# US 12,006,576 B2 · Plated steel sheet having excellent corrosion resistance, galling resistance, workability and surface property

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- Number: US 12,006,576 B2
- Document ID: US12006576B2
- Status: Granted
- Kind: B2
- Application number: 17/762,533
- Filed: 2020-09-24
- Published: 2022-10-27
- Granted: 2024-06-11
- Earliest claimed: 2019-09-24
- Assignees: Posco; Steel & Convergence Technology Research Association; Posco Coated & Color Steel Co., Ltd.
- Applicants: Posco; Steel & Convergence Technology Research Association; Posco Coated & Color Steel Co., Ltd.
- Inventors: Sung-Joo Kim; Kyung-Kwan Park; Moon-Hi Hong; Heung-Yun Kim; Tae-Yeul Park; Myung-Soo Kim; Il-Ryoung Sohn; Tae-Chul Kim; Dae-Young Kang
- Web page: https://patentgrep.com/patent/US12006576B2

## 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)}
- C21D 7/06: by shot-peening or the like
- C22C 18/00: Alloys based on zinc
- C22C 18/04: with aluminium as the next major constituent
- C23C 2/0035: {Means for continuously moving substrate through, into or out of the bath (C23C2/00344 takes precedence)}
- C23C 2/02: Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence)
- C23C 2/285: {for remelting the coating}
- C23C 2/29: {Cooling or quenching}
- C23C 2/40: Plates; Strips
- C23C 28/02: only coatings {only including layers} of metallic material
- 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 28/322: {only coatings of metal elements only}
- C23C 28/3225: {with at least one zinc-based layer}
- C23C 30/00: Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence)
- C23C 30/005: {on hard metal substrates}
- Y10T 428/12951: Fe-base component
- Y10T 428/12958: Next to 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 428/12993: Surface feature [e.g., rough, mirror]
- Y10T 428/24942: including components having same physical characteristic in differing degree
- Y10T 428/24983: Hardness
- Y10T 428/263: Coating layer not in excess of 5 mils thick or equivalent
- 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
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Provided are a plated steel sheet and a method for manufacturing same, the plated steel sheet comprising: a base steel sheet; a Zn—Mg—Al plating layer provided on at least one surface of the base steel sheet; and an Fe—Al inhibition layer provided between the base steel sheet and the Zn—Mg—Al plating layer. The plating layer comprises, by weight %, 4 to 10% of Mg and 5.1-25% of Al and the remainder being Zn and unavoidable impurities with respect to components not including iron (Fe) diffused from the base steel sheet. The plating layer comprises a 24-50% MgZn2 phase in phase fraction. In the MgZn2 phase, an Al single phase is present in the ratio of 1-30% relative to the cross-sectional area of the total MgZn2 phase.

## Claims

### Claim 1

A plated steel sheet comprising:
a base steel sheet;
a Zn—Mg—Al-based plating layer provided on at least one surface of the base steel sheet; and
a Fe—Al-based inhibition layer provided between the base steel sheet and the Zn—Mg—Al-based plating layer,
wherein the plating layer includes, by weight, 4 to 10% of Mg and 5.1 to 25% of Al, with a balance of Zn and unavoidable impurities, based on components other than iron (Fe) ,
the plating layer includes a MgZn2 phase at a phase fraction of 24 to 50 wt %, and
an Al single phase is present inside the MgZn2 phase at a ratio of 1 to 30% to a total cross-sectional area of the MgZn2 phase in a thickness direction.

### Claim 2 (depends on 1)

The plated steel sheet of claim 1, wherein the MgZn2 phase is exposed to at least a portion of a surface of the plating layer, and an average circle-equivalent diameter of the MgZn2 phase exposed to the surface is 5 to 50 μm.

### Claim 3 (depends on 1)

The plated steel sheet of claim 1, wherein a phase fraction of the Al single phase to a total area of the plating layer is 1 to 15%.

### Claim 4 (depends on 1)

The plated steel sheet of claim 1, wherein the plating layer has a surface roughness (Ra) of 0.5 to 2.0 μm.

### Claim 5 (depends on 1)

The plated steel sheet of claim 1, wherein the inhibition layer is formed of a Fe—Al-based intermetallic compound containing less than 10 wt % of Zn and the Fe—Al-based intermetallic compound is one or more of Fe2Al5, FeAl3, and FeAl5.

### Claim 6 (depends on 1)

The plated steel sheet of claim 1, wherein the inhibition layer has a thickness of 0.02 to 2 μm.