Patents by Inventor Yasunobu Nagataki

Yasunobu Nagataki 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: 20200009833
    Abstract: There is provided a high-strength hot-dipped steel sheet having excellent coating adhesion and a method for manufacturing the steel sheet. The steel sheet has a chemical composition, and a coating layer is disposed on the steel sheet. The chemical composition includes, by mass %, C: 0.02% or greater and 0.30% or less, Si: 0.01% or greater and 2.0% or less, Mn: 0.2% or greater and 3.0% or less, P: 0.08% or less, S: 0.02% or less, and Al: 0.001% or greater and 0.40% or less, with the balance being Fe and incidental impurities. The coating layer has a coating weight per side of 30 to 90 g/m2 and contains exfoliated base steel in an amount of 0.3 to 1.5 g/m2.
    Type: Application
    Filed: January 10, 2018
    Publication date: January 9, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Masaki KOBA, Yusuke FUSHIWAKI, Yasunobu NAGATAKI
  • Publication number: 20190390314
    Abstract: Provided are a high-strength galvanized hot-rolled steel sheet and a method for manufacturing the steel sheet. A steel sheet has a chemical composition, and a galvanized layer is disposed on the steel sheet. The chemical composition includes, in mass %, C: 0.02% or greater and 0.30% or less, Si: 0.01% or greater and 2.5% or less, Mn: 0.3% or greater and 3.0% or less, P: 0.08% or less, S: 0.02% or less, and Al: 0.001% or greater and 0.20% or less. The galvanized layer has a coating weight per side of 20 to 120 g/m2. A surface of the steel sheet has a specific surface area ratio, r, of 2.5 or less, and an amount of Si present in the galvanized layer and an amount of Mn present in the galvanized layer respectively satisfy: amount of Si×r?0.06, and amount of Mn×r?0.10.
    Type: Application
    Filed: January 9, 2018
    Publication date: December 26, 2019
    Applicant: JFE Steel Corporation
    Inventors: Masaki Koba, Yusuke Fushiwaki, Yasunobu Nagataki
  • 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
  • Patent number: 10449751
    Abstract: A method for manufacturing a high strength galvanized steel sheet which has a zinc coating layer with an amount of deposition of coating of 20 to 120 g/m2 per one surface on the surface of a base steel sheet having a chemical composition comprising C: 0.03% to 0.35%, Si: 0.01% to 0.50%, Mn: 3.6% to 8.0%, Al: 0.001% to 1.000%, P?0.10%, S?0.010%, and the balance comprising Fe and incidental impurities, on a percent by mass basis, is provided. In annealing and galvanization treatment of the base steel sheet in a continuous galvanizing line, the maximum steel sheet temperature in an annealing furnace is 600° C. or higher and 750° C. or lower, the steel sheet transit time in a temperature region of the steel sheet temperature of 600° C. or higher and 750° C. or lower is specified to be 30 seconds or more and 10 minutes or less, and the dew point in an atmosphere is specified to be ?10° C. or higher.
    Type: Grant
    Filed: March 7, 2013
    Date of Patent: October 22, 2019
    Assignee: JFE STEEL CORPORATION
    Inventors: Yusuke Fushiwaki, Yoshiyasu Kawasaki, Yasunobu Nagataki
  • Publication number: 20190276907
    Abstract: A steel sheet having TS of 590 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a predetermined steel microstructure, where an average aspect ratio of crystal grains of each phase (polygonal ferrite, martensite, and retained austenite) is 2.0 or more and 15.0 or less, wherein the polygonal ferrite has an average grain size of 6 ?m or less, the martensite has an average grain size of 3 ?m or less, the retained austenite has an average grain size of 3 ?m or less, and a value obtained by dividing a Mn content in the retained austenite in mass % by a Mn content in the polygonal ferrite in mass % equals 2.0 or more.
    Type: Application
    Filed: March 8, 2017
    Publication date: September 12, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Takako YAMASHITA, Yoshiyasu KAWASAKI, Takashi KOBAYASHI, Masayasu UENO, Yasunobu NAGATAKI
  • Patent number: 10337094
    Abstract: Provided are a high-strength hot-dip galvanized steel sheet having excellent formability and a tensile strength of 440 MPa or more and a method for manufacturing the same. A steel sheet has a microstructure containing a ferrite phase having an area fraction of 60% or more, a pearlite phase having an area fraction of 20% to 30%, and a bainite phase having an area fraction of 1% to 5%, the area fraction of a cementite phase present in a grain of the ferrite phase being 5% or less. Upon manufacture, a hot-rolled sheet or a cold-rolled sheet is heated to a temperature of 650° C. or higher at an average heating rate of 10° C./s or more, is held at a temperature of 700° C. to (Ac3-5)° C. for ten seconds or more, is cooled to a temperature of 300° C. to 500° C. at an average cooling rate of 10° C./s to 200° C./s, is held at a temperature of 300° C. to 500° C. for 30 seconds to 300 seconds, and is then hot-dip galvanized.
    Type: Grant
    Filed: August 1, 2012
    Date of Patent: July 2, 2019
    Assignee: JFE Steel Corporation
    Inventors: Nobusuke Kariya, Shinjiro Kaneko, Yasunobu Nagataki
  • Publication number: 20190106760
    Abstract: A steel sheet having TS of 980 MPa or more and YR of 68% or more is obtained by providing a predetermined chemical composition and a predetermined steel microstructure, where an average aspect ratio of crystal grains of each phase (polygonal ferrite, martensite, and retained austenite) is 2.0 or more and 20.0 or less, wherein the polygonal ferrite has an average grain size of 4 ?m or less, the martensite has an average grain size of 2 ?m or less, the retained austenite has an average grain size of 2 ?m or less, and a value obtained by dividing a Mn content in the retained austenite in mass % by a Mn content in the polygonal ferrite in mass % equals 2.0 or more.
    Type: Application
    Filed: March 8, 2017
    Publication date: April 11, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Takako YAMASHITA, Yoshiyasu KAWASAKI, Takashi KOBAYASHI, Masayasu UENO, Yasunobu NAGATAKI
  • Publication number: 20190106773
    Abstract: A hot rolled steel sheet having a chemical composition containing, by mass %, C: 0.04% or more and 0.20% or less, Si: 0.7% or more and 2.3% or less, Mn: 0.8% or more and 2.8% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.1% or less, N: 0.008% or less, and the balance being Fe and inevitable impurities. The microstructure of the hot rolled steel sheet includes ferrite and pearlites, in which the area ratio of the ferrite is 75% or more and less than 95%, the mean grain size of the ferrite is 6 ?m or more and 25 ?m or less, the area ratio of pearlite is 5% or more and less than 25%, the mean grain size of pearlite is 2.0 ?m or more, and the mean free path of pearlite is 5 ?m or more.
    Type: Application
    Filed: November 28, 2018
    Publication date: April 11, 2019
    Applicant: JFE Steel Corporation
    Inventors: Yoshiyasu Kawasaki, Shinjiro Kaneko, Yasunobu Nagataki
  • Publication number: 20190093190
    Abstract: A high-strength steel sheet exhibiting excellent ductility and stretch-flangeability, and a method for manufacturing such a high-strength steel sheet. The high-strength steel sheet has a chemical composition including specific proportions of components in which C/Mn is 0.08 to 0.20, the balance being iron and inevitable impurities, and includes microstructures including, in terms of area fraction relative to all the microstructures, 40% to 70% total of ferrite and bainitic ferrite, 5% to 35% martensite and 5% to 30% retained austenite. The proportion of martensite (including retained austenite) adjacent to bainitic ferrite is not less than 60% of all martensite (including retained austenite). The proportion of 4.0 GPa and smaller differences in microhardness measured at 0.5 ?m intervals is not less than 70%. The proportion of microstructures with 8.0 GPa or smaller microhardness is not less than 85% of all the microstructures.
    Type: Application
    Filed: January 30, 2017
    Publication date: March 28, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Fusae SHIIMORI, Shinjiro KANEKO, Yasunobu NAGATAKI
  • Patent number: 10190186
    Abstract: A method of manufacturing a galvanized steel sheet having a composition containing, by mass %, C: 0.05% or more and 0.5% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.5% or more and 3.5% or less, P: 0.003% or more and 0.100% or less, S: 0.02% or less, Al: 0.010% or more and 0.5% or less, B: 0.0002% or more and 0.005% or less, Ti: 0.05% or less, a relationship of Ti>4N being satisfied, and the balance comprising Fe and inevitable impurities, and a microstructure containing 60% or more and 95% or less of tempered martensite in terms of area ratio and 5% or more and 20% or less of retained austenite in terms of area ratio.
    Type: Grant
    Filed: February 12, 2016
    Date of Patent: January 29, 2019
    Assignee: JFE Steel Corporation
    Inventors: Hiroshi Hasegawa, Tatsuya Nakagaito, Shinjiro Kaneko, Yasunobu Nagataki, Yoshitsugu Suzuki
  • Patent number: 10174411
    Abstract: Provided is a high-strength steel sheet that has good chemical convertibility and good corrosion resistance after electro deposition painting despite high Si and Mn contents. Also provided are a method for producing the high-strength steel sheet, a high-strength galvanized steel sheet formed by using the high-strength steel sheet, and a method for producing the high-strength galvanized steel sheet. A steel sheet containing, in terms of % by mass, C: 0.03 to 0.35%, Si: 0.01 to 0.50%, Mn: 3.6 to 8.0%, Al: 0.001 to 1.00%, P?0.10%, S?0.010%, and the balance being Fe and unavoidable impurities is annealed under condition under which a dew point of an atmosphere in a temperature zone of 550° C. or higher and A° C. or lower (A is a particular value that satisfies 600?A?750) inside an annealing furnace is controlled to ?40° C. or lower.
    Type: Grant
    Filed: February 28, 2014
    Date of Patent: January 8, 2019
    Assignee: JFE Steel Corporation
    Inventors: Yusuke Fushiwaki, Yoshiyasu Kawasaki, Yasunobu Nagataki
  • Patent number: 10087500
    Abstract: There is provided a method for manufacturing a high-strength galvannealed steel sheet having excellent coating adhesiveness and corrosion resistance whose base material is a high-strength steel sheet containing Si and Mn. The method includes performing an oxidation treatment on a steel sheet including Si and Mn in a first zone having an atmosphere of an oxygen concentration in the range of more than 0 vol % and less than 1 vol %, thereafter performing an oxidation treatment in a second zone having an atmosphere of an oxygen concentration in the range of 1 vol % or more, thereafter performing reduction annealing and galvanizing, and further performing an alloying treatment by heating the galvanized steel sheet.
    Type: Grant
    Filed: May 19, 2014
    Date of Patent: October 2, 2018
    Assignee: JFE STEEL CORPORATION
    Inventors: Yoichi Makimizu, Yoshitsugu Suzuki, Yasunobu Nagataki
  • Patent number: 9982318
    Abstract: A galvanized steel sheet has formability and crashworthiness, consists of 0.03% to 0.13% C, 1.0% to 2.0% Si, 2.4% to 3.5% Mn, 0.001% to 0.05% P, 0.0001% to 0.01% S, 0.001% to 0.1% Al, 0.0005% to 0.01% N, and 0.0003% to 0.01% B on a mass basis; and optionally contains at least one selected from the following A-C: A: at least one selected from the group consisting of 0.0005% to 0.1% Ti and 0.0005% to 0.05% Nb on a mass basis; B: at least one selected from the group consisting of 0.01% to 1.0% Mo, 0.01% to 2.0% Ni, and 0.01% to 2.0% Cu on a mass basis; and C: 0.001% to 0.
    Type: Grant
    Filed: January 13, 2017
    Date of Patent: May 29, 2018
    Assignee: JFE Steel Corporation
    Inventors: Shinjiro Kaneko, Tatsuya Nakagaito, Hiroshi Hasegawa, Yasunobu Nagataki
  • Patent number: 9932659
    Abstract: A hot-dip galvanized steel sheet having a good appearance and good adhesion to a coating, the hot-dip galvanized steel sheet having a composition containing, on a mass basis: C: 0.08% or more and less than 0.20%, Si: 0.1% to 3.0%, Mn: 0.5% to 3.0%, P: 0.001% to 0.10%, Al: 0.01% to 3.00%, and S: 0.200% or less, a remainder being Fe and incidental impurities, wherein the hot-dip galvanized steel sheet includes an internal oxidation layer and a decarburized layer, the internal oxidation layer having a thickness of 5 ?m or less, the decarburized layer having a thickness of 20 ?m or less, and 50% or more by area of the internal oxidation layer is composed of a Si oxide containing Fe and/or Mn represented by Fe2XMn2-2XSiOY, wherein X ranges from 0 to 1, and Y is 3 or 4.
    Type: Grant
    Filed: September 11, 2014
    Date of Patent: April 3, 2018
    Assignee: JFE Steel Corporation
    Inventors: Minoru Tanaka, Yoshitsugu Suzuki, Yasunobu Nagataki
  • Patent number: 9873934
    Abstract: A hot-dip galvanized steel sheet having a good appearance and good adhesion to a coating, the hot-dip galvanized steel sheet having a composition including, on a mass basis: C: 0.20% to 0.50%, Si: 0.1% to 3.0%, Mn: 0.5% to 3.0%, P: 0.001% to 0.10%, Al: 0.01% to 3.00%, and S: 0.200% or less, a remainder being Fe and incidental impurities, wherein the hot-dip galvanized steel sheet includes an internal oxidation layer and a decarburized layer, the internal oxidation layer having a thickness of 4 ?m or less, the decarburized layer having a thickness of 16 ?m or less, and 50% or more by area of the internal oxidation layer is composed of a Si oxide containing Fe and/or Mn represented by Fe2XMn2-2XSiOY, wherein X ranges from 0 to 1, and Y is 3 or 4.
    Type: Grant
    Filed: September 11, 2014
    Date of Patent: January 23, 2018
    Assignee: JFE Steel Corporation
    Inventors: Minoru Tanaka, Yoshitsugu Suzuki, Yasunobu Nagataki
  • Patent number: 9840749
    Abstract: A high strength galvanized steel sheet has a composition including, C: 0.02% or more and 0.30% or less, Si: 0.01% or more and 2.5% or less, Mn: 0.1% or more and 3.0% or less, P: 0.003% or more and 0.08% or less, S: 0.01% or less, Al: 0.001% or more and 0.20% or less, Ti: 0.03% or more and 0.40% or less and the balance being Fe and inevitable impurities, and a zinc-coated layer having a coating weight per surface of 20 g/m2 or more and 120 g/m2 or less. The concentration ratio of C to Ti (C/Ti) in a portion within 10 ?m from the surface of the base steel sheet is 0.8 or more and 1.5 or less, and the total amount of oxides of one or more selected from Fe, Si, Mn, P, Al and Ti formed in a surface portion within 100 ?m from the surface of the base steel sheet is 0.05 g/m2 or less.
    Type: Grant
    Filed: February 25, 2013
    Date of Patent: December 12, 2017
    Assignee: JFE Steel Corporation
    Inventors: Daisuke Harako, Yoshitsugu Suzuki, Yasunobu Nagataki
  • Patent number: 9828663
    Abstract: Provided is a galvannealed steel sheet with excellent anti-powdering property when press forming is performed, without controlling the contents of chemical elements in steel which are effective for strengthening a steel sheet, such as Si and P, to be low in order to achieve required material properties and without increasing cost due to, for example, processes being complicated. A galvannealed steel sheet with excellent anti-powdering property has a coated layer taking in grains of a base steel sheet such that the grains constitute 2.0% or more and 15.0% or less of the coated layer in terms of cross section area ratio.
    Type: Grant
    Filed: June 18, 2013
    Date of Patent: November 28, 2017
    Assignee: JFE Steel Corporation
    Inventors: Yoichi Makimizu, Yoshitsugu Suzuki, Hideki Nagano, Yasunobu Nagataki
  • Patent number: 9821534
    Abstract: A galvannealed steel sheet includes a zinc coating layer containing 7 to 15% Fe on the surface of steel sheet including, C: 0.02% to 0.30%, Si: 0.01% to 2.5%, Mn: 0.1% to 3.0%, P: 0.003% to 0.08%, S: not more than 0.01%, Al: 0.001% to 0.20%, one or more selected from Ti: 0.03% to 0.40%, Nb: 0.001% to 0.2%, V: 0.001% to 0.2%, Mo: 0.01% to 0.5% and W: 0.001% to 0.2%. In the zinc coating layer, carbides with average particle size of 1 nm to 20 nm including one or more selected from titanium, niobium, vanadium, molybdenum and tungsten are present with a density of five or more particles per segment that is defined by the thickness of the coating layer and also by dividing a cross section of the coating layer at intervals of 1 ?m in a direction perpendicular to the thickness of the coating layer.
    Type: Grant
    Filed: June 15, 2012
    Date of Patent: November 21, 2017
    Assignee: JFE STEEL CORPORATION
    Inventors: Daisuke Harako, Yusuke Fushiwaki, Yoshitsugu Suzuki, Yasunobu Nagataki
  • Patent number: 9765413
    Abstract: A high-strength galvanized steel sheet with high yield ratio having excellent ductility and stretch flange formability, the steel sheet having a chemical composition containing, by mass %, C: 0.04% or more and 0.13% or less, Si: 0.9% or more and 2.3% or less, Mn: 0.8% or more and 2.4% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.1% or less, N: 0.008% or less, and the balance being Fe and inevitable impurities and a microstructure including, in terms of area ratio, 94% or more of a ferrite phase and 2% or less of a martensite ferrite phase, wherein mean grain size of ferrite is 10 ?m or less, Vickers hardness of ferrite is 140 or more, mean grain size of carbide particles existing at grain boundaries of ferrite is 0.5 ?m or less, and aspect ratio of carbide particles existing at the grain boundaries of ferrite is 2.0 or less.
    Type: Grant
    Filed: July 12, 2011
    Date of Patent: September 19, 2017
    Assignee: JFE Steel Corporation
    Inventors: Yoshiyasu Kawasaki, Tatsuya Nakagaito, Shinjiro Kaneko, Yasunobu Nagataki, Keisuke Fukushi
  • Patent number: 9758847
    Abstract: Provided is a hot-rolled steel sheet having a composition containing 0.04 mass percent to 0.20 mass percent C, 0.7 mass percent to 2.3 mass percent Si, 0.8 mass percent to 2.8 mass percent Mn, 0.1 mass percent or less P, 0.01 mass percent or less S, 0.1 mass percent or less Al, and 0.008 mass percent or less N, the remainder being Fe and inevitable impurities. Internal oxides containing one or more selected from the group consisting of Si, Mn, and Fe are present at grain boundaries and in grains in a base metal. The internal oxides present at the grain boundaries in the base metal are located within 5 ?m from the surface of the base metal. The difference between the depths at which the internal oxides are formed in the cross direction of the steel sheet is 2 ?m or less.
    Type: Grant
    Filed: November 2, 2012
    Date of Patent: September 12, 2017
    Assignee: JFE Steel Corporation
    Inventors: Mai Miyata, Yoshitsugu Suzuki, Yasunobu Nagataki, Yoshiyasu Kawasaki, Hirokazu Sugihara