Aluminum alloy-plated steel sheet having excellent workability and corrosion resistance and method for manufacturing same

Patent metadata

Field	Value
Publication number	US-11897229-B2
Application number	US-202017784729-A
Country	US
Kind code	B2
Filing date	Dec 18, 2020
Priority date	Dec 20, 2019
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

The present disclosure relates to an aluminum alloy-plated steel sheet having excellent workability and corrosion resistance and a method for manufacturing the same, and more particularly, to an aluminum alloy-plated steel sheet preventing microcracks generated during hot forming and has excellent seizure resistance and corrosion resistance, and a method for manufacturing the same.

First claim

The invention claimed is:

1. An aluminum alloy-plated steel sheet comprising:
a base steel sheet;
an alloy-plated layer formed on the base steel sheet; and
an unalloy-plated layer formed on the alloy-plated layer,
wherein the alloy-plated layer contains, by wt %, 35 to 50% of Fe, 1 to 20% of Zn, 0.1 to 1.5% of Si, and a balance of Al and unavoidable impurities,
the unalloy-plated layer contains, by wt %, 1 to 30% of Zn, 0.1 to 1.8% of Si, and a balance of Al and unavoidable impurities, and
an interface roughness R a , between the alloy-plated layer and the base steel sheet is 2.5 μm or less.

2. The aluminum alloy-plated steel sheet of claim 1 , wherein a thickness of the alloy-plated layer is 5 to 25 μm, and
a thickness of the unalloy-plated layer is 1 to 12 μm.

3. The aluminum alloy-plated steel sheet of claim 1 , wherein a content of Zn in the unalloy-plated layer is higher than a content of Zn in the alloy-plated layer.

4. The aluminum alloy-plated steel sheet of claim 1 , wherein a thickness of the alloy-plated layer is 50% or more of the entire thickness of the alloy-plated layer and the unalloy-plated layer.

5. The aluminum alloy-plated steel sheet of claim 1 , wherein the base steel sheet contains, by wt %, 0.05 to 0.3% of C, 0.1 to 1.5% of Si, 0.5 to 8% of Mn, 50 ppm or less of B, and a balance of Fe and unavoidable impurities.

6. The aluminum alloy-plated steel sheet of claim 1 , wherein a content of Si in the alloy-plated layer is 0.1 to 0.5% in terms of wt %.

7. A hot-formed member obtained by subjecting the aluminum alloy-plated steel sheet of claim 1 to hot press forming.

8. A method for manufacturing an aluminum alloy-plated steel sheet used for hot press forming, the method comprising:
preparing a base steel sheet;
dipping the base steel sheet in an aluminum plating bath that contains, by wt %, 3 to 30% of Zn, 0.1 to 1.5% of Si, and a balance of Al and unavoidable impurities to obtain an aluminum-plated steel sheet;
performing cooling by supplying air heated to 200 to 300° C. to the aluminum-plated steel sheet after the aluminum plating to form an oxide film on a surface of the aluminum-plated steel sheet; and
obtaining an aluminum alloy-plated steel sheet by on-line alloying in which a heat treatment is performed after the cooling while maintaining the aluminum-plated steel sheet in a heating temperature range of 550° C. or higher and lower than 650° C. for 1 to 20 seconds.

9. The method of claim 8 , further comprising, after the alloy treatment, performing cooling.

10. The method of claim 8 , wherein a plating weight in the plating is 20 to 100 g/m 2 per surface.

11. The method of claim 9 , wherein the cooling after the alloy treatment is air cooling.

12. The method of claim 8 , wherein the oxide film is formed on the surface of the aluminum-plated steel sheet at a thickness of 10% or more of the entire thickness of a hot-dip aluminum-plated layer.

Assignees

• Posco

Inventors

• Lee Suk-Kyu
• Hwang Hyeon-Seok
• Kim Myung-Soo

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• B32B15/012 Primary

  one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy · CPC title

• C22C21/02

  with silicon as the next major constituent · CPC title

• C22C21/10

  with zinc as the next major constituent · CPC title

• C22C38/02

  containing silicon · CPC title