Patents by Inventor Shusaku Takagi

Shusaku Takagi 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: 10837602
    Abstract: A hydrogen storage tank includes a liner layer to store hydrogen and a carbon fiber reinforced plastic layer disposed outside the liner layer. The liner layer is formed from a low-alloy steel, and the carbon fiber forming the carbon fiber reinforced plastic layer is a pitch based carbon fiber.
    Type: Grant
    Filed: April 24, 2014
    Date of Patent: November 17, 2020
    Assignee: JFE Steel Corporation
    Inventors: Shusaku Takagi, Akihide Nagao, Mitsuo Kimura, Nobuyuki Ishikawa, Toshio Takano
  • Patent number: 10697036
    Abstract: Steel material for composite pressure vessel liners that, when used as raw material for manufacturing a composite pressure vessel liner, yields a liner having sufficient strength and a high fatigue limit and enables the manufacture of an inexpensive composite pressure vessel is provided. Steel material for composite pressure vessel liners comprises: a chemical composition containing, in mass %, C: 0.10% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.1% to 5.0%, P: 0.0005% to 0.060%, S: 0.0001% to 0.010%, N: 0.0001% to 0.010%, and Al: 0.01% to 0.06%, with a balance being Fe and incidental impurities; and a metallic microstructure in which a mean grain size of prior austenite grains is 20 ?m or less, and a total area ratio of martensite and lower bainite is 90% or more.
    Type: Grant
    Filed: March 7, 2016
    Date of Patent: June 30, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Shusaku Takagi, Akihide Nagao, Mitsuo Kimura, Hiroshi Okano
  • Patent number: 10450626
    Abstract: A high-strength hot-dip galvanized steel sheet excellent in formability includes, on the basis of mass percent, 0.05-0.3% C, 1.4% or less (including 0%) Si, 0.08%-3% Mn, 0.003-0.1% P, 0.07% or less S, 0.1-2.5% Al, 0.1-0.5% Cr, and 0.007% or less N, Si+Al?0.5%, and the balance being Fe and incidental impurities, wherein the steel sheet has a retained austenite content of 3% or more by volume fraction, a stretch-flange formability ?>50% and wherein the average aspect ratio (major axis/minor axis) of retained austenite grains is less than 2.5.
    Type: Grant
    Filed: March 17, 2017
    Date of Patent: October 22, 2019
    Assignee: JFE Steel Corporation
    Inventors: Hiroshi Matsuda, Tatsuya Nakagaito, Takayuki Futatsuka, Shusaku Takagi, Yasunobu Nagataki
  • Publication number: 20190211414
    Abstract: A steel pipe or tube for pressure vessels having excellent quench crack resistance is provided. The steel pipe or tube for pressure vessels comprises: a specific chemical composition; and a metallic microstructure in which an average grain size of prior austenite grains is 500 ?m or less, and an area fraction of microstructures other than ferrite is 50% or more.
    Type: Application
    Filed: August 8, 2017
    Publication date: July 11, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Hiroshi OKANO, Shusaku TAKAGI
  • Publication number: 20190162364
    Abstract: A composite pressure vessel liner suitable for use in a composite pressure vessel for storing high-pressure hydrogen is provided. The composite pressure vessel liner is made of a steel material including: a predetermined chemical composition; and a metallic microstructure in which an area fraction of martensite at a position of ¼ of a wall thickness on an inner side is 30% or more, a total area fraction of martensite and bainite at the position of ¼ of the wall thickness on the inner side is 95% or more, and a total area fraction of martensite and bainite in a wall thickness center part is 95% or more, wherein the composite pressure vessel liner has a wall thickness of 20 mm or more in a longitudinal center part, and a tensile strength of 850 MPa or more in the wall thickness center part.
    Type: Application
    Filed: August 1, 2017
    Publication date: May 30, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Hiroshi OKANO, Shusaku TAKAGI
  • Patent number: 10295453
    Abstract: Provided is a gas-phase hydrogen permeation test device capable of safely measuring hydrogen permeation behavior in a material under a high-pressure hydrogen atmosphere. The gas-phase hydrogen permeation test device includes a high-pressure hydrogen feeder, an analyzer, a primary-side pipe, a secondary-side pipe, a secondary-side pressure gauge, a primary-side shut-off valve, a primary-side discharge valve, a secondary-side discharge valve, a passive discharger, a secondary-side shut-off valve, and a controller configured to, when the pressure measured by the secondary-side pressure gauge reaches or exceeds a specific value, place the primary-side shut-off valve and the secondary-side shut-off valve into a closed state and the primary-side discharge valve and the secondary-side discharge valve into an open state.
    Type: Grant
    Filed: March 7, 2016
    Date of Patent: May 21, 2019
    Assignee: JFE STEEL CORPORATION
    Inventors: Akihide Nagao, Shusaku Takagi
  • Patent number: 10196727
    Abstract: A method of manufacturing a galvanized steel sheet includes a two-stage temperature raising process which includes: primary heating the sheet from 200° C. to an intermediate temperature of 500 to 800° C. at a primary average heating rate of 5 to 50° C./second at an excess air ratio of 1.10 to 1.20 maintained up to the intermediate temperature; secondary heating the sheet from the intermediate temperature to an annealing temperature of 730 to 900° C. at a secondary average heating rate of 0.1 to 10° C./second at an excess air ratio of less than 1.10 maintained up to the annealing temperature; holding the sheet to the annealing temperature for 10 to 500 seconds; cooling the sheet to 450 to 550° C. at an average cooling rate of 1 to 30° C./second; and subjecting the sheet to a galvanizing process and, optionally, an alloying process.
    Type: Grant
    Filed: September 30, 2015
    Date of Patent: February 5, 2019
    Assignee: JFE Steel Corporation
    Inventors: Shusaku Takagi, Kohei Hasegawa
  • Publication number: 20180312935
    Abstract: By having a steel composition containing, by mass %, C: 0.02% to 0.50%, Si: 0.05% to 0.50%, Mn: 0.5% to 2.0%, P: 0.05% or less, S: 0.01% or less, Al: 0.01% to 0.10%, N: 0.0005% to 0.008%, O: 0.01% or less, and V: 0.05% to 0.30% and Mo: 0.05% to 1.13% where a ratio of number of V atoms to number of Mo atoms is in a range of 0.6 to 2.0, the balance being Fe and inevitable impurities, and controlling the average particle size of fine complex carbides of V and Mo in a range of 1 nm to 20 nm, a steel structure for hydrogen gas such as a hydrogen storage vessel or a hydrogen line pipe that has excellent hydrogen embrittlement resistance in high pressure hydrogen environment can be obtained.
    Type: Application
    Filed: September 16, 2016
    Publication date: November 1, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Akihide NAGAO, Shusaku TAKAGI
  • Patent number: 10106875
    Abstract: A steel material includes: a composition containing, by mass, C: 0.05% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.3% to 3.0%, P: 0.001% to 0.040%, S: 0.0001% to 0.010%, N: 0.0001% to 0.0060%, Al: 0.01% to 1.5%, one or more elements selected from Ti: 0.01% to 0.20%, Nb: 0.01% to 0.20%, and V: 0.01% or more and less than 0.05%, and one or more elements selected from B: 0.0001% to 0.01%, Mo: 0.005% to 2.0%, and Cr: 0.005% to 3.0%, with the balance being Fe and inevitable impurities; and a steel microstructure that includes 95% or more of tempered martensite on a volume fraction basis, that includes a precipitate having a diameter of 100 nm or less and including one or more elements selected from Ti, Nb, and V and one or more elements selected from carbon and nitrogen at a density of 50 particles/?m2 or more, and that includes prior austenite having a grain diameter of 3 ?m or more.
    Type: Grant
    Filed: March 28, 2014
    Date of Patent: October 23, 2018
    Assignee: JFE Steel Corporation
    Inventors: Shusaku Takagi, Akihide Nagao
  • Publication number: 20180230567
    Abstract: Steel material for composite pressure vessel liners that, when used as raw material for manufacturing a composite pressure vessel liner, yields a liner having sufficient strength and a high fatigue limit and enables the manufacture of an inexpensive composite pressure vessel is provided. Steel material for composite pressure vessel liners comprises: a chemical composition containing, in mass %, C: 0.10% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.1% to 5.0%, P: 0.0005% to 0.060%, S: 0.0001% to 0.010%, N: 0.0001% to 0.010%, and Al: 0.01% to 0.06%, with a balance being Fe and incidental impurities; and a metallic microstructure in which a mean grain size of prior austenite grains is 20 ?m or less, and a total area ratio of martensite and lower bainite is 90% or more.
    Type: Application
    Filed: March 7, 2016
    Publication date: August 16, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Shusaku TAKAGI, Akihide NAGAO, Mitsuo KIMURA, Hiroshi OKANO
  • Publication number: 20180231450
    Abstract: Provided is a gas-phase hydrogen permeation test device capable of safely measuring hydrogen permeation behavior in a material under a high-pressure hydrogen atmosphere. The gas-phase hydrogen permeation test device includes a high-pressure hydrogen feeder, an analyzer, a primary-side pipe, a secondary-side pipe, a secondary-side pressure gauge, a primary-side shut-off valve, a primary-side discharge valve, a secondary-side discharge valve, a passive discharger, a secondary-side shut-off valve, and a controller configured to, when the pressure measured by the secondary-side pressure gauge reaches or exceeds a specific value, place the primary-side shut-off valve and the secondary-side shut-off valve into a closed state and the primary-side discharge valve and the secondary-side discharge valve into an open state.
    Type: Application
    Filed: March 7, 2016
    Publication date: August 16, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Akihide NAGAO, Shusaku TAKAGI
  • Publication number: 20180044748
    Abstract: Steel material for composite pressure vessel liners that, when used as raw material for manufacturing a composite pressure vessel liner, yields a liner having sufficient strength and a high fatigue limit and enables the manufacture of an inexpensive composite pressure vessel is provided. Steel material for composite pressure vessel liners comprises: a chemical composition containing, in mass %, C: 0.10% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.1% to 5.0%, P: 0.0005% to 0.060%, S: 0.0001% to 0.010%, N: 0.0001% to 0.010%, and Al: 0.01% to 0.06%, with a balance being Fe and incidental impurities; and a metallic microstructure in which a mean grain size of prior austenite grains is 20 ?m or less, and a total area ratio of martensite and lower bainite is 90% or more.
    Type: Application
    Filed: March 7, 2016
    Publication date: February 15, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Shusaku TAKAGI, Akihide NAGAO, Mitsuo KIMURA, Hiroshi OKANO
  • Publication number: 20170191141
    Abstract: A high-strength hot-dip galvanized steel sheet excellent in formability includes, on the basis of mass percent, 0.05-0.3% C, 1.4% or less (including 0%) Si, 0.08%-3% Mn, 0.003-0.1% P, 0.07% or less S, 0.1-2.5% Al, 0.1-0.5% Cr, and 0.007% or less N, Si+Al?0.5%, and the balance being Fe and incidental impurities, wherein the steel sheet has a retained austenite content of 3% or more by volume fraction, a stretch-flange formability ?>50% and wherein the average aspect ratio (major axis/minor axis) of retained austenite grains is less than 2.5.
    Type: Application
    Filed: March 17, 2017
    Publication date: July 6, 2017
    Inventors: Hiroshi Matsuda, Tatsuya Nakagaito, Takayuki Futatsuka, Shusaku Takagi, Yasunobu Nagataki
  • Patent number: 9458521
    Abstract: A formable galvanized steel sheet includes, in terms of % by mass, 0.05 to 0.3% of C, 0.01 to 2.5% of Si, 0.5 to 3.5% of Mn, 0.003 to 0.100% of P, 0.02% or less of S, 0.010 to 1.5% of Al, and 0.01 to 0.2% in total of at least one element selected from Ti, Nb and V, the remainder being Fe and unavoidable impurities, having a microstructure composed of, in terms of area fraction, 20 to 87% of ferrite, 3 to 10% in total of martensite and residual austenite, and 10 to 60% of tempered martensite, and a second phase composed of the martensite, residual austenite, and tempered martensite having an average crystal grain diameter of 3 ?m or less, and having a ratio of absorption energy AE to tensile strength TS (AE/TS) not less than 0.063.
    Type: Grant
    Filed: July 2, 2014
    Date of Patent: October 4, 2016
    Assignee: JFE Steel Corporation
    Inventors: Tatsuya Nakagaito, Shusaku Takagi, Saiji Matsuoka, Shinjiro Kaneko
  • Patent number: 9452792
    Abstract: A vehicle collision energy absorbing member is excellent in collision energy absorbing performance in the axial direction upon collision. The vehicle collision energy absorbing member is formed of a high strength thin steel sheet having TS of at least 980 MPa and having an n-value and a limit bending radius Rc satisfying the following Formula: Rc/t?1.31×ln(n)+5.21.
    Type: Grant
    Filed: April 23, 2012
    Date of Patent: September 27, 2016
    Assignees: JFE Steel Corporation, Honda Motor Co., Ltd.
    Inventors: Shusaku Takagi, Kaneharu Okuda, Yoshikiyo Tamai, Takeshi Fujita, Yoshitaka Okitsu, Tadashi Naito, Naoki Takaki, Tomoaki Sugiura
  • Publication number: 20160091140
    Abstract: A hydrogen storage tank includes a liner layer to store hydrogen and a carbon fiber reinforced plastic layer disposed outside the liner layer. The liner layer is formed from a low-alloy steel, and the carbon fiber forming the carbon fiber reinforced plastic layer is a pitch based carbon fiber.
    Type: Application
    Filed: April 24, 2014
    Publication date: March 31, 2016
    Applicant: JEF STEEL CORPORATION
    Inventors: Shusaku Takagi, Akihide Nagao, Mitsuo Kimura, Nobuyuki Ishikawa, Toshio Takano
  • Publication number: 20160060738
    Abstract: Provided is a steel structure for hydrogen gas such as a hydrogen storage tank or a hydrogen line pipe which achieves a lower fatigue crack propagation rate in a high-pressure hydrogen atmosphere than steels used in the related art and has high hydrogen embrittlement resistance. The steel structure for hydrogen gas, which has high hydrogen embrittlement resistance in high-pressure hydrogen gas, has a steel microstructure including any one of 10% to 95% of bainite on an area-ratio basis, 10% to 95% of martensite on an area-ratio basis, and 10% to 95% of pearlite on an area-ratio basis, with the balance being substantially ferrite.
    Type: Application
    Filed: March 28, 2014
    Publication date: March 3, 2016
    Applicant: JFE STEEL CORPORATION
    Inventors: Akihide Nagao, Shusaku Takagi
  • Publication number: 20160053355
    Abstract: A steel material includes: a composition containing, by mass, C: 0.05% to 0.60%, Si: 0.01% to 2.0%, Mn: 0.3% to 3.0%, P: 0.001% to 0.040%, S: 0.0001% to 0.010%, N: 0.0001% to 0.0060%, Al: 0.01% to 1.5%, one or more elements selected from Ti: 0.01% to 0.20%, Nb: 0.01% to 0.20%, and V: 0.01% or more and less than 0.05%, and one or more elements selected from B: 0.0001% to 0.01%, Mo: 0.005% to 2.0%, and Cr: 0.005% to 3.0%, with the balance being Fe and inevitable impurities; and a steel microstructure that includes 95% or more of tempered martensite on a volume fraction basis, that includes a precipitate having a diameter of 100 nm or less and including one or more elements selected from Ti, Nb, and V and one or more elements selected from carbon and nitrogen at a density of 50 particles/?m2 or more, and that includes prior austenite having a grain diameter of 3 ?m or more.
    Type: Application
    Filed: March 28, 2014
    Publication date: February 25, 2016
    Applicant: JFE STEEL CORPORATION
    Inventors: Shusaku Takagi, Akihide Nagao
  • Publication number: 20160017473
    Abstract: A method of manufacturing a galvanized steel sheet includes a two-stage temperature raising process which includes: primary heating the sheet from 200° C. to an intermediate temperature of 500 to 800° C. at a primary average heating rate of 5 to 50° C./second at an excess air ratio of 1.10 to 1.20 maintained up to the intermediate temperature; secondary heating the sheet from the intermediate temperature to an annealing temperature of 730 to 900° C. at a secondary average heating rate of 0.1 to 10° C./second at an excess air ratio of less than 1.10 maintained up to the annealing temperature; holding the sheet to the annealing temperature for 10 to 500 seconds; cooling the sheet to 450 to 550° C. at an average cooling rate of 1 to 30° C./second; and subjecting the sheet to a galvanizing process and, optionally, an alloying process.
    Type: Application
    Filed: September 30, 2015
    Publication date: January 21, 2016
    Inventors: Shusaku Takagi, Kohei Hasegawa
  • Publication number: 20150274218
    Abstract: The present invention provides a vehicle collision energy absorbing member formed by shaping a thin steel sheet. At least one of the thin steel sheet and the vehicle collision energy absorbing member has tensile properties of a tensile strength TS of 980 MPa or more and a yield point elongation Y-El of 2% or more.
    Type: Application
    Filed: November 7, 2013
    Publication date: October 1, 2015
    Applicants: JFE STEEL CORPORATION, HONDA MOTOR CO., LTD.
    Inventors: Shusaku Takagi, Kaneharu Okuda, Yoshikiyo Tamai, Takeshi Fujita, Yoshitaka Okitsu, Tomoaki Sugiura, Naoki Takaki