	US 12,421,569 B2
	Steel sheet and method for producing same
Kengo Takeda, Tokyo (JP); Katsuya Nakano, Tokyo (JP); Yuya Suzuki, Tokyo (JP); and Eriko Tsukamoto, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/923,468
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Jun. 3, 2021, PCT No. PCT/JP2021/021249 § 371(c)(1), (2) Date Nov. 4, 2022, PCT Pub. No. WO2021/251275, PCT Pub. Date Dec. 16, 2021.
Claims priority of application No. 2020-099296 (JP), filed on Jun. 8, 2020.
Prior Publication US 2023/0183833 A1, Jun. 15, 2023
Int. Cl. C21D 9/46 (2006.01); B21C 47/02 (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 38/14 (2006.01); C23C 2/06 (2006.01); C23C 2/12 (2006.01); C23C 2/40 (2006.01); C23G 1/08 (2006.01)

CPC C21D 9/46 (2013.01) [B21C 47/02 (2013.01); C21D 8/0226 (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 38/14 (2013.01); C23C 2/06 (2013.01); C23C 2/12 (2013.01); C23C 2/40 (2013.01); C23G 1/08 (2013.01); C21D 2211/001 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01); C21D 2211/009 (2013.01)]

7 Claims

1. A steel sheet having a chemical composition comprising, by mass %,

C: 0.20 to 0.40%,

Si: 0.01 to 2.00%,

Mn: 0.10% to 4.00%,

P: 0.0200% or less,

S: 0.0200% or less,

Al: 1.500% or less,

N: 0.0200% or less,

Ti: 0.005 to 0.500%,

Co: 0 to 0.5000%,

Ni: 0 to 1.0000%,

Mo: 0 to 1.0000%,

Cr: 0 to 2.0000%,

O: 0 to 0.0200%,

B: 0 to 0.0100%,

Nb: 0 to 0.5000%,

V: 0 to 0.5000%,

Cu: 0 to 0.5000%,

W: 0 to 0.1000%,

Ta: 0 to 0.1000%,

Sn: 0 to 0.0500%,

Sb: 0 to 0.0500%,

As: 0 to 0.0500%,

Mg: 0 to 0.0500%,

Ca: 0 to 0.0500%,

Y: 0 to 0.0500%,

Zr: 0 to 0.0500%,

La: 0 to 0.0500%,

Ce: 0 to 0.0500%, and

a balance of Fe and impurities,

wherein precipitates having a diameter of less than 0.1 μm are present in a number density of 10 to 200/μm²in a depth region of 1 to 10 μm from a surface,

an amount of dissolved C in a depth region of 10 to 60 μm from the surface is less than 0.20 mass %, and

a tensile strength is 1200 MPa or more.