公开(公告)号：US11926881B2

公开(公告)日：2024-03-12

申请号：US17636714

申请日：2020-06-19

Applicant: JFE STEEL CORPORATION

Inventor： Yuji Tanaka ,  Hidekazu Minami ,  Naoki Takayama ,  Takako Yamashita

IPC: C21D9/46 ,  B32B15/01 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/28 ,  C23C2/40

CPC classification number: C21D9/46 ,  B32B15/013 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/16 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C23C2/29 ,  C23C2/40 ,  C21D2211/002 ,  C21D2211/008 ,  Y10T428/12799

Abstract: A high-strength cold-rolled steel sheet having a high yield ratio and excellent stretch flangeability and a method for manufacturing the steel sheet. The high-strength cold-rolled steel sheet has a chemical composition including, by mass %, C: 0.10 to 0.30%, Si: 0.50 to 2.00%, Mn: 2.5 to 4.0%, P: 0.050% or less, S: 0.020% or less, Al: 0.10% or less, N: 0.01% or less, Ti: 0.100% or less, and B: 0.0003 to 0.0030%, with the balance being Fe and incidental impurities. N and Ti satisfy a specified formula, and the total area fraction of martensite and bainite is 95% or more. The number density of bainite grains having an area of 3 μm2 or more and a carbon concentration of less than 0.7C is 1200 grains/mm2 or less.

公开(公告)号：US10472697B2

公开(公告)日：2019-11-12

申请号：US15547659

申请日：2016-01-27

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Shinjiro Kaneko ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/02 ,  C22C38/60 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14 ,  C22C38/04 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28

Abstract: A steel sheet has a microstructure that contains ferrite in an area ratio of 20% or more, martensite in an area ratio of 5% or more, and tempered martensite in an area ratio of 5% or more. The ferrite has a mean grain size of 20.0 μm or less. An inverse intensity ratio of γ-fiber to α-fiber in the ferrite is 1.00 or more and an inverse intensity ratio of γ-fiber to α-fiber in the martensite and the tempered martensite is 1.00 or more.

公开(公告)号：US20190127819A1

公开(公告)日：2019-05-02

申请号：US16087468

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C22C38/20 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  B32B15/01

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 m or more and 25 m 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：US11408058B2

公开(公告)日：2022-08-09

申请号：US16485197

申请日：2018-02-09

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takashi Kobayashi ,  Shinjiro Kaneko ,  Yuji Tanaka

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

Abstract: There is provided a high-strength steel sheet and a method for producing the same. The steel sheet has a specified chemical composition and a microstructure including, in terms of area percentage, 20.0% or more and 60.0% or less ferrite, 40.0% or more and 80.0% or less of a hard phase composed of bainitic ferrite, tempered martensite, fresh martensite, and retained austenite, 35.0% or more and 55.0% or less bainitic ferrite with respect to the entire hard phase, 20.0% or more and 40.0% or less tempered martensite with respect to the entire hard phase, 3.0% or more and 15.0% or less fresh martensite with respect to the entire hard phase, and 5.0% or more and 20.0% or less retained austenite with respect to the entire hard phase.

公开(公告)号：US11408044B2

公开(公告)日：2022-08-09

申请号：US16485083

申请日：2018-02-09

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Fusae Shiimori ,  Shinjiro Kaneko ,  Takashi Kobayashi ,  Yuji Tanaka

IPC: C21D9/46 ,  C21D8/02 ,  C21D6/00 ,  C21D1/26 ,  C22C38/24 ,  C22C38/60 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/10 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00

Abstract: There is provided a high-strength steel sheet and a method for producing the same. The high-strength steel sheet has a specified chemical composition and a steel microstructure including, by area fraction, 75.0% or more tempered martensite, 1.0% or more and 20.0% or less fresh martensite, and 5.0% or more and 20.0% or less retained austenite. A hardness ratio of the fresh martensite to the tempered martensite is 1.5 or more and 3.0 or less, the ratio of the maximum KAM value in the tempered martensite in the vicinity of the heterophase interface between the tempered martensite and the fresh martensite to the average KAM value in the tempered martensite is 1.5 or more and 30.0 or less, and the average of ratios of grain sizes of prior austenite grains in the rolling direction to those in the thickness direction is 2.0 or less.

公开(公告)号：US11008632B2

公开(公告)日：2021-05-18

申请号：US16086431

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa ,  Shinjiro Kaneko

IPC: C21D8/02 ,  C22C38/02 ,  C23C2/02 ,  C23C2/06 ,  C21D9/46 ,  C22C38/06 ,  C22C38/00 ,  C23C2/28 ,  C22C38/04 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/38

Abstract: A steel sheet is provided that has a tensile strength of 540 MPa or more, includes a particular composition; and has a steel structure containing ferrite and a secondary phase, in which an area fraction of the ferrite is 50% or more, the secondary phase contains 1.0% or more and 25.0% or less of martensite in terms of area fraction with respect to the entirety, the ferrite has an average crystal grain size of 3 μm or more, a difference in hardness between the ferrite and the martensite is 1.0 GPa or more and 8.0 GPa or less, and, in a texture of the ferrite, 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：US10563279B2

公开(公告)日：2020-02-18

申请号：US14909253

申请日：2014-07-16

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C22C38/12 ,  C21D9/46 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/14 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/08 ,  C22C38/16 ,  C22C38/38 ,  C22C38/60 ,  C21D8/02 ,  C21D6/00 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/40

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, and one or both of Ti: 0.001% or more and 0.200% or less and Nb: 0.001% or more and 0.200% or less, in which the contents of C, N, S, Ti, and Nb satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in the ferrite and the martensite.

公开(公告)号：US10385431B2

公开(公告)日：2019-08-20

申请号：US14909562

申请日：2014-07-16

Applicant: JFE STEEL CORPORATION

Inventor： Hidekazu Minami ,  Takeshi Yokota ,  Kazuhiro Seto

IPC: C21D9/46 ,  C22C38/12 ,  C21D8/02 ,  C22C38/60 ,  B21B1/22 ,  B21B3/00 ,  C23C2/02 ,  C23C2/06 ,  C23C2/28 ,  C22C38/00 ,  C22C38/58 ,  B32B15/01 ,  C21D6/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/22 ,  C22C38/24 ,  C22C38/26 ,  C22C38/38

Abstract: A high strength steel sheet having a high Young's modulus, the steel sheet having a chemical composition including, by mass %, C: 0.060% or more and 0.150% or less, Si: 0.50% or more and 2.20% or less, Mn: 1.00% or more and 3.00% or less, Nb: 0.001% or more and 0.200% or less, and V: 0.001% or more and 0.200% or less, in which the contents of C, Nb, and V satisfy the equation 500≤C*≤1300. The steel sheet has a microstructure including ferrite in an amount of 20% or more and martensite in an amount of 5% or more, in terms of area ratio, such that the average grain size of the ferrite is 20.0 μm or less and the inverse intensity ratio of γ-fiber for α-fiber is 1.00 or more in each of the ferrite and the martensite.

公开(公告)号：US20190100819A1

公开(公告)日：2019-04-04

申请号：US16086431

申请日：2017-03-07

Applicant: JFE Steel Corporation

Inventor： Hidekazu Minami ,  Yoshimasa Funakawa ,  Shinjiro Kaneko

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

Abstract: A steel sheet is provided that has a tensile strength of 540 MPa or more, includes a particular composition; and has a steel structure containing ferrite and a secondary phase, in which an area fraction of the ferrite is 50% or more, the secondary phase contains 1.0% or more and 25.0% or less of martensite in terms of area fraction with respect to the entirety, the ferrite has an average crystal grain size of 3 μm or more, a difference in hardness between the ferrite and the martensite is 1.0 GPa or more and 8.0 GPa or less, and, in a texture of the ferrite, 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：US20250137084A1

公开(公告)日：2025-05-01

申请号：US18683349

申请日：2022-08-05

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Hidekazu Minami ,  Yuki Toji

IPC: C21D9/46 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/32 ,  C22C38/38 ,  C22C38/60

Abstract: There is provided a high-strength steel sheet having a tensile strength of 1180 MPa or more. The high-strength steel sheet having a component composition containing C: 0.090 mass % or more and 0.390 mass % or less, Si: 0.01 mass % or more and 2.00 mass % or less, Mn: 2.00 mass % or more and 4.00 mass % or less, P: 0.100 mass % or less, S: 0.0200 mass % or less, Al: 1.000 mass % or less, N: 0.0100 mass % or less, and O: 0.0100 mass % or less, with a remaining part consisting of Fe and inevitable impurities; and a microstructure. In the microstructure, an area ratio of martensite is 70% or more, an area ratio of ferrite is 10% or less, an area ratio of retained austenite is 10% or less, and a proportion of the number of martensite blocks in which metastable carbides are present to the number of martensite blocks is 2% or more.