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：US11965223B2

公开(公告)日：2024-04-23

申请号：US17262878

申请日：2019-07-18

Applicant: JFE Steel Corporation

Inventor： Noriaki Kohsaka ,  Soshi Yoshimoto ,  Tomohiro Hashimukai ,  Takuya Hirashima

IPC: C21D9/46 ,  C21D1/60 ,  C21D1/63 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/60 ,  C21D1/63 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/60 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A thin steel sheet has a steel structure which has a ferrite area fraction of 30% or less, a bainite area fraction of 5% or less, a martensite and tempered martensite area fraction of 70% or more, and a retained austenite area fraction of 2.0% or less and in which the ratio of the dislocation density in the range of 0 μm to 20 μm from a surface of the steel sheet to the dislocation density of a through-thickness central portion of the steel sheet is 90% to 110% and the average of the top 10% of the sizes of cementite grains located in a depth of up to 100 μm from a surface of the steel sheet is 300 nm or less. The maximum camber of the steel sheet sheared to a length of 1 m in a longitudinal direction of the steel sheet is 15 mm or less.

公开(公告)号：US20200032364A1

公开(公告)日：2020-01-30

申请号：US16484563

申请日：2017-04-19

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Tatsuya Nakagaito ,  Masaki Koba ,  Tatsuya Ehashi ,  Makoto Imamura

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

Abstract: Provided are a high-strength galvanized steel sheet having excellent delayed fracture resistance by reducing the diffusible hydrogen content in the steel and a method for producing the same.The high-strength galvanized steel sheet includes a steel sheet having a prescribed composition and a microstructure including martensite and tempered martensite, the total area fraction of the martensite and the tempered martensite being 30% or more, and a galvanizing layer formed on the surface of the steel sheet. The diffusible hydrogen content in the high-strength galvanized steel sheet is 0.50 wt. ppm or less. The half-width of the hydrogen release peak of the high-strength galvanized steel sheet is 70° C. or less. The diffusible hydrogen content and the half-width of the hydrogen release peak are determined by a prescribed analysis method.

公开(公告)号：US12146204B2

公开(公告)日：2024-11-19

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

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.

公开(公告)号：US12043884B2

公开(公告)日：2024-07-23

申请号：US17285166

申请日：2019-08-06

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Shinjiro Kaneko

IPC: C22C38/06 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C25D3/22

CPC classification number: C22C38/06 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D9/46 ,  C22C38/001 ,  C22C38/02 ,  C22C38/04 ,  C25D3/22 ,  C21D2211/002 ,  C21D2211/008

Abstract: A high-ductility, high-strength electrolytic zinc-based coated steel sheet includes an electrolytic zinc-based coating on a base steel sheet, in which the base steel sheet has a predetermined composition and a steel microstructure in which the total area percentage of one or two of martensite containing a carbide having an average particle size of 50 nm or less and bainite containing a carbide having an average particle size of 50 nm or less is 90% or more in the entire steel microstructure, the total area percentage of one or two of the martensite containing a carbide having an average particle size of 50 nm or less and the bainite containing a carbide having an average particle size of 50 nm or less is 80% or more in a region extending from the surface of the base steel sheet to a depth of ⅛ of the thickness of the base steel sheet.

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：US20220275469A1

公开(公告)日：2022-09-01

申请号：US17629857

申请日：2020-07-29

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Yu Hashimoto ,  Shinjiro Kaneko ,  Yoshihiko Ono

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

Abstract: The high strength steel sheet of the present invention has a specific chemical composition, and contains, in terms of area fraction relative to an entire steel microstructure, 30% or more and 100% or less ferrite, 0% or more and 70% or less martensite, and less than 20% in total of pearlite, bainite and retained austenite, a total content of Nb and Ti contained in a precipitate having a particle size of smaller than 20 nm is 25 mass ppm or more and 220 mass ppm or less, and the difference between the maximum value and the minimum value of the total content of Nb and Ti contained in the precipitate having a particle size of smaller than 20 nm, in the longitudinal direction of the steel sheet, is smaller than 20 mass ppm.

公开(公告)号：US11208704B2

公开(公告)日：2021-12-28

申请号：US16475426

申请日：2017-04-19

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Hiromi Yoshitomi

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40

Abstract: A high-strength cold-rolled steel sheet has a component composition containing, on a percent by mass basis, C: 0.12% or more and 0.25% or less, Si: less than 0.5%, Mn: 2.0% or more and 3.0% or less, P: 0.05% or less, S: 0.005% or less, Al: 0.01% or more and 0.10% or less, and N: 0.010% or less, the balance being Fe and incidental impurities, the total area percentage of martensite and tempered martensite satisfying 20% or more and 90% or less, the area percentage of ferrite satisfying 10% or less, the area percentage of bainite satisfying 10% or more and 80% or less, the area percentage of a martensite-austenite constituent in the bainite being 1% or more and 10% or less, the area percentage of cementite having an average grain size of 1 μm or less in the bainite being 0.1% or more and 5.0% or less.

公开(公告)号：US11180823B2

公开(公告)日：2021-11-23

申请号：US16484563

申请日：2017-04-19

Applicant: JFE Steel Corporation

Inventor： Takuya Hirashima ,  Tatsuya Nakagaito ,  Masaki Koba ,  Tatsuya Ehashi ,  Makoto Imamura

IPC: C21D6/00 ,  C21D9/46 ,  C21D8/02 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/58 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C23C2/04 ,  C23C2/40 ,  C23C2/28 ,  C25D7/06 ,  C25D5/50 ,  C23C2/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/18 ,  C22C38/22 ,  C22C38/20 ,  C22C38/04 ,  C22C38/60 ,  C23C28/02 ,  C22C38/32 ,  C22C38/08 ,  B32B15/18 ,  C22C38/24 ,  C23C30/00 ,  C22C38/26 ,  C22C38/40 ,  C22C38/16 ,  C22C38/38 ,  C22C38/46 ,  C22C38/28 ,  B32B15/04 ,  C25D3/56

Abstract: Provided are a high-strength galvanized steel sheet having excellent delayed fracture resistance by reducing the diffusible hydrogen content in the steel and a method for producing the same. The high-strength galvanized steel sheet includes a steel sheet having a prescribed composition and a microstructure including martensite and tempered martensite, the total area fraction of the martensite and the tempered martensite being 30% or more, and a galvanizing layer formed on the surface of the steel sheet. The diffusible hydrogen content in the high-strength galvanized steel sheet is 0.50 wt. ppm or less. The half-width of the hydrogen release peak of the high-strength galvanized steel sheet is 70° C. or less. The diffusible hydrogen content and the half-width of the hydrogen release peak are determined by a prescribed analysis method.

公开(公告)号：US11603574B2

公开(公告)日：2023-03-14

申请号：US16964651

申请日：2019-01-24

Applicant: JFE STEEL CORPORATION

Inventor： Takuya Hirashima ,  Yoshihiko Ono

IPC: C21D9/46 ,  C21D1/26 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/16 ,  C22C38/18

Abstract: A high-ductility, high-strength steel sheet having excellent close-contact bendability and a method for producing the same. The steel sheet has a specified chemical composition and a microstructure comprising, by area percentage, 50% or more of a ferrite phase, 5% to 30% of a pearlite phase, and 15% or less in total of bainite, martensite, and retained austenite, in which the area percentage of ferrite grains each containing three or more cementite grains having an aspect ratio of 1.5 or less is 30% or less, and the number of inclusions having a particle size of 10 μm or more present in a portion extending from a surface to a ¼ thickness position is 2.0 particles/mm2 or less.