US 12,286,683 B2
High-strength steel sheet having excellent delayed fracture resistance
Kosuke Shibata, Kobe (JP); Junichiro Kinugasa, Kobe (JP); Keisuke Nakata, Kakogawa (JP); and Atsuhiro Shiraki, Kakogawa (JP)
Assigned to Kobe Steel, Ltd., Kobe (JP)
Appl. No. 17/790,890
Filed by Kobe Steel, Ltd., Kobe (JP)
PCT Filed Dec. 28, 2020, PCT No. PCT/JP2020/049182
§ 371(c)(1), (2) Date Jul. 5, 2022,
PCT Pub. No. WO2021/149463, PCT Pub. Date Jul. 29, 2021.
Claims priority of application No. 2020-007808 (JP), filed on Jan. 21, 2020.
Prior Publication US 2023/0040459 A1, Feb. 9, 2023
Int. Cl. C21D 9/46 (2006.01); C21D 8/02 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/08 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01)
CPC C21D 9/46 (2013.01) [C21D 8/0236 (2013.01); C21D 8/0273 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C21D 2211/008 (2013.01)] 2 Claims
OG exemplary drawing
 
1. A steel sheet, comprising:
C: 0.280 mass % or more and 0.404 mass % or less;
Si: 0 mass % or more and 0.6 mass % or less;
Mn: more than 0 mass % and 1.5 mass % or less;
Al: more than 0 mass % and 0.15 mass % or less;
B: more than 0 mass % and 0.01 mass % or less;
Cu: more than 0 mass % and 0.5 mass % or less;
Ni: more than 0 mass % and 0.5 mass % or less;
Ti: more than 0 mass % and 0.20 mass % or less;
N: more than 0 mass % and 0.01 mass % or less;
P: more than 0 mass % and 0.02 mass % or less;
S: more than 0 mass % and 0.01 mass % or less;
with the balance comprising Fe and inevitable impurities,
the steel sheet having a martensite structure whose ratio accounts for 95 area % or more of entire metallographic structure of the steel sheet,
the steel sheet having a transition metal carbide whose ratio accounts for 0.8 volume % or more of the entire metallographic structure of the steel sheet, and
the steel sheet having a tensile strength of 1700 MPa or larger.