Patents by Inventor Taro Kizu

Taro Kizu 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: 20210129491
    Abstract: Provided is a high-strength hot-rolled coated steel sheet with excellent formability, A high-strength hot-rolled coated steel sheet has a constituent composition containing, in a mass percent, C: 0.03% to 0.15%, Si: 0.4% or less, Mn: 1.2% to 1.9%, Ti: 0.05% to 0.25%, B: 0.0005% to 0.0050%, P: 0.03% or less, S: 0.005% or less, Al: 0.005% to 0.4%, and N: 0.01% or less, the balance being Fe and incidental impurities. The total area fraction of one or more of ferrite and tempered bainite is 90% or more. The steel sheet has a structure in which the volume fraction of Ti carbides having particle sizes of 20 nm or less is 0.05 vol % or more.
    Type: Application
    Filed: February 26, 2018
    Publication date: May 6, 2021
    Applicant: JFE Steel Corporation
    Inventors: Sota Goto, Kazuhiko Yamazaki, Taro Kizu, Shunsuke Toyoda
  • Publication number: 20210017636
    Abstract: There is provided a galvanized steel sheet more highly excellent in terms of punchability. The steel sheet has a specified chemical composition and a microstructure including a ferrite phase and a tempered bainite phase in a total amount of 95% or more in terms of area ratio, in which the average grain diameter of the microstructure is 5.0 ?m or less, the amount of Fe precipitated is 0.10 mass % or more, the amount of Ti, Nb, and V precipitated in the form of precipitates having a grain diameter of less than 20 nm is 0.025 mass % or more in terms of precipitate C equivalent, and half or more of precipitates having a grain diameter of less than 20 nm are formed at random.
    Type: Application
    Filed: February 1, 2018
    Publication date: January 21, 2021
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro KIZU, Noriaki MORIYASU, Shigeyuki NABESHIMA, Kazunori TAHARA, Kana SASAKI
  • Patent number: 10815547
    Abstract: A high strength steel sheet having high strength such as a tensile strength of 780 MPa or more and having excellent blanking workability and stretch flangeability and a manufacturing method therefor are provided. A high strength steel sheet comprises: a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.6% to 2.0%, Mn: 1.3% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 2.0% or less, N: 0.010% or less, and one or more of Ti, Nb, and V: 0.01% to 1.0% each, with a balance being Fe and incidental impurities; a ferrite microstructure of 50% or more in area ratio; an amount of precipitated Fe of 0.04 mass % or more; and a precipitate with a particle size of less than 20 nm, wherein C* and C*p satisfy specific conditions.
    Type: Grant
    Filed: March 1, 2016
    Date of Patent: October 27, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Shunsuke Toyoda, Akimasa Kido, Tetsushi Tadani
  • Patent number: 10533236
    Abstract: A method of manufacturing a high-strength hot rolled steel sheet by hot rolling a steel having a chemical composition including, by mass %: C: more than 0.010% and not more than 0.06%, Si: not more than 0.3%, Mn: not more than 0.8%, P: not more than 0.03%, S: not more than 0.02%, Al: not more than 0.1%, N: not more than 0.01% and Ti: 0.05 to 0.10%, the balance including Fe and inevitable impurities, including: after the steel is heated to an austenite single phase region, the steel is finish rolled at a finishing delivery temperature of 860° C. to 1050° C., the steel sheet is cooled at an average cooling rate of not less than 30° C./s in a temperature range of from a temperature after the completion of the finish rolling to 750° C., and the steel sheet is coiled into a coil at a coiling temperature of 580° C. to 700° C.
    Type: Grant
    Filed: April 11, 2017
    Date of Patent: January 14, 2020
    Assignee: JFE Steel Corporation
    Inventors: Yoshimasa Funakawa, Tetsuo Yamamoto, Hiroshi Uchomae, Hiroshi Nakano, Taro Kizu
  • Patent number: 10526678
    Abstract: This disclosure provides a predetermined composition, where a conversion value C* of total carbon contents in Ti, Nb and V precipitates whose grain sizes are less than 20 nm is 0.010 mass % to 0.100 mass %, Fe content in Fe precipitates is 0.03 mass % to 0.50 mass %, and an average grain size of ferrite grains whose grain sizes are top 5 % large in ferrite grain size distribution of rolling direction cross section is (4000/TS)2 ?m or less, the TS indicating tensile strength in unit of MPa.
    Type: Grant
    Filed: July 5, 2016
    Date of Patent: January 7, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Shunsuke Toyoda, Akimasa Kido, Tetsushi Tadani
  • Publication number: 20190309396
    Abstract: A steel sheet has a composition containing, by mass %, C: 0.04% to 0.20%, Si: 0.6% to 1.5%, Mn: 1.0% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, N: 0.010% or less, one, two, or all of Ti, Nb, and V in an amount of 0.01% to 1.0% each, and the balance being Fe and inevitable impurities, a microstructure including, in terms of area ratio, 50% or more of ferrite, in which an average grain diameter at a position located 50 ?m from a surface of the steel sheet in a thickness direction is 3000×(tensile strength TS (MPa))?0.85 ?m or less, C precipitates having a grain diameter of less than 20 nm formed in steel is 0.010 mass % or more, and a amount of precipitated Fe is 0.03 mass % to 1.0 mass %, and a roughness Ra of 3.0 ?m or less.
    Type: Application
    Filed: December 13, 2016
    Publication date: October 10, 2019
    Inventors: Taro Kizu, Akimasa Kido, Tetsushi Tadani
  • Publication number: 20190078172
    Abstract: A high-strength thin steel sheet having a high yield ratio and excellent formability and a manufacturing method therefor are provided. The steel sheet contains C: 0.04 to 0.25%, Si: 0.5 to 2.0%, Mn: 0.1 to 2.0%, P: 0.05% or less, S: 0.030% or less, Al: 0.10% or less, and N: 0.010% or less, with the balance being iron and incidental impurities; and has a microstructure containing, in area fraction, 90% or more of ferrite and bainite in total, where ferrite and bainite each have an aspect ratio of 3.0 or higher.
    Type: Application
    Filed: March 2, 2017
    Publication date: March 14, 2019
    Applicant: JFE Steel Corporation
    Inventor: Taro Kizu
  • Publication number: 20190055621
    Abstract: A steel sheet and a method for producing the steel sheet are provided. The steel sheet is provided having a composition including C: 0.05% to 0.15%, Si: 0.1% or less, Mn: 1.0% to 2.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, and N: 0.010% or less, and including one or two or more of Ti, Nb, and V, the remainder being iron and incidental impurities. The steel sheet has a microstructure containing, on an area percent basis, ferrite: 80% or more, and bainite and martensite: 1% to 20% in total. The ferrite has an average grain size of 10.0 ?m or less, and a phase containing bainite and martensite has an average grain size of 3.0 ?m or less. The ratio of the average grain size of the phase containing bainite and martensite to the average grain size of the ferrite is 0.3 or less.
    Type: Application
    Filed: March 21, 2017
    Publication date: February 21, 2019
    Applicant: JFE Steel Corporation
    Inventors: Taro Kizu, Imanuel Tarigan, Minoru Utake, Yuichi Ozawa
  • Publication number: 20180371574
    Abstract: This disclosure provides a predetermined composition, where a conversion value C* of total carbon contents in Ti, Nb and V precipitates whose grain sizes are less than 20 nm is 0.010 mass % to 0.100 mass %, Fe content in Fe precipitates is 0.03 mass % to 0.50 mass %, and an average grain size of ferrite grains whose grain sizes are top 5 % large in ferrite grain size distribution of rolling direction cross section is (4000/TS)2 ?m or less, the TS indicating tensile strength in unit of MPa.
    Type: Application
    Filed: July 5, 2016
    Publication date: December 27, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro KIZU, Shunsuke TOYODA, Akimasa KIDO, Tetsushi TADANI
  • Publication number: 20180155806
    Abstract: This disclosure provides a predetermined composition, where a conversion value C* of total carbon contents in Ti, Nb and V precipitates whose grain sizes are less than 20 nm is 0.010 mass % to 0.100 mass %, Fe content in Fe precipitates is 0.03 mass % to 0.50 mass %, and an average grain size of ferrite grains whose grain sizes are top 5 % large in ferrite grain size distribution of rolling direction cross section is (4000/TS)2 ?m or less, the TS indicating tensile strength in unit of MPa.
    Type: Application
    Filed: July 5, 2016
    Publication date: June 7, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro KIZU, Shunsuke TOYODA, Akimasa KIDO, Tetsushi TADANI
  • Publication number: 20180119240
    Abstract: A hot rolled steel sheet comprises: a predetermined chemical composition; a microstructure in which a total area ratio of a tempered bainite phase and a tempered martensite phase is 70% or more, a total area ratio of a coarse pearlite phase, a martensite phase, and a retained austenite phase is 10% or less, the tempered bainite phase and the tempered martensite phase have laths with an average width of 1.0 ?m or less as a substructure, a proportion of Fe-based carbides with an aspect ratio of 5 or less in Fe-based carbides precipitated inside and at boundaries of the laths is 80% or more, and MC-type carbides with an average particle size of 20 nm or less are dispersed and precipitated inside and at the boundaries of the laths; and an average dislocation density of 1.0×1014 m?2 or more and 5.0×1015 m?2 or less.
    Type: Application
    Filed: March 30, 2016
    Publication date: May 3, 2018
    Applicant: JFE Steel Corporation
    Inventors: Takaaki TANAKA, Taro KIZU, Shunsuke TOYODA
  • Publication number: 20180016657
    Abstract: A high strength steel sheet having high strength such as a tensile strength of 780 MPa or more and having excellent blanking workability and stretch flangeability and a manufacturing method therefor are provided. A high strength steel sheet comprises: a chemical composition containing, in mass %, C: 0.05% to 0.30%, Si: 0.6% to 2.0%, Mn: 1.3% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 2.0% or less, N: 0.010% or less, and one or more of Ti, Nb, and V: 0.01% to 1.0% each, with a balance being Fe and incidental impurities; a ferrite microstructure of 50% or more in area ratio; an amount of precipitated Fe of 0.04 mass % or more; and a precipitate with a particle size of less than 20 nm, wherein C* and C*p satisfy specific conditions.
    Type: Application
    Filed: March 1, 2016
    Publication date: January 18, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro KIZU, Shunsuke TOYODA, Akimasa KIDO, Tetsushi TADANI
  • Patent number: 9828648
    Abstract: A steel sheet and a method for producing the same are disclosed. The steel sheet has a composition containing 0.015% to 0.05% C, less than 0.10% Si, 0.1% to 2.0% Mn, 0.20% or less P, 0.1% or less S, 0.01% to 0.10% Al, 0.005% or less N, and 0.06% to 0.5% Ti in percent by mass, C and Ti satisfying the inequality Ti*/C?4, where Ti* (mass percent)=Ti?3.4N and Ti, C, and N represent the content (mass percent) of each element. The steel sheet has a microstructure which contains a ferrite phase as a base, in which the average grain diameter of the ferrite phase is 7 ?m or more, and in which the ratio of the rolling-direction average grain diameter to thickness-wise average grain diameter of the ferrite phase is 1.1 or more.
    Type: Grant
    Filed: December 10, 2012
    Date of Patent: November 28, 2017
    Assignee: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Koichiro Fujita
  • Publication number: 20170314108
    Abstract: A method of manufacturing a high strength steel sheet includes subjecting a steel having a chemical composition including C: 0.08% to 0.20%, Si: 0.3% or less, Mn: 0.1% to 3.0%, P: 0.10% or less, S: 0.030% or less, Al: 0.10% or less, N: 0.010% or less, V: 0.20% to 0.80%, and the remainder composed of Fe and incidental impurities on a percent by mass basis to a hot rolling process composed of heating, rough rolling, finish rolling, cooling, and coiling into the shape of a coil at a predetermined coiling temperature, wherein the heating is performed at a temperature of 1,100° C. or higher for 10 min or more, the rough rolling is performed at a finish rough rolling temperature of 1,000° C. or higher, the finish rolling is performed at a finishing temperature of 850° C. or higher, in which a reduction ratio in a temperature range of 1,000° C. or lower is 96% or less, a reduction ratio in a temperature range of 950° C.
    Type: Application
    Filed: July 14, 2017
    Publication date: November 2, 2017
    Inventors: Taro Kizu, Yoshimasa Funakawa, Hidekazu Ookubo, Tokunori Kanemura, Masato Shigemi, Shoji Kasai, Shinji Yamazaki, Yusuke Yasufuku
  • Patent number: 9738960
    Abstract: The high strength steel sheet has a chemical composition including 0.08% to 0.20% of C, 0.3% or less of Si, 0.1% to 3.0% of Mn, 0.10% or less of P, 0.030% or less of S, 0.10% or less of Al, 0.010% or less of N, 0.20% to 0.80% of V, and the remainder composed of Fe and incidental impurities on a percent by mass basis, and a microstructure which includes 95% or more of ferrite phase on an area percentage basis, in which fine precipitates are dispersed having a distribution in such a way that the number density of precipitates having a particle size of less than 10 nm is 1.0×105/?m3 or more and the standard deviation of natural logarithm values of precipitate particle sizes with respect to precipitates having a particle size of less than 10 nm is 1.5 or less.
    Type: Grant
    Filed: April 18, 2013
    Date of Patent: August 22, 2017
    Assignee: JFE Steel Corporation
    Inventors: Taro Kizu, Yoshimasa Funakawa, Hidekazu Ookubo, Tokunori Kanemura, Masato Shigemi, Shoji Kasai, Shinji Yamazaki, Yusuke Yasufuku
  • Publication number: 20170218474
    Abstract: A method of manufacturing a high-strength hot rolled steel sheet by hot rolling a steel having a chemical composition including, by mass %: C: more than 0.010% and not more than 0.06%, Si: not more than 0.3%, Mn: not more than 0.8%, P: not more than 0.03%, S: not more than 0.02%, Al: not more than 0.1%, N: not more than 0.01% and Ti: 0.05 to 0.10%, the balance including Fe and inevitable impurities, including: after the steel is heated to an austenite single phase region, the steel is finish rolled at a finishing delivery temperature of 860° C. to 1050° C., the steel sheet is cooled at an average cooling rate of not less than 30° C/s in a temperature range of from a temperature after the completion of the finish rolling to 750° C., and the steel sheet is coiled into a coil at a coiling temperature of 580° C. to 700° C.
    Type: Application
    Filed: April 11, 2017
    Publication date: August 3, 2017
    Inventors: Yoshimasa Funakawa, Tetsuo Yamamoto, Hiroshi Uchomae, Hiroshi Nakano, Taro Kizu
  • Patent number: 9657382
    Abstract: A high-strength hot rolled steel sheets with excellent stretch flangeability has small variations in mechanical properties in individual coils. Variations in strength from place to place in a coil are decreased by minimally reducing the Si and Mn contents to suppress the occurrence of problems such as segregation. Further, the microstructure of the steel sheets is configured such that a ferrite phase represents an area ratio of not less than 95%, the ferrite crystal grains have an average grain size of not less than 1 ?m, and the ferrite crystal grains contain TiC with an average particle size of not more than 7 nm dispersed in the crystal grains.
    Type: Grant
    Filed: December 14, 2012
    Date of Patent: May 23, 2017
    Assignee: JFE Steel Corporation
    Inventors: Yoshimasa Funakawa, Tetsuo Yamamoto, Hiroshi Uchomae, Hiroshi Nakano, Taro Kizu
  • Publication number: 20150252456
    Abstract: A steel material having a chemical composition contains 0.0010% to 0.0030% C, 0.05% or less Si, 0.1% to 0.5% Mn, 0.021% to 0.060% Ti, and 0.0005% to 0.0050% B on a mass basis such that B/C satisfies 0.5 or more, whereby a resulting cold-rolled steel sheet has a microstructure dominated by ferrite with an average grain size of 10 ?m to 30 ?m, a proportional limit of 100 MPa or less, and excellent shape fixability.
    Type: Application
    Filed: October 11, 2012
    Publication date: September 10, 2015
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Koichiro Fujita, Hideharu Koga, Masahide Morikawa, Kenji Tahara
  • Publication number: 20150056468
    Abstract: The high strength steel sheet has a chemical composition including 0.08% to 0.20% of C, 0.3% or less of Si, 0.1% to 3.0% of Mn, 0.10% or less of P, 0.030% or less of S, 0.10% or less of Al, 0.010% or less of N, 0.20% to 0.80% of V, and the remainder composed of Fe and incidental impurities on a percent by mass basis, and a microstructure which includes 95% or more of ferrite phase on an area percentage basis, in which fine precipitates are dispersed having a distribution in such a way that the number density of precipitates having a particle size of less than 10 nm is 1.0×105/?m3 or more and the standard deviation of natural logarithm values of precipitate particle sizes with respect to precipitates having a particle size of less than 10 nm is 1.5 or less.
    Type: Application
    Filed: April 18, 2013
    Publication date: February 26, 2015
    Inventors: Taro Kizu, Yoshimasa Funakawa, Hidekazu Ookubo, Tokunori Kanemura, Masato Shigemi, Shoji Kasai, Shinji Yamazaki, Yusuke Yasufuku
  • Publication number: 20140366994
    Abstract: A steel sheet and a method for producing the same are disclosed. The steel sheet has a composition containing 0.015% to 0.05% C, less than 0.10% Si, 0.1% to 2.0% Mn, 0.20% or less P, 0.1% or less S, 0.01% to 0.10% Al, 0.005% or less N, and 0.06% to 0.5% Ti in percent by mass, C and Ti satisfying the inequality Ti*/C?4, where Ti* (mass percent)=Ti-3.4N and Ti, C, and N represent the content (mass percent) of each element. The steel sheet has a microstructure which contains a ferrite phase as a base, in which the average grain diameter of the ferrite phase is 7 ?m or more, and in which the ratio of the rolling-direction average grain diameter to thickness-wise average grain diameter of the ferrite phase is 1.1 or more.
    Type: Application
    Filed: December 10, 2012
    Publication date: December 18, 2014
    Applicant: JFE STEEL CORPORATION
    Inventors: Taro Kizu, Koichiro Fujita