	US 12,297,524 B2
	Hot-rolled steel sheet
Hiroshi Shuto, Tokyo (JP); Kazumasa Tsutsui, Tokyo (JP); Koutarou Hayashi, Tokyo (JP); Akifumi Sakakibara, Tokyo (JP); Jun Ando, Tokyo (JP); and Shota Endo, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 17/760,933
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Sep. 4, 2020, PCT No. PCT/JP2020/033593 § 371(c)(1), (2) Date Mar. 16, 2022, PCT Pub. No. WO2021/065346, PCT Pub. Date Apr. 8, 2021.
Claims priority of application No. 2019-181314 (JP), filed on Oct. 1, 2019.
Prior Publication US 2022/0389554 A1, Dec. 8, 2022
Int. Cl. C22C 38/58 (2006.01); C22C 38/00 (2006.01); C22C 38/02 (2006.01); C22C 38/06 (2006.01); C22C 38/12 (2006.01); C22C 38/16 (2006.01); C22C 38/50 (2006.01)

CPC C22C 38/58 (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 38/06 (2013.01); C22C 38/12 (2013.01); C22C 38/16 (2013.01); C22C 38/50 (2013.01)]

5 Claims

1. A hot-rolled steel sheet comprising: as a chemical composition, by mass %:

C: 0.050% to 0.250%;

Si: 0.05% to 3.00%;

Mn: 1.00% to 4.00%;

one or two or more of Ti, Nb, or V: 0.060% to 0.500% in total;

sol. Al: 0.001% to 2.000%;

P: 0.100% or less;

S: 0.0300% or less;

N: 0.1000% or less;

O: 0.0100% or less;

Cu: 0% to 2.00%;

Cr: 0% to 2.00%;

Mo: 0% to 1.00%;

Ni: 0% to 2.00%;

B: 0% to 0.0100%;

Ca: 0% to 0.0200%;

Mg: 0% to 0.0200%;

REM: 0% to 0.1000%;

Bi: 0% to 0.020%;

one or two or more of Zr, Co, Zn, or W: 0% to 1.00% in total;

Sn: 0% to 0.050%; and

a remainder consisting of Fe and impurities,

wherein a microstructure at a depth of ¼ of a sheet thickness from a surface and at a center position in a sheet width direction in a cross section parallel to a rolling direction

contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, wherein a remainder in the microstructure is one or more of bainite and martensite,

has a ratio L₆₀/L₇of a length L₆₀of a grain boundary having a crystal misorientation of 60° to a length L₇of a grain boundary having a crystal misorientation of 7° about a <110> direction of less than 0.60,

has a standard deviation of a Mn concentration of 0.60 mass % or less, and

has a tensile strength of 980 MPa or more.