Patents by Inventor Kohichi Sano
Kohichi Sano 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: 11885025Abstract: A high-strength steel sheet includes a chemical composition including: by mass %, C: 0.080 to 0.500%, Si: 2.50% or less, Mn: 0.50 to 5.00%, P: 0.100% or less, S: 0.0100% or less, Al: 0.001 to 2.500%, N: 0.0150% or less, O: 0.0050% or less, and the balance: Fe and inevitable impurities. The high-strength steel sheet satisfying a predetermined formula has a microstructure in a region from ?t to ?t from a steel sheet surface. The microstructure includes: by volume %, 20% or more of acicular ferrite, 20% or more of an island-shaped hard structure including residual austenite, 2% to 25% of residual austenite, and 20% or less of aggregated ferrite.Type: GrantFiled: December 11, 2018Date of Patent: January 30, 2024Assignee: NIPPON STEEL CORPORATIONInventors: Hiroyuki Kawata, Eisaku Sakurada, Kohichi Sano, Takafumi Yokoyama
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Patent number: 11732341Abstract: In a metal coated steel sheet, a chemical composition contains, in mass %, at least C: 0.03% to 0.70%, Si: 0.25% to 2.50%, Mn: 1.00% to 5.00%, P: 0.100% or less, S: 0.010% or less, sol. Al: 0.001% to 2.500, N: 0.020% or less, and a balance composed of iron and impurities, a metal structure contains greater than 5.0 vol % of retained austenite and greater than 5.0 vol % of tempered martensite, and satisfies a C content in the retained austenite being 0.85 mass % or more.Type: GrantFiled: October 19, 2016Date of Patent: August 22, 2023Assignee: NIPPON STEEL CORPORATIONInventors: Jun Haga, Kohichi Sano, Koutarou Hayashi, Kunio Hayashi, Masaharu Kameda, Akihiro Uenishi, Hiroyuki Kawata
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Patent number: 11680303Abstract: This steel sheet has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder includes hard ferrite, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present, in ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of 3.0 or more is 50% or more, a volume fraction of retained austenite in the soft layer is 80% or less of the volume fraction of the retained austenite in the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 ?m and 10.0 ?m or less from the surface.Type: GrantFiled: March 30, 2018Date of Patent: June 20, 2023Assignee: NIPPON STEEL CORPORATIONInventors: Takafumi Yokoyama, Riki Okamoto, Kohichi Sano, Hiroyuki Kawata, Kohei Ueda, Eisaku Sakurada
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Patent number: 11649531Abstract: A steel sheet has a specific chemical composition and has a structure represented by, by area ratio, ferrite: 5 to 60%, and bainite: 40 to 95%. When a region that is surrounded by a grain boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 ?m or more is defined as a crystal grain, the proportion of crystal grains each having an intragranular misorientation of 5 to 14° to all crystal grains is 20 to 100% by area ratio. A precipitate density of Ti(C,N) and Nb(C,N) each having a circle-equivalent diameter of 10 nm or less is 1010 precipitates/mm3 or more. A ratio (Hvs/Hvc) of a hardness at 20 ?m in depth from a surface (Hvs) to a hardness of the center of a sheet thickness (Hvc) is 0.85 or more.Type: GrantFiled: August 4, 2017Date of Patent: May 16, 2023Assignee: NIPPON STEEL CORPORATIONInventors: Kohichi Sano, Makoto Uno, Ryoichi Nishiyama, Yuji Yamaguchi, Natsuko Sugiura, Masahiro Nakata
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Patent number: 11447848Abstract: A steel sheet wherein a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder including hard ferrite. In the steel sheet, in a ? to ? thickness range, a proportion of retained austenite having an aspect ratio of 2.0 or more is 50% or more, and a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present. When an emission intensity at a wavelength indicating Si is analyzed in the sheet thickness direction from the surface by a radio-frequency glow discharge analysis method, a peak of the emission intensity appears in a range of more than 0.2 ?m and 5.0 ?m or less from the surface.Type: GrantFiled: March 30, 2018Date of Patent: September 20, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Takafumi Yokoyama, Kohichi Sano, Riki Okamoto, Hiroyuki Kawata, Eisaku Sakurada, Yuji Yamaguchi, Kazuki Shiokawa, Yuichi Nakahira, Kohei Ueda, Masahiro Nakata, Satoshi Uchida
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Patent number: 11377710Abstract: A steel sheet has a chemical composition with a steel structure containing, by volume fraction, soft ferrite: 0-30%, retained austenite: 3-40%, fresh martensite: 0-30%, pearlite and cementite: 0-10%, and a remainder including hard ferrite. In the steel sheet, a number proportion of retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, and a soft layer having a thickness of 1-100 ?m is present. In the soft layer, a volume fraction of ferrite grains having an aspect ratio of less than 3.0 is 50% or more, and a volume fraction of retained austenite is 50% or more of the volume fraction of the retained austenite of the inside of the steel sheet. A peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 ?m to 5 ?m or less from the surface.Type: GrantFiled: March 30, 2018Date of Patent: July 5, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Takafumi Yokoyama, Kohichi Sano, Riki Okamoto, Hiroyuki Kawata, Eisaku Sakurada, Yuji Yamaguchi, Kazuki Shiokawa, Yuichi Nakahira, Kohei Ueda, Masahiro Nakata, Satoshi Uchida
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Publication number: 20220186337Abstract: This steel sheet has a predetermined chemical composition, in which the area ratio of plate martensite is 10% or more, the average grain size of prior austenite grains is 2.0 ?m to 10.0 ?m, the maximum diameter thereof is 20.0 ?m or less, the amount of solid solution C in martensite is 0.20 mass % or less, the average carbide size is 0.25 ?m or less, the crystal orientation difference between plate martensite and another martensite adjacent thereto in the same prior austenite grain is 10.0° or less, and the P concentration at grain boundaries of the prior austenite grains is 4.0 at % or less.Type: ApplicationFiled: April 8, 2020Publication date: June 16, 2022Applicant: NIPPON STEEL CORPORATIONInventors: Kohichi SANO, Hiroyuki KAWATA, Kengo TAKEDA
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Publication number: 20220127691Abstract: A high-strength steel sheet includes a chemical composition including: by mass %, C: 0.080 to 0.500%, Si: 2.50% or less, Mn: 0.50 to 5.00%, P: 0.100% or less, S: 0.0100% or less, Al: 0.001 to 2.500%, N: 0.0150% or less, O: 0.0050% or less, and the balance: Fe and inevitable impurities. The high-strength steel sheet satisfying a predetermined formula has a microstructure in a region from ?t to ?t from a steel sheet surface. The microstructure includes: by volume %, 20% or more of acicular ferrite, 20% or more of an island-shaped hard structure including residual austenite, 2% to 25% of residual austenite, and 20% or less of aggregated ferrite.Type: ApplicationFiled: December 11, 2018Publication date: April 28, 2022Applicant: NIPPON STEEL CORPORATIONInventors: Hiroyuki KAWATA, Eisaku SAKURADA, Kohichi SANO, Takafumi YOKOYAMA
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Publication number: 20220119909Abstract: A steel sheet of the present invention is a steel sheet having a predetermined chemical composition and containing at least ferrite, residual austenite, and/or martensite in a microstructure, and furthermore, is a steel sheet in which, in a plane parallel to a rolled surface, an average distance between centers of high Mn regions adjacent to each other is 1.00 mm or less, a density DA of the high Mn regions at a sheet width center portion and a density DB of the high Mn regions at a ¼ position from a sheet width end portion satisfy a relationship of 0.77?DA/DB?1.30, a ratio of an average hardness of the high Mn regions to an average hardness of the low Mn regions is 1.1 to 2.0, and a difference between an average of a top 5% and an average of a bottom 5% of Mn contents in the low Mn regions is 0.3% or more.Type: ApplicationFiled: April 8, 2020Publication date: April 21, 2022Applicant: NIPPON STEEL CORPORATIONInventors: Kohichi SANO, Hiroyuki KAWATA
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Patent number: 11236412Abstract: A steel sheet has a specific chemical composition and has a structure represented by, by area ratio, ferrite: 30 to 95%, and bainite: 5 to 70%. When a region that is surrounded by a grain boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 ?m or more is defined as a crystal grain, the proportion of crystal grains each having an intragranular misorientation of 5 to 14° to all crystal grains is 20 to 100% by area ratio. An average aspect ratio of ellipses equivalent to the crystal grains is 5 or less. An average distribution density of the total of Ti-based carbides and Nb-based carbides each having a grain size of 20 nm or more on ferrite grain boundaries is 10 carbides/?m or less.Type: GrantFiled: August 4, 2017Date of Patent: February 1, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Kohichi Sano, Makoto Uno, Ryoichi Nishiyama, Yuji Yamaguchi, Natsuko Sugiura, Masahiro Nakata
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Patent number: 11230755Abstract: A steel sheet has a specific chemical composition and has a structure represented by, by area ratio, ferrite: 0 to 30%, and bainite: 70 to 100%. When a region that is surrounded by a grain boundary having a misorientation of 15° or more and has a circle-equivalent diameter of 0.3 ?m or more is defined as a crystal grain, the proportion of crystal grains each having an intragranular misorientation of 5 to 14° to all crystal grains is 20 to 100% by area ratio. A grain boundary number density of solid-solution C or a grain boundary number density of the total of solid-solution C and solid-solution B is 1 piece/nm2 or more and 4.5 pieces/nm2 or less. An average grain size of cementite precipitated at grain boundaries is 2 ?m or less.Type: GrantFiled: August 4, 2017Date of Patent: January 25, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Kohichi Sano, Makoto Uno, Ryoichi Nishiyama, Yuji Yamaguchi, Natsuko Sugiura, Masahiro Nakata
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Patent number: 11225701Abstract: A hot dip galvanized steel sheet and hot dip galvannealed steel sheet improved in uniform ductility and local ductility, yield strength and tensile strength, and low temperature impact property, characterized by having a predetermined chemical composition, having a metal structure containing, by volume %, retained austenite: over 5.0% and tempered martensite: over 5.0%, having retained austenite containing C: 0.85 mass % or more, and having a ratio [C]?gb/[P]?gb of an amount of segregation of C (number of atoms/nm2): [C]?gb to an amount of segregation of P (number of atoms/nm2): [P]?gb at prior austenite grain boundaries of 4.0 or more.Type: GrantFiled: March 30, 2018Date of Patent: January 18, 2022Assignee: NIPPON STEEL CORPORATIONInventors: Jun Haga, Kohichi Sano, Koutarou Hayashi, Kunio Hayashi, Masaharu Kameda, Akihiro Uenishi, Hiroyuki Kawata
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Publication number: 20210340653Abstract: A high-strength steel sheet excellent in formability, toughness and weldability has a chemical composition including: by mass %, C: 0.05 to 0.30%, Si: 2.50% or less, Mn: 0.50 to 3.50%, P: 0.100% or less, S: 0.0100% or less, Al: 0.001 to 2.500%, N: 0.0150% or less, O: 0.0050% or less, and the balance consisting of Fe and inevitable impurities. The high-strength steel sheet has a microstructure in a region from ?t (t: sheet thickness) to ?t (t: sheet thickness) from a steel sheet surface, the microstructure including: by volume %, acicular ferrite (3): 20% or more, and martensite (4):10% or more, aggregated ferrite: 20% or less, residual austenite: 2.0% or less, and the martensite satisfies a formula (A), ? i = 1 5 ? ? d i a i 1.5 ? 10.Type: ApplicationFiled: December 11, 2018Publication date: November 4, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Hiroyuki KAWATA, Eisaku SAKURADA, Kohichi SANO, Takafumi YOKOYAMA
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Patent number: 11118252Abstract: A steel sheet includes a hot-dip galvanized layer or a galvannealed layer on a surface of the steel sheet, the steel sheet including: in mass %, C: 0.06% or more and 0.22% or less; Si: 0.50% or more and 2.00% or less; Mn: 1.50% or more and 2.80% or less; Al: 0.02% or more and 1.00% or less; P: 0.001% or more and 0.100% or less; S: 0.0005% or more and 0.0100% or less; N: 0.0005% or more and 0.0100% or less; and a balance: Fe and impurities.Type: GrantFiled: March 30, 2018Date of Patent: September 14, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Kohichi Sano, Hiroyuki Kawata, Yuji Yamaguchi, Satoshi Uchida, Yoshinori Imai, Riki Okamoto
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Publication number: 20210123122Abstract: This steel sheet has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder includes hard ferrite, in the inside of the steel sheet, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present, in ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of less than 3.0 is 50% or more, the volume fraction of retained austenite in the soft layer is less than 50% of the volume fraction of the retained austenite of the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 ?m and 5.0 ?m or less from the surface.Type: ApplicationFiled: March 30, 2018Publication date: April 29, 2021Applicant: Nippon Steel CorporationInventors: Takafumi YOKOYAMA, Kohichi SANO, Riki OKAMOTO, Hiroyuki KAWATA, Eisaku SAKURADA, Yuji YAMAGUCHI, Kazuki SHIOKAWA, Yuichi NAKAHIRA, Kohei UEDA, Masahiro NAKATA, Satoshi UCHIDA
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Publication number: 20210095356Abstract: A steel sheet according to an aspect of the present invention has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder including hard ferrite, in the inside of the steel sheet, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 ?m to 100 ?m from the surface is present in a sheet thickness direction, among ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of less than 3.0 is 50% or more, a volume fraction of retained austenite in the soft layer is 50% or more of the volume fraction of the retained austenite of the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.Type: ApplicationFiled: March 30, 2018Publication date: April 1, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Kohichi SANO, Riki OKAMOTO, Hiroyuki KAWATA, Eisaku SAKURADA, Yuji YAMAGUCHI, Kazuki SHIOKAWA, Yuichi NAKAHIRA, Kohei UEDA, Masahiro NAKATA, Satoshi UCHIDA
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Publication number: 20210047716Abstract: A steel sheet includes a hot-dip galvanized layer or a galvannealed layer on a surface of the steel sheet, the steel sheet including: in mass %, C: 0.06% or more and 0.22% or less; Si: 0.50% or more and 2.00% or less; Mn: 1.50% or more and 2.80% or less; Al: 0.02% or more and 1.00% or less; P: 0.001% or more and 0.100% or less; S: 0.0005% or more and 0.0100% or less; N: 0.0005% or more and 0.0100% or less; and a balance: Fe and impurities.Type: ApplicationFiled: March 30, 2018Publication date: February 18, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Kohichi SANO, Hiroyuki KAWATA, Yuji YAMAGUCHI, Satoshi UCHIDA, Yoshinori IMAI, Riki OKAMOTO
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Publication number: 20210017620Abstract: This steel sheet has a predetermined chemical composition, in which a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder includes hard ferrite, a number proportion of the retained austenite having an aspect ratio of 2.0 or more in the total retained austenite is 50% or more, a soft layer having a thickness of 1 to 100 ?m from a surface in a sheet thickness direction is present, in ferrite contained in the soft layer, a volume fraction of grains having an aspect ratio of 3.0 or more is 50% or more, a volume fraction of retained austenite in the soft layer is 80% or less of the volume fraction of the retained austenite in the inside of the steel sheet, and a peak of an emission intensity at a wavelength indicating Si appears in a range of more than 0.2 ?m and 10.0 ?m or less from the surface.Type: ApplicationFiled: March 30, 2018Publication date: January 21, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Takafumi YOKOYAMA, Riki OKAMOTO, Kohichi SANO, Hiroyuki KAWATA, Kohei UEDA, Eisaku SAKURADA
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Publication number: 20210017622Abstract: A hot dip galvanized steel sheet and hot dip galvannealed steel sheet improved in uniform ductility and local ductility, yield strength and tensile strength, and low temperature impact property, characterized by having a predetermined chemical composition, having a metal structure containing, by volume %, retained austenite: over 5.0% and tempered martensite: over 5.0%, having retained austenite containing C: 0.85 mass % or more, and having a ratio [C]?gb/[P]?gb of an amount of segregation of C (number of atoms/nm2): [C]?gb to an amount of segregation of P (number of atoms/nm2): [P]?gb at prior austenite grain boundaries of 4.0 or more.Type: ApplicationFiled: March 30, 2018Publication date: January 21, 2021Applicant: NIPPON STEEL CORPORATIONInventors: Jun HAGA, Kohichi SANO, Koutarou HAYASHI, Kunio HAYASHI, Masaharu KAMEDA, Akihiro UENISHI, Hiroyuki KAWATA
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Patent number: 10889879Abstract: A steel sheet having a specific chemical composition and structure represented by, by area ratio, ferrite: 5 to 95%, and bainite: 5 to 95%. The proportion of crystal grains having an intragranular misorientation of 5 to 14° to all crystal grains is 20 to 100% by area ratio. Hard crystal grains A in which precipitates or clusters with a maximum diameter of 8 nm or less are dispersed in the crystal grains with a number density of 1×1016 to 1×1019 pieces/cm3. Soft crystal grains B in which precipitates or clusters with a maximum diameter of 8 nm or less are dispersed in the crystal grains with a number density of 1×1015 pieces/cm3 or less are contained. The volume % of the hard crystal grains A/(the volume % of the hard crystal grains A+the volume % of the soft crystal grains B) is 0.1 to 0.9.Type: GrantFiled: August 4, 2017Date of Patent: January 12, 2021Assignee: NIPPON STEEL CORPORATIONInventors: Kohichi Sano, Makoto Uno, Ryoichi Nishiyama, Yuji Yamaguchi, Natsuko Sugiura, Masahiro Nakata