公开(公告)号：US12043883B2

公开(公告)日：2024-07-23

申请号：US17284933

申请日：2019-08-06

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Yoshihiko Ono

IPC: C22C38/02 ,  C21D8/02 ,  C21D9/46 ,  C22C38/04 ,  C22C38/06 ,  C25D5/36

CPC classification number: C22C38/02 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C21D9/46 ,  C22C38/04 ,  C22C38/06 ,  C25D5/36 ,  C21D2211/002 ,  C21D2211/008

Abstract: A high-yield-ratio high-strength electrogalvanized steel sheet having an electrogalvanized coating layer formed on a surface of a base steel sheet, in which the base steel sheet has a certain chemical composition, and a steel microstructure, in which a total area fraction of one or both of bainite containing carbides having an average grain diameter of 50 nm or less and tempered martensite containing carbides having an average grain diameter of 50 nm or less is 90% or more in the whole of the steel microstructure, and in which a total area fraction of one or both of the bainite containing and the tempered martensite containing carbides is 80% or more in a region from the surface of the base steel sheet to a position located at ⅛ of a thickness of the base steel sheet, and diffusible hydrogen in steel in an amount of 0.20 mass ppm or less.

公开(公告)号：US12043876B2

公开(公告)日：2024-07-23

申请号：US17285375

申请日：2019-10-16

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko Ono ,  Junya Tobata ,  Hiroyuki Akimoto ,  Yoichiro Matsui ,  Shinjiro Kaneko

IPC: C21D1/22 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

CPC classification number: C21D9/46 ,  C21D1/22 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet having a specified chemical composition and a method for producing the steel sheet. The steel sheet has a microstructure comprising ferrite: 5% or less, and at least one of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 95% to 100%, and retained γ: 5% to 20%. Retained γUB has a specified area percentage SγUB, retained γLB has a specified distribution number NγLB, and at least one of (i) fresh martensite has a specified equivalent circular grain diameter and aspect ratio and (ii) retained γ grains has a specified equivalent circular grain diameter and aspect ratio.

公开(公告)号：US11795520B2

公开(公告)日：2023-10-24

申请号：US17432349

申请日：2019-11-21

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Katsutoshi Takashima ,  Takayuki Futatsuka ,  Kentaro Sato

IPC: C21D8/02 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/02 ,  C21D9/48 ,  B32B15/01 ,  C21D6/00 ,  C22C38/00 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/40 ,  C23C2/12

CPC classification number: C21D9/48 ,  B32B15/012 ,  B32B15/013 ,  C21D6/002 ,  C21D6/005 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/16 ,  C22C38/26 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/40 ,  C21D2211/008 ,  C23C2/06 ,  C23C2/12

Abstract: A hot-pressed member having excellent bending collapsibility, a method for manufacturing the same, and a method for manufacturing a steel sheet for the hot-pressed member. The hot-pressed member includes a steel sheet as a base material, the steel sheet having a specified chemical composition. The hot-pressed member has a microstructure in which a martensite microstructure is present in a volume fraction of 70% or greater, and a number density of inclusions having a longest diameter of 25 μm or greater is 0.02/mm2 or less. The hot-pressed member has a tensile strength of 1.8 GPa or greater.

公开(公告)号：US11427880B2

公开(公告)日：2022-08-30

申请号：US16765708

申请日：2018-08-20

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Yasuaki Okita ,  Masaki Koba ,  Hiroshi Matsuda ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/60 ,  C23C2/06 ,  C23G1/00

Abstract: A high-strength galvanized steel sheet is excellent in the external appearance of plating and the hydrogen brittleness resistance, and has a high yield ratio, and a method for manufacturing the same. The high-strength galvanized steel sheet including a steel sheet having a specific component composition and a specific steel structure, the amount of diffusible hydrogen in the steel sheet being 0.20 mass ppm or less; and a galvanizing layer provided on a surface of the steel sheet, the galvanizing layer having a content amount of Fe of 8 to 15% in mass %, and an attachment amount of plating per one surface of 20 to 120 g/m2, wherein the amount of Mn oxides contained in the galvanizing layer is 0.050 g/m2 or less; and the high-strength galvanized steel sheet has a yield strength of 700 MPa or more and a yield strength ratio of 65% or more and less than 85%.

公开(公告)号：US20210381077A1

公开(公告)日：2021-12-09

申请号：US17284981

申请日：2019-10-15

Applicant: JFE Steel Corporation

Inventor： Noriaki Kohsaka ,  Junya Tobata ,  Shinjiro Kaneko ,  Yasushi Kitani ,  Yoshihiko Ono ,  Tadachika Chiba

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

Abstract: A thin steel sheet has a specific chemical composition. The thin steel sheet has a microstructure in which ferrite is present in an area fraction of 4% or less (including 0%), as-quenched martensite is present in an area fraction of 10% or less (including 0%), retained austenite is present in an amount of 7% or more and 20% or less, and upper bainite, lower bainite, and tempered martensite are present in a total area fraction of more than 71% and less than 93%; and BCC iron that has a misorientation of 1° or less and surrounds retained austenite having an equivalent circular diameter of 1 μm or less is present in an area fraction of 4% or more and 50% or less, and BCC iron that has a misorientation of more than 1° is present in an area fraction of 25% or more and 85% or less.

公开(公告)号：US20210381076A1

公开(公告)日：2021-12-09

申请号：US17284534

申请日：2019-10-15

Applicant: JFE Steel Corporation

Inventor： Noriaki Kohsaka ,  Shinjiro Kaneko ,  Akinori Nakamura ,  Yuma Honda ,  Tadachika Chiba ,  Yoshihiko Ono

IPC: C21D9/46 ,  C22C38/58 ,  C22C38/42 ,  C22C38/14 ,  C22C38/12 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

Abstract: A thin steel sheet has a specific chemical composition. The thin steel sheet has a microstructure in which ferrite is present in an area fraction of 5% or more and 60% or less, as-quenched martensite is present in an area fraction of 10% or less (including 0%), retained austenite is present in an area fraction of 5% or more and 20% or less, and upper bainite, lower bainite, and tempered martensite are present in a total area fraction of more than 15% and less than 85%; BCC iron that has a misorientation of 1° or less and surrounds retained austenite having an aspect ratio of 2.5 or higher is present in an area fraction of 5% or more and 70% or less; and a top 10% of retained austenite in terms of an equivalent circular diameter has an average aspect ratio of 2.5 or higher.

公开(公告)号：US20200291499A1

公开(公告)日：2020-09-17

申请号：US16765708

申请日：2018-08-20

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Yasuaki Okita ,  Masaki Koba ,  Hiroshi Matsuda ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D8/02 ,  C23G1/00 ,  C23C2/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/60

Abstract: There is provided a high-strength galvanized steel sheet excellent in the external appearance of plating and the hydrogen brittleness resistance, and has a high yield ratio suitable for building materials and automotive collision-resistant parts, and a method for manufacturing the same.Provided is a high-strength galvanized steel sheet including a specific component composition and a specific steel structure, the amount of diffusible hydrogen in the steel being 0.20 mass ppm or less; and a galvanizing layer provided on a surface of the steel sheet, having a content amount of Fe of 8 to 15% in mass %, and an attachment amount of plating per one surface of 20 to 120 g/m2, wherein the amount of Mn oxides contained in the galvanizing layer is 0.050 g/m2 or less, and a yield strength is 700 MPa or more and a yield strength ratio is 65% or more and less than 85%.

公开(公告)号：US20200071784A1

公开(公告)日：2020-03-05

申请号：US15999603

申请日：2017-02-15

Applicant: JFE Steel Corporation

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Hiroyuki Masuoka

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

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：US20180057919A1

公开(公告)日：2018-03-01

申请号：US15557547

申请日：2016-02-16

Applicant: JFE STEEL CORPORATION

Inventor： Nobusuke Kariya ,  Yoshihiko Ono ,  Yoshimasa Funakawa ,  Kazuma Mori ,  Reiko Sugihara

IPC: C22C38/60 ,  C21D8/02 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C21D9/46

CPC classification number: C22C38/60 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/005 ,  C22C38/02 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

Abstract: A high-strength, cold-rolled steel sheet having a tensile strength of 980 MPa or more, the steel sheet having a chemical composition containing, by mass %, C: 0.070% to 0.100%, Si: 0.50% to 0.70%, Mn: 2.40% to 2.80%, P: 0.025% or less, S: 0.0020% or less, Al: 0.020% to 0.060%, N: 0.0050% or less, Nb: 0.010% to 0.060%, Ti: 0.010% to 0.030%, B: 0.0005% to 0.0030%, Sb: 0.005% to 0.015%, Ca: 0.0015% or less, Cr: 0.01% to 2.00%, Mo: 0.01% to 1.00%, Ni: 0.01% to 5.00%, Cu: 0.01% to 5.00%, and the balance being Fe and inevitable impurities, a metallurgical microstructure including a ferrite phase in an amount of 30% or more in terms of area fraction, at least one selected from a bainite phase and a martensite phase in an amount of 40% to 65% in total in terms of area fraction, and a cementite in an amount of 5% or less in terms of area fraction at a position located at ¼ of the thickness from the surface of the steel sheet, and a metallurgical microstructure including a ferrite phase in an amount of 40% to 55% in terms of area fraction at a position located at 50 μm in the thickness direction from the surface of the steel sheet and a method for manufacturing the steel sheet.

公开(公告)号：US11795531B2

公开(公告)日：2023-10-24

申请号：US17042521

申请日：2019-03-29

Applicant: JFE Steel Corporation

Inventor： Hiromi Yoshitomi ,  Yoshihiko Ono ,  Tatsuya Nakagaito

IPC: C22C38/50 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46

CPC classification number: C22C38/50 ,  C21D8/0205 ,  C21D8/0236 ,  C21D9/46 ,  C22C38/001 ,  C22C38/002 ,  C22C38/04 ,  C22C38/06 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high-strength galvanized steel sheet of the present invention includes a steel sheet having a specific chemical composition, and a steel structure containing, in terms of area ratio, 4% or more and 20% or less of retained austenite, 30% or less (including 0%) of ferrite, 40% or more of martensite, and 10% or more and 50% or less of bainite; and a galvanized layer provided on the steel sheet, in which an amount of diffusible hydrogen in the steel is less than 0.20 mass ppm, a tensile strength is 1100 MPa or more, a relationship between a tensile strength TS (MPa), an elongation El (%), and a sheet thickness t (mm) satisfies a (1) formula below, and a yield ratio YR is 67% or more.

TS×(El+3−2.5t)≥13000   (1)