公开(公告)号：US20190194775A1

公开(公告)日：2019-06-27

申请号：US16329672

申请日：2017-09-28

Applicant: JFE STEEL CORPORATION

Inventor： Yoshihiko ONO ,  Shimpei YOSHIOKA ,  Nobuyuki NAKAMURA ,  Hiroshi HASEGAWA

IPC: C21D9/46 ,  C23C2/06 ,  C23C2/40 ,  C22C38/58 ,  C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/42 ,  C22C38/46 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/44 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/021 ,  C21D8/0236 ,  C21D8/0247 ,  C21D8/0405 ,  C21D8/041 ,  C21D8/0426 ,  C21D8/0436 ,  C21D8/0473 ,  C21D2211/002 ,  C21D2211/008 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/54 ,  C22C38/58 ,  C22C38/60 ,  C23C2/06 ,  C23C2/40

Abstract: A steel sheet having a specified chemical composition and a method for producing the steel sheet. The steel sheet has a microstructure including martensite and bainite. The total area fraction of the martensite and the bainite to the entirety of the microstructure is more than 90% and 100% or less. The microstructure includes inclusion clusters A and B, the content of the clusters A in the microstructure being 2 clusters/mm2 or less, and the content of the clusters B in the microstructure being 5 clusters/mm2 or less. The microstructure includes carbide particles including Fe as a main constituent which have an aspect ratio of 2.0 or less and a major axis of 0.30 μm or more and 2 μm or less. The content of the carbide particles in the microstructure is 4000 particles/mm2 or less. The microstructure includes prior γ grains having an average size of 6 to 15 μm.

公开(公告)号：US20240158883A1

公开(公告)日：2024-05-16

申请号：US18549920

申请日：2022-02-28

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Shinjiro KANEKO ,  Yuma HONDA

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 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/60 ,  C21D2211/008

Abstract: To provide a steel sheet with a tensile strength of 1310 MPa or more that can achieve excellent press formability in a steel having a martensite-dominant microstructure with excellent delayed fracture resistance properties. Disclosed is a steel sheet including: a chemical composition containing, by mass %, C: 0.12-0.40%, Si: 1.5% or less, Mn: 1.7% or less, P: 0.05% or less, S: 0.010% or less, sol.Al: 1.00% or less, N: 0.010% or less, Ti: 0.002-0.080%, and B: 0.0002-0.0050%, with the balance being Fe and inevitable impurities; a metallic structure in which an area ratio of martensite to an entire microstructure is 95% or more, and a ratio LS/LB satisfies a predetermined formula (1), where LS denotes a length of a sub-block boundary and LB denotes a length of a block boundary; and a tensile strength of 1310 MPa or more.

公开(公告)号：US20220090247A1

公开(公告)日：2022-03-24

申请号：US17415462

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yuma HONDA ,  Nobuyuki NAKAMURA

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

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 92% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [%Ti]+[%Nb]>0.007 and [%Ti]×[%Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US20240175102A1

公开(公告)日：2024-05-30

申请号：US18550132

申请日：2022-02-28

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Shinjiro KANEKO ,  Yuma HONDA

IPC: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60

CPC classification number: C21D9/46 ,  C21D1/18 ,  C21D1/84 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/008 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60 ,  C21D2211/008

Abstract: To provide a steel sheet with a tensile strength of 1310 MPa or more that can achieve excellent press formability in a steel having a martensite-dominant microstructure with excellent delayed fracture resistance properties. Disclosed is a steel sheet including: a chemical composition containing, by mass %, C: 0.12-0.40%, Si: 1.5% or less, Mn: more than 1.7% and 3.5% or less, P: 0.05% or less, S: 0.010% or less, sol.Al: 1.00% or less, N: 0.010% or less, Ti: 0.002-0.080%, and B: 0.0002-0.0050%, with the balance being Fe and inevitable impurities; a metallic structure in which an area ratio of martensite to an entire microstructure is 85% or more, and a ratio LS/LB satisfies a predetermined formula (1), where LS denotes a length of a sub-block boundary and LB denotes a length of a block boundary; and a tensile strength of 1310 MPa or more.

公开(公告)号：US20220056549A1

公开(公告)日：2022-02-24

申请号：US17415532

申请日：2019-10-25

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yuma HONDA ,  Nobuyuki NAKAMURA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C23C2/06 ,  B22D11/18

Abstract: A steel sheet having a specified chemical composition and a tensile strength of 1,320 MPa or more, and methods for producing the steel sheet. The steel sheet has a specified microstructure including martensite and bainite, the total area fraction of the martensite and the bainite being 95% or more and 100% or less, the balance being one or more selected from ferrite and retained austenite. The forumulae [% Ti]+[% Nb]>0.007 and [% Ti]×[% Nb]2≤7.5×10−6 are satisfied in the chemical composition.

公开(公告)号：US20220010414A1

公开(公告)日：2022-01-13

申请号：US17289951

申请日：2019-09-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Shimpei YOSHIOKA ,  Shinjiro KANEKO

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

Abstract: A high-strength member having excellent delayed fracture resistance, a method for manufacturing the high-strength member, and a method for manufacturing a steel sheet for the high-strength member. The high-strength member has a bent ridge portion obtained by using a steel sheet having a tensile strength of 1470 MPa or more, an edge surface of the bent ridge portion has a residual stress of 800 MPa or less, and a longest crack among cracks that extend from the edge surface of the bent ridge portion in a bent ridge direction D1 has a length of 10 μm or less.

公开(公告)号：US20210130919A1

公开(公告)日：2021-05-06

申请号：US16762501

申请日：2018-11-07

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Takayuki FUTATSUKA ,  Kentaro SATO ,  Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yoshimasa FUNAKAWA

IPC: C21D9/46 ,  B32B15/01 ,  C21D8/02 ,  C21D6/00 ,  C22C38/58 ,  C22C38/54 ,  C22C38/52 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C22C38/42 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C22C38/60

Abstract: Disclosed is a hot-pressed steel sheet member having a tensile strength of 1780 MPa or more and excellent bending collapsibility. The hot-pressed steel sheet member includes: a specific chemical composition; a microstructure in which an average grain size of prior austenite grains is 8 μm or less, a volume fraction of martensite is 90% or more, and a solute C content is 25% or less of a total C content; and a tensile strength of 1780 MPa or more.

公开(公告)号：US20200332382A1

公开(公告)日：2020-10-22

申请号：US16754135

申请日：2018-11-07

Applicant: JFE STEEL CORPORATION

Inventor： Katsutoshi TAKASHIMA ,  Takayuki FUTATSUKA ,  Kentaro SATO ,  Shimpei YOSHIOKA ,  Yoshihiko ONO ,  Yoshimasa FUNAKAWA

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/32 ,  C23C2/06 ,  C23C2/12

Abstract: Disclosed is a hot-pressed steel sheet member having a tensile strength of 1780 MPa or more and excellent bending collapsibility. The hot-pressed steel sheet member has: a specific chemical composition where a ratio of a C content in mass % to a Nb content in mass %, C/Nb, is from 22 to 100; a microstructure in which an average grain size of prior austenite grains is 8 μm or less, a volume fraction of martensite is 90% or more, and a solute C content is 25% or less of a total C content; and a tensile strength of 1780 MPa or more.

公开(公告)号：US20220298594A1

公开(公告)日：2022-09-22

申请号：US17639086

申请日：2020-08-25

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Shimpei YOSHIOKA ,  Shinjiro KANEKO ,  Soshi YOSHIMOTO ,  Tomohiro HASHIMUKAI ,  Yoshihiko ONO

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

Abstract: A steel sheet having a steel microstructure including, by area %, martensite in a range of 20% or more and 100% or less, ferrite in a range of 0% or more and 80% or less, and the balance being 5% or less. A residual stress generated at the transverse center of the steel sheet when the steel sheet is subjected to a V-bending process is 800 MPa or less. A residual stress generated at the transverse end of the steel sheet when the steel sheet is subjected to a V-bending process is 90% or more and 110% or less of the residual stress generated at the transverse center of the steel sheet. The maximum amount of warpage of the steel sheet sheared to a length of 1 m in the longitudinal direction is 15 mm or less.

公开(公告)号：US20220056552A1

公开(公告)日：2022-02-24

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

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.