Patents by Inventor Masataka Yoshino

Masataka Yoshino 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).

  • Patent number: 10968499
    Abstract: Ferritic stainless steel that has excellent formability and ridging resistance and can be produced with high productivity is provided. The ferritic stainless steel has: a predetermined chemical composition; a microstructure containing ferrite crystal grains which satisfy at least one of a C concentration of 2CC or more and an N concentration of 2CN or more, the ferrite crystal grains having a volume fraction with respect to a whole volume of the microstructure of 5% or more and 50% or less, where CC and CN are respectively C content and N content in the steel in mass %; and a Vickers hardness of 180 or less.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: April 6, 2021
    Assignee: JFE STEEL CORPORATION
    Inventors: Akito Mizutani, Masataka Yoshino, Mitsuyuki Fujisawa, Ayako Ta
  • Publication number: 20200385835
    Abstract: The present invention provides a hot-rolled and annealed ferritic stainless steel sheet which has sufficient corrosion resistance and in which cracks can be prevented during blanking into a thick flange, and a method for manufacturing the same. A hot-rolled and annealed ferritic stainless steel sheet has a chemical composition containing, in percent by mass, C: 0.001% to 0.020%, Si: 0.05% to 1.00%, Mn: 0.05% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.100%, Cr: 10.0% to 19.0%, Ni: 0.65% to 1.50%, Ti: 0.10% to 0.40%, and N: 0.001% to 0.020%, with the balance being Fe and unavoidable impurities, and has a threshold stress intensity factor KIC of 35 MPa·m1/2 or more.
    Type: Application
    Filed: April 24, 2018
    Publication date: December 10, 2020
    Applicant: JFE Steel Corporation
    Inventors: Masataka Yoshino, Keishi Inoue, Mitsuyuki Fujisawa
  • Publication number: 20200385834
    Abstract: A raw material for a steel sheet, the raw material being suitable for manufacturing a cold-rolled ferritic stainless steel sheet having excellent corrosion resistance, formability, and ridging resistance, and a manufacturing method therefor are provided. A raw material for a cold-rolled stainless steel sheet has a chemical composition containing, in terms of mass %, C: 0.005 to 0.030%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.040% or less, S: 0.030% or less, Al: 0.001 to 0.150%, Cr: 10.8 to 14.4%, Ni: 0.01 to 2.50%, and N: 0.005 to 0.060%, with the balance being Fe and incidental impurities, in which the raw material has a structure containing 10 to 90% of a martensite phase in terms of area ratio with the balance being a ferrite phase.
    Type: Application
    Filed: April 13, 2018
    Publication date: December 10, 2020
    Applicant: JFE Steel Corporation
    Inventors: Shuji Nishida, Tomohiro Ishii, Masataka Yoshino, Mitsuyuki Fujisawa
  • Publication number: 20200347475
    Abstract: The present invention provides a ferritic stainless steel sheet and a method for manufacturing the same. A ferritic stainless steel sheet has a composition containing C: 0.001 to 0.020%, Si: 0.05 to 0.35%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001 to 0.300%, Cr: 10.0 to 13.0%, Ni: 0.75 to 1.50%, Ti: 0.05 to 0.35%, and N: 0.001 to 0.020%, with the balance being Fe and inevitable impurities, in which ?I [AD] represented by formula (1) below is 65% or more, and a metal structure has an average crystal grain size of 45 ?m or less: ?I [%]=24Ni+12Mn+6Cu?18Si?12Cr?12Mo+188 (1), where Ni, Mn, Cu, Si, Cr, and Mo represent contents of the respective elements (percent by mass), and an element not contained represents 0.
    Type: Application
    Filed: October 16, 2018
    Publication date: November 5, 2020
    Applicant: JFE Steel Corporation
    Inventors: Keishi Inoue, Hidetaka Kawabe, Masataka Yoshino, Mitsuyuki Fujisawa
  • Patent number: 10801084
    Abstract: Provided are a material for cold rolled stainless steel sheets having sufficient corrosion resistance, excellent surface quality, excellent formability, and excellent ridging resistance; a method for manufacturing the same; and a cold rolled steel sheet. A material for cold rolled stainless steel sheets according to the present invention contains C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.0%, P: 0.040% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 1.0%, Al: 0.001% to 0.10%, and N: 0.005% to 0.025% on a mass basis, the remainder being Fe and inevitable impurities, and has a metallographic structure containing 5% to 20% of a martensite phase in terms of volume fraction, the remainder being a ferrite phase.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: October 13, 2020
    Assignee: JFE Steel Corporation
    Inventors: Akito Mizutani, Masataka Yoshino, Mitsuyuki Fujisawa, Chikara Kami
  • Publication number: 20200299800
    Abstract: A ferritic stainless steel sheet having excellent corrosion resistance, formability, and ridging resistance and a method for manufacturing the same are provided. A ferritic stainless steel sheet has a chemical composition containing, in terms of mass %, C: 0.005 to 0.030%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.040% or less, S: 0.030% or less, Al: 0.001 to 0.150%, Cr: 10.8 to 14.4%, Ni: 0.01 to 2.50%, and N: 0.005 to 0.060%, with the balance being Fe and incidental impurities. The elongation after fracture is 28% or more, and the ridging height of a surface of a steel sheet to which a tensile strain of 23% has been applied in a rolling direction is 3.0 ?m or less.
    Type: Application
    Filed: April 13, 2018
    Publication date: September 24, 2020
    Applicant: JFE STEEL CORPORATION
    Inventors: Shuji NISHIDA, Tomohiro ISHII, Masataka YOSHINO, Mitsuyuki FUJISAWA
  • Patent number: 10633730
    Abstract: Provided is a material for a cold-rolled stainless steel sheet having a chemical composition containing, by mass %, C: 0.01% to 0.05%, Si: 0.02% to 0.75%, Mn: 0.1% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06% and the balance being Fe and inevitable impurities. The material has a metallographic structure including a martensite phase having an area ratio of 5% to 50% and the balance being a ferrite phase. A ferrite phase in portions extending from surface layers of front and back surfaces of a steel sheet has an average grain diameter of 20 ?m or more and 50 ?m or less, and a ferrite phase in a central portion of the sheet includes an unrecrystallized ferrite phase.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: April 28, 2020
    Assignee: JFE Steel Corporation
    Inventors: Ayako Ta, Yukihiro Matsubara, Yukio Kimura, Masataka Yoshino, Keisuke Nakazono, Sumio Kaiho, Saiichi Murata, Nobukazu Kitagawa
  • Patent number: 10626486
    Abstract: Stainless steel that has excellent formability and ridging resistance and can be produced with high productivity is provided. The stainless steel comprises: a chemical composition containing, in mass %, C: 0.005% to 0.050%, Si: 0.01% to 1.00%, Mn: 0.01% to 1.0%, P: 0.040% or less, S: 0.010% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 1.0%, Al: 0.001% to 0.10%, and N: 0.005% to 0.06%, with a balance being Fe and incidental impurities; and a microstructure containing a martensite phase of 1% to 10% in volume fraction with respect to a whole volume of the microstructure.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: April 21, 2020
    Assignee: JFE STEEL CORPORATION
    Inventors: Akito Mizutani, Masataka Yoshino, Mitsuyuki Fujisawa, Ayako Ta
  • Patent number: 10550454
    Abstract: Provided is a cold-rolled ferritic stainless steel sheet having a chemical composition that contains, by mass %, C: 0.01% or more and 0.05% or less, Si: 0.02% or more and 0.75% or less, Mn: 0.1% or more and 1.0% or less, P: 0.04% or less, S: 0.01% or less, Al: 0.001% or more and 0.10% or less, N: 0.01% or more and 0.06% or less, Cr: 16.0% or more and 18.0% or less, and the balance being Fe and inevitable impurities. The metallographic structure includes a ferrite phase, in which the average grain diameter is 10 ?m or less, in which the proportion of ferrite grains having a grain diameter of 10 ?m or more and less than 40 ?m is 60% or more, and in which the proportion of ferrite grains having a grain diameter of less than 5 ?m is less than 20%.
    Type: Grant
    Filed: July 2, 2015
    Date of Patent: February 4, 2020
    Assignee: JFE Steel Corporation
    Inventors: Ayako Ta, Yukihiro Matsubara, Yukio Kimura, Keisuke Nakazono, Masataka Yoshino
  • Publication number: 20200002779
    Abstract: Provided is a hot-rolled ferritic stainless steel sheet which has sufficient corrosion resistance and which can prevent the occurrence of cracking when subjected to blanking to be formed into a thick flange, and also provided is a method for manufacturing the hot-rolled ferritic stainless steel sheet. A hot-rolled ferritic stainless steel sheet having a chemical composition containing, in mass %, C: 0.001 to 0.020%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001 to 0.50%, N: 0.001 to 0.020%, Cr: 11.0 to 24.0%, Ni: 0.01 to 2.00%, and Nb: 0.12 to 0.80%, with the balance being Fe and incidental impurities, wherein the hot-rolled ferritic stainless steel sheet has a threshold stress intensity factor KIC of 25 MPa·m1/2 or more.
    Type: Application
    Filed: January 12, 2018
    Publication date: January 2, 2020
    Applicant: JFE Steel Corporation
    Inventors: Masataka YOSHINO, Mitsuyuki FUJISAWA
  • Publication number: 20190226045
    Abstract: A hot-rolled and annealed ferritic stainless steel sheet which has sufficient corrosion resistance and with which it is possible to inhibit a crack from occurring when punching work is performed to form a thick-walled flange and a method for manufacturing the steel sheet. The hot-rolled and annealed ferritic stainless steel sheet has a chemical composition comprising, by mass %, C: 0.001% to 0.020%, Si: 0.05% to 1.00%, Mn: 0.05% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.100%, Cr: 10.0% to 24.0%, Ni: 0.01% to 0.60%, Ti: 0.10% to 0.40%, N: 0.001% to 0.020%, and the balance being Fe and inevitable impurities, and a threshold stress intensity factor KIC of 20 MPa·m1/2 or more.
    Type: Application
    Filed: September 27, 2017
    Publication date: July 25, 2019
    Applicant: JFE STEEL CORPORATION
    Inventors: Masataka YOSHINO, Mitsuyuki FUJISAWA
  • Publication number: 20180363083
    Abstract: Provided are a material for cold rolled stainless steel sheets having sufficient corrosion resistance, excellent surface quality, excellent formability, and excellent ridging resistance; a method for manufacturing the same; and a cold rolled steel sheet. A material for cold rolled stainless steel sheets according to the present invention contains C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.0%, P: 0.040% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 1.0%, Al: 0.001% to 0.10%, and N: 0.005% to 0.025% on a mass basis, the remainder being Fe and inevitable impurities, and has a metallographic structure containing 5% to 20% of a martensite phase in terms of volume fraction, the remainder being a ferrite phase.
    Type: Application
    Filed: July 2, 2015
    Publication date: December 20, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Akito Mizutani, Masataka Yoshino, Misuyuki Fujisawa, Chikara Kami
  • Publication number: 20180265951
    Abstract: A ferritic stainless steel having sufficient corrosion resistance and excellent formability and ridging resistance. The ferritic stainless steel having a chemical composition comprising, by mass %, C: 0.005% or more and 0.035% or less, Si: 0.25% or more and less than 0.40%, Mn: 0.05% or more and 0.35% or less, P: 0.040% or less, S: 0.01% or less, Cr: 15.5% or more and 18.0% or less, Al: 0.001% or more and 0.10% or less, N: 0.01% or more and 0.06% or less, and the balance being Fe and inevitable impurities. Si and Mn satisfy the relational expression 29.5×Si?50×Mn+6?0, where Si and Mn in the relational expression respectively denote the content, by mass %, of the corresponding chemical element.
    Type: Application
    Filed: October 2, 2014
    Publication date: September 20, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Masataka YOSHINO, Akito MIZUTANI, Mitsuyuki FUJISAWA, Ayako TA
  • Publication number: 20180202023
    Abstract: Provided are a hot rolled ferritic stainless steel sheet and a hot rolled and annealed ferritic stainless steel sheet and methods for manufacturing these steel sheets. A hot rolled ferritic stainless steel sheet having a chemical composition containing, by mass %, C: 0.005% to 0.060%, Si: 0.02% to 0.50%, Mn: 0.01% to 1.00%, P: 0.04% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Al: 0.001% to 0.10%, N: 0.005% to 0.100%, Ni: 0.1% to 1.0%, and the balance being Fe and inevitable impurities and an absolute value of planar anisotropy in terms of modulus of longitudinal elasticity below of 35 GPa or less.
    Type: Application
    Filed: July 11, 2016
    Publication date: July 19, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Masataka Yoshino, Mitsuyuki Fujisawa, Chikara Kami
  • Publication number: 20180171430
    Abstract: Provided are a ferritic stainless steel sheet and a method for manufacturing the steel sheet. The ferritic stainless steel sheet according to the present invention has a chemical composition containing, by mass %, C: 0.005% to 0.025%, Si: 0.02% to 0.50%, Mn: 0.55% to 1.00%, P: 0.04% or less, S: 0.01% or less, Al: 0.001% to 0.10%, Cr: 15.5% to 18.0%, Ni: 0.1% to 1.0%, N: 0.005% to 0.025%, and the balance being Fe and inevitable impurities, an elongation after fracture of 28% or more, an average r-value of 0.75 or more, and a minimum value of maximum logarithmic strain at the forming limit, which is, determined on the basis of a forming limit diagram (FLD), of 0.15 or more.
    Type: Application
    Filed: July 2, 2015
    Publication date: June 21, 2018
    Applicant: JFE STEEL CORPORATION
    Inventors: Masataka Yoshino, Akito Mizutani, Mitsuyuki Fujisawa, Chikara Kami
  • Patent number: 10000824
    Abstract: A material for stainless steel cold rolling suitable for producing a cold-rolled stainless steel sheet that has sufficient corrosion resistance and ridging resistance as well as excellent formability and surface properties is provided. The material for stainless steel cold rolling according to the present invention contains, in terms of % by mass, C: 0.007% to 0.05%, Si: 0.02% to 0.50%, Mn: 0.05% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 15.5% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06%, and the balance being Fe and unavoidable impurities, wherein the material has a microstructure that includes 10% to 60% of a martensite phase in terms of area fraction, with the remainder being a ferrite phase, and the martensite phase has a hardness of HV500 or less.
    Type: Grant
    Filed: January 20, 2015
    Date of Patent: June 19, 2018
    Assignee: JFE STEEL CORPORATION
    Inventors: Masataka Yoshino, Hiroki Ota, Ayako Ta, Yukihiro Matsubara, Akito Mizutani, Mitsuyuki Fujisawa
  • Publication number: 20170349984
    Abstract: Stainless steel that has excellent formability and ridging resistance and can be produced with high productivity is provided. The stainless steel comprises: a chemical composition containing, in mass %, C: 0.005% to 0.050%, Si: 0.01% to 1.00%, Mn: 0.01% to 1.0%, P: 0.040% or less, S: 0.010% or less, Cr: 15.5% to 18.0%, Ni: 0.01% to 1.0%, Al: 0.001% to 0.10%, and N: 0.005% to 0.06%, with a balance being Fe and incidental impurities; and a microstructure containing a martensite phase of 1% to 10% in volume fraction with respect to a whole volume of the microstructure.
    Type: Application
    Filed: July 2, 2015
    Publication date: December 7, 2017
    Applicant: JFE STEEL CORPORATION
    Inventors: Akito MIZUTANI, Masataka YOSHINO, Mitsuyuki FUJISAWA, Ayako TA
  • Publication number: 20170327921
    Abstract: Ferritic stainless steel that has excellent formability and ridging resistance and can be produced with high productivity is provided. The ferritic stainless steel has: a predetermined chemical composition; a microstructure containing ferrite crystal grains which satisfy at least one of a C concentration of 2CC or more and an N concentration of 2CN or more, the ferrite crystal grains having a volume fraction with respect to a whole volume of the microstructure of 5% or more and 50% or less, where CC and CN are respectively C content and N content in the steel in mass %; and a Vickers hardness of 180 or less.
    Type: Application
    Filed: July 2, 2015
    Publication date: November 16, 2017
    Applicant: JFE STEEL CORPORATION
    Inventors: Akito MIZUTANI, Masataka YOSHINO, Mitsuyuki FUJISAWA, Ayako TA
  • Publication number: 20170283923
    Abstract: Provided is a cold-rolled ferritic stainless steel sheet having a chemical composition that contains, by mass %, C: 0.01% or more and 0.05% or less, Si: 0.02% or more and 0.75% or less, Mn: 0.1% or more and 1.0% or less, P: 0.04% or less, S: 0.01% or less, Al: 0.001% or more and 0.10% or less, N: 0.01% or more and 0.06% or less, Cr: 16.0% or more and 18.0% or less, and the balance being Fe and inevitable impurities. The metallographic structure includes a ferrite phase, in which the average grain diameter is 10 ?m or less, in which the proportion of ferrite grains having a grain diameter of 10 ?m or more and less than 40 ?m is 60% or more, and in which the proportion of ferrite grains having a grain diameter of less than 5 ?m is less than 20%.
    Type: Application
    Filed: July 2, 2015
    Publication date: October 5, 2017
    Applicant: JFE STEEL CORPORATION
    Inventors: Ayako Ta, Yukihiro Matsubara, Yukio Kimura, Keisuke Nakazono, Masataka Yoshino
  • Publication number: 20170275744
    Abstract: Provided is a material for a cold-rolled stainless steel sheet having a chemical composition containing, by mass %, C: 0.01% to 0.05%, Si: 0.02% to 0.75%, Mn: 0.1% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06% and the balance being Fe and inevitable impurities. The material has a metallographic structure including a martensite phase having an area ratio of 5% to 50% and the balance being a ferrite phase. A ferrite phase in portions extending from surface layers of front and back surfaces of a steel sheet has an average grain diameter of 20 ?m or more and 50 ?m or less, and a ferrite phase in a central portion of the sheet includes an unrecrystallized ferrite phase.
    Type: Application
    Filed: July 2, 2015
    Publication date: September 28, 2017
    Applicant: JFE STEEL CORPORATION
    Inventors: Ayako Ta, Yukihiro Matsubara, Yukio Kimura, Masataka Yoshino, Keisuke Nakazono, Sumio Kaiho, Saiichi Murata, Nobukazu Kitagawa