公开(公告)号：US11268164B2

公开(公告)日：2022-03-08

申请号：US16329504

申请日：2017-09-28

Applicant: JFE STEEL CORPORATION

Inventor： Shimpei Yoshioka ,  Yoshihiko Ono ,  Kenta Hidaka ,  Ryosuke Yamaguchi

IPC: C21D9/46 ,  C21D8/02 ,  C22C38/12 ,  C23C2/06 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/08 ,  C22C38/14 ,  C22C38/16 ,  C22C38/22 ,  C22C38/26 ,  C22C38/28 ,  C23C2/02 ,  C23C2/40 ,  C21D1/18 ,  C22C38/18 ,  C23C2/28 ,  C22C38/60

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 95% or more and 100% or less. The balance of the microstructure is at least one of ferrite and retained austenite. The microstructure includes specific inclusion clusters, the content of the inclusion clusters in the microstructure being 5 clusters/mm2 or less. The microstructure includes prior-austenite grains having an average size of more than 5 μm. The steel sheet has a tensile strength of 1320 MPa or more.