公开(公告)号：US20200270717A1

公开(公告)日：2020-08-27

申请号：US16089846

申请日：2017-01-16

Applicant: JFE STEEL CORPORATION

Inventor： Tatsuya NAKAGAITO ,  Yoshimasa FUNAKAWA ,  Yoshihiko ONO ,  Hiroshi HASEGAWA

IPC: C21D9/46 ,  B32B15/01 ,  C22C38/38 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A steel sheet having excellent fatigue resistance as a material for automobile parts and a TS of 590 MPa or more, and a method for producing the same. The steel sheet having a specified chemical composition and a microstructure of 50% or more and 90% or less of martensite, 10% to 50% of ferrite and bainite in total, in terms of an area ratio, and an average concentration of solute Mn in ferrite in a region from a surface of a base steel to a depth of 0.5 μm is 60% or more relative to an average concentration of solute Mn in ferrite at a location of ¼ in the thickness of the steel sheet.

公开(公告)号：US20190284656A1

公开(公告)日：2019-09-19

申请号：US16349422

申请日：2017-11-15

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Takako YAMASHITA ,  Masayasu UENO ,  Yuki TOJI ,  Takashi KOBAYASHI ,  Yoshimasa FUNAKAWA

IPC: C21D8/02 ,  C22C38/60 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/14 ,  C21D9/46 ,  C23C2/40 ,  C23C2/06 ,  C23C2/12 ,  C23C2/02 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/38 ,  C22C38/08

Abstract: To provide a high-strength steel sheet with excellent ductility and hole expansion formability, a yield ratio of less than 68%, and a tensile strength of 980 MPa or more, by having a predetermined chemical composition and a microstructure where ferrite is 15% or more and 55% or less and martensite is 15% or more and 30% or less in area ratio, retained austenite is 12% or more in volume fraction, the average grain size of ferrite, martensite and retained austenite is 4.0 μm or less, 2.0 μm or less and 2.0 μm or less respectively, the average aspect ratio of crystal grain of ferrite, martensite and retained austenite is each more than 2.0 and 15.0 or less, and the value obtained by dividing the Mn content (mass %) in retained austenite by the Mn content (mass %) in ferrite is 2.0 or more.

公开(公告)号：US20190271051A1

公开(公告)日：2019-09-05

申请号：US16349443

申请日：2017-11-15

Applicant: JFE STEEL CORPORATION

Inventor： Yoshiyasu KAWASAKI ,  Takako YAMASHITA ,  Masayasu UENO ,  Yuki TOJI ,  Takashi KOBAYASHI ,  Yoshimasa FUNAKAWA

IPC: C21D8/02 ,  C23C2/12 ,  C23C2/40 ,  C23C2/02 ,  C22C38/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/14 ,  C22C38/60 ,  C22C38/38 ,  C22C38/12 ,  C22C38/16 ,  C22C38/08 ,  C21D9/46

Abstract: To provide a high-strength steel sheet with excellent ductility and hole expansion formability, a yield ratio of less than 68%, and a tensile strength of 590 MPa or more, by having a predetermined chemical composition and a microstructure where ferrite is 35% or more and 80% or less and martensite is 5% or more and 25% or less in area ratio, retained austenite is 8% or more in volume fraction, the average grain size of ferrite, martensite and retained austenite is 6.0 μm or less, 3.0 μm or less and 3.0 μm or less respectively, the average aspect ratio of crystal grain of ferrite, martensite and retained austenite is each more than 2.0 and 15.0 or less, and the value obtained by dividing the Mn content (mass %) in retained austenite by the Mn content (mass %) in ferrite is 2.0 or more.

公开(公告)号：US20190112681A1

公开(公告)日：2019-04-18

申请号：US16089051

申请日：2017-01-16

Applicant: JFE STEEL CORPORATION

Inventor： Tatsuya NAKAGAITO ,  Yoshimasa FUNAKAWA ,  Yoshihiko ONO ,  Hiroshi HASEGAWA

IPC: C21D8/02 ,  C22C38/04 ,  C22C38/02 ,  C22C38/06 ,  C22C38/00 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C21D9/46

Abstract: A steel sheet having excellent fatigue resistance as a material for automobile parts and a TS of 590 MPa or more, and a method for producing the same. The steel sheet has a composition comprising, by mass %, C: 0.04% or more and 0.15% or less, Si: 0.3% or less, Mn: 1.0% or more and 2.6% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.1% or less, N: 0.015% or less, one or two of Ti and Nb: 0.01% or more and 0.2% or less in a total, and the balance being Fe and unavoidable impurities. The steel sheet has 50% or more of ferrite and 10% or more and 50% or less of martensite in terms of an area ratio, and a microstructure in which a standard deviation of nano-hardness is 1.50 GPa or less and tensile strength of 590 MPa or more.

公开(公告)号：US20180080099A1

公开(公告)日：2018-03-22

申请号：US15561365

申请日：2016-03-18

Applicant: JFE STEEL CORPORATION

Inventor： Yuma HONDA ,  Yoshimasa FUNAKAWA ,  Kozo HARADA

IPC: C21D9/46 ,  C22C38/54 ,  C22C38/48 ,  C22C38/16 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C23C2/28 ,  B32B15/01

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0273 ,  C21D2211/005 ,  C21D2211/009 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/16 ,  C22C38/48 ,  C22C38/54 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40

Abstract: A high-strength steel sheet having a high yield ratio and excellent stretch flangeability, and a method for producing the high-strength steel sheet. The high-strength steel sheet has a composition containing, by mass: C: 0.02% or more and less than 0.10%, Si: less than 0.10%, Mn: less than 1.0%, P: 0.10% or less, S: 0.020% or less, Al: 0.01% or more and 0.10% or less, N: 0.010% or less, Nb: 0.005% or more and less than 0.070%, and the balance being Fe and inevitable impurities; and a microstructure including, by area: ferrite: 85% or more, pearlite: 0% to 15%, and a total of martensite, retained austenite and cementite: 0% to 3%. The average crystal grain diameter of the ferrite is 15.0 μm or less. The grain diameter of a Nb carbide is 5 to 50 nm. The amount of Nb carbide precipitate is 0.005% to 0.050% in terms of volume fraction.

公开(公告)号：US20230145099A1

公开(公告)日：2023-05-11

申请号：US17906346

申请日：2021-03-17

Applicant: JFE STEEL CORPORATION

Inventor： Yoshimasa FUNAKAWA

IPC: G05B19/418 ,  G05B19/4093

CPC classification number: G05B19/4183 ,  G05B19/40932

Abstract: A method and device capable of calculating required material properties from a part shape, and determining a set of manufacturing conditions for a material satisfying the material properties are provided. A product information determining method includes a property acquisition step (S300) for acquiring, based on input information including shape data on a part, material properties required to work a material of the part into the part; and a product information determination step (S400) for determining product information including chemical compositions and a set of manufacturing conditions to manufacture the material satisfying the material properties.

公开(公告)号：US20210130919A1

公开(公告)日：2021-05-06

申请号：US16762501

申请日：2018-11-07

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Takayuki FUTATSUKA ,  Kentaro SATO ,  Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yoshimasa FUNAKAWA

IPC: C21D9/46 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00 ,  C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60

Abstract: Disclosed is a hot-pressed steel sheet member having a tensile strength of 1780 MPa or more and excellent bending collapsibility. The hot-pressed steel sheet member includes: a specific chemical composition; a microstructure in which an average grain size of prior austenite grains is 8 μm or less, a volume fraction of martensite is 90% or more, and a solute C content is 25% or less of a total C content; and a tensile strength of 1780 MPa or more.

公开(公告)号：US20210115541A1

公开(公告)日：2021-04-22

申请号：US17042250

申请日：2019-03-20

Applicant: JFE STEEL CORPORATION

Inventor： Kazuki ENDO ,  Yoshiyasu KAWASAKI ,  Yuki TOJI ,  Yoshimasa FUNAKAWA ,  Mai AOYAMA

IPC: C22C38/04 ,  C22C33/02 ,  B21B27/10 ,  C21D6/00 ,  C21D8/02

Abstract: A high-strength steel sheet includes a steel structure with: ferrite being 35% to 80%, martensite being 5% to 35%, and tempered martensite being 0% to 5% in terms of area fraction; retained austenite being 8% or more in terms of volume fraction; an average grain size of: the ferrite being 6 μm or less; and the retained austenite being 3 μm or less; a value obtained by dividing an area fraction of blocky austenite by a sum of area fractions of lath-like austenite and the blocky austenite being 0.6 or more; a value obtained by dividing, by mass %, an average Mn content in the retained austenite by an average Mn content in the ferrite being 1.5 or more; and a value obtained by dividing, by mass %, an average C content in the retained austenite by an average C content in the ferrite being 3.0 or more.

公开(公告)号：US20200332382A1

公开(公告)日：2020-10-22

申请号：US16754135

申请日：2018-11-07

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Takayuki FUTATSUKA ,  Kentaro SATO ,  Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yoshimasa FUNAKAWA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/32 ,  C23C2/06 ,  C23C2/12

Abstract: Disclosed is a hot-pressed steel sheet member having a tensile strength of 1780 MPa or more and excellent bending collapsibility. The hot-pressed steel sheet member has: a specific chemical composition where a ratio of a C content in mass % to a Nb content in mass %, C/Nb, is from 22 to 100; a microstructure in which an average grain size of prior austenite grains is 8 μm or less, a volume fraction of martensite is 90% or more, and a solute C content is 25% or less of a total C content; and a tensile strength of 1780 MPa or more.

公开(公告)号：US20190071744A1

公开(公告)日：2019-03-07

申请号：US16089973

申请日：2017-01-17

Applicant: JFE STEEL CORPORATION

Inventor： Hiroshi HASEGAWA ,  Yoshimasa FUNAKAWA

IPC: C21D8/02 ,  C23C2/06 ,  C23C2/02 ,  C23C2/26 ,  C22C38/00 ,  C22C38/06 ,  C22C38/02 ,  C22C38/14 ,  C22C38/12

Abstract: A steel sheet, a plated steel sheet, and methods for producing a hot-rolled steel sheet, a cold-rolled full hard steel sheet, and a steel sheet. The steel sheet has a specified composition and a microstructure including 0 to 60% of polygonal ferrite and 40 to 100% of a total of martensite, bainite, and residual austenite in terms of an area ratio within 20 μm from the steel sheet surface. The content of Mn in martensite present within 20 μm of the steel sheet surface ([Mn]SM) and the content of Mn in a bulk ([Mn]B) satisfy [Mn]SM/[Mn]B≤1.5. At a location 300 μm from the steel sheet surface, an area ratio of the martensite is in a range of 40 to 80%, and the polygonal ferrite and the bainite have an average crystal grain size of less than 15 μm.