Patents by Inventor Tomohiko Omura

Tomohiko Omura 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: 10662497
    Abstract: A high-strength austenitic stainless steel, which has good hydrogen embrittlement resistance and hydrogen fatigue resistance, has a chemical composition including, in mass %, C: up to 0.10%; Si: up to 1.0%; Mn: not less than 3.0% and less than 7.0 %; Cr: 15 to 30%; Ni: not less than 12.0% and less than 17.0%; Al: up to 0.10%; N: 0.10 to 0.50%; P: up to 0.050%; S: up to 0.050%; at least one of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%; and other elements, the balance being Fe and impurities, wherein the ratio of the minor axis to the major axis of the austenite crystal grains is greater than 0.1, the crystal grain size number of austenite crystal grains is not lower than 8.0, and the tensile strength is not less than 1000 MPa.
    Type: Grant
    Filed: October 22, 2015
    Date of Patent: May 26, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Jun Nakamura, Tomohiko Omura, Hiroyuki Hirata, Kana Jotoku, Takahiro Osuki
  • Patent number: 10556298
    Abstract: A welded joint having high strength and good hydrogen embrittlement resistance is provided. A welded joint is a welded joint obtained by welding a base material using a welding material. The base material has a chemical composition of, in mass %: C: 0.005 to 0.1%; Si: up to 1.2%; Mn: 2.5 to 6.5%; Ni: 8 to 15%; Cr: 19 to 25%; Mo: 0.01 to 4.5%; V: 0.01 to 0.5%; Nb: 0.01 to 0.5% Al: less than 0.05%; N: 0.15 to 0.45%; O: up to 0.02%; P: up to 0.05%; and S: up to 0.04%, and a balance being iron and impurities, and which satisfies Equation (1). The welding material has a chemical composition which satisfies Equations (1) and (2). Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6C?29??(1) 0.31C+0.048Si?0.02Mn?0.056Cr+0.007Ni?0.013Mo??1.
    Type: Grant
    Filed: February 20, 2015
    Date of Patent: February 11, 2020
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Kana Jotoku, Hiroyuki Hirata, Tomohiko Omura, Jun Nakamura, Takahiro Osuki
  • Patent number: 10407758
    Abstract: A steel for oil country tubular goods includes, as a chemical composition, by mass %, C, Si, Mn, Al, Mo, P, S, O, N, and a balance containing Fe and impurities, wherein a full width at half maximum HW of a crystal plane corresponding to a (211) crystal plane of an ? phase and a carbon content expressed in mass % in the chemical composition satisfy HW×C1/2?0.38, the carbon content and a molybdenum content expressed in mass % in the chemical composition satisfy C×Mo?0.6, a number of M2C carbides having a hexagonal crystal structure and having an equivalent circle diameter of 1 nm or more is 5 pieces or more per one square micron, and an yield strength is 758 MPa or more.
    Type: Grant
    Filed: June 17, 2013
    Date of Patent: September 10, 2019
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Tomohiko Omura, Yuji Arai, Kaori Kawano, Akihiro Sakamoto, Kazuo Okamura, Kenji Yamamoto, Keiichi Kondo, Koji Nagahashi, Masanao Seo
  • Patent number: 10316383
    Abstract: There is provided an austenitic stainless steel having a high strength and an excellent hydrogen brittleness resistance and further having an excellent machinability. The austenitic stainless steel of the present embodiment has a chemical composition including: in mass %, C: 0.10% or less; Si: 1.0% or less; Mn: 2.1 to 6.0%; P: 0.045% or less; S: 0.1% or less; Ni: 8.0 to 16.0%; Cr: 15.0 to 30.0%; Mo: 1.0 to 5.0%; N: 0.05 to 0.45%; Nb: 0 to 0.50%; and V: 0 to 0.50%, with the balance being Fe and impurities, and satisfying Formula (1). The austenitic stainless steel of the present embodiment has a grain size number of less than 8.0 and a tensile strength of 690 MPa or more. 15?12.6C+1.
    Type: Grant
    Filed: April 17, 2015
    Date of Patent: June 11, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Etsuo Dan, Masaaki Terunuma, Takahiro Osuki, Tomohiko Omura, Jun Nakamura
  • Patent number: 10266909
    Abstract: There is provided an austenitic stainless steel for high-pressure hydrogen gas consisting, by mass percent, of C: 0.10% or less, Si: 1.0% or less, Mn: 3% or more to less than 7%, Cr: 15 to 30%, Ni: 10% or more to less than 17%, Al: 0.10% or less, N: 0.10 to 0.50%, and at least one kind of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%, the balance being Fe and impurities, wherein in the impurities, the P content is 0.050% or less and the S content is 0.050% or less, the tensile strength is 800 MPa or higher, the grain size number (ASTM E112) is No. 8 or higher, and alloy carbo-nitrides having a maximum diameter of 50 to 1000 nm are contained in the number of 0.4/?m2 or larger in cross section observation.
    Type: Grant
    Filed: March 19, 2012
    Date of Patent: April 23, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tomohiko Omura, Jun Nakamura, Hirokazu Okada, Hiroyuki Semba, Yusaku Tomio, Hiroyuki Hirata, Masaaki Igarashi, Kazuhiro Ogawa, Masaaki Terunuma
  • Patent number: 10260125
    Abstract: There is provided an austenitic stainless steel for high-pressure hydrogen gas consisting, by mass percent, of C: 0.10% or less, Si: 1.0% or less, Mn: 3% or more to less than 7%, Cr: 15 to 30%, Ni: 10% or more to less than 17%, Al: 0.10% or less, N: 0.10 to 0.50%, and at least one kind of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%, the balance being Fe and impurities, wherein in the impurities, the P content is 0.050% or less and the S content is 0.050% or less, the tensile strength is 800 MPa or higher, the grain size number (ASTM E112) is No. 8 or higher, and alloy carbo-nitrides having a maximum diameter of 50 to 1000 nm are contained in the number of 0.4/?m2 or larger in cross section observation.
    Type: Grant
    Filed: June 28, 2016
    Date of Patent: April 16, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tomohiko Omura, Jun Nakamura, Hirokazu Okada, Hiroyuki Semba, Yusaku Tomio, Hiroyuki Hirata, Masaaki Igarashi, Kazuhiro Ogawa, Masaaki Terunuma
  • Patent number: 10246765
    Abstract: A martensitic Cr-containing steel having excellent corrosion resistance, SSC resistance, and IGHIC resistance is provided. A martensitic Cr-containing steel according to the present invention includes: a chemical composition consisting of, by mass %, Si: 0.05 to 1.0%, Mn: 0.1 to 1.0%, Cr: 8 to 12%, V: 0.01 to 1.0%, sol. Al: 0.005 to 0.10%, with the balance being Fe and impurities, wherein an effective Cr amount defined by “Cr?16.6×C” is not less than 8%, and an Mo equivalent defined by “Mo+0.5×W” is 0.03 to 2%; a micro-structure wherein a grain size number of prior-austenite crystal grain is not less than 8.0; and a yield strength of less than 379 to 551 MPa, wherein a grain-boundary segregation ratio of Mo and W is not less than 1.5.
    Type: Grant
    Filed: December 24, 2014
    Date of Patent: April 2, 2019
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tomohiko Omura, Yusaku Tomio, Hideki Takabe, Toshio Mochizuki
  • Publication number: 20180258505
    Abstract: An austenitic stainless steel with improved strength, ductility and weldability is provided. An austenitic stainless steel has a chemical composition of, in mass %: 0.005 to 0.07% C; 0.1 to 1.2% Si; 3.2 to 6.5% Mn; 9 to 14% Ni; a total of not less than 0.005% and less than 3% of at least one of Cu and Co; 19 to 24% Cr; 1 to 4% Mo; 0.05 to 0.4% Nb; 0.15 to 0.50% N; up to 0.05% Al; up to 0.03% P; up to 0.002% S; up to 0.02% O; 0 to 0.5% V; 0 to 0.5% Ti; 0 to 0.01% B; 0 to 0.05% Ca; 0 to 0.05% Mg; 0 to 0.5% REM; and the balance being Fe and impurities, where the amount of Nb analyzed as residues after electrolytic extraction is 0.01 to 0.3 mass %.
    Type: Application
    Filed: July 6, 2016
    Publication date: September 13, 2018
    Inventors: Hiroyuki Hirata, Kana Jotoku, Tomohiko Omura, Jun Nakamura, Masaaki Terunuma, Takahiro Osuki, Masaki Ueyama
  • Patent number: 10036078
    Abstract: Low-alloy oil-well steel pipe includes a composition consisting, in mass %, of C: 0.40 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.020% or less, S: 0.0020% or less, Cu: 0.15% or less, Cr: 0.40 to 1.50%, Mo: 0.50 to 2.50%, V: 0.05 to 0.25%, Ti: 0 to less than 0.01%, Nb: 0.01 to 0.2%, sol. Al: 0.010 to 0.100%, N: 0.006% or less, B: 0 to 0.0015%, and Ca: 0 to 0.003%, the balance being Fe and impurities. The structure has tempered martensite and 0 to less than 2% volume ratio of retained austenite. A grain size number of prior-austenite grain in the structure is 9.0 or more. An equivalent circular diameter of a sub-structure surrounded by a boundary having a crystal orientation difference of 15° or more from a packet boundary, a block boundary and a lath boundary is 3 ?m or less for the tempered martensite.
    Type: Grant
    Filed: July 23, 2014
    Date of Patent: July 31, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Yuji Arai, Tomohiko Omura, Keiichi Kondo
  • Publication number: 20180135154
    Abstract: The low alloy steel for oil country tubular goods according to the present invention has a chemical composition containing, by mass percent, C: 0.56 to 1.00%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: at most 0.025%, 5: at most 0.010%, Al: 0.005 to 0.100%, Mo: 0.40 to 1.00%, V: 0.05 to 0.30%, and O: at most 0.010%, the balance being Fe and impurities, wherein the yield stress thereof is at least 862 MPa, and the half-value width of a [211] crystal surface obtained by X-ray diffraction is at most 0.50°.
    Type: Application
    Filed: January 10, 2018
    Publication date: May 17, 2018
    Inventors: Tomohiko OMURA, Yuji ARAI, Kaori KAWANO, Akihiro SAKAMOTO, Kazuo OKAMURA, Kenji YAMAMOTO, Keiichi KONDO
  • Patent number: 9909198
    Abstract: The low alloy steel for oil country tubular goods according to the present invention has a chemical composition containing, by mass percent, C: 0.56 to 1.00%, Si: 0.05 to 0.50%, Mn: 0.05 to 1.00%, P: at most 0.025%, S: at most 0.010%, Al: 0.005 to 0.100%, Mo: 0.40 to 1.00%, V: 0.05 to 0.30%, and O: at most 0.010%, the balance being Fe and impurities, wherein the yield stress thereof is at least 862 MPa, and the half-value width of a [211] crystal surface obtained by X-ray diffraction is at most 0.50°.
    Type: Grant
    Filed: November 5, 2012
    Date of Patent: March 6, 2018
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Tomohiko Omura, Yuji Arai, Kaori Kawano, Akihiro Sakamoto, Kazuo Okamura, Kenji Yamamoto, Keiichi Kondo
  • Publication number: 20170314092
    Abstract: A high-strength austenitic stainless steel, which has good hydrogen embrittlement resistance and hydrogen fatigue resistance, has a chemical composition including, in mass %, C: up to 0.10%; Si: up to 1.0%; Mn: not less than 3.0% and less than 7.0 %; Cr: 15 to 30%; Ni: not less than 12.0% and less than 17.0%; Al: up to 0.10%; N: 0.10 to 0.50%; P: up to 0.050%; S: up to 0.050%; at least one of V: 0.01 to 1.0% and Nb: 0.01 to 0.50%; and other elements, the balance being Fe and impurities, wherein the ratio of the minor axis to the major axis of the austenite crystal grains is greater than 0.1, the crystal grain size number of austenite crystal grains is not lower than 8.0, and the tensile strength is not less than 1000 MPa.
    Type: Application
    Filed: October 22, 2015
    Publication date: November 2, 2017
    Applicant: Nippon Steel & Sumitomo Metal Corporation
    Inventors: Jun NAKAMURA, Tomohiko OMURA, Hiroyuki HIRATA, Kana JOTOKU, Takahiro OSUKI
  • Patent number: 9783876
    Abstract: A stainless steel for oil wells which has excellent high-temperature corrosion resistance and can stably obtain a strength of not less than 758 MPa is provided. The stainless steel for oil wells contains, by masse, C: not more than 0.05%, Si: not more than 1.0%, Mn: 0.01 to 1.0%, P: not more than 0.05%, S: less than 0.002%, Cr: 16 to 18%, Mo: 1.8 to 3%, Cu: 1.0 to 3.5%, Ni: 3.0 to 5.5%, Co: 0.01 to 1.0%, Al: 0.001 to 0.1%, O: not more than 0.05%, and N: not more than 0.05%, the balance being Fe and impurities, and satisfies Formulas (1) and (2): Cr+4Ni+3Mo+2Cu?44??(1) Cr+3Ni+4Mo+2Cu/3?46??(2) where each symbol of element in Formulas (1) and (2) is substituted by the content (mass %) of a corresponding element.
    Type: Grant
    Filed: February 27, 2013
    Date of Patent: October 10, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Shinjiro Nakatsuka, Taro Ohe, Hisashi Amaya, Hideki Takabe, Yohei Otome, Yusaku Tomio, Masanao Seo, Tomohiko Omura, Kunio Kondo
  • Patent number: 9777352
    Abstract: To provide an oil-well steel pipe having excellent SSC resistance. The oil-well steel pipe according to the present invention contains, by mass percent, C: 0.15 to 0.35%, Si: 0.1 to 0.75%, Mn: 0.1 to 1.0%, Cr: 0.1 to 1.7%, Mo: 0.1 to 1.2%, Ti: 0.01 to 0.05%, Nb: 0.010 to 0.030%, Al: 0.01 to 0.1%, P: at most 0.03%, S: at most 0.01%, N: at most 0.007%, and O: at most 0.01%, the balance being Fe and impurities. The Ti content and the Nb content in a residue obtained by bromine-methanol extraction satisfy equation (1): 100×[Nb]/([Ti]+[Nb])?27.5??(1) where the Ti content (mass %) and the Nb content (mass %) in the residue are substituted for [Ti] and [Nb].
    Type: Grant
    Filed: August 17, 2012
    Date of Patent: October 3, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Atsushi Soma, Tomohiko Omura, Yuji Arai, Mitsuhiro Numata, Toru Takayama, Masanao Seo
  • Publication number: 20170029911
    Abstract: There is provided an austenitic stainless steel having a high strength and an excellent hydrogen brittleness resistance and further having an excellent machinability. The austenitic stainless steel of the present embodiment has a chemical composition including: in mass %, C: 0.10% or less; Si: 1.0% or less; Mn: 2.1 to 6.0%; P: 0.045% or less; S: 0.1% or less; Ni: 8.0 to 16.0%; Cr: 15.0 to 30.0%; Mo: 1.0 to 5.0%; N: 0.05 to 0.45%; Nb: 0 to 0.50%; and V: 0 to 0.50%, with the balance being Fe and impurities, and satisfying Formula (1). The austenitic stainless steel of the present embodiment has a grain size number of less than 8.0 and a tensile strength of 690 MPa or more. 15?12.6C+1.
    Type: Application
    Filed: April 17, 2015
    Publication date: February 2, 2017
    Inventors: Etsuo DAN, Masaaki TERUNUMA, Takahiro OSUKI, Tomohiko OMURA, Jun NAKAMURA
  • Patent number: 9546408
    Abstract: A method for quenching a steel pipe by water cooling from an outer surface thereof, where pipe end portions are not subjected to water cooling, and at least part of a main body other than the pipe end portions is subjected to water cooling. A region(s) that is not subjected to direct water cooling over an entire circumference thereof can be along an axial direction at least in part of the main body other than the pipe end portions. The start and stop of water cooling can be intermittent at least in part of the quenching. During the water cooling of the pipe outer surface, an intensified water cooling can be performed in a temperature range in which the pipe outer surface temperature is higher than Ms point. Thereafter, the cooling can be switched to moderate cooling so that the outer surface is cooled down to Ms point or lower.
    Type: Grant
    Filed: March 13, 2012
    Date of Patent: January 17, 2017
    Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATION
    Inventors: Akihiro Sakamoto, Kazuo Okamura, Kenji Yamamoto, Tomohiko Omura, Yuji Arai
  • Publication number: 20160354870
    Abstract: A welded joint having high strength and good hydrogen embrittlement resistance is provided. A welded joint is a welded joint obtained by welding a base material using a welding material. The base material has a chemical composition of, in mass %: C: 0.005 to 0.1%; Si: up to 1.2%; Mn: 2.5 to 6.5%; Ni: 8 to 15%; Cr: 19 to 25%; Mo: 0.01 to 4.5%; V: 0.01 to 0.5%; Nb: 0.01 to 0.5% Al: less than 0.05%; N: 0.15 to 0.45%; O: up to 0.02%; P: up to 0.05%; and S: up to 0.04%, and a balance being iron and impurities, and which satisfies Equation (1). The welding material has a chemical composition which satisfies Equations (1) and (2). Ni+0.65Cr+0.98Mo+1.05Mn+0.35Si+12.6C?29??(1) 0.31C+0.048Si—0.02Mn?0.056Cr+0.007Ni?0.013Mo??1.
    Type: Application
    Filed: February 20, 2015
    Publication date: December 8, 2016
    Inventors: Kana JOTOKU, Hiroyuki HIRATA, Tomohiko OMURA, Jun NAKAMURA, Takihiro OSUKI
  • Publication number: 20160326617
    Abstract: A martensitic Cr-containing steel having excellent corrosion resistance, SSC resistance, and IGHIC resistance is provided. A martensitic Cr-containing steel according to the present invention includes: a chemical composition consisting of, by mass %, Si: 0.05 to 1.0%, Mn: 0.1 to 1.0%, Cr: 8 to 12%, V: 0.01 to 1.0%, sol. Al: 0.005 to 0.10%, with the balance being Fe and impurities, wherein an effective Cr amount defined by “Cr?16.6×C” is not less than 8%, and an Mo equivalent defined by “Mo+0.5×W” is 0.03 to 2%; a micro-structure wherein a grain size number of prior-austenite crystal grain is not less than 8.0; and a yield strength of less than 379 to 551 MPa, wherein a grain-boundary segregation ratio of Mo and W is not less than 1.5.
    Type: Application
    Filed: December 24, 2014
    Publication date: November 10, 2016
    Inventors: Tomohiko Omura, Yusaku Tomio, Hideki Takabe, Toshio Mochizuki
  • Publication number: 20160304983
    Abstract: There is provided an austenitic stainless steel for high-pressure hydrogen gas consisting, by mass percent, of C: 0.10% or less, Si: 1.0% or less, Mn: 3% or more to less than 7%, Cr: 15 to 30%, Ni: 10% or more to less than 17%, Al: 0.10% or less, N: 0.10 to 0.50%, and at least one kind of V: 0.01 to 1.0% and Nb; 0.01 to 0.50%, the balance being Fe and impurities, wherein in the impurities, the P content is 0.050% or less and the S content is 0.050% or less, the tensile strength is 800 MPa or higher, the grain size number (ASTM E112) is No. 8 or higher, and alloy carbo-nitrides having a maximum diameter of 50 to 1000 nm are contained in the number of 0.4/?m2 or larger in cross section observation.
    Type: Application
    Filed: June 28, 2016
    Publication date: October 20, 2016
    Inventors: Tomohiko OMURA, Jun Nakamura, Hirokazu Okada, Hiroyuki Semba, Yusaku Tomio, Hiroyuki Hirata, Masaaki Igarashi, Kazuhiro Ogawa, Masaaki Terunuma
  • Publication number: 20160160307
    Abstract: Low-alloy oil-well steel pipe includes a composition consisting, in mass %, of C: 0.40 to 0.65%, Si: 0.05 to 0.50%, Mn: 0.10 to 1.00%, P: 0.020% or less, S: 0.0020% or less, Cu: 0.15% or less, Cr: 0.40 to 1.50%, Mo: 0.50 to 2.50%, V: 0.05 to 0.25%, Ti: 0 to less than 0.01%, Nb: 0.01 to 0.2%, sol.Al: 0.010 to 0.100%, N: 0.006% or less, B: 0 to 0.0015%, and Ca: 0 to 0.003%, the balance being Fe and impurities. The structure has tempered martensite and 0 to less than 2% volume ratio of retained austenite. A grain size number of prior-austenite grain in the structure is 9.0 or more. An equivalent circular diameter of a sub-structure surrounded by a boundary having a crystal orientation difference of 15° or more from a packet boundary, a block boundary and a lath boundary is 3 ?m or less for the tempered martensite.
    Type: Application
    Filed: July 23, 2014
    Publication date: June 9, 2016
    Inventors: Yuji ARAI, Tomohiko OMURA, Keiichi KONDO