公开(公告)号：US20250043380A1

公开(公告)日：2025-02-06

申请号：US18847046

申请日：2023-03-20

Applicant: NIPPON STEEL CORPORATION

Inventor： Kengo HATA ,  Shinji YOSHIDA ,  Rina FUJIMURA ,  Natsumi OOURA

IPC: C21D9/46 ,  C21D1/18 ,  C21D6/00 ,  C21D8/02 ,  C22C38/00 ,  C22C38/02 ,  C22C38/04 ,  C22C38/06 ,  C22C38/12 ,  C22C38/14

Abstract: A cold-rolled steel sheet having a chemical composition of, in mass %: 0.10 to 0.30% C; up to 2.50% Si; 0.50 to 3.50% Mn; up to 0.100% P; up to 0.020% S; 0.010 to 0.100% Al; up to 0.0100% N; 0 to 0.100% Ti; 0 to 0.100% Nb; 0 to 0.50% V; 0 to 0.50 % Mo; 0 to 0.50% W; 0 to 0.0050% B; 0 to 0.0100% Ca; 0 to 0.0100% Mg; 0 to 0.0100% REM; and balance Fe and impurities, the microstructure containing tempered martensite and bainite in not less than 85 volume % in total, with other structure(s) being present in not more than 5 volume %, the regions where the Mn concentration in the microstructure is not lower than 8.0 mass % being present in 0.05 to 1.5 area %.