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：US12157923B2

公开(公告)日：2024-12-03

申请号：US17417865

申请日：2019-08-23

Applicant: JFE Steel Corporation

Inventor： Hiroshi Hasegawa ,  Hidekazu Minami ,  Tatsuya Nakagaito

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/38 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C23C2/40 ,  C23G1/02 ,  C21D9/00

Abstract: A high-strength hot-dip galvanized steel sheet includes a hot-dip galvanized layer on a surface of the steel sheet and has a specific component composition and a steel microstructure containing, on an area percentage basis, 90% to 100% of martensite and carbide-containing bainite in total and 0% to 10% of retained austenite, and containing prior austenite grains having an aspect ratio of 2.0 or less, in a region extending from 300 μm to 400 μm from the surface layer, in which the ratio of the average amount of C at 5 μm from the surface layer to the average amount of C at 70 μm from the surface layer is 0.2 to 0.8, and the ratio of the standard deviation of the amount of C to the average amount of C in a region extending from 300 μm to 400 μm from the surface layer is 0.40 or less.

公开(公告)号：US11965222B2

公开(公告)日：2024-04-23

申请号：US17158097

申请日：2021-01-26

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa

IPC: C21D9/46 ,  B32B15/01 ,  B32B15/04 ,  B32B15/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/00 ,  C23C2/04 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/40 ,  C23C30/00 ,  C25D5/50 ,  C25D7/06

CPC classification number: C21D9/46 ,  B32B15/01 ,  B32B15/013 ,  B32B15/04 ,  B32B15/043 ,  B32B15/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/004 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  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 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C22C38/60 ,  C23C2/00 ,  C23C2/04 ,  C23C2/06 ,  C23C2/12 ,  C23C2/28 ,  C23C2/40 ,  C23C30/00 ,  C23C30/005 ,  C25D5/50 ,  C25D7/0614 ,  Y10T428/12757 ,  Y10T428/12799 ,  Y10T428/12951 ,  Y10T428/12972

Abstract: A method of producing a hot-rolled steel sheet and a method for producing a cold-rolled full hard steel sheet are provided. The methods comprising heating a steel slab having a composition containing, in terms of mass %, C: 0.010% or more and 0.150% or less, Si: 0.20% or less, Mn: 1.00% or less, P: 0.100% or less, S: 0.0500% or less, Al: 0.001% or more and 0.100% or less, N: 0.0100% or less, and the balance being Fe and unavoidable impurities, in which 0.002%≤[% P]+[% S]≤0.070% ([% M] denotes a content (mass %) of M element in steel) is satisfied.

公开(公告)号：US11946111B2

公开(公告)日：2024-04-02

申请号：US16086044

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa ,  Shinjiro Kaneko

IPC: C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C23C2/02 ,  C23C2/28

CPC classification number: C21D8/0226 ,  C21D8/0236 ,  C21D8/0247 ,  C22C38/001 ,  C22C38/002 ,  C22C38/02 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52 ,  C22C38/54 ,  C23C2/02 ,  C23C2/0224 ,  C23C2/024 ,  C23C2/28 ,  C21D2211/005 ,  C21D2211/008

Abstract: A steel sheet is provided, having a tensile strength of 590 MPa or more, a particular composition and a steel structure that contains, in terms of area fraction, particular amounts of ferrite and martensite, in which the ferrite average crystal grain size is 20 μm or less, the martensite average size is 15 μm or less, the ratio of the average crystal grain size of the ferrite to the average size of the martensite (ferrite average crystal grain size/martensite average size) is 0.5 to 10.0, the ratio of the hardness of the martensite to the hardness of the ferrite (martensite hardness/ferrite hardness) is 1.0 or more and 5.0 or less, and, in the texture of the ferrite, the inverse intensity ratio of γ-fiber to the α-fiber is 0.8 or more and 7.0 or less.

公开(公告)号：US11332804B2

公开(公告)日：2022-05-17

申请号：US16966762

申请日：2019-01-21

Applicant: JFE STEEL CORPORATION

Inventor： Seigo Tsuchihashi ,  Shinsuke Komine ,  Tatsuya Nakagaito ,  Hidekazu Minami

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/20 ,  C22C38/32 ,  C22C38/60 ,  C23C2/06

Abstract: A high-strength cold-rolled steel sheet or high-strength coated steel sheet that has a tensile strength (TS) of 780 MPa or more and has high ductility, stretch-flangeability, and in-plane stability of stretch-flangeability and methods for producing the same. The high-strength cold-rolled steel sheet has a specified chemical composition and a microstructure comprising, by area fraction, in a range of 50% to 80% of ferrite, 8% or less of martensite with an average grain size of 2.5 μm or less, in a range of 6% to 15% of retained austenite, and in a range of 3% to 40% of tempered martensite. A ratio fM/fM+TM being 50% or less, where fM denotes the area fraction of martensite and fM+TM denotes the total area fraction of martensite and tempered martensite, and a standard deviation of the grain size of martensite at certain portions being 0.7 μm 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：US10941461B2

公开(公告)日：2021-03-09

申请号：US16087468

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa

IPC: C22C38/20 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01 ,  C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C23C2/06 ,  C22C38/60 ,  C25D5/50 ,  C23C2/40 ,  C23C2/12 ,  C23C2/28 ,  C25D7/06 ,  C22C38/30 ,  C22C38/32 ,  C22C38/52 ,  C22C38/16 ,  C23C30/00 ,  C22C38/28 ,  C22C38/48 ,  C22C38/40 ,  C22C38/22 ,  C22C38/24 ,  C22C38/54 ,  C22C38/42 ,  C22C38/26 ,  C23C2/00 ,  C22C38/18 ,  C22C38/44 ,  C22C38/50 ,  C23C2/04 ,  C22C38/46 ,  B32B15/04 ,  B32B15/18

Abstract: A steel sheet is provided, having a tensile strength of 340 MPa or more, a particular composition and a steel structure in which ferrite has an average crystal grain size of 5 μm or more and 25 μm or less, 40% or more of cementite in terms of area fraction precipitates in ferrite grain boundaries, and the ferrite has a texture in which an inverse intensity ratio of γ-fiber to α-fiber is 0.8 or more and 7.0 or less.

公开(公告)号：US20200248280A1

公开(公告)日：2020-08-06

申请号：US16086044

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa ,  Shinjiro Kaneko

IPC: C21D8/02 ,  C22C38/50 ,  C22C38/44 ,  C22C38/42 ,  C22C38/48 ,  C22C38/46 ,  C22C38/54 ,  C22C38/52 ,  C22C38/02 ,  C22C38/00

Abstract: A steel sheet is provided, having a tensile strength of 590 MPa or more, a particular composition and a steel structure that contains, in terms of area fraction, particular amounts of ferrite and martensite, in which the ferrite average crystal grain size is 20 μm or less, the martensite average size is 15 μm or less, the ratio of the average crystal grain size of the ferrite to the average size of the martensite (ferrite average crystal grain size/martensite average size) is 0.5 to 10.0, the ratio of the hardness of the martensite to the hardness of the ferrite (martensite hardness/ferrite hardness) is 1.0 or more and 5.0 or less, and, in the texture of the ferrite, the inverse intensity ratio of γ-fiber to the α-fiber is 0.8 or more and 7.0 or less.

公开(公告)号：US12258646B2

公开(公告)日：2025-03-25

申请号：US17593062

申请日：2020-02-21

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Yuji Tanaka ,  Takeshi Yokota

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/20 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/32 ,  C22C38/38 ,  C22C38/40 ,  C23C2/02 ,  C23C2/28

Abstract: A high-strength steel sheet comprises: a chemical composition containing C, Si, Mn, P, S, Al, N, Mo, Cr, Ca, and Sb with a balance consisting of Fe and inevitable impurities, wherein [% Si], [% Mn], [% P], [% Mo], and [% Cr] satisfy a predetermined relationship; a steel microstructure that contains ferrite, hard phase, and retained austenite and in which a carbon concentration in the retained austenite is 0.55% or more and 1.10% or less, an amount of diffusible hydrogen in the steel sheet is 0.80 mass ppm or less, a surface layer softening thickness is 5 μm or more and 150 μm or less, and a corresponding grain boundary frequency in a surface layer of the steel sheet after a high-temperature tensile test is 0.45 or less; and a tensile strength of 980 MPa or more.

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.