Patent ID: 11905570
Assignee: NIPPON STEEL CORPORATION
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 0:
1. A hot dip galvanized steel sheet comprising a base steel sheet and a hot dip galvanized layer on at least one surface of the base steel sheet, wherein the base steel sheet has a chemical composition comprising, by mass %,
C: 0.050% to 0.350%,
Si: 0.10% to 2.50%,
Mn: 1.00% to 3.50%,
P: greater than 0% to 0.050%,
S: greater than 0% to 0.0100%,
Al: 0.001% to 1.500%,
N: greater than 0% to 0.0100%,
O: greater than 0% to 0.0100%,
Ti: 0.005% to 0.200%,
B: 0.0005% to 0.0100%,
V: 0% to 1.00%,
Nb: 0% to 0.100%,
Cr: 0% to 2.00%,
Ni: 0% to 1.00%,
Cu: 0% to 1.00%,
Co: 0% to 1.00%,
Mo: 0% to 1.00%,
W: 0% to 1.00%,
Sn: 0% to 1.00%,
Sb: 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%,
REM other than Ce and La: 0% to 0.0100% and
a balance of Fe and impurities,
a steel microstructure at a range of ⅛ thickness to ⅜ thickness centered about a position of ¼ thickness from a surface of the base steel sheet contains, by volume fraction,
ferrite: 0% to 50%,
retained austenite: 6% to 30%
tempered martensite: 5% or more,
fresh martensite: 0% to 10%, and
pearlite and cementite in total: 0% to 5%,
when there are remaining structures, the remaining structures comprise bainite,
a concentration of B atoms at prior austenite grain boundaries is 2.0 atm % or more, and an average effective crystal grain size is 7.0 μm or less.