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：US12209299B2

公开(公告)日：2025-01-28

申请号：US17442744

申请日：2020-03-26

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yasushi Kitani ,  Hiroyuki Akimoto ,  Yoichiro Matsui

IPC: C22C38/00 ,  C21D1/25 ,  C21D1/76 ,  C21D8/02 ,  C21D8/04 ,  C21D9/48 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/34 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/58 ,  C22C38/60 ,  C23C2/28

Abstract: The steel sheet has a steel microstructure containing ferrite: 6% to 90% by area, a microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 10% to 94% by area in total, and retained γ: 3% to 20% by volume, a ratio (SUB/S2nd)×100(%) of an area ratio SUB of an upper bainite with a width in the range of 0.8 to 7 μm, a length in the range of 2 to 15 μm, and an aspect ratio of 2.2 or more in contact with retained γUB with a grain width in the range of 0.17 to 0.80 μm and an aspect ratio in the range of 4 to 25 to an area ratio S2nd of the microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ ranges from 2.0% to 15%.

公开(公告)号：US11365460B2

公开(公告)日：2022-06-21

申请号：US16971719

申请日：2019-02-20

Applicant: JFE STEEL CORPORATION

Inventor： Yuka Miyamoto ,  Yoichiro Matsui ,  Shogo Sato ,  Takeshi Yokota

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/18 ,  C23G1/00

Abstract: A high-carbon cold rolled steel sheet having a specified chemical composition, and a method for manufacturing the same. The method includes forming a hot rolled steel sheet, performing cooling at an average cooling rate of 30° C./s or more and 70° C./s or less through a temperature range of a finish rolling end temperature to 660° C., coiling a hot rolled steel sheet at a temperature of 500° C. or more and 660° C. or less, and, optionally, pickling the coiled hot rolled steel sheet, and then performing a first box-annealing of holding at an annealing temperature in a temperature range of 650 to 720° C., then performing cold rolling at a rolling reduction ratio of 20 to 50%, and then performing a second box-annealing of holding at an annealing temperature in a temperature range of 650 to 720° C.

公开(公告)号：US20250122602A1

公开(公告)日：2025-04-17

申请号：US18683839

申请日：2022-08-15

Applicant: JFE Steel Corporation

Inventor： Yoichiro Matsui ,  Tadachika Chiba ,  Shinjiro Kaneko ,  Akinori Nakamura

IPC: C22C38/60 ,  B32B15/01 ,  C21D1/26 ,  C21D6/00 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58

Abstract: Provided are a steel sheet; a related member; and methods for manufacturing the same. The steel sheet has a chemical composition including, in mass %, C: 0.06 to 0.25%, Si: 0.4 to 2.5%, Mn: 1.5 to 3.5%, P: 0.02% or less, S: 0.01% or less, sol. Al: less than 1.0%, and N: less than 0.015%, the balance being Fe and incidental impurities, the steel sheet being such that the steel sheet includes a steel microstructure including, in area fraction, polygonal ferrite: 10% or less (including 0%), tempered martensite: 40% or more, fresh martensite: 20% or less (including 0%), bainitic ferrite having 20 or less internal carbides per 10 μm2: 3 to 40%, and, in volume fraction, retained austenite: 5 to 20%, and the steel sheet has SC≥0.5/SC≥0.3×100 of 20% or more.

公开(公告)号：US20240425943A1

公开(公告)日：2024-12-26

申请号：US18692920

申请日：2022-09-09

Applicant: JFE Steel Corporation

Inventor： Tadachika Chiba ,  Yoichiro Matsui ,  Fangyi Wang ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Shuto Ozono

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 ,  C22C38/38 ,  C22C38/60

Abstract: A steel sheet; a related member; and methods for manufacturing them are disclosed. The steel sheet has a chemical composition including specific amounts of C, Si, Mn, P, S, sol. Al, and N in mass %. The steel sheet has a specific ratio of the total of polygonal ferrite, upper bainite, retained γ, fresh martensite, tempered martensite, and lower bainite, and a specific ratio of a remaining microstructure. The steel sheet has a specific ratio of the number of fresh martensite grains and retained γ grains having an equivalent circular diameter of less than 1.2 μm, and has a specific ratio of the number of fresh martensite grains and retained γ grains having an aspect ratio of 2.5 or more and an equivalent circular diameter of 1.2 μm or more.

公开(公告)号：US20240368722A1

公开(公告)日：2024-11-07

申请号：US18683857

申请日：2022-08-15

Applicant: JFE Steel Corporation

Inventor： Yoichiro Matsui ,  Tadachika Chiba ,  Shinjiro Kaneko

IPC: C21D9/46 ,  B32B15/01 ,  C21D1/18 ,  C21D1/84 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/02 ,  C23C2/28 ,  C23C2/40 ,  C25D5/50

Abstract: Provided are a steel sheet; a related member; and methods for manufacturing the same.
The steel sheet has a chemical composition including, in mass %, C: 0.06 to 0.25%, Si: 0.4 to 2.5%, Mn: 1.5 to 3.5%, P: 0.02% or less, S: 0.01% or less, sol. Al: less than 1.0%, and N: less than 0.015%, the balance being Fe and incidental impurities, the steel sheet being such that the steel sheet includes a steel microstructure including, in area fraction, polygonal ferrite: 10% or less (including 0%), tempered martensite: 30% or more, fresh martensite: 20% or less (including 0%), lower bainite: 5 to 50%, and, in volume fraction, retained austenite: 5 to 20%, and the steel sheet has SC≥0.5/SC≥0.3×100 of 15% or more.

公开(公告)号：US20220235442A1

公开(公告)日：2022-07-28

申请号：US17442744

申请日：2020-03-26

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Yasushi Kitani ,  Hiroyuki Akimoto ,  Yoichiro Matsui

IPC: C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/34 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/58 ,  C22C38/60 ,  C21D1/25 ,  C21D1/76 ,  C21D8/02 ,  C21D8/04 ,  C21D9/48

Abstract: The steel sheet has a steel microstructure containing ferrite: 6% to 90% by area, a microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ: 10% to 94% by area in total, and retained γ: 3% to 20% by volume, a ratio (SUB/S2nd)×100(%) of an area ratio SUB of an upper bainite with a width in the range of 0.8 to 7 μm, a length in the range of 2 to 15 μm, and an aspect ratio of 2.2 or more in contact with retained γUB with a grain width in the range of 0.17 to 0.80 μm and an aspect ratio in the range of 4 to 25 to an area ratio S2nd of the microstructure composed of one or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ ranges from 2.0% to 15%.

公开(公告)号：US20240384379A1

公开(公告)日：2024-11-21

申请号：US18692925

申请日：2022-09-09

Applicant: JFE Steel Corporation

Inventor： Tadachika Chiba ,  Fangyi Wang ,  Yoichiro Matsui ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Shuto Ozono

IPC: C22C38/04 ,  C21D6/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06

Abstract: A steel sheet; a related member; and methods for manufacturing them are disclosed. The steel sheet has a chemical composition including specific amounts of C, Si, Mn, P, S, sol. Al, and N in mass %. The steel sheet has a specific ratio of the total of polygonal ferrite, upper bainite, retained γ, fresh martensite, tempered martensite, and lower bainite, and a specific ratio of a remaining microstructure. The steel sheet has a specific ratio of the number of fresh martensite grains and retained γ grains having an equivalent circular diameter of less than 0.8 μm, and has a specific ratio of the number of fresh martensite grains and retained γ grains having an aspect ratio of 2.0 or more and an equivalent circular diameter of 0.8 μm or more.

公开(公告)号：US12123069B2

公开(公告)日：2024-10-22

申请号：US17286148

申请日：2019-10-16

Applicant: JFE STEEL CORPORATION

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

IPC: C21D9/46 ,  C21D1/20 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/20 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/42 ,  C22C38/44 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  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% by area percentage, and retained γ: 4% to 15% by volume percentage. 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：US12110568B2

公开(公告)日：2024-10-08

申请号：US17434255

申请日：2020-02-28

Applicant: JFE STEEL CORPORATION

Inventor： Yoichiro Matsui ,  Yuka Miyamoto ,  Takeshi Yokota

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/54

CPC classification number: C21D9/46 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/54 ,  C21D2211/004 ,  C21D2211/005

Abstract: A steel sheet and a member excellent in cold workability, hardenability, and post-quenching surface layer hardness, and methods for manufacturing the steel sheet and the member. The steel sheet has a specified chemical composition and a microstructure containing ferrite and carbides, a ratio of the volume of ferrite and carbides to the volume of the entire microstructure is 90% or more, a ratio of the volume of proeutectoid ferrite to the volume of the entire microstructure is 20% or more and 80% or less, a Mn concentration in the carbides is 0.10 mass % or more and 0.50 mass % or less, and a ratio of the number of carbides with particle diameters of 1 μm or more to the total number of carbides is 30% or more and 60% or less.