US 11,981,984 B2
Hot rolled steel sheet
Takeshi Toyoda, Tokyo (JP); and Eisaku Sakurada, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 18/009,852
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Aug. 10, 2021, PCT No. PCT/JP2021/029553
§ 371(c)(1), (2) Date Dec. 12, 2022,
PCT Pub. No. WO2022/070621, PCT Pub. Date Apr. 7, 2022.
Claims priority of application No. 2020-163474 (JP), filed on Sep. 29, 2020.
Prior Publication US 2023/0265548 A1, Aug. 24, 2023
Int. Cl. C22C 38/54 (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 38/42 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01)
CPC C22C 38/54 (2013.01) [C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/008 (2013.01); C21D 8/0226 (2013.01); C21D 9/46 (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 38/42 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C21D 2211/002 (2013.01); C21D 2211/005 (2013.01); C21D 2211/008 (2013.01)] 7 Claims
 
1. A hot rolled steel sheet having a tensile strength of 980 MPa or more, a sheet thickness of 1.2 to 4.0 mm, and a sheet width of 750 mm or more, and satisfying the following formula 1:
−15≤(λW 1+λW 2)/2−λC≤15  formula 1
where λW 1 and λW 2 respectively indicate hole expansion ratios (%) at ⅛ positions of the sheet width from one end of the hot rolled steel sheet in a sheet width direction perpendicular to a rolling direction and the other end at an opposite side, λC indicates a hole expansion ratio (%) of a sheet width center part, and λW 1, λW 2, and λC are respectively 40% or more,
wherein the hot rolled steel sheet has a chemical composition comprising, by mass %,
C: 0.01 to 0.50%,
Si: 0.01 to 3.50%,
Mn: 0.20 to 3.00%,
P: 0.100% or less,
S: 0.0200% or less,
N: 0.0100% or less,
Al: 0.001 to 1.000%,
Cu: 0 to 1.00%,
Ni: 0 to 0.50%,
Cr: 0 to 2.00%,
Mo: 0 to 3.00%,
W: 0 to 0.10%,
Nb: 0 to 0.060%,
V: 0 to 1.00%,
Ti: 0 to 0.20%,
B: 0 to 0.0040%,
O: 0 to 0.020%,
Ta: 0 to 0.10%,
Co: 0 to 3.00%,
Sn: 0 to 1.00%,
Sb: 0 to 0.50%,
As: 0 to 0.050%,
Mg: 0 to 0.050%,
Zr: 0 to 0.050%,
Ca: 0 to 0.0500%,
REM: 0 to 0.0500%, and
balance: Fe and impurities.