公开(公告)号：US11939642B2

公开(公告)日：2024-03-26

申请号：US17283840

申请日：2019-08-20

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Yuji Tanaka ,  Junya Tobata ,  Takeshi Yokota

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/02 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23G1/00 ,  C25D3/22 ,  C25D3/44

CPC classification number: C21D9/46 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/024 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23G1/00 ,  C25D3/22 ,  C25D3/44 ,  C21D2211/001 ,  C21D2211/008

Abstract: A high-strength steel sheet having a tensile strength of 1,180 MPa or more, and specified chemical composition. The steel sheet includes a steel structure in which an area fraction of martensite having a carbon concentration of more than 0.7×[% C] and less than 1.5×[% C] is 55% or more, an area fraction of tempered martensite having a carbon concentration of 0.7×[% C] or less is 5% or more and 40% or less, a ratio of a carbon concentration in retained austenite to a volume fraction of retained austenite is 0.05 or more and 0.40 or less, and the martensite and the tempered martensite each have an average grain size of 5.3 μm or less, where [% C] represents the content, by mass %, of compositional element C in steel.

公开(公告)号：US20240352552A1

公开(公告)日：2024-10-24

申请号：US18685815

申请日：2022-04-20

Applicant: Cleveland-Cliffs Steel Properties Inc. ,  JFE Steel Corporation

Inventor： Amrinder Singh Gill ,  Grant Aaron Thomas ,  Junya Tobata ,  Shigehiro Takajo ,  Yuki Toji

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/20 ,  C22C38/38 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0221 ,  C21D8/0247 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/20 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/001 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet has a chemical composition containing a predetermined amount of C, Si, Mn, Cu, P, S, Al, and N, and optionally a predetermined amount of one or more selected from the group consisting of Ti, B, Nb, Cr, V, Mo, Ni, As, Sb, Sn, Ta, Ca, Mg, Zn, Co, Zr, and REM, with the balance being Fe and inevitable impurities; a microstructure comprising, in volume fraction, tempered martensite: 90% or more, retained austenite: 1% to 7%, one or both of bainitic ferrite and fresh martensite: 3% to 9% in total, and ferrite: 0% to 5%, where the retained austenite has a carbon concentration of 0.35% or more; a tensile strength TS of 1470 MPa to 1650 MPa, and a yield strength YS of 1100 MPa or more.

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：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：US20210310095A1

公开(公告)日：2021-10-07

申请号：US17295950

申请日：2019-11-18

Applicant: JFE Steel Corporation

Inventor： Junya Tobata ,  Hidekazu Minami ,  Takashi Kobayashi

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/24 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/14 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18 ,  B32B15/01

Abstract: There is provided a high-strength steel sheet in which content amounts of a specific steel composition are limited and manufacturing conditions are optimized and that has a steel structure that contains ferrite and a harder phase and in which ferrite accounts for 30% to 70% in terms of area ratio, the harder phase contains bainitic ferrite, tempered martensite, martensite (including 0%), and retained austenite (including 0%), the maximum grain diameter of ferrite dmax is 2.5 μm or less, and the area ratio of ferrite AF and the average grain diameter of ferrite dF satisfy AF [%]/dF [μm]≤15.

公开(公告)号：US20240376562A1

公开(公告)日：2024-11-14

申请号：US18564791

申请日：2022-05-19

Applicant: JFE Steel Corporation

Inventor： Junya Tobata ,  Yuki Toji

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60

Abstract: A high strength steel sheet includes a specific microstructure having a specific chemical composition and satisfying the formulas (1) and (2) defined below: KAM ⁢ ( S ) / KAM ⁢ ( C )

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：US20240287636A1

公开(公告)日：2024-08-29

申请号：US18564783

申请日：2022-05-19

Applicant: JFE Steel Corporation

Inventor： Junya Tobata ,  Yuki Toji ,  Hidekazu Minami

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/40 ,  C25D3/22

CPC classification number: C21D9/46 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C23C2/06 ,  C23C2/40 ,  C25D3/22 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: A high strength steel sheet includes a specific microstructure having a specific chemical composition and satisfying the formulas (1) and (2) defined below:









KAM
⁡
(
S
)

/

KAM
⁡
(
C
)

公开(公告)号：US20200157647A1

公开(公告)日：2020-05-21

申请号：US16604398

申请日：2018-04-13

Applicant: JFE Steel Corporation

Inventor： Yoshihiko Ono ,  Junya Tobata ,  Hiroyuki Akimoto

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

Abstract: A steel sheet and a manufacturing method therefor are provided.A steel sheet has a component composition and contains 6 to 80% of ferrite and 20 to 94% of a microstructure composed of one or two or more of upper bainite, fresh martensite, tempered martensite, lower bainite, and retained γ, and contains 7 to 20% of retained γ, where: an area ratio (SγUB) of retained γ having a particle width of 0.18 to 0.60 μm, a particle length of 1.7 to 7.0 μm, and an aspect ratio of 5 to 15 is 0.2 to 5%; and a total area ratio (SγBlock) of fresh martensite having an equivalent circle diameter of 1.5 to 15 μm and an aspect ratio of 3 or less and/or retained γ particles having an equivalent circle diameter of 1.5 to 15 μm and an aspect ratio of 3 or less is 3% or less (including 0%).