US 12,473,623 B2
Steel sheet
Satoshi Hironaka, Tokyo (JP); Mai Nagano, Tokyo (JP); and Yasuhiro Ito, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 18/290,465
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Mar. 4, 2022, PCT No. PCT/JP2022/009304
§ 371(c)(1), (2) Date Nov. 14, 2023,
PCT Pub. No. WO2022/254847, PCT Pub. Date Dec. 8, 2022.
Claims priority of application No. 2021-091649 (JP), filed on May 31, 2021.
Prior Publication US 2024/0271261 A1, Aug. 15, 2024
Int. Cl. C22C 38/60 (2006.01); C21D 1/84 (2006.01); C21D 6/00 (2006.01); C21D 8/02 (2006.01); C21D 9/46 (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 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/24 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/32 (2006.01); C22C 38/38 (2006.01)
CPC C22C 38/60 (2013.01) [C21D 1/84 (2013.01); C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0205 (2013.01); C21D 8/021 (2013.01); C21D 8/0226 (2013.01); C21D 8/0236 (2013.01); C21D 8/0263 (2013.01); C21D 8/0278 (2013.01); C21D 9/46 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/005 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/04 (2013.01); C22C 38/06 (2013.01); C22C 38/08 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/24 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/32 (2013.01); C22C 38/38 (2013.01); C21D 2211/005 (2013.01)] 9 Claims
 
9. A steel sheet comprising
a chemical composition comprising, in mass %:
C: 0.030% to 0.145%,
Si: 0% to 0.500%,
Mn: 0.50% to 2.50%,
P: 0% to 0.100%,
S: 0% to 0.020%,
Al: 0% to 1.000%,
N: 0% to 0.0100%,
B: 0% to 0.0050%,
Mo: 0% to 0.80%,
Ti: 0% to 0.200%,
Nb: 0% to 0.10%,
V: 0% to 0.20%,
Cr: 0% to 0.80%,
Ni: 0% to 0.25%,
O: 0% to 0.0100%,
Cu: 0% to 1.00%,
W: 0% to 1.00%,
Sn: 0% to 1.00%,
Sb: 0% to 0.20%,
Ca: 0% to 0.0100%,
Mg: 0% to 0.0100%,
Zr: 0% to 0.0100%, and
REM: 0% to 0.0100%,
with the balance comprising Fe and impurities, wherein
a metal micro-structure comprising 70 to 95% ferrite in volume fraction and 5 to 30% hard phases in volume fraction,
a value X1 obtained by dividing a standard deviation of Vickers hardnesses H1/4 at ¼ sheet-thickness positions by an average value of the Vickers hardnesses H1/4 is 0.025 or less, and
a value X2 obtained by dividing a standard deviation of Vickers hardnesses H1/2 at a ½ sheet-thickness position by an average Value of the Vickers hardnesses H1/2 is 0.030 or less.