# US 8,785,000 B2 · Steel sheet with hot dip galvanized zinc alloy coating and process to produce it

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- Number: US 8,785,000 B2
- Document ID: US8785000B2
- Status: Granted
- Kind: B2
- Application number: 11/571,221
- Filed: 2005-06-23
- Published: 2009-12-03
- Granted: 2014-07-22
- Earliest claimed: 2004-06-29
- Assignees: Tata Steel Ijmuiden B.V.
- Applicants: Theodorus Franciscus Jozef Maalman; Robert Bleeker; Margot Julia Vlot
- Inventors: Theodorus Franciscus Jozef Maalman; Robert Bleeker; Margot Julia Vlot
- Web page: https://patentgrep.com/patent/US8785000B2

## CPC

- C23C 2/06: Zinc or cadmium or alloys based thereon
- B32B 15/01: all layers being exclusively metallic {(making layered metal workpieces by pressure cladding B23K20/22; making coatings with a metallic material characterised by its composition C23C30/00)}
- B32B 15/013: {one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium}
- B32B 15/04: comprising metal as the main or only constituent of a layer, {which is} next to another layer of {the same or of} a {different material (next to a bituminous or tarry layer B32B11/08; next to a water-setting substance layer B32B13/06; next to a glass layer B32B17/061; next to a cellulosic plastic layer B32B23/042)}
- B32B 15/043: {of metal (B32B15/01 takes precedence)}
- B32B 15/18: comprising iron or steel {(B32B15/011, B32B15/012 and B32B15/013 take precedence)}
- B32B 15/20: comprising aluminium or copper {(B32B15/016 and B32B15/017 take precedence)}
- C22C 18/00: Alloys based on zinc
- C22C 18/04: with aluminium as the next major constituent
- C23C 2/0224: {Two or more thermal pretreatments}
- C23C 2/024: {by cleaning or etching}
- C23C 2/04: characterised by the coating material
- C23C 2/20: Strips; Plates
- C23C 2/34: characterised by the shape of the material to be treated (C23C2/14 takes precedence)
- C23C 2/40: Plates; Strips
- Y10T 428/12792: Zn-base component
- Y10T 428/12799: Next to Fe-base component [e.g., galvanized]
- Y10T 428/12951: Fe-base component
- Y10T 428/12972: Containing 0.01-1.7% carbon [i.e., steel]
- Y10T 428/12979: Containing more than 10% nonferrous elements [e.g., high alloy, stainless]
- Y10T 428/263: Coating layer not in excess of 5 mils thick or equivalent
- Y10T 428/264: Up to 3 mils
- Y10T 428/265: 1 mil or less
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## 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 consisting 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.

## Claims

### Claim 1

Steel strip provided with a hot dip galvanized zinc alloy coating layer, wherein the zinc alloy consists of:
magnesium;
aluminium;
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 magnesium and aluminum content in the zinc alloy layer is selected from a member of the group consisting of:
1.6-1.9 weight % aluminium and 1.4-1.7 weight % magnesium;
wherein the zinc alloy coating layer has a thickness of 3-10 μm,
wherein silicon content in the zinc alloy layer is below 0.0010 weight %.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 2)

Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 2, wherein the one or more additional elements are present in the zinc alloy coating, each <0.02 weight %.

### Claim 4 (depends on 2)

Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 2, wherein the amount of aluminium in weight % is within 0.3 weight % of the amount of magnesium in weight %.

### Claim 5 (depends on 1)

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.

### Claim 6 (depends on 5)

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

### Claim 7 (depends on 5)

Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 5, wherein the amount of aluminium in weight % is within 0.3 weight % of the amount of magnesium in weight %.

### Claim 8 (depends on 1)

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 %.

### Claim 9 (depends on 8)

Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 8, wherein the amount of aluminium in weight % is within 0.3 weight % of the amount of magnesium in weight %.

### Claim 10 (depends on 1)

Steel strip provided with a hot dip galvanized zinc alloy coating layer according to claim 1, wherein the amount of aluminium in weight % is within 0.3 weight % of the amount of magnesium in weight %.

### Claim 11 (depends on 1)

Process for making the steel strip provided with a hot dip galvanized zinc alloy coating layer of claim 1 comprising hot dip galvanising a steel strip with a 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 coating layer consists of:
magnesium;
aluminium;
less than 0.0010 weight % of silicon;
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 magnesium and aluminum content in the zinc alloy coating layer is selected from a member of the group consisting of:
1.6-1.9 weight % aluminium and 1.4-1.7 weight % magnesium;
wherein the zinc alloy coating layer has a thickness of 3-10 μm,
wherein silicon content in the zinc alloy layer is below 0.0010 weight %.

### Claim 12 (depends on 11)

Process according to claim 11, wherein the temperature of the bath of molten zinc is kept between 380° C. and 550° C.

### Claim 13 (depends on 11)

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

### Claim 14 (depends on 11)

Process according to claim 11, wherein the steel strip enters the bath of molten zinc alloy having a speed higher than 9 meters per minute.

### Claim 15 (depends on 11)

Process according to claim 11, wherein the temperature of the bath of molten zinc is kept between 420° C. and 480° C.

### Claim 16 (depends on 11)

Process according to claim 11, 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.

### Claim 17 (depends on 11)

Process according to claim 11, wherein the steel strip enters the bath of molten zinc alloy having a speed higher than 15 meters per minute.

### Claim 18 (depends on 11)

Process according to claim 11, wherein the steel strip enters the bath of molten zinc alloy having a speed higher than 30 meters per minute.

### Claim 19 (depends on 11)

Steel strip provided with a hot dip galvanized zinc alloy coating produced with the method according to claim 11.

### Claim 20 (depends on 1)

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

### Claim 21 (depends on 1)

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 %.