Patent ID: 11913087
Assignee: JFE STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C | IPC C

Claim 0:
1. A high-strength steel sheet comprising a chemical composition containing, in mass %,
C: 0.03% or more and 0.15% or less,
Si: 0.01% or more and 0.05% or less,
Mn: more than 0.6% and 1.5% or less,
P: 0.025% or less,
S: 0.02% or less,
Al: 0.01% or more and 0.088% or less,
N: 0.0005% or more and 0.0100% or less,
Ti: 0.005% or more and 0.020% or less,
B: 0.0005% or more and 0.0100% or less,
Nb: 0.005% or more and 0.020% or less, and
optionally at least one selected from the group consisting of
Cr: 0.005% or more and 0.100% or less,
Ni: 0.005% or more and 0.150% or less, and
Mo: 0.005% or more and 0.050% or less,

with the balance being Fe and inevitable impurities, wherein
the high-strength steel sheet has a metallic structure consisting of, in area ratio, 90% or more and 99% or less of ferrite and 1% or more and 10% or less of martensite, the martensite has a maximum grain size of 5 μm or less, and a ratio of martensite having a grain size of 2 μm or less is 80% or more,
the high-strength steel sheet has a tensile strength of 512 MPa or more, and
the high-strength steel sheet has a sheet thickness of 0.1 to 0.8 mm.