Patents by Inventor Eisaku Sakurada

Eisaku Sakurada 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: 20240167133
    Abstract: This hot-rolled steel sheet has a predetermined chemical composition and has a metallographic structure containing ferrite with an area ratio of 53.0% or more and 76.0% or less, martensite with an area ratio of 3.0% or more and 10.0% or less, bainite with an area ratio of 14.0% or more and 39.0% or less, and pearlite with an area ratio of 2.6% or less, and with an average diameter of martensite of 0.26 ?m or more and 0.70 ?m or less, wherein, among all interfaces of the martensite, the total length of the interfaces between the martensite and the bainite is 75.0% or more with respect to the total length of all interfaces of the martensite.
    Type: Application
    Filed: June 22, 2021
    Publication date: May 23, 2024
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Naoko KATOU, Eisaku SAKURADA, Hitoshi NIKAIDO
  • Patent number: 11981984
    Abstract: Provided is a hot rolled steel sheet having a tensile strength of 780 MPa or more, a sheet thickness of 1.2 to 4.0 mm, and a sheet width of 750 mm or more, and satisfying ?15?(?W 1+?W 2)/2??C?15 (where ?W 1 and ?W 2 respectively indicate hole expansion ratios (%) at ? positions of the sheet width from one end of the hot rolled steel sheet in a sheet width direction perpendicular to a rolling direction and the other end at an opposite side, and ?C indicates a hole expansion ratio (%) of a sheet width center part).
    Type: Grant
    Filed: August 10, 2021
    Date of Patent: May 14, 2024
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Takeshi Toyoda, Eisaku Sakurada
  • Publication number: 20240068066
    Abstract: There is provided a steel sheet having a chemical composition comprising, in mass %, C: 0.05 to 0.25%, Si: 0.2 to 2.0%, Mn: 1.2 to 3.0%, P: 0.030% or less, S: 0.050% or less, Al: 0.01 to 0.55%, N: 0.0100% or less, and Ti: 0.010 to 0.250%, with the balance: Fe and impurities, wherein a random intensity ratio of a texture in a near-surface portion of the steel sheet is 8.0 or less, and a minimum angle formed between a maximum strength orientation in a {110} pole figure of the texture and a normal direction of a rolled surface of the steel sheet is 10° or less.
    Type: Application
    Filed: February 22, 2022
    Publication date: February 29, 2024
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Yasuaki TANAKA, Shohei YABU, Hiroshi SHUTO, Koutarou HAYASHI, Takashi YASUTOMI, Eisaku SAKURADA
  • Patent number: 11885025
    Abstract: 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: Grant
    Filed: December 11, 2018
    Date of Patent: January 30, 2024
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Hiroyuki Kawata, Eisaku Sakurada, Kohichi Sano, Takafumi Yokoyama
  • Publication number: 20230416859
    Abstract: This steel sheet has a predetermined chemical composition, has a microstructure in which a number density of alloy carbides present at grain boundaries and having a major axis of 10 to 100 nm is 1.0×108 to 1.0×1011/cm2 and a number density of alloy carbides present in grains and having a major axis of 10 nm or less is 1.0×1016 to 1.0×1019/cm3, and has a tensile strength of 1,030 MPa or more.
    Type: Application
    Filed: November 18, 2021
    Publication date: December 28, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Hideto HIROSHIMA, Takashi YASUTOMI, Eisaku SAKURADA
  • Publication number: 20230416856
    Abstract: This steel sheet for gas soft nitriding has a predetermined chemical composition and metallographic structure, in which, when a sheet thickness is indicated as t, a sheet width, which is a width in a direction perpendicular to a rolling direction, is indicated as w, and effective grain sizes are measured at seven positions of w/8, w/4, 3w/8, w/2, 5w/8, 3w/4, and 7w/8 in a width direction from an end portion in the width direction at a t/4 depth position from a surface, an average effective grain size, which is an average of the effective grain sizes at the seven positions, is 8.0 to 35.0 ?m, and an effective grain size difference, which is a difference between a maximum value and a minimum value among the effective grain sizes at the seven positions, is 10.0 ?m or less.
    Type: Application
    Filed: February 18, 2022
    Publication date: December 28, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Masafumi AZUMA, Shinya SAITOH, Eisaku SAKURADA
  • Publication number: 20230407430
    Abstract: This steel sheet has predetermined chemical composition and microstructure, in a crystal orientation distribution function of a texture at a sheet thickness ¼ position, when A/B that is a ratio of a maximum value A of pole densities at ?=20° to 60° and ?1=30° to 90° in a cross section of ?2=45° to a maximum value B of pole densities at ?=120° to 60° and ?1=30° to 90° in the cross section of ?2=45° is 1.50 or less, a total of the maximum value A and the maximum value B is 6.00 or less, and a tensile strength is 1030 MPa or more.
    Type: Application
    Filed: November 19, 2021
    Publication date: December 21, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Takashi YASUTOMI, Eisaku SAKURADA
  • Publication number: 20230265548
    Abstract: Provided is a hot rolled steel sheet having a tensile strength of 780 MPa or more, a sheet thickness of 1.2 to 4.0 mm, and a sheet width of 750 mm or more, and satisfying -15?(?W 1 +?W2)/2-?C ?15 (where ?W1 and ?W2 respectively indicate hole expansion ratios (%) at ? positions of the sheet width from one end of the hot rolled steel sheet in a sheet width direction perpendicular to a rolling direction and the other end at an opposite side, and ?C indicates a hole expansion ratio (%) of a sheet width center part).
    Type: Application
    Filed: August 10, 2021
    Publication date: August 24, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Takeshi TOYODA, Eisaku SAKURADA
  • Patent number: 11680303
    Abstract: 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: Grant
    Filed: March 30, 2018
    Date of Patent: June 20, 2023
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Takafumi Yokoyama, Riki Okamoto, Kohichi Sano, Hiroyuki Kawata, Kohei Ueda, Eisaku Sakurada
  • Publication number: 20230140766
    Abstract: This hot-rolled steel sheet has a predetermined chemical composition and predetermined metallographic structure, a ratio between a maximum depth of a region where, on one surface, a rotation angle between a normal line of the one surface and a (011) pole near the normal line of the one surface is 5° or less and a maximum depth of a region where, on the other surface, a rotation angle between a normal line of the other surface and a (011) pole near the normal line of the other surface is 5° or less is 1.00 to 1.20, and a tensile strength is 1150 MPa or more.
    Type: Application
    Filed: April 21, 2021
    Publication date: May 4, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Eisaku SAKURADA, Takashi YASUTOMI, Genki ABUKAWA
  • Publication number: 20230097055
    Abstract: Adopted are a hot-rolled steel sheet having a predetermined chemical composition, in which a region, where a rotation angle between a normal line of a surface and a (011) pole near the normal line becomes 5° or less, is 0.150 or less from the surface in terms of a sheet thickness direction position standardized by a sheet thickness, and a region, where the rotation angle becomes 20° or more, is 0.250 or more from the surface in terms of the sheet thickness direction position standardized by the sheet thickness and a manufacturing method thereof.
    Type: Application
    Filed: April 21, 2021
    Publication date: March 30, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Eisaku SAKURADA, Takashi YASUTOMI, Genki ABUKAWA
  • Patent number: 11572610
    Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, martensite: 2% to 30%, and upper bainite, lower bainite, tempered martensite, retained austenite, and pearlite: 5% or less in total.
    Type: Grant
    Filed: January 25, 2017
    Date of Patent: February 7, 2023
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Katsuya Nakano, Kunio Hayashi, Yuri Toda, Eisaku Sakurada, Akihiro Uenishi
  • Publication number: 20230002848
    Abstract: This hot-rolled steel sheet has a predetermined chemical composition, a microstructure includes 80% or more of tempered martensite by a volume percentage and a remainder consisting of one or more of ferrite, pearlite, bainite, fresh martensite, and residual austenite, the tempered martensite includes 5×109 pieces/mm3 or more of precipitates containing Ti and having an equivalent circle diameter of 5 nm or less per unit volume, in a surface layer region that is a range from a surface to a 1/10 position of a sheet thickness, a sum of an average pole density of a crystal orientation group consisting of {211}<111> to {111}<112> and a pole density in a crystal orientation of {110}<001> is 6.0 or less, and a tensile strength is 980 MPa or more.
    Type: Application
    Filed: December 15, 2020
    Publication date: January 5, 2023
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Genki ABUKAWA, Masafumi AZUMA, Eisaku SAKURADA, Shohei YABU
  • Patent number: 11492687
    Abstract: A steel sheet has a predetermined chemical composition and a metal structure represented by, in area fraction, polygonal ferrite: 40% or less, martensite: 20% or less, bainitic ferrite: 50% to 95%, and retained austenite: 5% to 50%. In area fraction, 80% or more of the bainitic ferrite is composed of bainitic ferrite grains that have an aspect ratio of 0.1 to 1.0 and have a dislocation density of 8×102 (cm/cm3) or less in a region surrounded by a grain boundary with a misorientation angle of 15° or more. In area fraction, 80% or more of the retained austenite is composed of retained austenite grains that have an aspect ratio of 0.1 to 1.0, have a major axis length of 1.0 ?m to 28.0 ?m, and have a minor axis length of 0.1 ?m to 2.8 ?m.
    Type: Grant
    Filed: March 30, 2018
    Date of Patent: November 8, 2022
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Yuri Toda, Eisaku Sakurada, Kunio Hayashi, Akihiro Uenishi
  • Patent number: 11447848
    Abstract: 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: Grant
    Filed: March 30, 2018
    Date of Patent: September 20, 2022
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Takafumi Yokoyama, Kohichi Sano, Riki Okamoto, Hiroyuki Kawata, Eisaku Sakurada, Yuji Yamaguchi, Kazuki Shiokawa, Yuichi Nakahira, Kohei Ueda, Masahiro Nakata, Satoshi Uchida
  • Patent number: 11427900
    Abstract: A steel sheet includes a predetermined chemical composition and a metal structure represented by, in area fraction, ferrite: 50% to 95%, granular bainite: 5% to 48%, tempered martensite: 2% to 30%, upper bainite, lower bainite, fresh martensite, retained austenite, and pearlite: 5% or less in total, and the product of the area fraction of the tempered martensite and a Vickers hardness of the tempered martensite: 800 to 10500.
    Type: Grant
    Filed: January 31, 2017
    Date of Patent: August 30, 2022
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Katsuya Nakano, Kunio Hayashi, Yuri Toda, Eisaku Sakurada, Akihiro Uenishi
  • Patent number: 11377710
    Abstract: 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: Grant
    Filed: March 30, 2018
    Date of Patent: July 5, 2022
    Assignee: NIPPON STEEL CORPORATION
    Inventors: Takafumi Yokoyama, Kohichi Sano, Riki Okamoto, Hiroyuki Kawata, Eisaku Sakurada, Yuji Yamaguchi, Kazuki Shiokawa, Yuichi Nakahira, Kohei Ueda, Masahiro Nakata, Satoshi Uchida
  • Publication number: 20220186333
    Abstract: A high-strength steel sheet includes a predetermined chemical composition, a microstructure contains, by volume percentage, 95% or more of tempered martensite and bainite in total, and a remainder consists of ferrite and pearlite, the microstructure contains 5.0×109 pieces/mm or more of, per unit volume, precipitate having an equivalent circle diameter of 5.0 nm or less and containing Ti, Hvs/Hvc which is a ratio of an average hardness Hvs at a position of a depth of 20 ?m from a surface to an average hardness Hvc at a position of 0.20 to 0.50 mm from the surface is 0.85 or more, a tensile strength is 980 MPa or more, and a product of the tensile strength and elongation is 12,000 MPa×% or more.
    Type: Application
    Filed: March 19, 2020
    Publication date: June 16, 2022
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Masafumi AZUMA, Eisaku SAKURADA, Genki ABUKAWA, Kenichiro OTSUKA, Takeshi TOYODA
  • Publication number: 20220127691
    Abstract: 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: Application
    Filed: December 11, 2018
    Publication date: April 28, 2022
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Hiroyuki KAWATA, Eisaku SAKURADA, Kohichi SANO, Takafumi YOKOYAMA
  • Publication number: 20220112574
    Abstract: A high-strength steel sheet includes a predetermined chemical composition, a microstructure contains, by volume percentage, 80% or more of tempered martensite, and a remainder consists of ferrite and bainite, the microstructure contains 5.0×1011 pieces/mm3 or more of, per unit volume, precipitate containing Ti and having an equivalent circle diameter of 5.0 nm or less, Hvs/Hvc which is a ratio of an average hardness Hvs at a position of a depth of 20 ?m from a surface to an average hardness Hvc at a position of 0.20 to 0.50 mm from the surface is 0.85 or more, and the tensile strength is 1,180 MPa or more.
    Type: Application
    Filed: March 19, 2020
    Publication date: April 14, 2022
    Applicant: NIPPON STEEL CORPORATION
    Inventors: Masafumi AZUMA, Eisaku SAKURADA, Genki ABUKAWA, Kenichiro OTSUKA, Takeshi TOYODA