公开(公告)号：US20230349019A1

公开(公告)日：2023-11-02

申请号：US17800650

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota ,  Shunsuke Yamamoto ,  Yuki Takeda

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

CPC classification number: C21D9/46 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/001 ,  C22C38/002 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C23C2/40 ,  C21D2211/005 ,  C21D2211/002 ,  C21D2211/001 ,  C21D2211/008 ,  C21D2211/003

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 60% or more and 85% or less, bainite: 3% or more and 15% or less, retained austenite: 3% or more and 15% or less, fresh martensite: 3% or more and 15% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 590 MPa or more and less than 780 MPa.

公开(公告)号：US20230072557A1

公开(公告)日：2023-03-09

申请号：US17800957

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

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

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 20% or more and 60% or less, a total of bainite and tempered martensite: 25% or more and 60% or less, retained austenite: 7% or more and 20% or less, fresh martensite: 8% or more and 40% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 980 MPa or more.

公开(公告)号：US12258647B2

公开(公告)日：2025-03-25

申请号：US17800669

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

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 ,  C22C38/34 ,  C22C38/38 ,  C22C38/60 ,  C23C2/06

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 40% or more and 70% or less, a total of bainite and tempered martensite: 5% or more and 30% or less, retained austenite: 4% or more and 18% or less, fresh martensite: 8% or more and 35% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 780 MPa or more and less than 980 MPa.

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.

公开(公告)号：US20230349020A1

公开(公告)日：2023-11-02

申请号：US17800669

申请日：2021-02-24

Applicant: JFE Steel Corporation

Inventor： Yusuke Wada ,  Tatsuya Nakagaito ,  Shotaro Terashima ,  Lingling Yang ,  Takeshi Yokota

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18 ,  C23C2/06

CPC classification number: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/34 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0278 ,  C21D8/0263 ,  C21D8/0226 ,  C21D8/0236 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C23C2/06

Abstract: A steel sheet according to the present invention has a specific chemical composition and a steel microstructure including, in terms of area fraction, ferrite: 40% or more and 70% or less, a total of bainite and tempered martensite: 5% or more and 30% or less, retained austenite: 4% or more and 18% or less, fresh martensite: 8% or more and 35% or less, and the remainder: 5% or less. Cementite particles are present in the retained austenite, a ratio of an area fraction of the cementite particles in the retained austenite to an area fraction of the retained austenite is 5% or more and 25% or less, and the steel sheet has a tensile strength of 780 MPa or more and less than 980 MPa.