公开(公告)号：US20250003021A1

公开(公告)日：2025-01-02

申请号：US18709028

申请日：2022-10-14

Applicant: JFE STEEL CORPORATION

Inventor： Katsuya HATA ,  Shotaro TERASHIMA ,  Tatsuya NAKAGAITO ,  Seisuke TSUDA

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 ,  C22C38/24 ,  C22C38/28 ,  C22C38/38 ,  C22C38/60 ,  C23C2/02 ,  C23C2/06 ,  C23C2/40

Abstract: A steel sheet having high strength, excellent ductility, high YR, and excellent bendability is provided. The steel sheet includes a defined chemical composition, the steel microstructure includes: area ratio of ferrite: 5% or more and 65% or less, area ratio of martensite: 10% or more and 60% or less, area ratio of bainite: 10% or more and 60% or less, and area ratio of retained austenite: 5% or more. The relationship in the following Formula (1) is satisfied. Average solute C concentration of the retained austenite [C]γ is 0.5 mass % or more, and standard deviation of C concentration distribution in the retained austenite is 0.250 mass % or less. [ Mn ] γ ⁢ / [ Mn ] ≤ 1.2 ( 1 )

公开(公告)号：US20240026481A1

公开(公告)日：2024-01-25

申请号：US18257151

申请日：2021-12-15

Applicant: JFE STEEL CORPORATION

Inventor： Takuya HIRASHIMA ,  Tatsuya NAKAGAITO ,  Masaki KOBA ,  Kyoko NAITO ,  Seisuke TSUDA ,  Katsuya HATA ,  Shotaro TERASHIMA

IPC: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00 ,  C21D1/18

CPC classification number: C21D9/46 ,  C22C38/60 ,  C22C38/38 ,  C22C38/26 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/008 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/001 ,  C21D6/002 ,  C21D6/005 ,  C21D6/008 ,  C21D1/18 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/005 ,  C21D2211/008

Abstract: Provided is a steel sheet having excellent workability while ensuring excellent strength. The steel sheet comprises: a predetermined chemical composition; and a steel microstructure that contains ferrite: 45% to 90%, martensite: 5% to 30%, bainite: 1% to 25%, and retained austenite: 3% or more and in which [Mn]M/[Mn] is 1.00 to 1.15 and [Mn]M/[Mn]F is 1.00 to 1.30, wherein TS×El is 16000 MPa·% or more.