US 12,460,286 B2
Steel sheet and welded joint
Yuya Suzuki, Tokyo (JP)
Assigned to NIPPON STEEL CORPORATION, Tokyo (JP)
Appl. No. 18/273,453
Filed by NIPPON STEEL CORPORATION, Tokyo (JP)
PCT Filed Feb. 18, 2022, PCT No. PCT/JP2022/006706
§ 371(c)(1), (2) Date Jul. 20, 2023,
PCT Pub. No. WO2022/202020, PCT Pub. Date Sep. 29, 2022.
Claims priority of application No. 2021-051017 (JP), filed on Mar. 25, 2021.
Prior Publication US 2024/0141467 A1, May 2, 2024
Int. Cl. B23K 11/11 (2006.01); C21D 1/18 (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 38/10 (2006.01); C22C 38/12 (2006.01); C22C 38/14 (2006.01); C22C 38/16 (2006.01); C22C 38/20 (2006.01); C22C 38/22 (2006.01); C22C 38/26 (2006.01); C22C 38/28 (2006.01); C22C 38/30 (2006.01); C22C 38/32 (2006.01); C22C 38/34 (2006.01); C22C 38/38 (2006.01); C22C 38/44 (2006.01); C22C 38/46 (2006.01); C22C 38/48 (2006.01); C22C 38/50 (2006.01); C22C 38/52 (2006.01); C22C 38/54 (2006.01); C22C 38/58 (2006.01); C22C 38/60 (2006.01); C23C 2/28 (2006.01)
CPC C22C 38/60 (2013.01) [B23K 11/11 (2013.01); C21D 1/18 (2013.01); C21D 1/84 (2013.01); C21D 6/001 (2013.01); C21D 6/002 (2013.01); C21D 6/004 (2013.01); C21D 6/005 (2013.01); C21D 6/007 (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 38/10 (2013.01); C22C 38/12 (2013.01); C22C 38/14 (2013.01); C22C 38/16 (2013.01); C22C 38/20 (2013.01); C22C 38/22 (2013.01); C22C 38/26 (2013.01); C22C 38/28 (2013.01); C22C 38/30 (2013.01); C22C 38/32 (2013.01); C22C 38/34 (2013.01); C22C 38/38 (2013.01); C22C 38/44 (2013.01); C22C 38/46 (2013.01); C22C 38/48 (2013.01); C22C 38/50 (2013.01); C22C 38/52 (2013.01); C22C 38/54 (2013.01); C22C 38/58 (2013.01); C23C 2/285 (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)] 8 Claims
OG exemplary drawing
 
1. A steel sheet comprising, as a chemical composition, by mass %:
C: 0.05% to 0.25%;
Si: 0.05% to 2.00%;
Mn: 1.50% to 3.00%;
Al: 0.005% to 1.500%;
P: 0% to 0.040%;
S: 0% to 0.010%;
N: 0% to 0.0100%;
O: 0% to 0.0060%;
Cr: 0% to 0.50%;
Ni: 0% to 1.00%;
Cu: 0% to 1.00%;
Mo: 0% to 0.50%;
Ti: 0% to 0.200%;
Nb: 0% to 0.200%;
V: 0% to 0.500%;
B: 0% to 0.0100%;
W: 0% to 0.1000%;
Ta: 0% to 0.1000%;
Sn: 0% to 0.0500%;
Co: 0% to 0.5000%;
Sb: 0% to 0.0500%;
As: 0% to 0.0500%;
Mg: 0% to 0.0500%;
Ca: 0% to 0.0400%;
Y: 0% to 0.0500%;
La: 0% to 0.0500%;
Ce: 0% to 0.0500%;
Zr: 0% to 0.0500%; and
a remainder: Fe and impurities,
wherein when a sheet thickness is denoted by t, a metallographic structure at a t/4-position, which is a position t/4 away from a surface, in a cross section in a sheet thickness direction includes, by volume percentage,
ferrite: 20% or greater,
bainite and martensite: 40% or greater in total, and
a remainder consisting of one or more selected from residual austenite and pearlite,
when a Mn concentration is measured at a plurality of measurement points at intervals of 1 μm in a square region with a side length of t/4 centered at the t/4-position in the cross section in the sheet thickness direction, a proportion of measurement points at which the Mn concentration is 1.1 times or greater an average of the Mn concentrations at all of the plurality of measurement points is less than 10.0%,
a tensile strength is 980 MPa or greater, and
a product of the tensile strength and a total elongation is 10,500 MPa·% or greater.