# US 9,040,167 B2 · Method for the production of a flat steel product and flat steel product

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- Number: US 9,040,167 B2
- Document ID: US9040167B2
- Status: Granted
- Kind: B2
- Application number: 13/321,212
- Filed: 2010-05-20
- Published: 2012-05-24
- Granted: 2015-05-26
- Earliest claimed: 2009-05-25
- Assignees: ThyssenKrupp Steel Europe AG
- Applicants: Bernd Schuhmacher; Christian Schwerdt; Nicole Weiher; Richard Weinhold
- Inventors: Bernd Schuhmacher; Christian Schwerdt; Nicole Weiher; Richard Weinhold
- Web page: https://patentgrep.com/patent/US9040167B2

## CPC

- C23C 14/025: {Metallic sublayers}
- B32B 15/012: {one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy}
- 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 15/18: 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 1/02: by melting {(C22C1/1036 takes precedence)}
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- C23C 14/16: on metallic substrates or on substrates of boron or silicon
- C23C 14/5806: {Thermal treatment}
- C23C 28/021: {including at least one metal alloy layer}
- C23C 28/023: {only coatings of metal elements only}
- C23C 28/025: {with at least one zinc-based layer}
- C23C 28/028: {Including graded layers in composition or in physical properties, e.g. density, porosity, grain size}
- C23C 30/005: {on hard metal substrates}
- C25D 7/0614: {Strips or foils}
- C25D 5/50: by heat-treatment
- Y10T 428/12729: Group IIA metal-base component
- Y10T 428/12736: Al-base component
- Y10T 428/12757: Fe
- Y10T 428/12799: Next to Fe-base component [e.g., galvanized]
- Y10T 428/12972: Containing 0.01-1.7% carbon [i.e., steel]
- 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)
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A flat steel product having a base layer of a steel material and a multilayer coating applied thereto, and a method for producing the flat steel product. The method having the following steps: providing a steel base layer; applying a zinc layer to the base layer by electrolytic coating; applying an aluminum layer to the surface of the zinc layer, wherein no treatment is made to the surface of the zinc layer in regard to the oxides and sulfides present thereon at the end of the electrolytic zinc coating step or occurring during the course of the aluminum coating step; applying a magnesium layer to the aluminum layer; and subsequently heat treating the flat steel product in such a way that an MgZn2 layer forms in the coating above the Al layer.

## Claims

### Claim 1

A method for the production of a flat steel product that is formed from a base layer consisting of a steel material and a multilayer anticorrosion coating applied thereto, comprising the following operating steps:
providing the base layer;
applying a zinc layer to the base layer by electrolytic deposition;
applying an aluminium layer directly to the as-deposited surface of the zinc layer;
applying a magnesium layer to the aluminium layer; and
thermally post-treating the flat steel product provided with the coating formed from the zinc layer applied to the base layer, the aluminium layer and the magnesium layer, in such a way that an MgZn2 layer is formed in the coating above the Al layer,
wherein the aluminium layer has a maximum thickness of 25 nm.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the zinc layer comprises up to 99.9 wt. % of Zn.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the zinc layer is applied in a thickness of 2-10 μm to the base layer.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the zinc layer is applied in a thickness of less than 8 μM to the base layer.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the aluminium layer is applied in a thickness of at least 8 nm to the zinc layer.

### Claim 6 (depends on 5)

The method according to claim 5, wherein the aluminium layer applied to the zinc layer is 8.5-13 nm thick.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the aluminium layer is applied by a cathode sputtering method.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the magnesium layer is applied in a thickness of 200-1500 nm to the aluminium layer.

### Claim 9 (depends on 8)

The method according to claim 8, wherein the magnesium layer applied to the aluminium layer is 300-800 nm thick.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the temperature of the thermal post-treatment is 280° C.-350° C.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the Al layer is applied to the Zn layer immediately after electrolytic deposition of the Zn layer without any further processing of the Zn layer prior to application of the Al layer.

### Claim 12

A flat steel product, comprising:
a base layer consisting of a steel material; and
a multilayer coating applied thereto, wherein the coating comprises a Zn layer covering the base layer, Al layer covering the Zn layer, and a MgZn2 diffusion layer covering the Al layer.

### Claim 13 (depends on 12)

The flat steel product according to claim 12, wherein the thickness of the MgZn2 layer is 400-2500 nm.

### Claim 14 (depends on 1, 12)

The flat steel product according to claim 12, wherein it is produced by a method carried out according to claim 1.