公开(公告)号：US20240110264A1

公开(公告)日：2024-04-04

申请号：US18285524

申请日：2022-03-02

Applicant: JFE Steel Corporation

Inventor： Lingling Yang ,  Yuki Toji ,  Ryohei Morimoto ,  Katsutoshi Takashima

IPC: C22C38/04 ,  C21D8/02 ,  C22C38/02 ,  C22C38/06 ,  C23C2/02 ,  C23C2/06

CPC classification number: C22C38/04 ,  C21D8/0205 ,  C21D8/0226 ,  C21D8/0236 ,  C21D8/0273 ,  C22C38/02 ,  C22C38/06 ,  C23C2/0224 ,  C23C2/06 ,  C21D2211/001 ,  C21D2211/002 ,  C21D2211/008

Abstract: A high-strength cold-rolled steel sheet has a chemical composition containing C: 0.150 to 0.350 mass %, Si: 0.80 to 3.00 mass %, Mn: 1.50 to 3.50 mass %, P: 0.100 mass % or less, S: 0.0200 mass % or less, Al: 0.100 mass % or less, N: 0.0100 mass % or less, and O: 0.0100 mass % or less, with a remaining part consisting of Fe and impurities. The amount of diffusible hydrogen is 0.50 mass ppm or less, the area ratio of tempered martensite and bainite is 55 to 95%, the area ratio of retained austenite is 5 to 30%, a prior austenite grain has an average circle equivalent diameter of 15.0 μm or less, and the ratio b/a is 0.80 or less, where a circumferential length of the prior austenite grain is a, and a circumferential length of a portion of the prior austenite grain having a carbon concentration of 0.6 mass % or more is b.