	US 12,215,405 B2
	Hot-pressed member, cold-rolled steel sheet for hot pressing, and manufacturing methods therefor
Katsutoshi Takashima, Tokyo (JP); Minoru Tanaka, Tokyo (JP); Yoshie Obata, Tokyo (JP); and Michitaka Sakurai, Tokyo (JP)
Assigned to JFE STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/432,218
Filed by JFE STEEL CORPORATION, Tokyo (JP)
PCT Filed Jan. 17, 2020, PCT No. PCT/JP2020/001584 § 371(c)(1), (2) Date Aug. 19, 2021, PCT Pub. No. WO2020/170667, PCT Pub. Date Aug. 27, 2020.
Claims priority of application No. 2019-029806 (JP), filed on Feb. 21, 2019.
Prior Publication US 2022/0186339 A1, Jun. 16, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. C21D 9/48 (2006.01); B32B 15/01 (2006.01); C21D 6/00 (2006.01); C21D 8/04 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/04 (2006.01); C22C 38/06 (2006.01); C22C 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/54 (2006.01); C22C 38/58 (2006.01); C22C 38/60 (2006.01); C21D 9/00 (2006.01); C23C 2/06 (2006.01); C23C 2/40 (2006.01)

CPC C21D 9/48 (2013.01) [B32B 15/013 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0405 (2013.01); C21D 8/0426 (2013.01); C21D 8/0436 (2013.01); C21D 8/0463 (2013.01); C22C 38/001 (2013.01); C22C 38/002 (2013.01); C22C 38/008 (2013.01); C22C 38/02 (2013.01); C22C 38/06 (2013.01); C22C 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/54 (2013.01); C22C 38/58 (2013.01); C22C 38/60 (2013.01); C21D 2211/001 (2013.01); C21D 2211/004 (2013.01); C21D 2211/008 (2013.01); C23C 2/06 (2013.01); C23C 2/40 (2013.01)]

10 Claims

1. A hot-pressed member, comprising:

a chemical composition consisting of, in mass %,

C: 0.31% or more and less than 0.55%,

Si: 0.01% or more and 1.0% or less,

Mn: 1.0% or more and 2.5% or less,

P: 0.05% or less,

S: 0.005% or less,

Al: 0.01% or more and 0.50% or less,

N: 0.01% or less, and

Cu: 0.002% or more and 0.25% or less,

and optionally one or more one or more selected from the group consisting of

Mo: 0.005% or more and 0.35% or less,

Cr: 0.005% or more and 0.35% or less,

Nb: 0.001% or more and 0.05% or less,

Ti: 0.001% or more and 0.050% or less,

B: 0.0002% or more and 0.0050% or less,

Ca: 0.005% or less,

V: 0.05% or less,

Sb: 0.001% or more and 0.020% or less,

Ni: 0.50% or less, and

Sn: 0.50% or less,

with a balance consisting of Fe and inevitable impurities;

a microstructure in which a prior austenite average grain size is 8 μm or less, a volume fraction of martensite is 95% or more, and a volume fraction of granular carbide of 0.1 μm or more in grain size is 0.10% or more and 4.0% or less;

a Ni diffusion region of 2.0 μm or more in a depth direction in a surface layer; and

a tensile strength of 1850 MPa or more.