High-strength galvanized steel sheet
AssigneeJfe Steel Corporation
InventorYoshitsugu SUZUKI
Life of this patent
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Abstract
A high-strength galvanized steel sheet comprising a cold-rolled steel sheet, an intermetallic compound formed on the cold-rolled steel sheet, and a galvanizing layer formed on the intermetallic compound, the cold-rolled steel sheet having a specific composition and a microstructure having a martensite area ratio of 7% or more and less than 25% and a ferrite area ratio of 50% or more and which includes a base metal surface portion in which the amount of internal oxides per single side is 0.05 g/m2 or less.
Claims1
A high-strength galvanized steel sheet comprising a cold-rolled steel sheet, an intermetallic compound formed on the cold-rolled steel sheet, and a galvanizing layer formed on the intermetallic compound, the cold-rolled steel sheet having a composition comprising, by mass %:
- C:
- 0.06% or more and 0.09% or less;
- Si:
- 0.30% or less;
- Mn:
- 1.7% or more and 2.3% or less;
- P:
- 0.001% or more and 0.020% or less;
- S:
- 0.010% or less;
- Mo:
- 0.05% or more and 0.30% or less;
- N:
- 0.005% or less;
- Al:
- 0.01% or more and 0.10% or less;
- and
- the remainder being Fe and inevitable impurities,
- wherein the cold-rolled steel sheet (i) has a microstructure having a martensite area ratio in a range of 7% to less than 25% and a ferrite area ratio of 50% or more, and (ii) includes a base metal surface portion in which an amount of internal oxides per single side is 0.05 g/m2 or less,
- the intermetallic compound comprises Al in a range of 0.12 g/m2 or more and 0.22 g/m2 or less and Fe2Al5 with an average grain size of less than 1.0 μm,
- the galvanizing layer comprises 0.3%≦Al %≦0.6%, where Al % represents the content (by mass %) of Al in the galvanizing layer, the galvanizing layer having a surface roughness Ra in a range of 0.8 μm or more and 1.6 μm or less, the galvanizing layer having a glossiness (G value) in a range of 550 or more and 750 or less,
- in the galvanizing layer, the zinc basal plane orientation ratio Zn (002)/(004) defined by equation (1) is in a range of 60% or more and 90% or less:
- Zn
-
- (
- 002
- )
-
- /
-
- (
- 004
- )
- =
- {
- Zn
-
-
- crystal
-
-
- orientation
-
-
- of
-
-
- (
- 002
- )
-
-
- plane
- }
- ×
- 100
-
- /
-
- {
- Zn
-
-
- crystal
-
-
- orientation
-
-
- of
-
-
- (
- 004
- )
-
-
- plane
- }
-
-
- Zn
-
-
- crystal
-
-
- orientation
-
-
- of
-
-
- (
- xyz
- )
-
-
- plane
- =
- I
- (
- xyz
- )
-
- /
-
- Σ
-
-
- I
- (
- xyz
- )
- I
- std
-
- (
- xyz
- )
-
- /
-
- Σ
-
-
- I
- std
-
- (
- xyz
- )
- ×
- 100
- (
- 1
- )
- where I(xyz) is an intensity of Zn in a (xyz) plane of a sample measured using an X-ray and Istd(xyz) is an intensity of Zn in a (xyz) plane of a standard sample of pure Zn powder measured using an X-ray.
Dependencies are inferred from the claim text.