Hot-dipped aluminum coated steel sheet having excellent corrosion resistance and heat resistance, and production method thereof

• US 5,789,089 A
• Filed: 05/17/1996
• Issued: 08/04/1998
• Est. Priority Date: 05/18/1995
• Status: Expired due to Fees

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel Corporation
• Inventors: Yamamoto, Masaaki, Ando, Yu, Enjuji, Masaaki, Maki, Jun, Eguchi, Haruhiko, Ohmori, Takayuki, Okada, Nobuyoshi, Oyama, Yusho
• Primary Examiner(s): Thibodeau, Paul J.
• Assistant Examiner(s): Rickman, Holly C.
• Application Number:
  US08/649,363
• Time in Patent Office: 809 Days
• Field of Search: 428/653, 428/654, 428/684, 428/685, 428/682, 428/939, 428/623, 428/626, 428/632, 420/548, 420/550, 420/78, 420/79, 427/405, 427/409, 427/419.2, 427/436
• US Class Current: 428/623
• CPC Class Codes: C23C 2/12 Aluminium or alloys based thereon
• CPC Class Codes: Y10S 428/939 Molten or fused coating
• CPC Class Codes: Y10T 428/12549 Adjacent to each other
• CPC Class Codes: Y10T 428/12569 Synthetic resin
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12757 Fe
• CPC Class Codes: Y10T 428/12764 Next to Al-base component
• CPC Class Codes: Y10T 428/12958 Next to Fe-base component
• CPC Class Codes: Y10T 428/12972 Containing 0.01-1.7% carbon [i.e., steel]
• CPC Class Codes: Y10T 428/12979 Containing more than 10% nonferrous elements [e.g., high alloy, stainless]

Abstract

A hot-dipped aluminum coated steel sheet including, on the surface thereof, a coating layer consisting of 2 to 15 wt % of Si, not greater than 1.2 wt % of Fe, 0.005 to 0.6 wt % of Mn, 0.002 to 0.05 wt % of Cr and the balance of Al and unavoidable impurities, and an alloy layer disposed between the coating layer and the steel sheet, having a thickness of not greater than 7 μm and having a mean composition consisting of 20 to 50 wt % of Fe, 3 to 20 wt % of Si, 0.1 to 10 wt % of Mn, 0.05 to 1.0 wt % of Cr and the balance substantially consisting of Al. This steel sheet can be produced by conducting coating in a coating bath consisting of 3 to 15 wt % of Si, 0.5 to 3.5 wt % of Fe, 0.05 to 1.5 wt % of Mn, 0.01 to 0.2 wt % of Cr and the balance substantially consisting of Al, or by adjusting the sum of the concentrations of Zn and Sn in the impurities in the coating layer to not greater than 1 wt %.

Claims

1. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet, comprising:

a coating layer disposed on the surface of said steel sheet, and consisting of, in terms of percentage by weight;

Si;

2 to 15%,

Fe;

not greater than 1.2%,

Mn;

0.005 to 0.6%,

Cr;

0.002 to 0.05%, and

the balance of Al and unavoidable impurities including Sn and Zn, wherein Sn the amount of and Zn in total in said impurities is from 0 to 1%, and

an alloy layer disposed between said steel sheet and said coating layer, having a thickness of not greater than 7 μ

m, and having a composition consisting of, in terms of percentage by weight;

Fe;

20 to 50%,

Si;

3 to 20%,

Mn;

0.1 to 10%,

Cr;

0.05 to 1%, and

the balance of Al and unavoidable impurities.

2. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 1, wherein a chromate processed coat film and an organic resin coat film on said chromate processed coat film are disposed on the surface of said coating layer of said hot-dipped aluminum coated steel sheet.

3. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 2, wherein said organic resin coat film is transparent and has a thickness of 1 to 15 μ

m.

4. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 1, wherein the steel sheet consists of, in terms of percentage by weight:

C;

not greater than 0.02%,

Mn;

0.1 to 0.6%,

Ti;

0.1 to 0.5%,

N;

not greater than 0.004%,

Al;

0.01 to 0.08%, and

the balance substantially consisting of Fe and unavoidable impurity elements.

5. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 4, wherein said steel contains not greater than 1% of Cr in terms of percentage by weight.

6. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 1, wherein said steel sheet contains, in terms of percentage by weight:

at least one member selected from the group consisting of not greater than 1.5% of Si, not greater than 0.1% of P and not greater than 0.0003% of B, in addition to the steel composition consisting of, in terms of percentage by weight;

C;

not greater than 0.02%,

Mn;

0.6 to 2%,

Ti;

0.1 to 0.5%,

N;

not greater than 0.004%,

Al;

0.01 to 0.08%, and

the balance substantially consisting of Fe and unavoidable impurity elements.

7. A corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 1, wherein said steel sheet consists of, in terms of percentage by weight:

C;

not greater than 0.01%,

Si;

not greater than 0.1%,

N;

0.0015 to 0.006%,

Al;

not greater than 0.01%, and

the balance substantially consisting of Fe and unavoidable impurity elements.

8. A chromium-containing type corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 1, wherein said steel sheets consists of, in terms of percentage by weight:

C;

not greater than 0.02%,

Mn;

0.1 to 1.5%,

Si;

not greater than 0.2%,

Ti;

0.1 to 0.5%,

Cr;

1 to 9%,

N;

not greater than 0.004%,

Al;

0.01 to 0.08%, and

the balance substantially consisting of Fe and unavoidable impurity elements.

9. A stainless type corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet, comprising a stainless steel sheet containing, as steel components thereof, in terms of percentage by weight:

C;

not greater than 0.02%,

Mn;

0.1 to 1.5%,

Si;

not greater than 0.2%,

Ti;

0.1 to 0.5%,

Cr;

10 to 25%,

N;

not greater than 0.004%,

Al;

0.01 to 0.08%,

at least one member selected from the group consisting of;

Ni;

0.1 to 1%,

Mo;

0.1 to 2%, and

Cu;

0.1 to 1%, and

the balance substantially consisting of Fe and unavoidable impurity elements;

said steel sheet including;

a coating layer consisting of, in terms of percentage by weight;

Si;

2 to 15%,

Fe;

not greater than 1.2%,

Mn;

0.005 to 0.6%,

Cr;

0.05 to 0.2%, and

the balance consisting of Al and unavoidable impurities including Sn and Zn, wherein Sn the amount of and Zn in total in said unavoidable impurities is from 0 to 1%, and disposed on the surface of said steel sheet; and

an alloy layer disposed between said steel sheet and said coating layer, having a thickness of not greater than 7 μ

m and having a composition consisting of, in terms of percentage by weight;

Fe;

20 to 50%,

Si;

3 to 20%,

Mn;

0.1 to 10%,

Cr;

1 to 5%, and

the balance consisting of Al an unavoidable impurities.

10. A production method for a corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet comprising:

forming a coating layer consisting of, in terms of percentage by weight;

Si;

2 to 15%,

Fe;

not greater than 1.2%,

Mn;

0.005 to 0.6%,

Cr;

0.002 to 0.05%, and

the balance consisting of Al and unavoidable impurities including Sn and Zn, wherein Sn the amount of and Zn in total in said impurities is from 0 to 1%;

on the surface of a steel sheet; and

forming an alloy layer between said steel sheet and said coating layer, having a thickness of not greater than 7 μ

m and having a composition consisting of, in terms of percentage by weight;

Fe;

20 to 50%,

Si;

3 to 20%,

Mn;

0.1 to 10%,

Cr;

0.05 to 1%, and

the balance consisting of Al and unavoidable impurities;

said alloy layer formed by using a bath having a composition consisting of;

Si;

3 to 15%,

Fe;

0.5 to 3.5%,

Mn;

0.05 to 1.5%,

Cr;

0.01 to 0.2%, and

the balance consisting of Al an unavoidable impurities, wherein Sn and Zn in total in said impurities is not greater than 1%.

11. A production method for a corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 10, wherein a Cr concentration in said coating bath is 0.01 to less than 0.1% in terms of percentage by weight.

12. A production method for a corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet according to claim 10, wherein a deposition quantity of said coating layer is at least 60 g/m² on both surfaces of said steel sheet, and heat-treatment is carried out in a region encompassed by the following coordinates axes A, B, C, D, E and F:

A;

(5 seconds, 510°

C.), D;

(30 hours, 300°

C.),

B;

(1 minute, 530°

C.), E;

(1 minute, 300°

C.),

C;

(30 hours, 530°

C.), F;

(5 seconds, 450°

C.).

13. A production method for a corrosion resistant and heat resistant hot-dipped aluminum coated steel sheet for building material according to claim 12, wherein chromate processing and resin coating are carried out in succession onto said coating layer.