Patent ID: 11859259
Assignee: NIPPON STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A zinc-plated steel sheet comprising:
a base steel sheet; and
a zinc-plated layer disposed on a surface of the base steel sheet,
wherein the base steel sheet has a chemical composition containing, by mass %,
C: 0.200% to 0.500%,
Si: 1.00% to 2.50%,
Mn: 1.50% to 5.00%,
P: greater than 0% to 0.100%,
S: greater than 0% to 0.0100%,
Al: 0.001% to 1.000%,
N: greater than 0% to 0.0100%,
O: greater than 0% to 0.0100%,
Cr: 0% to 2.00%,
Mo: 0% to 1.00%,
B: 0% to 0.010%,
Cu: 0% to 1.00%,
Ni: 0% to 1.00%,
Co: 0% to 1.00%,
W: 0% to 1.00%,
Sn: 0% to 1.00%,
Sb: 0% to 0.50%,
Ti: 0% to 0.30%,
Nb: 0% to 0.30%,
V: 0% to 1.00%,
Ca: 0% to 0.0100%,
Mg: 0% to 0.0100%,
Ce: 0% to 0.0100%,
Zr: 0% to 0.0100%,
La: 0% to 0.0100%,
Hf: 0% to 0.0100%,
Bi: 0% to 0.0100%, and
REM: 0% to 0.0100%
with a remainder including Fe and an impurity,
steel microstructures in a range of ⅛ thickness to ⅜ thickness, having a center at ¼ thickness from the surface of the base steel sheet, include, by vol %,
ferrite: 0% to 10%,
bainite: 0% to 30%,
tempered martensite: 50% or more,
fresh martensite: 0% to 10%,
retained austenite: more than 10% and 30% or less, and
pearlite: 0% to 5%,
an amount of hydrogen that is emitted when the base steel sheet is heated up to 200° C. from room temperature after removal of the zinc-plated layer is 0.40 ppm or less per mass of the base steel sheet,
a tensile strength is 1470 MPa or more, and
cracking does not occur in a U-shape bending test in which a stress equivalent to 1000 MPa is applied for 24 hours.