公开(公告)号：US12065711B2

公开(公告)日：2024-08-20

申请号：US17262884

申请日：2019-06-10

Applicant: JFE Steel Corporation

Inventor： Kazuhiko Yamazaki ,  Takeshi Yokota ,  Sumio Kaiho ,  Noriaki Moriyasu

IPC: C22C38/00 ,  C21D6/00 ,  C21D8/00 ,  C21D8/02 ,  C21D9/46 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38

CPC classification number: C21D9/46 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D8/005 ,  C21D8/0226 ,  C21D8/0263 ,  C22C38/001 ,  C22C38/002 ,  C22C38/005 ,  C22C38/02 ,  C22C38/06 ,  C22C38/08 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C22C38/32 ,  C22C38/38 ,  C21D2211/002 ,  C21D2211/008

Abstract: A high-strength hot rolled steel sheet and a method for manufacturing the high-strength hot rolled steel sheet are disclosed. The high-strength hot rolled steel sheet includes a specific chemical composition, and a steel structure in which a lower bainite phase and/or a tempered martensite phase at 90% or more in terms of a total area fraction is contained as a dominant phase, an average grain size of the dominant phase is 10.0 μm or less, and an amount of Fe in Fe-based precipitates is 0.70% or less in mass %, in which an arithmetic average roughness (Ra) of a surface is 2.50 μm or less, and a tensile strength TS is 1180 MPa or more.

公开(公告)号：US20200063227A1

公开(公告)日：2020-02-27

申请号：US16485978

申请日：2018-02-06

Applicant: JFE Steel Corporation

Inventor： Kazuhiko Yamazaki ,  Shunsuke Toyoda ,  Noriaki Moriyasu ,  Sumio Kaiho

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

Abstract: There are provided a high-strength hot-rolled steel sheet having a tensile strength of 980 MPa or more and a production method therefor. The high-strength hot-rolled steel sheet has a predetermined component composition and a microstructure containing 75.0% or more by area and less than 97.0% by area of a primary phase composed of an upper bainite phase, the primary phase having an average grain size of 12.0 μm or less, and more than 3.0% by area and 25.0% or less by area of a secondary phase that is a structure composed of one or two of a lower bainite phase and/or a tempered martensite phase, and a martensite phase, in which the number density of grains of the secondary phase having an equivalent circular diameter of 0.5 μm or more is 150,000 grains/mm2 or less, and the steel sheet has an arithmetic mean surface roughness of 2.00 μm or less.

公开(公告)号：US11603571B2

公开(公告)日：2023-03-14

申请号：US16485978

申请日：2018-02-06

Applicant: JFE Steel Corporation

Inventor： Kazuhiko Yamazaki ,  Shunsuke Toyoda ,  Noriaki Moriyasu ,  Sumio Kaiho

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

Abstract: There are provided a high-strength hot-rolled steel sheet having a tensile strength of 980 MPa or more and a production method therefor. The high-strength hot-rolled steel sheet has a predetermined component composition and a microstructure containing 75.0% or more by area and less than 97.0% by area of a primary phase composed of an upper bainite phase, the primary phase having an average grain size of 12.0 μm or less, and more than 3.0% by area and 25.0% or less by area of a secondary phase that is a structure composed of one or two of a lower bainite phase and/or a tempered martensite phase, and a martensite phase, in which the number density of grains of the secondary phase having an equivalent circular diameter of 0.5 μm or more is 150,000 grains/mm2 or less, and the steel sheet has an arithmetic mean surface roughness of 2.00 μm or less.

公开(公告)号：US20210140007A1

公开(公告)日：2021-05-13

申请号：US17262884

申请日：2019-06-10

Applicant: JFE Steel Corporation

Inventor： Kazuhiko Yamazaki ,  Takeshi Yokota ,  Sumio Kaiho ,  Noriaki Moriyasu

IPC: C21D9/46 ,  C22C38/38 ,  C22C38/32 ,  C22C38/28 ,  C22C38/26 ,  C22C38/22 ,  C22C38/16 ,  C22C38/08 ,  C22C38/06 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D8/00 ,  C21D6/00

Abstract: Provided is a high-strength hot rolled steel sheet that has excellent stretch flange formability, bendability, and low-temperature toughness while maintaining high strength of a tensile strength TS of 1180 MPa or more, and a method for manufacturing the high-strength hot rolled steel sheet.
The high-strength hot rolled steel sheet includes a specific chemical composition, and a steel structure in which a lower bainite phase and/or a tempered martensite phase at 90% or more in terms of a total area fraction is contained as a dominant phase, an average grain size of the dominant phase is 10.0 μm or less, and an amount of Fe in Fe-based precipitates is 0.70% or less in mass %, in which an arithmetic average roughness (Ra) of a surface is 2.50 μm or less, and a tensile strength TS is 1180 MPa or more.

公开(公告)号：US20170275744A1

公开(公告)日：2017-09-28

申请号：US15508665

申请日：2015-07-02

Applicant: JFE STEEL CORPORATION

Inventor： Ayako Ta ,  Yukihiro Matsubara ,  Yukio Kimura ,  Masataka Yoshino ,  Keisuke Nakazono ,  Sumio Kaiho ,  Saiichi Murata ,  Nobukazu Kitagawa

IPC: C22C38/54 ,  C22C38/50 ,  C22C38/48 ,  C22C38/46 ,  C22C38/44 ,  C21D6/00 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D9/46 ,  C21D8/02 ,  C22C38/52 ,  C22C38/42

CPC classification number: C22C38/54 ,  C21D6/004 ,  C21D6/005 ,  C21D6/007 ,  C21D6/008 ,  C21D8/02 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C21D9/46 ,  C21D2211/005 ,  C21D2211/008 ,  C22C38/00 ,  C22C38/001 ,  C22C38/002 ,  C22C38/004 ,  C22C38/005 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/10 ,  C22C38/105 ,  C22C38/12 ,  C22C38/14 ,  C22C38/16 ,  C22C38/18 ,  C22C38/20 ,  C22C38/24 ,  C22C38/26 ,  C22C38/28 ,  C22C38/30 ,  C22C38/40 ,  C22C38/42 ,  C22C38/44 ,  C22C38/46 ,  C22C38/48 ,  C22C38/50 ,  C22C38/52

Abstract: Provided is a material for a cold-rolled stainless steel sheet having a chemical composition containing, by mass %, C: 0.01% to 0.05%, Si: 0.02% to 0.75%, Mn: 0.1% to 1.0%, P: 0.04% or less, S: 0.01% or less, Cr: 16.0% to 18.0%, Al: 0.001% to 0.10%, N: 0.01% to 0.06% and the balance being Fe and inevitable impurities. The material has a metallographic structure including a martensite phase having an area ratio of 5% to 50% and the balance being a ferrite phase. A ferrite phase in portions extending from surface layers of front and back surfaces of a steel sheet has an average grain diameter of 20 μm or more and 50 μm or less, and a ferrite phase in a central portion of the sheet includes an unrecrystallized ferrite phase.