Patents by Inventor Nobusato Kojima
Nobusato Kojima 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: 20230034898Abstract: A hot-rolled steel sheet has a predetermined chemical composition in which a microstructure includes 99% or more of martensite by volume fraction and a remainder in microstructure including residual austenite and ferrite, in a cross section parallel to a rolling direction, an average aspect ratio of prior austenite grains is less than 3.0, a proportion of sulfides having an aspect ratio of more than 3.0 among sulfides having an area of 1.0 ?m2 or more is 1.0% or, less, in a thickness middle portion, and a pole density of {211} <011> orientation is 3.0 or less, and a tensile strength TS is 980 MPa or higher.Type: ApplicationFiled: January 29, 2021Publication date: February 2, 2023Applicant: NIPPON STEEL CORPORATIONInventors: Masaharu OKA, Nobusato KOJIMA, Mitsuru YOSHIDA
-
Patent number: 11313009Abstract: A hot-rolled steel sheet according to an aspect of the present invention has a predetermined chemical composition, in which, in a location at a depth of ¼ of a sheet thickness from a surface, an area ratio of ferrite is 10% to 55%, a total area ratio of bainite and martensite is 45% to 90%, a total area ratio of the ferrite, the bainite, and the martensite is 90% or more, an average crystal grain size is 12.0 ?m or less, in a texture measured in a sheet thickness central portion, a maximum pole density of orientation groups of {100} <011>, {211} <011>, {311} <011>, {110} <011>, and {332} <113> is 8.0 or less, a total of pole densities of {211} <011> and {332} <113> is 10.0 or less, and a tensile strength is 950 MPa or more.Type: GrantFiled: July 6, 2018Date of Patent: April 26, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Mitsuru Yoshida, Nobusato Kojima, Yuuki Kanzawa, Kohhei Kamiya
-
Publication number: 20220025499Abstract: This steel sheet has a predetermined chemical composition and the steel sheet in which, at a ¼ depth position of a sheet thickness from a surface, an average grain size is 15.0 ?m or less, a total grain boundary number density of solute C and solute B is 1.0 solute/nm2 or more and 12.0 solutes/nm2 or less, a total of pole densities of {211}<011> and {332}<113> in a thickness middle portion is 12.0 or less, and a tensile strength is 780 MPa or more is adopted.Type: ApplicationFiled: March 3, 2020Publication date: January 27, 2022Applicant: NIPPON STEEL CORPORATIONInventors: Mitsuru YOSHIDA, Nobusato KOJIMA
-
Publication number: 20210140005Abstract: A hot-rolled steel sheet according to an aspect of the present invention has a predetermined chemical composition, in which, in a location at a depth of ¼ of a sheet thickness from a surface, an area ratio of ferrite is 10% to 55%, a total area ratio of bainite and martensite is 45% to 90%, a total area ratio of the ferrite, the bainite, and the martensite is 90% or more, an average crystal grain size is 12.0 ?m or less, in a texture measured in a sheet thickness central portion, a maximum pole density of orientation groups of {100} <011>, {211} <011>, {311} <011>, {110} <011>, and {332} <113>is 8.0 or less, a total of pole densities of {211} <011>and {332} <113> is 10.0 or less, and a tensile strength is 950 MPa or more.Type: ApplicationFiled: July 6, 2018Publication date: May 13, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Mitsuru YOSHIDA, Nobusato KOJIMA, Yuuki KANZAWA, Kohhei KAMIYA
-
Patent number: 10907236Abstract: A steel sheet for a drawn can has a predetermined chemical composition and has a ferrite single-phase structure with a crystal grain size number of 11.0 or more, the sheet thickness is 0.15 to 0.50 mm, in an L direction of the steel sheet after an ageing treatment at 100° C. for one hour, an yield strength YP is 220 to 290 MPa, a tensile strength TS is 330 to 390 MPa, a total elongation EL is 32% or more, an yield point elongation YP-EL is 0%, an average plastic strain ratio rm is more than 1.35, and an in-plane anisotropy ?r is ?0.30 to +0.15.Type: GrantFiled: April 19, 2018Date of Patent: February 2, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Masaharu Oka, Nobusato Kojima, Yuta Dairokuno, Michihiro Nono
-
Patent number: 10815553Abstract: Provided is a galvannealed steel sheet having high strength and excellent deep drawability, and being further excellent in slab cracking resistance and secondary working embrittlement resistance. A base metal steel sheet of the galvannealed steel sheet has a chemical composition containing, in mass %: C: 0.0080% or less; Si: 0.7% or less; Mn: 1.0 to 2.5%; P: more than 0.030 to 0.048%; S: 0.025% or less; Al: 0.005 to 0.20%; N: 0.010% or less; Ti: 0.005 to 0.040%; Nb: 0.005 to 0.060%; and B: 0.0005 to 0.0030%, with the balance being Fe and impurities, satisfying Formula (1) to (4). A galvannealed layer contains 7 to 15 mass % of Fe. 25×P+4×Si?3.6??(1) B?X1?0.0005??(2) C?(12/93)×Nb?X2??0.Type: GrantFiled: August 22, 2016Date of Patent: October 27, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Masaharu Oka, Nobusato Kojima, Tetsuya Okada
-
Patent number: 10718033Abstract: A heat-treated steel material is provided having strength of 2.000 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+51×[Si]+102×[Mn]+605>2000” is satisfied. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.2×1016 m?2.Type: GrantFiled: May 26, 2015Date of Patent: July 21, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima
-
Patent number: 10662494Abstract: A heat-treated steel material is provided having strength of 1.800 GPa or more. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+102×[Mn]+605?1800” is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.0×1015 m?2.Type: GrantFiled: May 26, 2015Date of Patent: May 26, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima
-
Patent number: 10603703Abstract: The present invention provides a method of manufacturing a press-formed product. The method includes: a first process of preparing a material that is long in a first direction, and when viewed in a cross-section perpendicular to the first direction, the cross-section is a hollow cross-section that is long in a second direction perpendicular to the first direction; and a second process of bending the material in a direction intersecting the second direction when viewed from the first direction, by pressing the material along the second direction.Type: GrantFiled: September 30, 2015Date of Patent: March 31, 2020Assignee: NIPPON STEEL CORPORATIONInventors: Eiji Isogai, Nobusato Kojima, Riki Okamoto, Yutaka Mikazuki
-
Publication number: 20200048730Abstract: A steel sheet for a drawn can has a predetermined chemical composition and has a ferrite single-phase structure with a crystal grain size number of 11.0 or more, the sheet thickness is 0.15 to 0.50 mm, in an L direction of the steel sheet after an ageing treatment at 100° C. for one hour, an yield strength YP is 220 to 290 MPa, a tensile strength TS is 330 to 390 MPa, a total elongation EL is 32% or more, an yield point elongation YP-EL is 0%, an average plastic strain ratio rm is more than 1.35, and an in-plane anisotropy ?r is ?0.30 to +0.15.Type: ApplicationFiled: April 19, 2018Publication date: February 13, 2020Applicant: NIPPON STEEL CORPORATIONInventors: Masaharu OKA, Nobusato KOJIMA, Yuta DAIROKUNO, Michihiro NONO
-
Patent number: 10435761Abstract: A heat-treated steel material includes: a chemical composition expressed by, in mass %: C: 0.16% to 0.38%; Mn: 0.6% to 1.5%; Cr: 0.4% to 2.0%; Ti: 0.01% to 0.10%; B: 0.001% to 0.010%; Si: 0.20% or less; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ni: 0% to 2.0%; Cu: 0% to 1.0%; Mo: 0% to 1.0%; V: 0% to 1.0%; Al: 0% to 1.0%; Nb: 0% to 1.0%; REM: 0% to 0.1%; and the balance: Fe and impurities; and a structure expressed by: retained austenite: 1.5 volume % or less; and the balance: martensite.Type: GrantFiled: June 6, 2014Date of Patent: October 8, 2019Assignee: NIPPON STEEL CORPORATIONInventors: Shinichiro Tabata, Kazuo Hikida, Nobusato Kojima, Naomitsu Mizui
-
Publication number: 20190218637Abstract: A manufacturing method of a steel component includes: heating a steel sheet in a carburizing atmosphere to form a carburized layer on a surface of the steel sheet, the steel sheet having: a chemical composition represented by: in mass %, C: 0.0005 to 0.1%; Si: 0.01 to 2.0%; Mn: 0.05 to 3.0%; Al: 0.9% or less; P: 0.05% or less; S: 0.01% or less; Ti: 0.0 to 0.2%; Nb: 0.0 to 0.1%; Cr: 0 to 2%; Mo: 0.0 to 0.2%; B: 0.000 to 0.005%; and the balance: Fe and impurities; and a steel structure represented by ferrite with an area fraction of 70% or more; and forming the steel sheet by using metal dies, and performing quenching on the steel sheet in a state of housing the steel sheet in the metal dies to transform the carburized layer into martensite and make a part of the steel sheet on the further inside than the carburized layer to be a steel structure represented by ferrite with an area fraction of 50% or more.Type: ApplicationFiled: October 31, 2016Publication date: July 18, 2019Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Riki OKAMOTO, Nobusato KOJIMA, Kazuo HIKIDA, Noriyuki MAEKAWA
-
Publication number: 20180258514Abstract: Provided is a galvannealed steel sheet having high strength and excellent deep drawability, and being further excellent in slab cracking resistance and secondary working embrittlement resistance. A base metal steel sheet of the galvannealed steel sheet has a chemical composition containing, in mass %: C: 0.0080% or less; Si: 0.7% or less; Mn: 1.0 to 2.5%; P: more than 0.030 to 0.048%; S: 0.025% or less; Al: 0.005 to 0.20%; N: 0.010% or less; Ti: 0.005 to 0.040%; Nb: 0.005 to 0.060%; and B: 0.0005 to 0.0030%, with the balance being Fe and impurities, satisfying Formula (1) to (4). A galvannealed layer contains 7 to 15 mass % of Fe. 25×P+4×Si?3.6??(1) B?X1?0.0005??(2) C?(12/93)×Nb?X2??0.Type: ApplicationFiled: August 22, 2016Publication date: September 13, 2018Inventors: Masaharu OKA, Nobusato KOJIMA, Tetsuya OKADA
-
Patent number: 10060005Abstract: A high-strength hot-formed steel sheet member exhibiting both a consistent hardness and delayed-fracture resistance, and is characterized in that: the high-strength hot-formed steel sheet member has a prescribed chemical composition; the degree of Mn segregation ? (=[maximum Mn concentration (mass %) at the sheet center in the thickness direction]/[average Mn concentration (mass %) at a depth of ¼ of the total thickness of the sheet from the surface]) is less than or equal to 1.6; the steel purity value as defined in JIS G 0555 (2003) is less than or equal to 0.08%; the average grain size for prior ? grains is less than or equal to 10 ?m; and the number density of the residual carbides is less than or equal to 4×103 particles/mm2.Type: GrantFiled: March 26, 2015Date of Patent: August 28, 2018Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kazuo Hikida, Shinichiro Tabata, Nobusato Kojima, Takahiro Moriki
-
Publication number: 20170232492Abstract: The present invention provides a method of manufacturing a press-formed product. The method includes: a first process of preparing a material that is long in a first direction, and when viewed in a cross-section perpendicular to the first direction, the cross-section is a hollow cross-section that is long in a second direction perpendicular to the first direction; and a second process of bending the material in a direction intersecting the second direction when viewed from the first direction, by pressing the material along the second direction.Type: ApplicationFiled: September 30, 2015Publication date: August 17, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Eiji ISOGAI, Nobusato KOJIMA, Riki OKAMOTO, Yutaka MIKAZUKI
-
Publication number: 20170096724Abstract: A high-strength hot-formed steel sheet member exhibiting both a consistent hardness and delayed-fracture resistance, and is characterized in that: the high-strength hot-formed steel sheet member has a prescribed chemical composition; the degree of Mn segregation ? (=[maximum Mn concentration (mass %) at the sheet center in the thickness direction]/[average Mn concentration (mass %) at a depth of ¼ of the total thickness of the sheet from the surface]) is less than or equal to 1.6; the steel purity value as defined in JIS G 0555 (2003) is less than or equal to 0.08%; the average grain size for prior ? grains is less than or equal to 10 ?m; and the number density of the residual carbides is less than or equal to 4×103 particles/mm2.Type: ApplicationFiled: March 26, 2015Publication date: April 6, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kazuo HIKIDA, Shinichiro TABATA, Nobusato KOJIMA, Takahiro MORIKI
-
Publication number: 20170081741Abstract: The present invention provides a heat-treated steel material having strength of 1.800 GPa or more with obtaining excellent toughness and weldability. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0010% to 0.0100%; Si: 0.08% or less; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+102×[Mn]+605?1800” is satisfied where [C] denotes a C content and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 9.0×1015 m?2.Type: ApplicationFiled: May 26, 2015Publication date: March 23, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA
-
Publication number: 20170081742Abstract: The present invention provides a heat-treated steel material having strength of 2.000 GPa or more with obtaining excellent toughness and weldability. The heat-treated steel material includes a chemical composition represented by, in mass %: C: 0.05% to 0.30%; Si: 0.50% to 5.00%; Mn: 2.0% to 10.0%; Cr: 0.01% to 1.00%; Ti: 0.010% to 0.100%; B: 0.0020% to 0.0100%; P: 0.050% or less; S: 0.0500% or less; N: 0.0100% or less; Ni: 0% to 2.0%; each of Cu, Mo, and V: 0% to 1.0%; each of Al and Nb: 0% to 1.00%; and the balance: Fe and impurities. “4612×[C]+51×[Si]+102×[Mn]+605?2000” is satisfied where [C] denotes a C content, [Si] denotes a Si content, and [Mn] denotes a Mn content. The heat-treated steel material includes a microstructure in which 90 volume % or more is formed of martensite, and a dislocation density in the martensite is equal to or more than 1.2×1016 m?2.Type: ApplicationFiled: May 26, 2015Publication date: March 23, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA
-
Publication number: 20170073792Abstract: A hot-formed steel sheet member having a chemical composition includes, in terms of mass %, from 0.08 to 0.16% of C, 0.19% or less of Si, from 0.40 to 1.50% of Mn, 0.02% or less of P, 0.01% or less of S, from 0.01 to 1.0% of sol. Al, 0.01% or less of N, from 0.25 to 3.00% of Cr, from 0.01 to 0.05% of Ti, from 0.001 to 0.01% of B, and a reminder consisting of Fe and impurities, wherein a total volume fraction of martensite, tempered martensite, and bainite is 50% or more, and a volume fraction of ferrite is 3% or less, an average grain size of prior ? grains is 10 ?m or less, and a number density of residual carbides which are present is 4×103 per mm2 or less.Type: ApplicationFiled: May 15, 2015Publication date: March 16, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kazuo HIKIDA, Nobusato KOJIMA, Shinichiro TABATA
-
Publication number: 20160102380Abstract: A heat-treated steel material includes: a chemical composition expressed by, in mass %: C: 0.16% to 0.38%; Mn: 0.6% to 1.5%; Cr: 0.4% to 2.0%; Ti: 0.01% to 0.10%; B: 0.001% to 0.010%; Si: 0.20% or less; P: 0.05% or less; S: 0.05% or less; N: 0.01% or less; Ni: 0% to 2.0%; Cu: 0% to 1.0%; Mo: 0% to 1.0%; V: 0% to 1.0%; Al: 0% to 1.0%; Nb: 0% to 1.0%; REM: 0% to 0.1%; and the balance: Fe and impurities; and a structure expressed by: retained austenite: 1.5 volume % or less; and the balance: martensite.Type: ApplicationFiled: June 6, 2014Publication date: April 14, 2016Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Shinichiro TABATA, Kazuo HIKIDA, Nobusato KOJIMA, Naomitsu MIZUI