication date: March 16, 2017
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kazuo HIKIDA, Nobusato KOJIMA, Shinichiro TABATA
  • Publication number: 20160102380
    Abstract: A heat-treated steel material includes: a chemical composition expressed by, in mass %: C: 0.16% to 0.38%; Mn: 0.6% to 1.5%; Cr: 0.4% to 2.0%; Ti: 0.01% to 0.10%; B: 0.001% to 0.010%; Si: 0.20% or less; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ni: 0% to 2.0%; Cu: 0% to 1.0%; Mo: 0% to 1.0%; V: 0% to 1.0%; Al: 0% to 1.0%; Nb: 0% to 1.0%; REM: 0% to 0.1%; and the balance: Fe and impurities; and a structure expressed by: retained austenite: 1.5 volume % or less; and the balance: martensite.
    Type: Application
    Filed: June 6, 2014
    Publication date: April 14, 2016
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA, Naomitsu MIZUI
  • Publication number: 20150225821
    Abstract: In a steel sheet, a cleanliness of a metal structure is 0.08% or less, a which is an Mn segregation degree is 1.6 or less, and a difference ?Hv between a low strain formed portion that undergoes a plastic strain of 5% or less and a high strain formed portion that undergoes a plastic strain of 20% or higher in a hot forming in average hardness after the hot forming is 40 or less.
    Type: Application
    Filed: August 28, 2013
    Publication date: August 13, 2015
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kazuo Hikida, Akari Tamaki, Nobusato Kojima, Masaru Takahashi
  • Patent number: 9045817
    Abstract: A heat treated galvannealed steel material having excellent post-painting corrosion resistance and a high strength which is suitable for use as an automotive part and a method for its manufacture are provided. A galvannealed steel material having a galvannealed coating on at least one side thereof is heat treated by heating at least a portion thereof to a temperature range in which hardening is possible. The coating remaining on the surface of at least a part of the portion which underwent heat treatment has a coating weight of at least 20 g/m2 and at most 80 g/m2 per side and an Fe content of at least 15% and at most 35%, an ? phase is present in the coating, and the centerline average roughness Ra of the surface of the coating is at most 1.5 ?m.
    Type: Grant
    Filed: July 23, 2010
    Date of Patent: June 2, 2015
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tamotsu Toki, Atsushi Tomizawa, Nobusato Kojima, Kazuya Ishii, Kazuhito Imai, Toyomitsu Nakamura, Naoaki Shimada
  • Patent number: 8920582
    Abstract: A steel material which is suitable for hot press working or hot three-dimensional bending and direct quench and which can be used to manufacture a high-strength formed article with sufficient quench hardening even by short time heating at a low temperature has a chemical composition comprising, in mass percent, C: 0.05-0.35%, Si: at most 0.5%, Mn: 0.5-2.5%, P: at most 0.03%, S: at most 0.01%, sol. Al: at most 0.1%, N: at most 0.01%, and optionally at least one element selected from the group consisting of B: 0.0001-0.005%, Ti: 0.01-0.1%, Cr: 0.18-0.5%, Nb: 0.03-0.1%, Ni: 0.18-1.0%, and Mo: 0.03-0.5% and has a steel structure in which the spheroidization ratio of carbides is 0.60-0.90.
    Type: Grant
    Filed: August 22, 2012
    Date of Patent: December 30, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Kazuo Hikita, Nobusato Kojima
  • Patent number: 8899665
    Abstract: A side structure for an automobile body has an A-pillar having a first portion which has a closed cross section and which is connected to a side sill and extends upwards, and a second portion which has a closed cross section and which is continuous with the first portion and extends along a slope therefrom, and a roof rail side member which has a closed cross section and which is continuous with the A-pillar and is connected to a B-pillar. The side reinforcing member having a closed cross section and a shape which is bent three-dimensionally and which is constituted by a single member in the axial direction and has undergone high frequency quenching is disposed so a to extend at least inside the second portion and inside the roof rail side member to be positioned to the rear of the connection with the B-pillar.
    Type: Grant
    Filed: May 1, 2013
    Date of Patent: December 2, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Michitaka Yoshida, Nobusato Kojima, Atsushi Tomizawa, Naoaki Shimada
  • Patent number: 8828153
    Abstract: A high-strength cold-rolled steel sheet providing a product with a good surface condition after press forming, having excellent bake hardenability and anti room temperature aging property, and having a dual phase structure with a tensile strength of at least 340 MPa is provided. A high-strength cold-rolled steel sheet has a structure comprising a main phase which is a ferrite and a secondary phase which is a low temperature transformation product including a martensite and has a hardness distribution of the ferrite phase in an arbitrary cross section having a length of 10 mm in the widthwise 10 direction of the sheet which satisfies the relationship prescribed by (HV(max)?HV(ave))<0.5×(Hv(ave). HV(max) is the maximum Vickers hardness of ferrite grains in a region at a distance of from (?)t to (¼)t in the thickness direction from the surface when the thickness of the high-strength cold-rolled steel sheet is t, and Hv(ave) is the average Vickers hardness of ferrite grains in this region.
    Type: Grant
    Filed: December 8, 2010
    Date of Patent: September 9, 2014
    Assignee: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Jun Haga, Nobusato Kojima