Patents by Inventor Riki Okamoto
Riki Okamoto 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).
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Patent number: 10066283Abstract: This high-strength cold-rolled steel sheet having excellent uniform elongation and hole expandability contains, C: 0.01 to 0.4%; Si: 0.001 to 2.5%; Mn: 0.001 to 4.0%; P: 0.001 to 0.15%; S: 0.0005 to 0.03%; Al: 0.001 to 2.0%; N: 0.0005 to 0.01%; and O: 0.0005 to 0.01%; in which Si+Al is limited to less than 1.0%, and a balance being composed of iron and inevitable impurities, in which at a sheet thickness center portion, an average value of pole densities of the {100}<011> to {223}<110> orientation group is 5.0 or less, and a pole density of the {332}<113> crystal orientation is 4.0 or less, a metal structure contains 5 to 80% of ferrite, 5 to 80% of bainite, and 1% or less of martensite in terms of an area ratio and the total of martensite, pearlite, and retained austenite is 5% or less, and an r value (rC) in a direction perpendicular to a rolling direction is 0.70 or more and an r value (r30) in a direction 30° from the rolling direction is 1.10 or less.Type: GrantFiled: August 29, 2016Date of Patent: September 4, 2018Assignee: NIPPON STEEL AND SUMITOMO METAL CORPORATIONInventors: Yuri Toda, Riki Okamoto, Nobuhiro Fujita, Kohichi Sano, Hiroshi Yoshida, Toshio Ogawa
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Patent number: 10060006Abstract: This high-strength cold-rolled steel sheet contains, in mass %, C: 0.02% to 0.20%; Si: 0.001% to 2.5%; Mn: 0.01% to 4.0%; P: 0.001% to 0.15%; S: 0.0005% to 0.03%; Al: 0.001% to 2.0%; N: 0.0005% to 0.01%; and O: 0.0005% to 0.01%; in which Si+Al is limited to less than 1.0%, and a balance being composed of iron and inevitable impurities, in which an area ratio of bainite in a metal structure is 95% or more, at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a mean volume diameter of crystal grains in the metal structure is 7 ?m or less.Type: GrantFiled: April 20, 2016Date of Patent: August 28, 2018Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yoshihiro Suwa, Kazuaki Nakano, Kunio Hayashi, Riki Okamoto, Nobuhiro Fujita, Kohichi Sano
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Publication number: 20180237881Abstract: 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: ApplicationFiled: August 21, 2015Publication date: August 23, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Riki OKAMOTO, Hiroyuki KAWATA, Masafumi AZUMA, Akihiro UENISHI, Naoki MARUYAMA
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Publication number: 20180230581Abstract: 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: ApplicationFiled: August 31, 2015Publication date: August 16, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Riki OKAMOTO, Hiroyuki KAWATA, Masafumi AZUMA, Akihiro UENISHI, Naoki MARUYAMA
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Publication number: 20180202016Abstract: 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: ApplicationFiled: June 29, 2016Publication date: July 19, 2018Inventors: Takafumi YOKOYAMA, Hiroyuki KAWATA, Riki OKAMOTO
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Patent number: 9988697Abstract: This high-strength hot-rolled steel sheet having excellent local deformability contains, in mass %, C: 0.07% to 0.20%; Si: 0.001% to 2.5%; Mn: 0.01% to 4.0%; P: 0.001% to 0.15%; S: 0.0005% to 0.03%; Al: 0.001% to 2.0%; N: 0.0005% to 0.01%; and O: 0.0005% to 0.01%; and a balance being composed of iron and inevitable impurities, in which an area ratio of bainite in a metal structure is 95% or more, at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet, an average value of pole densities of the {100}<011> to {223}<110> orientation group is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 5.0 or less, and a mean volume diameter of crystal grains in the metal structure is 10 ?m or less.Type: GrantFiled: April 12, 2012Date of Patent: June 5, 2018Assignee: NIPPON STEEL AND SUMITOMO METAL CORPORATIONInventors: Yoshihiro Suwa, Kazuaki Nakano, Kunio Hayashi, Riki Okamoto, Nobuhiro Fujita, Kohichi Sano
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Publication number: 20180148809Abstract: A high-strength steel sheet includes a specific chemical composition, and a microstructure represented by, in area %, martensite: 5% or more; ferrite: 20% or more; and perlite: 5% or less. An average diameter of martensite grain is 4 ?m or less in equivalent circle diameter. A ratio of the number of bulging type martensite grains to the number of martensite grains on grain boundary triple points of a matrix is 70% or more, wherein: the bulging type martensite grain is on one of the grain boundary triple points of the matrix; and at least one of grain boundaries of the bulging type martensite grain, the grain boundaries connecting two adjacent grain boundary triple points of the bulging type martensite grain and grains of the matrix, has a convex curvature to an outer side with respect to line segments connecting the two adjacent grain boundary triple points. An area ratio represented by VM/A0 is 1.Type: ApplicationFiled: May 6, 2016Publication date: May 31, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Riki OKAMOTO, Yoshinari ISHIDA, Yoshihiro SUWA, Takafumi YOKOYAMA
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Patent number: 9970074Abstract: 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: GrantFiled: July 1, 2014Date of Patent: May 15, 2018Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kaoru Kawasaki, Masaharu Kameda, Kohichi Sano, Riki Okamoto
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Publication number: 20180043412Abstract: In performing burring processing on a sheet-like member, the following processes are performed: a punching process of performing punching processing of the sheet-like member; a hole expansion process of performing hole expansion processing of a punched hole formed by the punching process; a re-punching process of performing punching processing again on a portion surrounding the punched hole expanded by force in the hole expansion process; and a burring process of pushing a portion surrounding a re-punched hole that is a punched hole formed by the re-punching process and forming a vertical wall.Type: ApplicationFiled: March 9, 2016Publication date: February 15, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Eiji ISOGAI, Yutaka MIKAZUKI, Riki OKAMOTO
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Publication number: 20180023172Abstract: A steel sheet includes: a base iron; a scale of 10.0 ?m or less in thickness on a surface of the base iron; a subscale between the base iron and the scale. In the subscale, an average value of Cr concentrations is 1.50 mass % to 5.00 mass %, and one part or more exist(s) where a ratio of Cr concentrations between two adjacent measurement regions separate by 1 ?m is 0.90 or less or 1.11 or more in a range of 50 ?m in length in a rolling direction. A percentage of an amount of Ti contained in carbide or carbonitride of 100 nm or more and 1 ?m or less in grain diameter to a parameter Tieff represented by a formula “Tieff=[Ti]?48/14[N]” is 30% or less in which [Ti] denotes a Ti content (mass %) and [N] denotes a N content (mass %).Type: ApplicationFiled: March 28, 2016Publication date: January 25, 2018Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yoshinari ISHIDA, Riki OKAMOTO, Daisuke MAEDA
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Patent number: 9797024Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group of {100}<011> to {223}<110>, which is represented by an arithmetic average of pole density of each orientation of {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> in a center portion of a sheet thickness which is a range of the sheet thickness of ? to ? from a surface of the steel sheet, is 1.0 or more and 4.0 or less, the pole density of a crystal orientation of {332}<113> is 1.0 or more and 4.8 or less, an average grain size in a center in the sheet thickness is 10 ?m or less, and a microstructure includes, by a structural fraction, pearlite more than 6% and ferrite in the balance.Type: GrantFiled: August 17, 2016Date of Patent: October 24, 2017Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Tatsuo Yokoi, Hiroshi Shuto, Riki Okamoto, Nobuhiro Fujita, Kazuaki Nakano, Takeshi Yamamoto
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Patent number: 9752217Abstract: In a hot-rolled steel sheet, an average pole density of an orientation group {100}<011> to {223}<110>, which is represented by an arithmetic mean of pole densities of orientations {100}<011>, {116}<110>, {114}<110>, {112}<110>, and {223}<110> is 1.0 to 4.0 and a pole density of a crystal orientation {332}<113> is 1.0 to 4.8, in a thickness center portion which is a thickness range of ? to ? from the surface of the steel sheet; an average grain size in the thickness center portion is less than or equal to 10 ?m and a grain size of cementite precipitating in a grain boundary of the steel sheet is less than or equal to 2 ?m; and an average grain size of precipitates containing TiC in grains is less than or equal to 3 nm and a number density per unit volume is greater than or equal to 1×1016 grains/cm3.Type: GrantFiled: April 13, 2012Date of Patent: September 5, 2017Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Tatsuo Yokoi, Hiroshi Shuto, Riki Okamoto, Nobuhiro Fujita, Kazuaki Nakano, Takeshi Yamamoto
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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
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Publication number: 20170191140Abstract: A hot-rolled steel sheet wherein an average pole density of orientation group of {100}<011> to {223}<110> is 1.0 to 5.0 and pole density of crystal orientation {332}<113> is 1.0 to 4.0. The hot-rolled steel sheet includes, as a metallographic structure, by area %, 30% to 99% ferrite and bainite in total, and 1% to 70% martensite. The hot-rolled steel sheet satisfies Expression 1: dia?13 ?m, and also satisfies Expression 2: TS/fM×dis/dia?500, wherein an area fraction of the martensite is defined as fM in unit of area %, an average size of the martensite is defined as dia in unit of ?m, an average distance between the martensite is defined as dis in unit of ?m, and tensile strength of the steel sheet is defined as TS in unit of MPa.Type: ApplicationFiled: March 15, 2017Publication date: July 6, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Kohichi SANO, Kunio HAYASHI, Kazuaki NAKANO, Riki OKAMOTO, Nobuhiro FUJITA
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Publication number: 20170183756Abstract: A cold-rolled steel sheet satisfies that an average pole density of an orientation group of {100}<011> to {223}<110> is 1.0 to 5.0, a pole density of a crystal orientation {332}<113> is 1.0 to 4.0, a Lankford-value rC in a direction perpendicular to a rolling direction is 0.70 to 1.50, and a Lankford-value r30 in a direction making an angle of 30° with the rolling direction is 0.70 to 1.50. Moreover, the cold-rolled steel sheet includes, as a metallographic structure, by area %, a ferrite and a bainite of 30% to 99% in total and a martensite of 1% to 70%.Type: ApplicationFiled: January 4, 2017Publication date: June 29, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Yuri TODA, Riki OKAMOTO, Nobuhiro FUJITA, Kohichi SANO, Hiroshi YOSHIDA, Toshio OGAWA, Kunio HAYASHI, Kazuaki NAKANO
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Publication number: 20170159149Abstract: A hot-rolled steel sheet has predetermined chemical composition, a sum of a Si content and an Al content is higher than 0.20% and lower than 0.81%, a microstructure includes, by area fraction, 90% to 99% of a ferrite, 1% to 10% of a martensite, and a bainite limited to 5% or less, the grain size of the martensite is 1 to 10 ?m, the X-ray random intensity ratio of a {211}<011> orientation which is parallel to a rolled surface of the steel sheet and is parallel to a rolling direction is 3.0 or less.Type: ApplicationFiled: May 28, 2014Publication date: June 8, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Takeshi TOYODA, Riki OKAMOTO, Ryohta NIIYA, Hiroshi SAKAI, Hidetoshi SHINDO
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Publication number: 20170130294Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.Type: ApplicationFiled: January 20, 2017Publication date: May 11, 2017Applicant: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Tatsuo YOKOI, Hiroshi SHUTO, Riki OKAMOTO, Nobuhiro FUJITA, Kazuaki NAKANO, Takeshi YAMAMOTO
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Patent number: 9631265Abstract: A hot-rolled steel sheet satisfies that average pole density of orientation group of {100}<011> to {223}<110> is 1.0 to 5.0 and pole density of crystal orientation {332}<113> is 1.0 to 4.0. Moreover, the hot-rolled steel sheet includes, as a metallographic structure, by area %, ferrite and bainite of 30% to 99% in total and martensite of 1% to 70%. Moreover, the hot-rolled steel sheet satisfies following Expressions 1 and 2 when area fraction of the martensite is defined as fM in unit of area %, average size of the martensite is defined as dia in unit of ?m, average distance between the martensite is defined as dis in unit of ?m, and tensile strength of the steel sheet is defined as TS in unit of MPa.Type: GrantFiled: May 24, 2012Date of Patent: April 25, 2017Assignees: NIPPON STEEL, SUMITOMO METAL CORPORATIONInventors: Kohichi Sano, Kunio Hayashi, Kazuaki Nakano, Riki Okamoto, Nobuhiro Fujita
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Patent number: 9587319Abstract: A hot-rolled steel sheet has an average value of the X-ray random intensity ratio of a {100} <011> to {223} <110> orientation group at least in a sheet thickness central portion that is in a sheet thickness range of ? to ? from a steel sheet surface of 1.0 to 6.0, an X-ray random intensity ratio of a {332} <113> crystal orientation of 1.0 to 5.0, rC which is an r value in a direction perpendicular to a rolling direction of 0.70 to 1.10, and r30 which is an r value in a direction that forms an angle of 30° with respect to the rolling direction of 0.70 to 1.10.Type: GrantFiled: January 19, 2016Date of Patent: March 7, 2017Assignee: NIPPON STEEL & SUMITOMO METAL CORPORATIONInventors: Nobuhiro Fujita, Kunio Hayashi, Riki Okamoto, Manabu Takahashi, Tetsuo Kishimoto, Hiroshi Yoshida
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Patent number: 9587287Abstract: The present invention provides a bainite-containing-type high-strength hot-rolled steel sheet. The steel sheet, containing C: greater than 0.07 to 0.2%, Si: 0.001 to 2.5%, Mn: 0.01 to 4%, P: 0.15% or less, S: 0.03% or less, N: 0.01% or less, Al: 0.001 to 2% and a balance being composed of Fe and impurities, has an average value of pole densities of the {100}<011> to {223}<110> orientation group at a sheet thickness center portion being a range of ? to ? in sheet thickness from the surface of the steel sheet is 4.0 or less, and a pole density of the {332}<113> crystal orientation is 4.8 or less, an average crystal grain diameter is 10 ?m or less and vTrs is ?20° C. or lower, and a microstructure is composed of 35% or less in a structural fraction of pro-eutectoid ferrite and a balance of a low-temperature transformation generating phase.Type: GrantFiled: March 29, 2012Date of Patent: March 7, 2017Assignee: NIPPON STEEL AND SUMITOMO METAL CORPORATIONInventors: Tatsuo Yokoi, Hiroshi Shuto, Riki Okamoto, Nobuhiro Fujita, Kazuaki Nakano, Takeshi Yamamoto