Hot-dip galvanized steel sheet
There is provided a hot-dip galvanized steel sheet with a microstructure in a ⅛ thickness to ⅜ thickness range whose middle is a ¼ thickness from a surface of a base steel sheet, the microstructure contains ferrite phase is 50% or more and 97% or less by volume fraction, and a predetermined phase wherein at an interface between a hot-dip galvanizing layer and the base steel sheet, a Fe—Al alloy layer has an average thickness of 0.1 μm to 2.0 μm, and a difference between a maximum thickness and a minimum thickness in a steel sheet width direction is within 0.5 μm, and in a fine-grain layer directly brought into contact with the Fe—Al alloy layer, the fine-grain has a difference between a maximum thickness and a minimum thickness of the fine-grain layer in the steel sheet width direction is within 2.0 μm.
1. A hot-dip galvanized steel sheet comprising a hot-dip galvanizing layer on at least one side of a base steel sheet, wherein:
the base steel sheet has chemical components containing, in mass %,
C: 0.040% to 0.280%,
Si: 0.05% to 2.00%,
Mn: 0.50% to 3.50%,
P: 0.0001% to 0.1000%,
S: 0.0001% to 0.0100%,
Al: 0.001% to 1.500%,
N: 0.0001% to 0.0100%,
O: 0.0001% to 0.0100%,
Ti: 0% to 0.150%,
Nb: 0% to 0.100%,
V: 0% to 0.300%,
Cr: 0% to 2.00%,
Ni: 0% to 2.00%,
Cu: 0% to 2.00%,
Mo: 0% to 2.00%,
B: 0% to 0.0100%,
W: 0% to 2.00%,
Ce, Mg, Zr, La, and REM: 0% to 0.0100% in total, and
a balance comprising Fe and impurities;
the base steel sheet has a microstructure in which:
in a ⅛ thickness to ⅜ thickness range whose middle is a ¼ thickness of a total thickness of the base steel sheet from a surface of the base steel sheet,
ferrite phase is 50% or more and 97% or less by volume fraction,
a total of a hard structure consisting of one or more of bainite phase, bainitic ferrite phase, fresh martensite phase, and tempered martensite phase is 3% or more by volume fraction,
retained austenite phase is 0% to 8% by volume fraction, and
a total of pearlite phase and coarse cementite phase is 0% to 8% by volume fraction;
in a surface layer portion from an interface between the hot-dip galvanizing layer and the base steel sheet up to a 20 μm depth in a steel sheet thickness direction,
retained austenite is 0% to 3% by volume fraction; and
V1/V2 being a ratio between a volume fraction V1 of the hard structure in the surface layer portion and a volume fraction V2 of the hard structure in the ⅛ thickness to ⅜ thickness range whose middle is the ¼ thickness from the surface of the steel sheet, is set to fall within a range of 0.10 or more and 0.90 or less; and
in the hot-dip galvanizing layer, a Fe content is more than 0% and 3.0% or less, and an Al content is more than 0% and 1.0% or less,
the hot-dip galvanized steel sheet comprising:
at an interface between the hot-dip galvanizing layer and the base steel sheet, a Fe—Al alloy layer in which an average thickness is 0.1 μm to 2.0 μm, and a difference between a maximum thickness and a minimum thickness in a steel sheet width direction is within 0.5 μm; and
a fine-grain layer directly brought into contact with the Fe—Al alloy layer in the base steel sheet, the fine-grain layer with an average thickness of 0.1 urn to 5.0 μm, and an average grain diameter of 0.1 μm to 3.0 μm, the fine-grain layer containing an oxide of one or more of Si and Mn with a maximum diameter of 0.01 μm to 0.4 μm, and the fine-grain layer with a difference between a maximum thickness and a minimum thickness in the steel sheet width direction of within 2.0 μm.
2. The hot-dip galvanized steel sheet according to claim 1 , wherein
a plating deposition amount per one side of the hot-dip galvanizing layer is 10 g/m 2 or more and 100 g/m 2 or less.
3. The hot-dip galvanized steel sheet according to claim 2 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of
Ti: 0.001% to 0.150%,
Nb: 0.001% to 0.100%, and
V: 0.001% to 0.300%.
4. The hot-dip galvanized steel sheet according to claim 2 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of
Cr: 0.01% to 2.00%,
Ni 0.01% to 2.00%,
Cu: 0.01% to 2.00%,
Mo: 0.01% to 2.00%,
B: 0.0001% to 0.0100%, and
W: 0.01% to 2.00%.
5. The hot-dip galvanized steel sheet according to claim 2 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of Ca, Ce, Mg, Zr, La, and REM of 0.0001% to 0.0100% in total.
6. The hot-dip galvanized steel sheet according to claim 1 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of
Ti: 0.001% to 0.150%,
Nb: 0.001% to 0.100%, and
V: 0.001% to 0.300%.
7. The hot-dip galvanized steel sheet according to claim 1 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of
Cr: 0.01% to 2.00%,
Ni: 0.01% to 2.00%,
Cu: 0.01% to 2.00%,
Mo: 0.01% to 2.00%,
B: 0.0001% to 0.0100%, and
W: 0.01% to 2.00%.
8. The hot-dip galvanized steel sheet according to claim 1 , wherein
the base steel sheet further contains, in mass %, one or two or more selected from a group consisting of Ca, Ce, Mg, Zr, La, and REM of 0.0001% to 0.0100% in total.