公开(公告)号：US11846003B2

公开(公告)日：2023-12-19

申请号：US17290155

申请日：2019-09-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya Hirashima ,  Shimpei Yoshioka ,  Shinjiro Kaneko

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/24 ,  C22C38/22 ,  C22C38/20

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/002 ,  C21D2211/004 ,  C21D2211/008

Abstract: A high-strength steel sheet having high delayed fracture resistance and a method for manufacturing the high-strength steel sheet. The high-strength steel sheet has a specified chemical composition. Relative to the whole microstructure of the steel sheet, the total area fraction of at least one of (i) bainite containing carbide grains having an average grain size of 50 nm or less and (ii) martensite containing carbide grains having an average grain size of 50 nm or less is 90% or more. The average number of inclusions having an average grain size of 5 μm or more that are present in a section of the steel sheet perpendicular to a rolling direction is 5.0/mm2 or less.

公开(公告)号：US20210340641A1

公开(公告)日：2021-11-04

申请号：US17271663

申请日：2019-08-22

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yuma Honda ,  Shimpei Yoshioka ,  Koichi Taniguchi ,  Nobuyuki Nakamura ,  Takeshi Murai

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C21D6/02 ,  C22C38/58 ,  C22C38/60 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C22C38/06 ,  C23C2/06 ,  C23C2/40 ,  C23C2/02

Abstract: A high-strength steel sheet of the present invention has a specific chemical composition. Furthermore, in the steel sheet, a degree of Mn segregation in a specific region is 1.5 or less; a maximum P concentration in a specific region is 0.08 mass % or less; in a specific region, the number of specific MnS particle groups is 2.0 or fewer per 1 mm2, and the number of specific oxide-based inclusions is 8 or fewer per 1 mm2; of all of the oxide-based inclusions, oxide-based inclusions having a specified composition are present in a number ratio of 80% or greater; the microstructure includes, in terms of a volume fraction, 30 to 95% martensite and bainite in total, 5 to 70% ferrite phase, and less than 3% (and 0% or greater) austenite phase; and a tensile strength is 980 MPa or greater.

公开(公告)号：US11085099B2

公开(公告)日：2021-08-10

申请号：US15999603

申请日：2017-02-15

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Hiroyuki Masuoka

IPC: C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/38 ,  C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C23G1/08

Abstract: A high-strength cold-rolled steel sheet has a composition that contains, in terms of mass %, C: 0.10% or more and 0.50% or less, Si: 1.0% or more and 3.0% or less, Mn: 1.0% or more and 2.5% or less, P: 0.05% or less, S: 0.02% or less, Al: 0.01% or more and 1.5% or less, N: 0.005% or less, Cu: 0.05% or more and 0.50% or less, and the balance being Fe and unavoidable impurities, wherein a proportion of a steel sheet surface covered with oxides mainly composed of Si is 1% or less, a proportion of the steel sheet surface covered with Fe oxides is 40% or less, CuS/CuB is 4.0 or less, and a tensile strength is 1180 MPa or more, when CuS denotes the Cu content in a steel sheet surface layer and CuB denotes the Cu content in a base material.

公开(公告)号：US20180037969A1

公开(公告)日：2018-02-08

申请号：US15556448

申请日：2016-02-16

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Katsutoshi Takashima ,  Kohei Hasegawa ,  Yoshimasa Funakawa

IPC: C21D9/46 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C23G1/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C22C38/38 ,  C22C38/08

CPC classification number: C21D9/46 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0273 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/38 ,  C22C38/60 ,  C23G1/00 ,  C23G1/08 ,  C23G1/081

Abstract: A steel sheet contains C: 0.15% to 0.22%, Si: 1.0% to 2.0%, Mn: 1.7% to 2.5%, P: 0.05% or less, S: 0.02% or less, Al: 0.01% to 0.05%, N: 0.005% or less, O: 0.01% or less, and the balance being iron and unavoidable impurities while satisfying [Si]/[Mn]≧0.5 ([Si] and [Mn] represent Si and Mn contents, wherein the steel sheet has a structure including, in terms of area fraction, 60% to less than 100% of tempered martensite, 5% or less including 0% of untransformed austenite, and the balance being ferrite, and the ferrite has an average crystal grain size of less than 3.5 μm, wherein less than 10 particles/100 μm2 of Si—Mn compound oxide particles having a circle equivalent diameter of 5 μm or less are present on a surface of the steel sheet, and the surface is covered with Si-based oxide at a coverage of 1% or less.

公开(公告)号：US20240132986A1

公开(公告)日：2024-04-25

申请号：US18277874

申请日：2022-01-28

Applicant: JFE Steel Corporation

Inventor： Katsuya Hata ,  Shimpei Yoshioka ,  Shinjiro Kaneko

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/34 ,  C22C38/38 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/28 ,  C22C38/34 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/008

Abstract: A steel sheet has a chemical composition containing, by mass %, C: 0.20% or more and 0.40% or less, Si: more than 1.0% and 3.0% or less, Mn: 1.5% or more and 3.5% or less, P: 0.002% or more and 0.010% or less, S: 0.0002% or more and 0.0020% or less, sol. Al: 0.40% or less (not including 0%), and N: 0.0100% or less, with the balance being Fe and incidental impurities; and a steel microstructure containing, in area fraction, tempered martensite: 45% or more and 83% or less, bainite: 15% or more and 53% or less, and retained austenite: 2% or more. Carbides in the tempered martensite have an average particle size of 0.40 μm or less, an average amount of C in the retained austenite is 0.5% by mass or more, and a tensile strength is 1,470 MPa or more.

公开(公告)号：US20240068065A1

公开(公告)日：2024-02-29

申请号：US18267921

申请日：2021-12-24

Applicant: JFE Steel Corporation

Inventor： Taiyo Asakawa ,  Shimpei Yoshioka ,  Shinjiro Kaneko

IPC: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/008

Abstract: Provided are a steel sheet having high strength and high delayed fracture resistance and a method for manufacturing the steel sheet. The steel sheet has a specific chemical composition and a microstructure in which the area fraction of martensite is 95% to 100%, with the balance being one or more of bainite, ferrite, and retained austenite. In the steel sheet, prior-austenite grains have an average grain size of 18 μm or less, 90 mass % or more of the total content of Nb and Ti contained is present as a carbonitride having an equivalent circular diameter of 100 nm or more, and a Nb carbonitride and a Ti carbonitride, having an equivalent circular diameter of 1.0 μm or more, are present at a rate of 800 pieces/mm2 or less in total. The steel sheet has a tensile strength of 1310 MPa or more.

公开(公告)号：US11898230B2

公开(公告)日：2024-02-13

申请号：US17269312

申请日：2019-06-10

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono

IPC: C22C38/06 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04

CPC classification number: C22C38/06 ,  C21D8/0236 ,  C21D9/46 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength steel sheet according to the present invention includes a specific chemical composition, and a steel structure in which a total area fraction of martensite and bainite in a position of ¼ of a sheet thickness is 95% or more and 100% or less, the balance in a case where the total area fraction is not 100% contains retained austenite, and an area fraction of ferrite in a region extending up to 10 μm in a sheet thickness direction from a surface is 10% or more and 40% or less, in which a tensile strength is 1320 MPa or more, and a Vickers hardness in a position of 15 μm in the sheet thickness direction from the surface satisfies a specified formula.

公开(公告)号：US11846002B2

公开(公告)日：2023-12-19

申请号：US17269326

申请日：2019-06-10

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Yuma Honda ,  Nobuyuki Nakamura

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/48 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/48 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: The high-strength steel sheet according to the present invention includes a specific chemical composition, a steel structure in which a total area fraction of martensite and bainite in a position of ¼ of a sheet thickness is 92% or more and 100% or less, the balance in a case where the total area fraction is not 100% contains retained austenite, and an area fraction of ferrite in a region extending up to 10 μm in a sheet thickness direction from a surface is 10% or more and 40% or less, in which a tensile strength is 1320 MPa or more, and a Vickers hardness in a position of 15 μm in the sheet thickness direction from the surface satisfies a specified formula.

公开(公告)号：US20230069838A1

公开(公告)日：2023-03-09

申请号：US17794418

申请日：2021-01-21

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Shinjiro Kaneko ,  Yuma Honda

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

Abstract: A steel sheet has a tensile strength of 1310 MPa or higher, a specified chemical composition, and a steel microstructure containing martensite at an area ratio of 70% or more, bainite at an area ratio of 30% or less, and ferrite and retained austenite at a total area ratio of 5% or less, in which, at a ¼ thickness position of the steel sheet, a number density of carbides having long axes of 0.5 μm or more is 60000 carbides/mm2 or less, in a ¼-to-¾ thickness region of the steel sheet, a number density of inclusion grains having equivalent circle diameters of 4.0 μm or more is 10 grains/mm2 or more and 30 grains/mm2 or less, and, in a surface-to-¼ thickness region of the steel sheet, a number density of inclusion grains having equivalent circle diameters of 4.0 μm or more is 27 grains/mm2 or less.

公开(公告)号：US20220364198A1

公开(公告)日：2022-11-17

申请号：US17769829

申请日：2020-10-23

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Shimpei Yoshioka ,  Shinjiro Kaneko ,  Soshi Yoshimoto ,  Tomohiro Hashimukai

IPC: C21D9/50 ,  C21D9/42 ,  C21D8/02 ,  C21D6/00 ,  C22C38/60 ,  C22C38/18 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: The steel sheet of the present invention has a steel microstructure containing, in area fraction, martensite: 20% to 100%, ferrite: 0% to 80%, and another metal phase: 5% or less, in which, on a surface of the steel sheet, a ratio of dislocation density in metal phases at a widthwise edge of the steel sheet to dislocation density in the metal phases at a widthwise center of the steel sheet is 100% to 140%, and, at a thicknesswise center of the steel sheet, a ratio of dislocation density in the metal phases at the widthwise edge of the steel sheet to dislocation density in the metal phases at the widthwise center of the steel sheet is 100% to 140%. The maximum amount of warpage of the steel sheet when the steel sheet is sheared to a length of 1 m in a rolling direction is 15 mm or less.