Patents by Inventor Kaoru Kawasaki

Kaoru Kawasaki 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: 11027522
    Abstract: A steel sheet for hot stamping includes a steel structure represented by an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and a product of a number density (pieces/?m2) of carbides and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more.
    Type: Grant
    Filed: January 17, 2017
    Date of Patent: June 8, 2021
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Genki Abukawa, Kunio Hayashi, Kazuo Hikida, Kaoru Kawasaki
  • Patent number: 11028469
    Abstract: A hot press-formed part according to an aspect of the present invention contains a predetermined chemical composition; in which a microstructure in a thickness ¼ portion includes, by unit vol %, tempered martensite: 20% to 90%, bainite: 5% to 75%, and residual austenite: 5% to 25%, and ferrite is limited to 10% or less; and a pole density of an orientation {211}<011> in the thickness ¼ portion is 3.0 or higher.
    Type: Grant
    Filed: August 16, 2016
    Date of Patent: June 8, 2021
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Mutsumi Sakakibara, Natsuko Sugiura, Kunio Hayashi, Kaoru Kawasaki
  • Patent number: 10807138
    Abstract: A tailored blank for hot stamping includes a welded portion formed by butt-welding a first aluminum-plated steel sheet and a second aluminum-plated steel sheet, an Average Al concentration of a weld metal in the welded portion is in a range of 0.3 mass % to 1.5 mass %, an Ac3 point of the weld metal is 1250° C. or lower, and furthermore, an aluminum layer formed during the butt-welding is present on a surface of the welded portion.
    Type: Grant
    Filed: January 5, 2018
    Date of Patent: October 20, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Yasunobu Miyazaki, Yasuaki Naito, Kaoru Kawasaki, Takahiro Yoshinaga
  • Publication number: 20200157666
    Abstract: A hot press-formed part according to an aspect of the present invention contains a predetermined chemical composition; in which a microstructure in a thickness ¼ portion includes, by unit vol %, tempered martensite: 20% to 90%, bainite: 5% to 75%, and residual austenite: 5% to 25%, and ferrite is limited to 10% or less; and a pole density of an orientation {211}<011> in the thickness ¼ portion is 3.0 or higher.
    Type: Application
    Filed: August 16, 2016
    Publication date: May 21, 2020
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Mutsumi SAKAKIBARA, Natsuko SUGIURA, Kunio HAYASHI, Kaoru KAWASAKI
  • Publication number: 20200094525
    Abstract: A steel sheet for hot stamping includes a steel structure represented by an area fraction of bainite, fresh martensite and tempered martensite: 80% or more in total, and a product of a number density (pieces/?m2) of carbides and a proportion of carbides precipitated into prior austenite grains in carbides: 0.50 or more.
    Type: Application
    Filed: January 17, 2017
    Publication date: March 26, 2020
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Genki ABUKAWA, Kunio HAYASHI, Kazuo HIKIDA, Kaoru KAWASAKI
  • Publication number: 20190330711
    Abstract: A blank material is formed from a steel sheet, a first quenching of the blank material is performed, and a second quenching of the blank material is performed after the first quenching. When the first quenching is performed, the blank material is heated to a first temperature of not lower than (Ac3 point—50)° C. nor higher than 1200° C. at an average heating rate of 2° C./sec or more, and the blank material is cooled from the first temperature to a second temperature of 250° C. or lower. When the second quenching is performed, the blank material is heated from the second temperature to a third temperature of not lower than (Ac3 point—50)° C. nor higher than 1200° C. at an average heating rate of 2° C./sec or more, and the blank material is cooled from the third temperature to a fourth temperature of 250° C. or lower. Forming of the blank material is performed in the first quenching or the second quenching or both of the above.
    Type: Application
    Filed: January 17, 2017
    Publication date: October 31, 2019
    Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Genki ABUKAWA, Kunio HAYASHI, Kazuo HIKIDA, Kaoru KAWASAKI
  • Patent number: 10301699
    Abstract: A hot-stamped part includes a chemical composition represented by, in mass %: C: 0.120% to 0.400%; Si: 0.005% to 2.000%; Mn or Cr, or both thereof: 1.00% to 3.00% in total; Al: 0.005% to 0.100%; B: 0.0003% to 0.0020%; P: not more than 0.030%; S: not more than 0.0100%; O: not more than 0.0070%; N: not more than 0.0070%; Ti: 0% to 0.100%; Nb: 0% to 0.100%; V: 0% to 0.100%; Ni: 0% to 2.00%; Cu: 0% to 2.00%; Mo: 0% to 0.50%; Ca or REM, or both thereof: 0% to 0.0300% in total; and the balance: Fe and impurities, and a structure represented by: an area fraction of martensite or bainite, or both thereof: not less than 95% in total; a coverage factor of prior austenite grain boundary by iron-based carbides: not more than 80%; and a number density of iron-based carbides in prior austenite grains: not less than 45/?m2.
    Type: Grant
    Filed: September 12, 2014
    Date of Patent: May 28, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kaoru Kawasaki, Masafumi Azuma, Genki Abukawa
  • Patent number: 10072324
    Abstract: A cold-rolled steel sheet has a predetermined chemical composition, in which a structure before and after a hot-stamping includes ferrite: 30 area % to 90 area %, martensite: 0 area % or more and less than 20 area %, pearlite: 0 area % to 10 area %, retained austenite: 5 volume % to 20 volume %, and rest structure: bainite, a hardness of the retained austenite measured with a nano indenter before and after the hot-stamping satisfies relations of H2/H1<1.1 and ?HM<20, and a relation of TS×El?20000 MPa·% is satisfied.
    Type: Grant
    Filed: August 5, 2013
    Date of Patent: September 11, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 10023931
    Abstract: The present invention provides a method of production of hot dip galvannealed steel sheet with excellent workability compared with the Sendzimir method or non-oxidizing furnace method and further with excellent powdering or slidability, that is, a method of production of hot dip galvannealed steel sheet with excellent workability, powdering, and slidability characterized by processing a slab containing, by mass %, C: 0.01 to 0.12%, Mn: 0.05 to 0.6%, Si: 0.002 to 0.1%, P: 0.05% or less, S: 0.03% or less, sol. Al: 0.005 to 0.1%, and N: 0.01% or less and having a balance of Fe and unavoidable impurities by hot rolling, pickling, cold rolling, then annealing at 650 to 900° C., cooling to 250 to 450° C., holding at said temperature range for 120 seconds or more, then cooling to room temperature, pickling, preplating Ni or Ni—Fe without intermediate temper rolling, heating by 5° C./sec or more down to 430 to 500° C., galvanizing in a galvanization bath, wiping, then heating by a rate of temperature rise of 20° C.
    Type: Grant
    Filed: March 28, 2007
    Date of Patent: July 17, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Junji Haji, Kaoru Kawasaki, Kiyokazu Ishizuka, Teruaki Yamada
  • Patent number: 10023925
    Abstract: A hot stamped article has a component composition containing, in terms of % by mass, 0.002% to 0.1% of C, 0.01% to 0.5% of Si, 0.5% to 2.5% of Mn+Cr, 0.1% or less of P, 0.01% or less of S, 0.05% or less of t-Al, 0.005% or less of N, and 0.0005% to 0.004% of B which is optionally contained in a case where the Mn+Cr is 1.0% or more, the remainder being Fe and unavoidable impurities. The hot stamped article has a microstructure composed of, in terms of an area ratio, 0% or more and less than 90% of martensite, 10% to 100% of bainite, and less than 0.5% of unavoidable inclusion structures, or a microstructure composed of, in terms of an area ratio, 99.5% to 100% of bainitic ferrite, and less than 0.5% of unavoidable inclusion structures.
    Type: Grant
    Filed: May 11, 2012
    Date of Patent: July 17, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventor: Kaoru Kawasaki
  • Patent number: 9970074
    Abstract: A cold-rolled steel sheet includes a predetermined chemical composition, and includes a structure expressed by: an area fraction of ferrite: 95% or more; an area fraction of retained austenite and an area fraction of martensite: 1% to 3% in total; a product of the area fraction of retained austenite and a carbon concentration in retained austenite: 1 or more; a value of I(111)/{I(100)+I(110)} at a region where a depth from a surface is ¼ of a thickness of the cold-rolled steel sheet when intensity of a (hkl) plane is expressed by I(hkl): 2 or less.
    Type: Grant
    Filed: July 1, 2014
    Date of Patent: May 15, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kaoru Kawasaki, Masaharu Kameda, Kohichi Sano, Riki Okamoto
  • Publication number: 20180126437
    Abstract: A tailored blank for hot stamping includes a welded portion formed by butt-welding a first aluminum-plated steel sheet and a second aluminum-plated steel sheet, an Average Al concentration of a weld metal in the welded portion is in a range of 0.3 mass % to 1.5 mass %, an Ac3 point of the weld metal is 1250° C. or lower, and furthermore, an aluminum layer formed during the butt-welding is present on a surface of the welded portion.
    Type: Application
    Filed: January 5, 2018
    Publication date: May 10, 2018
    Applicant: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Yasunobu Miyazaki, Yasuaki Naito, Kaoru Kawasaki, Takahiro Yoshinaga
  • Patent number: 9945013
    Abstract: A hot stamped steel according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure after hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20, and TS×?, which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.
    Type: Grant
    Filed: January 11, 2013
    Date of Patent: April 17, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9920407
    Abstract: A cold rolled steel sheet according to the present invention satisfies an expression of (5×[Si]+[Mn])/[C]>11 when [C] represents an amount of C by mass %, [Si] represents an amount of Si by mass %, and [Mn] represents an amount of Mn by mass %, a metallographic structure before hot stamping includes 40% to 90% of a ferrite and 10% to 60% of a martensite in an area fraction, a total of an area fraction of the ferrite and an area fraction of the martensite is 60% or more, a hardness of the martensite measured with a nanoindenter satisfies an H2/H1<1.10 and ?HM<20 before the hot stamping, and TS×? which is a product of a tensile strength TS and a hole expansion ratio ? is 50000 MPa·% or more.
    Type: Grant
    Filed: January 11, 2013
    Date of Patent: March 20, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9901969
    Abstract: A tailored blank for hot stamping includes a welded portion formed by butt-welding a first aluminum-plated steel sheet and a second aluminum-plated steel sheet, an Average Al concentration of a weld metal in the welded portion is in a range of 0.3 mass % to 1.5 mass %, an Ac3 point of the weld metal is 1250° C. or lower, and furthermore, an aluminum layer formed during the butt-welding is present on a surface of the welded portion.
    Type: Grant
    Filed: March 28, 2013
    Date of Patent: February 27, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yasunobu Miyazaki, Yasuaki Naito, Kaoru Kawasaki, Takahiro Yoshinaga
  • Patent number: 9725782
    Abstract: In a hot stamped steel, when [C] represents an amount of C (mass %), [Si] represents an amount of Si (mass %), and [Mn] represents an amount of Mn (mass %), an expression of 5×[Si]+[Mn])/[C]>10 is satisfied, a metallographic structure includes 80% or more of a martensite in an area fraction, and optionally, further includes one or more of 10% or less of a pearlite in an area fraction, 5% or less of a retained austenite in a volume ratio, 20% or less of a ferrite in an area fraction, and less than 20% of a bainite in an area fraction, TS×?, which is a product of TS that is a tensile strength and ? that is a hole expansion ratio is 50000 MPa·% or more, and a hardness of the martensite measured with a nanoindenter satisfies H2/H1<1.10 and ?HM<20.
    Type: Grant
    Filed: January 11, 2013
    Date of Patent: August 8, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9650690
    Abstract: A high-strength steel sheet includes: 0.03 to 0.20% of C, 0.08 to 1.5% of Si, 0.5 to 3.0% of Mn, 0.05% or less of P, 0.0005% or more of S, 0.008 to 0.20% of acid-soluble Ti, 0.0005 to 0.01% of N, more than 0.01% of acid-soluble Al, and 0.001 to 0.04% of one or both of Ce and La in terms of mass %; and the balance including Fe and inevitable impurities. The ratio of (Ce+La)/acid-soluble Al is equal to or more than 0.1 and the ratio of (Ce+La)/S is in the range of 0.4 to 50 in a mass base, and the density of the number of inclusions, having a circle equivalent diameter of 2 ?m or less, which are present in the steel sheet is equal to or more than 15/mm2.
    Type: Grant
    Filed: June 15, 2009
    Date of Patent: May 16, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kenichi Yamamoto, Katsuhiro Sasai, Hideaki Yamamura, Hiroshi Harada, Kaoru Kawasaki
  • Patent number: 9605329
    Abstract: When the amount of C, the amount of Si and the amount of Mn are respectively represented by [C], [Si] and [Mn] in unit mass %, the cold rolled steel sheet satisfies a relationship of (5×[Si]+[Mn])/[C]>10, the metallographic structure contains, by area ratio, 40% to 90% of a ferrite and 10% to 60% of a martensite, further contains one or more of 10% or less of a pearlite by area ratio, 5% or less of a retained austenite by volume ratio and 20% or less of a bainite by area ratio, the hardness of the martensite measured using a nanoindenter satisfies H20/H10<1.10 and ?HM0<20, and TS×? representing the product of TS that is a tensile strength and ? that is a hole expansion ratio is 50000 MPa·% or more.
    Type: Grant
    Filed: January 11, 2013
    Date of Patent: March 28, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Toshiki Nonaka, Satoshi Kato, Kaoru Kawasaki, Toshimasa Tomokiyo
  • Patent number: 9499894
    Abstract: Exemplary embodiments of the present invention can provide a method for producing hot dip galvannealed steel sheet which exhibits high strength, high ductility, and a significant degree of alloying. Such exemplary method can be applied to, e.g., a pickled hot rolled steel sheet or an annealed and pickled cold rolled steel sheet containing between about 0.02% and about 0.2% C and between about 0.15% and about 2.5% Mn, and may include one or more procedures for rinsing the sheet, preplating the sheet with Ni, rapidly heating the sheet in a nonoxidizing atmosphere to a sheet temperature of about 430° C. to 500° C., then hot dip plating the sheet in a galvanizing bath containing between about 0.05% and about 0.2% Al, and then immediately heating the sheet rapidly for an alloying treatment. Such exemplary method can provide an improved alloying speed, improved plating appearance and better plating adhesion.
    Type: Grant
    Filed: December 26, 2013
    Date of Patent: November 22, 2016
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Kiyokazu Ishizuka, Kazumi Nishimura, Ikuo Kikuchi, Kaoru Kawasaki, Junji Haji
  • Patent number: 9410231
    Abstract: A steel sheet, including: as chemical components, by mass %, 0.05% to 0.35% of C; 0.05% to 2.0% of Si; 0.8% to 3.0% of Mn; 0.01% to 2.0% of Al; equal to or less than 0.1% of P; equal to or less than 0.05% of S; equal to or less than 0.01% of N; and the balance including iron and inevitable impurities, wherein the steel sheet comprises 50% or more of a ferrite phase, a bainite phase, and a tempered martensite phase, 3% or more of a retained austenite phase, and 50% or more of the crystal grains of the retained austenite phase satisfy Expression 1, wherein a carbon concentration at a position of center of gravity is Cgc and a carbon concentration at a grain boundary is Cgb.
    Type: Grant
    Filed: January 31, 2011
    Date of Patent: August 9, 2016
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Riki Okamoto, Natsuko Sugiura, Kohichi Sano, Chisato Wakabayashi, Naoki Yoshinaga, Kaoru Kawasaki