公开(公告)号：US20230203615A1

公开(公告)日：2023-06-29

申请号：US17920851

申请日：2021-04-28

Applicant: JFE Steel Corporation

Inventor： Tadachika Chiba ,  Shinjiro Kaneko ,  Yoichiro Matsui ,  Noriaki Kosaka

IPC: C21D9/46 ,  C22C38/58 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/60 ,  C22C38/00 ,  C21D8/02 ,  C21D6/00

CPC classification number: C21D9/46 ,  C22C38/58 ,  C22C38/16 ,  C22C38/14 ,  C22C38/12 ,  C22C38/08 ,  C22C38/06 ,  C22C38/04 ,  C22C38/02 ,  C22C38/60 ,  C22C38/005 ,  C22C38/002 ,  C22C38/001 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0263 ,  C21D8/0278 ,  C21D6/001 ,  C21D6/004 ,  C21D6/005 ,  C21D6/008 ,  C21D2211/005 ,  C21D2211/001 ,  C21D2211/008

Abstract: A steel sheet has a specified chemical composition and a specified steel microstructure. An average grain size of ferrite and/or bainitic ferrite is 7.0 μm or less. On the basis of a distribution in the width direction of the steel sheet, a ratio of a deviation of the grain size of the ferrite and/or the bainitic ferrite to the average grain size of the ferrite and/or the bainitic ferrite is 10% or less. On the basis of a distribution in the width direction of the steel sheet, a ratio of a deviation of the area fraction of as-quenched martensite to the area fraction of the as-quenched martensite is 10% or less. On the basis of a distribution in the width direction of the steel sheet, a ratio of a deviation of the area fraction of retained austenite to the area fraction of the retained austenite is 10% or less.