Patents by Inventor Seiji Nakajima

Seiji Nakajima 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).

  • Publication number: 20230392226
    Abstract: A hot-pressed member, a steel sheet for hot pressing, and methods for producing the hot-pressed member and the steel sheet for hot pressing. The hot-pressed member includes a steel sheet and a Zn-based alloy coated layer disposed on at least one surface of the steel sheet. The Zn-based alloy coated layer includes a solid solution phase including Zn with the balance being Fe and incidental impurities, an intermetallic compound phase including Fe with the balance being Zn and incidental impurities, and an oxide layer including Zn. The oxide layer serves as an uppermost layer of the Zn-based alloy coated layer and splits the intermetallic compound phase. The split density in at least one cross-section of the oxide layer per unit cross-section is 10 split positions/mm or more.
    Type: Application
    Filed: August 18, 2021
    Publication date: December 7, 2023
    Applicant: JFE STEEL CORPORATION
    Inventors: Shuhei OGAWA, Minoru TANAKA, Rinta SATO, Daisuke MIZUNO, Seiji NAKAJIMA
  • Patent number: 11420247
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing of 1780 MPa or more, excellent delayed fracture resistance, and high cross tensile strength after resistance spot welding by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 8 ?m or less, a volume fraction of martensite is 90% or more, and at least 10 cementite grains having a grain size of 0.05 ?m or more are present on average per 200 ?m2 of a cross section parallel to a thickness direction of the member, and such that at least 10 Ti-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of the cross section parallel to the thickness direction of the member in a range of 100 ?m in the thickness direction from a surface of the member.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: August 23, 2022
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Takashi Kobayashi, Yoshimasa Funakawa, Seiji Nakajima
  • Patent number: 11377709
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing, excellent delayed fracture resistance, and high tensile shear stress after resistance spot welding by properly adjusting its chemical composition and its microstructure such that at least 20 Nb-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member, a prior austenite average grain size is 8 ?m or less, an average aspect ratio of prior austenite grains is 2.5 or less, and a volume fraction of martensite is 90% or more, and such that a standard deviation of Vickers hardness measured every 200 ?m on a surface of the member is 40 or less.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: July 5, 2022
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Takashi Kobayashi, Yoshimasa Funakawa, Seiji Nakajima
  • Patent number: 11236406
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent indentation peeling strength at projection welds by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7 ?m or less within a range of 50 ?m or less in a thickness direction from a surface of the member, a volume fraction of martensite is 90% or more, and an average intergrain distance of Nb and Ti carbonitrides having a grain size of less than 0.10 ?m within a depth range of 20 ?m to 100 ?m in the thickness direction from the surface of the member is 5 ?m or less.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: February 1, 2022
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Takashi Kobayashi, Yoshimasa Funakawa, Seiji Nakajima
  • Patent number: 11168378
    Abstract: A hot-pressed member is formed using a tailored blank material obtained by butt joining respective ends of two or more coated steel sheets. The hot-pressed member has two or more sites formed by the respective coated steel sheets and at least one joining portion between the sites. Depending on a type of a coated layer of each of the coated steel sheets, tw/t0 is appropriately controlled where tw is a thickness of a thinnest portion in the joining portion and t0 is a thickness of a thinnest site of the sites. A tensile strength of each of the sites is 1180 MPa or more.
    Type: Grant
    Filed: March 3, 2016
    Date of Patent: November 9, 2021
    Assignee: JFE STEEL CORPORATION
    Inventors: Yasuaki Okita, Rinsei Ikeda, Seiji Nakajima, Koichi Nakagawa
  • Patent number: 11111558
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent resistance to resistance welding cracking by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7.5 ?m or less, a volume fraction of martensite is 95% or more, and at least 10 Nb-based and Ti-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member within a range of 100 ?m or less in the thickness direction from the surface of the member, and such that a B concentration in prior austenite grain boundaries is at least 3.0 times a B concentration at a position 5 nm away from the grain boundaries.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: September 7, 2021
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Takashi Kobayashi, Yoshimasa Funakawa, Seiji Nakajima
  • Patent number: 11085101
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more and excellent delayed fracture resistance after projection welding by properly adjusting its chemical composition and its microstructure such that at least 5 Ti-based precipitates having a grain size of 0.10 ?m or less are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member within a range of 100 ?m in a thickness direction from a surface of the member, a volume fraction of martensite is 95% to 100% within a depth range of 20 ?m to 100 ?m in the thickness direction from the surface of the member, and at least 10 cementite grains having a grain size of less than 0.20 ?m are present on average in a prior austenite grain.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: August 10, 2021
    Assignee: JFE STEEL CORPORATION
    Inventors: Katsutoshi Takashima, Takashi Kobayashi, Yoshimasa Funakawa, Seiji Nakajima
  • Publication number: 20200370140
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent indentation peeling strength at projection welds by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7 ?m or less within a range of 50 ?m or less in a thickness direction from a surface of the member, a volume fraction of martensite is 90% or more, and an average intergrain distance of Nb and Ti carbonitrides having a grain size of less than 0.10 ?m within a depth range of 20 ?m to 100 ?m in the thickness direction from the surface of the member is 5 ?m or less.
    Type: Application
    Filed: March 30, 2018
    Publication date: November 26, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi TAKASHIMA, Takashi KOBAYASHI, Yoshimasa FUNAKAWA, Seiji NAKAJIMA
  • Publication number: 20200353527
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing of 1780 MPa or more, excellent delayed fracture resistance, and high cross tensile strength after resistance spot welding by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 8 ?m or less, a volume fraction of martensite is 90% or more, and at least 10 cementite grains having a grain size of 0.05 ?m or more are present on average per 200 ?m2 of a cross section parallel to a thickness direction of the member, and such that at least 10 Ti-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of the cross section parallel to the thickness direction of the member in a range of 100 ?m in the thickness direction from a surface of the member.
    Type: Application
    Filed: March 30, 2018
    Publication date: November 12, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi TAKASHIMA, Takashi KOBAYASHI, Yoshimasa FUNAKAWA, Seiji NAKAJIMA
  • Publication number: 20200172991
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing, excellent delayed fracture resistance, and high tensile shear stress after resistance spot welding by properly adjusting its chemical composition and its microstructure such that at least 20 Nb-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member, a prior austenite average grain size is 8 ?m or less, an average aspect ratio of prior austenite grains is 2.5 or less, and a volume fraction of martensite is 90% or more, and such that a standard deviation of Vickers hardness measured every 200 ?m on a surface of the member is 40 or less.
    Type: Application
    Filed: March 30, 2018
    Publication date: June 4, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi TAKASHIMA, Takashi KOBAYASHI, Yoshimasa FUNAKAWA, Seiji NAKAJIMA
  • Publication number: 20200131596
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more and excellent delayed fracture resistance after projection welding by properly adjusting its chemical composition and its microstructure such that at least 5 Ti-based precipitates having a grain size of 0.10 ?m or less are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member within a range of 100 ?m in a thickness direction from a surface of the member, a volume fraction of martensite is 95% to 100% within a depth range of 20 ?m to 100 ?m in the thickness direction from the surface of the member, and at least 10 cementite grains having a grain size of less than 0.20 ?m are present on average in a prior austenite grain.
    Type: Application
    Filed: March 30, 2018
    Publication date: April 30, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi TAKASHIMA, Takashi KOBAYASHI, Yoshimasa FUNAKAWA, Seiji NAKAJIMA
  • Publication number: 20200131597
    Abstract: Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent resistance to resistance welding cracking by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7.5 ?m or less, a volume fraction of martensite is 95% or more, and at least 10 Nb-based and Ti-based precipitates having a grain size of less than 0.10 ?m are present on average per 100 ?m2 of a cross section parallel to a thickness direction of the member within a range of 100 ?m or less in the thickness direction from the surface of the member, and such that a B concentration in prior austenite grain boundaries is at least 3.0 times a B concentration at a position 5 nm away from the grain boundaries.
    Type: Application
    Filed: March 30, 2018
    Publication date: April 30, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Katsutoshi TAKASHIMA, Takashi KOBAYASHI, Yoshimasa FUNAKAWA, Seiji NAKAJIMA
  • Patent number: 10434556
    Abstract: Provided is a hot-pressed member excellent in terms of paint adhesiveness and a method of manufacturing the hot-pressed member. A hot-pressed member has a coating layer containing Zn and Ni on the surface of a steel sheet of which the member is formed, an oxide film containing Zn on the coating layer, and a void formation rate is 80% or less for voids formed between the coating layer and the oxide film.
    Type: Grant
    Filed: May 13, 2014
    Date of Patent: October 8, 2019
    Assignee: JFE Steel Corporation
    Inventors: Seiji Nakajima, Minako Morimoto, Satoru Ando
  • Patent number: 10427394
    Abstract: The present invention provides a method with which curing can be carried out in a short time without a heat load on an adherend and a cured product having stable quality can be obtained. The resin composition curing method in accordance with the present invention includes the step (a) of directly and/or indirectly irradiating, with laser light, a resin composition (A) which contains (i) an epoxy resin, (ii) an encapsulated curing agent including a core that contains a curing agent and a shell that covers the core, (iii) a filler, and (iv) a color material.
    Type: Grant
    Filed: November 6, 2014
    Date of Patent: October 1, 2019
    Assignee: OMRON Corporation
    Inventors: Seiji Nakajima, Yosuke Tatsuno, Mitsuo Ito, Satoshi Hirono, Yuzo Morisaki, Junji Kawamoto
  • Patent number: 10384254
    Abstract: A method of manufacturing a hot-pressed member including heating a coated steel sheet to 850° C. to 950° C., the coated steel sheet including a substrate steel sheet and a coating layer formed on the substrate steel sheet and containing 10% to 25% by mass of Ni and the balance being Zn and incidental impurities, in which the coating weight of the coating layer is 10 to 90 g/m2 per a side; and starting hot press forming when the temperature of the coated steel sheet which has been heated is 650° C. to 800° C.
    Type: Grant
    Filed: June 2, 2014
    Date of Patent: August 20, 2019
    Assignee: JFE Steel Corporation
    Inventors: Seiji Nakajima, Minako Morimoto, Satoru Ando
  • Patent number: 10316381
    Abstract: A method is provided for producing a hot-pressed member including heating a Ni-based coated steel sheet, which includes, on a surface thereof, a Zn—Ni alloy coating layer containing 13% by mass or more of Ni, in a temperature region of an Ac3 transformation point to 1200° C.; and then hot-pressing the steel sheet.
    Type: Grant
    Filed: December 2, 2013
    Date of Patent: June 11, 2019
    Assignee: JFE Steel Corporation
    Inventors: Hiroki Nakamaru, Seiji Nakajima, Tatsuya Miyoshi, Hiroyuki Masuoka, Shinji Ootsuka
  • Patent number: 10253386
    Abstract: The invention provides a steel sheet for hot press-forming that can reliably give hot press-formed parts having excellent paint adhesiveness, perforation corrosion resistance and joint corrosion resistance, and also provides a method for manufacturing the steel sheet for hot press-forming, and a method for producing hot press-formed parts using the steel sheet for hot press-forming. The steel sheet for hot press-forming includes a base steel sheet and a Zn-based coating layer with a mass of coating of 10 to 90 g/m2 on the base steel sheet, wherein the average ferrite grain diameter in the surface microstructure of the base steel sheet is not more than 20 ?m.
    Type: Grant
    Filed: March 4, 2013
    Date of Patent: April 9, 2019
    Assignee: JFE Steel Corporation
    Inventors: Tatsuya Miyoshi, Seiji Nakajima, Satoru Ando
  • Patent number: 10144196
    Abstract: A steel sheet for hot pressing that is capable of suppressing formation of scales or ZnO in hot pressing and excellent in oxidation resistance, and a method for manufacturing a hot-pressed member using the steel sheet are provided. The steel sheet for hot pressing includes a base steel sheet and a plating layer that is formed on a surface of the base steel sheet at a coating weight of 10 to 90 g/m2 and contains 10 to 25% by mass of Ni and the balance Zn with inevitable impurities.
    Type: Grant
    Filed: November 18, 2011
    Date of Patent: December 4, 2018
    Assignee: JFE Steel Corporation
    Inventors: Seiji Nakajima, Tatsuya Miyoshi, Hiroki Nakamaru
  • Patent number: 10138348
    Abstract: The present invention provides a resin composition which can be cured in a short time without a heat load on an adherend and with which a cured product having stable quality can be obtained. The resin composition in accordance with the present invention contains (i) a bisphenol A epoxy resin, (ii) an encapsulated curing agent including a core that contains a curing agent and a shell that covers the core, (iii) a filler, and (iv) a color material.
    Type: Grant
    Filed: November 6, 2014
    Date of Patent: November 27, 2018
    Assignee: OMRON CORPORATION
    Inventors: Seiji Nakajima, Yosuke Tatsuno, Mitsuo Ito, Satoshi Hirono, Yuzo Morisaki, Junji Kawamoto
  • Patent number: 10100381
    Abstract: A hot-pressing steel sheet has excellent oxidation resistance to be capable of suppressing the formation of scales and ZnO during hot pressing as well as is excellent in cold pressing properties. A process of manufacturing a hot pressed member uses the steel sheet. The hot-pressing steel sheet includes a coating layer containing 10 to 25 mass % of Ni and a balance of Zn and inevitable impurities and having a mass per unit area of 10 to 90 g/m2, and a lubricating layer containing a solid lubricant, in the order named on the surface of a steel sheet.
    Type: Grant
    Filed: May 23, 2012
    Date of Patent: October 16, 2018
    Assignee: JFE STEEL CORPORATION
    Inventors: Tatsuya Miyoshi, Seiji Nakajima, Hiroki Nakamaru