Steel sheet with hot dip galvanized zinc alloy coating and process to produce it

Patent metadata

Field	Value
Publication number	US-9677164-B2
Application number	US-201414308099-A
Country	US
Kind code	B2
Filing date	Jun 18, 2014
Priority date	Jun 29, 2004
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

Steel strip provided with a hot dip galvanized zinc alloy coating layer, in which the coating of the steel strip is carried out in a bath of molten zinc alloy, the zinc alloy in the coating of: 0.3-2.3 weight % magnesium; 0.6-2.3 weight % aluminum; optional <0.2 weight % of one or more additional elements; unavoidable impurities; the remainder being zinc in which the zinc alloy coating layer has a thickness of 3-12 μm.

First claim

The invention claimed is:

1. Steel strip provided with a hot dip galvanized zinc alloy coating layer, wherein the zinc alloy consists of:
1.6-1.9 weight % aluminium,
wherein magnesium is present such that the amount of aluminium in weight % is the same as the amount of magnesium in weight % plus or minus a maximum of 0.3 weight %;
optional <0.2 weight % of one or more additional elements selected from the group consisting of Pb, Sb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni, Zr and Bi;
unavoidable impurities;
the remainder being zinc;

wherein the zinc alloy coating layer has a thickness of 3-12 μm,
wherein the silicon content in the zinc alloy layer is below 0.0010 weight %.

2. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the zinc alloy coating layer has a thickness of 3-10 μm.

3. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the zinc alloy coating layer has a thickness of 3-8 μm.

4. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the zinc alloy coating layer has a thickness of 3-7 μm.

5. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the one or more additional elements are present in the zinc alloy coating, each <0.02 weight.

6. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the one or more additional elements are present in the zinc alloy coating, each <0.01 weight %.

7. Automotive part manufactured from a steel strip according to claim 1 .

8. Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1 , wherein the level of Mg is 1.3-1.7%.

9. Process for producing a steel strip provided with a hot dip galvanized zinc alloy coating of claim 1 , comprising:
hot dip galvanising the steel strip with the zinc alloy coating layer, in which the coating of the steel strip is carried out in a bath of molten zinc alloy, wherein the zinc alloy consists of:
1.6-1.9 weight % aluminium,
wherein magnesium is present such that the amount of aluminium in weight % is the same as the amount of magnesium in weight % plus or minus a maximum of 0.3 weight %;
optional <0.2 weight % of one or more additional elements selected from the group consisting of Pb, Sb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni, Zr and Bi;
unavoidable impurities;
the remainder being zinc;

wherein the zinc alloy coating layer has a thickness of 3-12 μm,
wherein the silicon content in the zinc alloy layer is below 0.0010 weight %.

10. Process according to claim 7 , wherein the temperature of the bath of molten zinc is kept between 380° C. and 550° C.

11. Process according to claim 7 , wherein the temperature of the steel strip before entering the bath of molten zinc alloy is between 380° C. and 850° C.

12. Process according to claim 7 , wherein the temperature of the steel strip before entering the bath of molten zinc alloy is between the temperature of the bath of molten zinc alloy and 25° C. above the bath temperature.

Assignees

• Tata Steel Ijmuiden Bv

Inventors

• Maalman Theodorus Franciscus Jozef
• Bleeker Robert
• Vlot Margot Julia

Classifications

• C23C2/34

  characterised by the shape of the material to be treated (C23C2/14 takes precedence) · CPC title

• Y10T428/12951

  Fe-base component · CPC title

• B32B15/043

  of metal (B32B15/01 takes precedence) · CPC title

• C22C18/00

  Alloys based on zinc · CPC title

• C23C2/20

  Strips; Plates · CPC title