Patents by Inventor Hiroyuki Kawata

Hiroyuki Kawata 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: 20190226046
    Abstract: A steel sheet according to an aspect of the present invention has a chemical composition within a predetermined range; in which a metallographic structure at a thickness ¼ portion includes, by unit area %, ferrite: 10% or more and less than 50%, granular bainite: 5% or more and less than 50%, and martensite: 20% or more and less than 60%; in the metallographic structure at the thickness ¼ portion, a total of upper bainite, lower bainite, residual austenite, and pearlite is 0% or more and less than 15% by unit area %; at the thickness ¼ portion, a product of an area ratio Vm of the martensite and an average hardness Hv of the martensite is 12,000 to 34,000; and a tensile strength is 980 MPa or higher.
    Type: Application
    Filed: September 13, 2016
    Publication date: July 25, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yuri TODA, Kunio HAYASHI, Katsuya NAKANO, Hiroyuki KAWATA, Akihiro UENISHI
  • Publication number: 20190218652
    Abstract: In a metal coated steel sheet, a chemical composition contains, in mass %, at least C: 0.03% to 0.70%, Si: 0.25% to 2.50%, Mn: 1.00% to 5.00%, P: 0.100% or less, S: 0.010% or less, sol. Al: 0.001% to 2.500, N: 0.020% or less, and a balance composed of iron and impurities, a metal structure contains greater than 5.0 vol % of retained austenite and greater than 5.0 vol % of tempered martensite, and satisfies a C content in the retained austenite being 0.85 mass % or more.
    Type: Application
    Filed: October 19, 2016
    Publication date: July 18, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Jun HAGA, Kohichi SANO, Koutarou HAYASHI, Kunio HAYASHI, Masaharu KAMEDA, Akihiro UENISHI, Hiroyuki KAWATA
  • Patent number: 10351937
    Abstract: The present invention provides a high-strength steel sheet excellent in impact resistance. The high-strength steel sheet contains predetermined contents of C, Si, Mn, P, S, Al, Ti, N, and O, with the balance being iron and inevitable impurities, and has a steel sheet structure in which, in a ? thickness to ? thickness region across ¼ of a sheet thickness, 1 to 8% retained austenite is contained in volume fraction, an average aspect ratio of the retained austenite is 2.0 or less, an amount of solid-solution Mn in the retained austenite is 1.1 times an average amount of Mn or more, and TiN grains having a 0.5 ?m average grain diameter or less are contained, and a density of AlN grains with a 1 ?m grain diameter or more is 1.0 pieces/mm2 or less, wherein a maximum tensile strength is 900 MPa or more.
    Type: Grant
    Filed: July 27, 2012
    Date of Patent: July 16, 2019
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Hiroyuki Kawata, Naoki Maruyama, Akinobu Murasato, Akinobu Minami, Hajime Hasegawa, Chisato Wakabayashi, Tsuyoshi Oki
  • Patent number: 10350701
    Abstract: A spot welding method able to simply prevent liquid metal embrittlement cracks in spot welding of plated steel sheets, comprising, before spot welding, removing the plating at least in a zone including the inside of a circle centered at a scheduled location where the center of the nugget is formed and having an outer circumference of the inside of the outer edge of a weld affected zone or a zone at the mated surfaces of the steel sheets to be welded at the inside of a circle sharing a center of a scheduled location becoming the center of the nugget formed at the mated surfaces of the steel sheets and having an outer circumference of the inside of the outer edge of a weld affected zone.
    Type: Grant
    Filed: March 30, 2016
    Date of Patent: July 16, 2019
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Yasunobu Miyazaki, Fuminori Watanabe, Chisato Wakabayashi, Kunio Hayashi, Hiroyuki Kawata, Seiji Furusako, Sho Matsui
  • Publication number: 20190169729
    Abstract: A hot-dip galvanized steel sheet includes: a predetermined chemical composition; and a steel structure represented by: in terms of area ratio, polygonal ferrite: 10% or less; upper bainite: 20% or less; retained austenite: 5% or less; and martensite: 70% or more, in which: martensite having Fe carbides at a number density of 1×106/mm2 or more is contained by 50% or more, in terms of area ratio, with respect to the entire amount of martensite; and the steel structure has an average effective crystal grain diameter of 5.0 ?m or less.
    Type: Application
    Filed: July 15, 2016
    Publication date: June 6, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takafumi YOKOYAMA, Kunio HAYASHI, Masafumi AZUMA, Eisaku SAKURADA, Hiroyuki KAWATA, Genki ABUKAWA
  • Publication number: 20190030637
    Abstract: By obtaining a spot-welded joint being a spot-welded joint formed by overlapping a plurality of pieces of steel plates (1A, 1B) and performing spot welding on the steel plates, including a high-strength steel plate whose tensile strength is 750 (MPa) to 2500 (MPa), being at least one piece of steel plate out of the plurality of pieces of steel plates, in which a carbon equivalent Ceq of the high-strength steel plate is 0.20 mass % to 0.55 mass %, and ten or more of iron-based carbides in each of which a length of a longest portion is 0.1 (?m) or more exist in a square region 103 within a heat-affected zone 4 of a cross section that passes through a center of a welding mark, and is cut along a plate thickness direction of the steel plates (1A, 1B), a cross tensile strength of the spot-welded joint to be formed is improved.
    Type: Application
    Filed: September 28, 2018
    Publication date: January 31, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Chisato WAKABAYASHI, Fuminori WATANABE, Seiji FURUSAKO, Yasunobu MIYAZAKI, Hiroyuki KAWATA, Tohru OKADA, Hideki HAMATANI
  • Publication number: 20190024208
    Abstract: The present method for manufacturing a high strength steel sheet having a tensile strength of 780 MPa or higher includes continuous annealing by heating a steel sheet having a predetermined chemical composition to 750° C. to 900° C. and holding the steel sheet in the temperature range for 0 seconds to 300 seconds, in which, during heating and holding, a hydrogen concentration in a furnace atmosphere is less than 10 volume %, when a temperature of the steel sheet is 700° C. or lower, a furnace body average value is higher than ?3.01 and lower than ?0.07, when the temperature is higher than 700° C. and 800° C. or lower, the value is higher than ?1.36 and lower than ?0.07, when the temperature is higher than 800° C., the value is higher than ?3.01 and ?0.53 or lower, and a dew point is lower than ?10° C.
    Type: Application
    Filed: February 25, 2016
    Publication date: January 24, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takayuki KITAZAWA, Kohei UEDA, Hiroyuki KAWATA, Kaoru HIRAMATSU
  • Publication number: 20190003009
    Abstract: A high-strength steel sheet includes: a specific chemical composition; and a microstructure represented by, in a ? thickness to ? thickness range with ¼ thickness of a sheet thickness from a surface being a center, in volume fraction, ferrite: 85% or less, bainite: 3% or more and 95% or less, tempered martensite: 1% or more and 80% or less, retained austenite: 1% or more and 25% or less, pearlite and coarse cementite: 5% or less in total, and fresh martensite: 5% or less, in which the solid-solution carbon content in the retained austenite is 0.70 to 1.30 mass %, and to all grain boundaries of retained austenite grains having an aspect ratio of 2.50 or less and a circle-equivalent diameter of 0.80 ?m or more, the proportion of interfaces with the tempered martensite or the fresh martensite is 75% or less.
    Type: Application
    Filed: March 23, 2017
    Publication date: January 3, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Hiroyuki KAWATA, Yuji YAMAGUCHI, Takayuki KITAZAWA, Satoshi UCHIDA, Kohei UEDA, Naoki MARUYAMA
  • Publication number: 20180312954
    Abstract: A high-strength hot-dip galvanized steel sheet including a hot-dip galvanized plating layer on a steel sheet base material whose tensile strength is 590 MPa or more, wherein the plating layer includes projecting alloy layers being in contact with the steel sheet base material, a number density of the projecting alloy layers is 4 pieces/mm or more per unit length of an interface between the steel sheet base material and the plating layer when seen from a sectional direction, and a maximum diameter of the projecting alloy layers at the interface is 100 ?m or less, wherein the steel sheet base material includes: a miniaturized layer being directly in contact with the interface between the steel sheet base material and the plating layer; a decarburized layer being in contact with the miniaturized layer and existing on an inward side of the steel sheet base material; and an inner layer other than the miniaturized layer and the decarburized layer, and one kind or two kinds or more of oxides of Si and Mn are contain
    Type: Application
    Filed: February 25, 2016
    Publication date: November 1, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Takeshi YASUI, Hiroyuki KAWATA, Yuji YAMAGUCHI, Ryosuke KOMAMI, Satoshi UCHIDA, Akinobu MURASATO
  • Patent number: 10113223
    Abstract: A hot-dip galvanized steel sheet having a base steel sheet and a hot-dip galvanized layer, a ferrite phase is, by volume fraction, 50% or less in a range of ? thickness to ? thickness centered at a position of ¼ thickness from the surface of the base steel sheet, a hard structure is 50% or more, wherein the hot-dip galvanized steel sheet has the hot-dip galvanized layer in which Fe is 5.0% or less and Al is 1.0% or less, and columnar grains formed of a ? phase is 20% or more in an entire interface between the plated layer and the base steel sheet. On the surface of the base steel sheet, a volume fraction of a residual austenite is 3% or less.
    Type: Grant
    Filed: November 5, 2015
    Date of Patent: October 30, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Hiroyuki Kawata, Takeshi Yasui, Kohei Ueda, Naoki Maruyama, Yuji Yamaguchi, Satoshi Uchida, Ryosuke Komami, Hayato Arai, Toyomitsu Nakamura
  • Publication number: 20180298462
    Abstract: A steel sheet for galvannealed steel contains, by mass %, C: 0.25 to 0.70%, Si: 0.25 to 2.50%, Mn: 1.00 to 5.00%, Al: 0.005 to 3.50%, P: 0.15% or less, S: 0.03% or less, N £ 0.02%, O £ 0.01%, and optionally one or more selected from Ti, Nb, V, Cr, Mo, Cu, Ni, B, Ca, REM, Mg, W, Zr, Sb, Sn, As, Te, Y, Hf and Co, a balance being Fe and impurities. The microstructure consists of, by vol. %, retained g: 10.0 to 60.0%, high-temperature tempered martensite3 5.0%, low-temperature tempered martensite3 5.0%, fresh martensite £ 10.0%, a: 0 to 15.0%, P: 0 to 10.0%, a balance being bainite. Total volume ratio of tempered martensite and bainite is 30.0% or more, tensile strength is 1470 MPa or more, tensile strength×uniform elongation is 13000 MPa % or more, and tensile strength×local elongation is 5000 MPa % or more.
    Type: Application
    Filed: June 10, 2016
    Publication date: October 18, 2018
    Inventors: Kohichi SANO, Jun HAGA, Koutarou HAYASHI, Hiroyuki KAWATA, Riki OKAMOTO, Akihiro UENISHI
  • Publication number: 20180274069
    Abstract: A steel sheet has a predetermined chemical composition, and a surface exhibits an absorption peak at which a reflectance is not less than 50% nor more than 85% in a range of wave numbers of 1200 cm?1 to 1300 cm?1 by a Fourier transform-infrared spectroscopy analysis by a reflection absorption spectrometry method, and does not exhibit an absorption peak in a range of wave numbers of 1000 cm?1 to 1100 cm?1, or exhibits an absorption peak at which a reflectance is 85% or more in the range of wave numbers of 1000 cm?1 to 1100 cm?1, wherein Ni of 3 mg/m2 to 100 mg/m2 adheres to the surface.
    Type: Application
    Filed: September 25, 2015
    Publication date: September 27, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kohei UEDA, Hiroyuki KAWATA, Takayuki KITAZAWA, Takeshi YASUI, Hiroyuki BAN
  • Publication number: 20180243853
    Abstract: The present invention provides a spot welding method for a member to be welded constituted of a plurality of steel sheets that are overlapped with each other at at least a welding zone, in which at least an overlapped face of at least one of the plurality of steel sheets at the welding zone is coated with zinc plating, a total sheet thickness t (mm) of the plurality of steel sheets is 1.35 mm or more, a squeeze time St (seconds) from the time when welding electrodes are brought into contact with the member to be welded to the time when electric current flow for welding starts satisfies “0.020?St”, and a hold time Ht( seconds) after welding from the time when electric current flow for welding between the welding electrodes ends to the time when the welding electrodes and the member to be welded are brought out of contact satisfies “0.015t2+0.020?Ht”.
    Type: Application
    Filed: September 2, 2016
    Publication date: August 30, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Chisato YOSHINAGA, Yasunobu MIYAZAKI, Kunio HAYASHI, Hiroyuki KAWATA, Masanori YASUYAMA
  • Publication number: 20180237881
    Abstract: A steel sheet includes: a predetermined chemical composition; and a steel structure containing, in are a fraction, 2% or more of ferrite and bainite, in which an average dislocation density in the ferrite and an average dislocation density in the bainite are both h3×1012 m/m3 to 1×1014 m/m3, and an average grain diameter of the ferrite and the bainite is 5 ?m or less.
    Type: Application
    Filed: August 21, 2015
    Publication date: August 23, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Riki OKAMOTO, Hiroyuki KAWATA, Masafumi AZUMA, Akihiro UENISHI, Naoki MARUYAMA
  • Publication number: 20180230581
    Abstract: A steel sheet includes: a predetermined chemical composition; and a steel structure represented by, in area %, first martensite in which two or more iron carbides each having a circle-equivalent diameter of 2 nm to 500 nm are contained in each lath: 20% to 95%, ferrite: 15% or less, retained austenite: 15% or less, and the balance: bainite, or second martensite in which less than two iron carbides each having a circle-equivalent diameter of 2 nm to 500 nm are contained in each lath, or the both of these, in which the total area fraction of ND//<111> orientation grains and ND//<100> orientation grains is 40% or less, and the content of solid-solution C is 0.44 ppm or more.
    Type: Application
    Filed: August 31, 2015
    Publication date: August 16, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Riki OKAMOTO, Hiroyuki KAWATA, Masafumi AZUMA, Akihiro UENISHI, Naoki MARUYAMA
  • Publication number: 20180209006
    Abstract: A steel sheet according to an aspect of the present invention has predetermined chemical composition, in which a structure at a thickness ¼ portion includes, in terms of volume ratios, tempered martensite: 30% to 70% and one or both of ferrite and bainite: a total of 20% to 70%, in the structure at the thickness ¼ portion, a volume ratio of residual austenite is less than 10%, a volume ratio of fresh martensite is 10% or less, a volume ratio of pearlite is 10% or less, and a total volume ratio of the residual austenite, the fresh martensite, and the pearlite is 15% or less, a number density of iron-based carbides having a major axis of 5 nm or more in the tempered martensite at the thickness ¼ portion is 5×107 particles/mm2 or more, a ratio of the number of ?-type carbides in the number of the iron-based carbides having the major axis of 5 nm or more at the thickness ¼ portion is 20% or more, and a tensile strength is 780 MPa or higher.
    Type: Application
    Filed: July 13, 2015
    Publication date: July 26, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yuri TODA, Masafumi AZUMA, Akihiro UENISHI, Hiroyuki KAWATA, Naoki MARUYAMA, Genichi SHIGESATO
  • Publication number: 20180202019
    Abstract: A steel sheet according to an aspect of the present invention has predetermined chemical composition, in which a structure at a thickness ¼ portion includes, in terms of volume ratios, tempered martensite: 70% or more and one or both of ferrite and bainite: a total of less than 20%, in the structure at the thickness ¼ portion, a volume ratio of residual austenite is less than 10%, a volume ratio of fresh martensite is 10% or less, a volume ratio of pearlite is 10% or less, and a total volume ratio of the residual austenite, the fresh martensite, and the pearlite is 15% or less, a number density of iron-based carbides having a major axis of 5 nm or more in the tempered martensite at the thickness ¼ portion is 5×107 particles/mm2 or more, a ratio of the number of ?-type carbides in the number of the iron-based carbides having the major axis of 5 nm or more at the thickness ¼ portion is 20% or more, and a tensile strength is 780 MPa or higher.
    Type: Application
    Filed: July 13, 2015
    Publication date: July 19, 2018
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yuri TODA, Masafumi AZUMA, Akihiro UENISHI, Hiroyuki KAWATA, Naoki MARUYAMA, Genichi SHIGESATO
  • Publication number: 20180202016
    Abstract: A high-strength cold-rolled steel sheet is provided that has a chemical composition that consists of, by mass %, C: 0.050 to 0.40%, Si: 0.01 to 3.0%, Mn: 1.0 to 5.0%, sol. Al: 0.001 to 1.0%, Ti: 0.005 to 0.20%, B: 0.0005 to 0.010%, P: 0.1% or less, S: 0.01% or less, O: 0.1% or less, N: 0.01% or less, Cr: 0 to 1.0%, Mo: 0 to 1.0%, Ni: 0 to 1.0%, Cu: 0 to 1.0%, Sn: 0 to 0.50%, Nb: 0 to 0.20%, V: 0 to 0.50%, W: 0 to 0.50%, Ca: 0 to 0.01%, Mg: 0 to 0.01%, Bi: 0 to 0.01%, Sb: 0 to 0.10%, Zr: 0 to 0.01%, and REM: 0 to 0.01%, with the balance being Fe and impurities, and that satisfies the formulas [sol. Bs/B?0.50] and [sol. Bq/B>0.50] (where, B: B amount in the steel; sol. Bs: soluble B amount in a surface layer portion of the steel; and sol. Bq: soluble B amount in the steel interior).
    Type: Application
    Filed: June 29, 2016
    Publication date: July 19, 2018
    Inventors: Takafumi YOKOYAMA, Hiroyuki KAWATA, Riki OKAMOTO
  • Patent number: 10023947
    Abstract: High strength steel plate with an ultimate tensile strength of 900 MPa or more which is excellent in hydrogen embrittlement resistance characterized in that, in the structure of the steel plate, (a) by volume fraction, ferrite is present in 10 to 50%, bainitic ferrite and/or bainite in 10 to 60%, and tempered martensite in 10 to 50%, and (b) iron-based carbides which contain Si or Si and Al in 0.1% or more are present in 4×108 (particles/mm3) or more.
    Type: Grant
    Filed: November 30, 2010
    Date of Patent: July 17, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Masafumi Azuma, Noriyuki Suzuki, Naoki Maruyama, Akinobu Murasato, Yasuharu Sakuma, Hiroyuki Kawata, Chisato Wakabayashi
  • Patent number: 9988700
    Abstract: The present invention provides a high-strength steel sheet excellent in shape fixability. The high-strength steel sheet contains C, Si, Mn, P, S, Al, N, and O with predetermined contents, in which a retained austenite phase of 5 to 20% in volume fraction is contained, an amount of solid-solution C contained in the retained austenite phase is 0.80 to 1.00% in mass %, WSi? is 1.10 times or more WSi*, WMn? is 1.10 times or more WMn*, and when a frequency distribution is measured with respect to a sum of a ratio between WSi and WSi* and a ratio between WAl and WAl*, a mode value of the frequency distribution is 1.95 to 2.05, and a kurtosis is 2.00 or more.
    Type: Grant
    Filed: July 27, 2012
    Date of Patent: June 5, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Akinobu Minami, Hiroyuki Kawata, Akinobu Murasato, Yuji Yamaguchi, Natsuko Sugiura, Takuya Kuwayama, Naoki Maruyama, Takamasa Suzuki