# US 11,306,381 B2 · High-strength hot-dip zinc plated steel material having excellent plating properties and method for preparing same

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- Number: US 11,306,381 B2
- Document ID: US11306381B2
- Status: Granted
- Kind: B2
- Application number: 16/064,757
- Filed: 2016-12-21
- Published: 2018-12-27
- Granted: 2022-04-19
- Earliest claimed: 2015-12-24
- Assignees: Posco
- Applicants: Posco
- Inventors: Il-Ryoung Sohn; Dae-Young Kang; Jong-Sang Kim; Tae-Chul Kim; Min-Suk Oh
- Web page: https://patentgrep.com/patent/US11306381B2

## CPC

- C23C 2/06: Zinc or cadmium or alloys based thereon
- C21D 6/005: {containing Mn}
- C21D 6/008: {containing Si}
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- C22C 38/001: {containing N}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C23C 2/02: Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence)
- C23C 2/0222: {in a reactive atmosphere, e.g. oxidising or reducing atmosphere (C23C2/024 takes precedence)}
- C23C 2/12: Aluminium or alloys based thereon
- 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}
- C22C 38/22: with molybdenum or tungsten
- C22C 38/26: with niobium or tantalum
- C22C 38/28: with titanium or zirconium
- C22C 38/30: with cobalt
- C22C 38/32: with boron
- 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)
- 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)

## Abstract

Provided are a hot-dip zinc plated steel material and a method for preparing same, the hot-dip zinc plated steel material comprising: base iron comprising 0.01-1.6 wt % of Si and 1.2-3.1 wt % of Mn; a Zn—Al—Mg alloy plating layer; and an Al-rich layer formed on the interface of the base iron and Zn—Al—Mg alloy plating layer, wherein the rate of occupied surface area of the Al-rich layer is 70% or higher (including 100%).

## Claims

### Claim 1

A high-strength hot-dip zinc plated steel material, comprising:
a base steel comprising, by weight percent, 0.05% to 0.25% of C, 0.01% to 1.6% of Si, 0.5% to 3.1% of Mn, 0.001% to 0.10% of P, 0.01% to 0.8% of Al, 0.001 to 0.03% of N, with a remainder of Fe and unavoidable impurities;
a Zn—Al—Mg alloy plating layer comprising, by weight percent, 0.2% to 15% of Al, 0.5% to 3.5% of Mg, with a remainder of Zn and unavoidable impurities; and
an interfacial layer formed at the interface of the base steel and the Zn—Al—Mg alloy plating layer,
wherein a sum of contents of Al and Fe contained in the interfacial layer is 50 wt % or higher excluding 100 wt %,
wherein a rate of occupied surface area of the interfacial layer is 70% or higher including 100%.

### Claim 2 (depends on 1)

The high-strength hot-dip zinc plated steel material of claim 1,
wherein the interfacial layer has I, defined by Equation (1) below, with I being 0.40 or less:
I=[O]/{[Si]+[Mn]+[Fe]} [Equation 1]
where each of [O], [Si], [Mn], and [Fe] denotes the content (wt %) of the corresponding element contained in the interfacial layer.

### Claim 3 (depends on 1)

The high-strength hot-dip zinc plated steel material of claim 1,
wherein the base steel further includes 0.9 wt % or less of Cr excluding 0 wt %,
and the interfacial layer has I defined by Equation (2) below, with I being 0.40 or less:
I=[O]/{[Si]+[Mn]+[Cr]+[Fe]} [Equation 2]
where each of [O], [Si], [Mn], [Cr] and [Fe] denotes the content (wt %) of the corresponding element contained in the interfacial layer.

### Claim 4 (depends on 1)

The high-strength hot-dip zinc plated steel material of claim 1, wherein the base steel further includes one or more selected from the group consisting of, by weight percent, 0.9% or less of Cr excluding 0%, 0.004% or less of B excluding 0%, 0.1% or less of Mo excluding 0%, 1.0% or less of Co excluding 0%, 0.2% or less of Ti excluding 0% and 0.2% or less of Nb excluding 0%.

### Claim 5 (depends on 1)

The high-strength hot-dip zinc plated steel material of claim 1, wherein a ratio ([Si]/[Mn]) of the content of Si to the content of Mn contained in the base steel is 0.3 or higher, the base steel includes an internal oxide layer formed directly below a surface thereof, and an average thickness (nm) of the internal oxide layer is 100×[Si]/[Mn] or higher.

### Claim 6 (depends on 5)

The high-strength hot-dip zinc plated steel material of claim 5, wherein the average thickness of the internal oxide layer is 1,500 nm or less.

### Claim 7 (depends on 5)

The high-strength hot-dip zinc plated steel material of claim 5, wherein the internal oxide layer includes a Si single oxide and a Si—Mn composite oxide.

### Claim 8 (depends on 5)

The high-strength hot-dip zinc plated steel material of claim 5, satisfying b/a>1,
where ‘a’ is a ratio of the Si content to the Mn content contained in the internal oxide layer of Si and Mn, and ‘b’ is a ratio of the Si content to the Mn content contained in the base steel, excluding the internal oxide layer of Si and Mn.