KR20200076830A - Alloy-coated steel sheet and manufacturing method of the same - Google Patents

Abstract

Disclosed is an alloy-coated steel sheet, which includes: a steel sheet; an AI-Mg-Si alloy layer positioned on the steel sheet; and a post-processed layer positioned on the Al-Mg-Si alloy layer, wherein the post-processed layer includes an olefin-based resin. Therefore, the alloy-coated steel sheet can have excellent corrosion resistance at surfaces and cut portions.

Description

ALLOY-COATED STEEL SHEET AND MANUFACTURING METHOD OF THE SAME

The present invention relates to an alloy coated steel sheet and a method for manufacturing the same. More specifically, it relates to an alloy coated steel sheet having excellent surface corrosion resistance and cut corrosion resistance, and a method for manufacturing the same.

Iron is the most widely used metal in the industry due to its abundant resources, excellent properties and low price. Iron has a disadvantage in that corrosion occurs in the air despite these advantages. Corrosion of iron is a phenomenon in which iron and oxygen or water cause an electrochemical reaction and iron ions elute. When such a reaction proceeds, iron oxide (FeOOH) is generated in the eluted portion, which is called rust.

Iron rust is composed of various stoichiometric oxides and hydroxides, and it is one of the characteristics of iron that oxidation occurs continuously over time. Iron is processed and used in various forms, and in the case of automobiles, construction materials, and home appliances, cold rolled steel sheets, that is, cold rolled steel sheets, are mainly used. A representative method for preventing corrosion of the steel sheet is to plate other metal on the surface of the steel sheet.

The type of the plating film can be divided into a sacrificial type coating and a blocking type coating. The sacrificial type coating is coated with a metal that is more easily oxidized than iron, such as zinc, magnesium, or aluminum, and is prone to rust, and the coated metal is preferentially corroded to protect the steel sheet. The barrier-type coating is coated with a metal that is harder to corrode than a steel sheet such as lead or tin to block water and oxygen from reaching iron.

Galvanization is currently the most widely used to prevent corrosion of steel sheets. Since the development of galvanized steel, various efforts have been made to improve corrosion resistance, one of which is to coat zinc alloys. Zn-Al, Zn-Ni, Zn-Fe, and Zn-Al-Mg are examples of high corrosion-resistant materials using alloys. Such zinc or zinc alloy plated steel sheets are widely used in automobiles, construction materials and home appliances.

Aluminum is also used to prevent corrosion of steel plates. Aluminum has a wider range of applications than zinc. The aluminum film has a beautiful color and excellent corrosion resistance and heat resistance, so it can be used for coating of conductive films of semiconductors, magnetic materials and steel plates, protective films of magnetic materials, heating appliances, automotive mufflers, as well as decorative films such as cosmetic cases and accessories. Is becoming.

The coating of aluminum is prepared by vacuum coating, electroplating or hot dip plating. However, in the case of electroplating, since its efficiency is low and productivity decreases, most of the hot dipping and vacuum coating methods are used. The aluminum plated steel plate manufactured by the hot dip plating method has a plated steel plate (Type I) containing only 8 to 10% of silicon and a plated steel plate (Type II) made of pure aluminum only. Type I is generally used for heat resistance and weather resistance Type II is mainly used for the necessary construction materials.

Type I aluminum plated steel sheet is used as a muffler material for automobile exhaust systems and is used for household or kitchen appliances such as toasters, ranges, dryers, stacks, stoves, boilers, drying furnaces, etc. Type II aluminum plated steel sheets are galvanized steel sheets It has a weather resistance of about 4 times, and is used as a steel for construction.

While aluminum plated steel sheet has excellent corrosion resistance, there is a disadvantage in that corrosion occurs intensively at the site when a defect occurs in the film, because aluminum is less sacrificial than zinc. Therefore, in the case of a hot-dip galvanized steel sheet, the thickness is over 15 microns to overcome this. The hot-dip galvanized steel sheet also has a disadvantage in that the process is performed at a high temperature, so that an Al-Fe-Si alloy is formed at the interface, resulting in poor processability.

Product development is underway to improve corrosion resistance and sacrificial corrosion resistance by adding magnesium to a molten aluminum plated steel sheet containing silicon. The conventional technique of producing an Al-Si-Mg plated steel sheet by hot-dip plating has limitations in controlling the Mg content because it is produced by hot-dip plating, and in the case of thin plating, there is a disadvantage in that corrosion resistance falls rapidly.

Provided is an alloy coated steel sheet having excellent surface corrosion resistance and cut corrosion resistance, and a method for manufacturing the same.

Alloy coated steel sheet according to an embodiment of the present invention is a steel sheet; Al-Mg-Si alloy layer located on the steel sheet; And a post-treatment layer positioned on the Al-Mg-Si alloy layer, and the post-treatment layer includes an olefin-based resin.

The post-treatment layer may further include at least one of a chromium compound, a chromium-free composition, and a zirconium-based chelating agent.

The Al-Mg-Si alloy layer may contain 30 wt% or less of Mg based on 100 wt% of the total.

The Al-Mg-Si alloy layer may include at least one of Al-Mg alloy phase and Mg-Si alloy phase.

The Al-Mg alloy phase may include one or more of Al ₃ Mg ₂ and Al ₁₂ Mg ₁₇ .

The Mg-Si alloy phase may include Mg ₂ Si.

In the Al-Mg-Si alloy layer, the Mg may exist as the Al-Mg alloy phase or may exist as the Mg-Si alloy phase.

It may further include; Al-Fe-Si alloy layer located between the steel sheet and the Al-Mg-Si alloy layer.

The Al-Mg-Si alloy layer may include 60 to 90% by weight of Al, 30% by weight or less of Mg, and 1 to 10% by weight of Si based on 100% by weight.

Method for manufacturing an alloy coated steel sheet according to an embodiment of the present invention comprises a preparing step of preparing a plated steel sheet having a plating layer comprising Al and Si; A coating step of forming an Mg coating layer containing Mg on the plating layer; A heat treatment step of diffusing the Mg into the plating layer by heat-treating the plated steel sheet on which the Mg coating layer is formed; And a post-treatment step of applying a post-treatment solution on the Al-Mg-Si alloy layer formed by diffusion of the Mg; and the post-treatment solution includes an olefin-based resin.

In the preparing step, the plated steel sheet may be a molten aluminum plated steel sheet.

In the coating step, the Mg coating layer may be formed using physical vapor deposition (PVD).

In the heat treatment step, heat treatment may be performed at a temperature of 300 to 450°C.

In the heat treatment step, heat treatment may be performed for 5 to 600 seconds.

In the post-treatment step, the post-treatment solution may be applied at 0.5 to 2 g/m ² on the Al-Mg-Si alloy layer.

According to the alloy coated steel sheet according to an embodiment of the present invention and its manufacturing method, an Mg coating layer is formed on a plating layer containing Al and Si and then heat-treated, and then a post-treatment layer is applied to the alloy layer by applying a post-treatment solution. By forming, it is possible to expect an effect of excellent surface corrosion resistance and corrosion resistance of the cut portion.

1 is a schematic schematic diagram of a continuous coating device that can be used in the manufacture of an alloy coated steel sheet.
Figure 2 is a schematic cross-sectional view before the post-treatment layer is formed in the alloy coated steel sheet according to an embodiment of the present invention.
3 is a view showing an X-ray diffraction graph of the alloy coated steel sheet according to Example 1 of the present invention.
4 is a view showing an X-ray diffraction graph of the alloy coated steel sheet according to Example 2 of the present invention.
5 is a view showing a photo of white rust generated according to Example 1 and Example 2 of the present invention.

Terms such as first, second and third are used to describe various parts, components, regions, layers and/or sections, but are not limited thereto. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first portion, component, region, layer or section described below may be referred to as a second portion, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only for referring to a specific embodiment, and is not intended to limit the present invention. The singular forms used herein also include plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of “comprising” embodies a particular property, region, integer, step, action, element, and/or component, and the presence or presence of another property, region, integer, step, action, element, and/or component. It does not exclude addition.

When a part is said to be "on" or "on" another part, it may be directly on or on the other part, or another part may be involved therebetween. In contrast, if one part is said to be "just above" another part, no other part is interposed therebetween.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present invention pertains.

Commonly used dictionary-defined terms are additionally interpreted as having meanings consistent with related technical documents and currently disclosed contents, and are not interpreted as ideal or very formal meanings unless defined.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

Method for manufacturing alloy coated steel sheet

The method for manufacturing an alloy coated steel sheet according to an embodiment of the present invention includes a preparation step of preparing a plated steel sheet having a plating layer containing Al and Si, a coating step of forming an Mg coating layer containing Mg on the plating layer, and an Mg coating layer formed. It includes a heat treatment step of diffusing Mg into the plating layer by heat-treating the plated steel sheet and a post-treatment step of applying a post-treatment solution containing an olefin-based resin on the Al-Mg-Si alloy layer formed by diffusion of Mg.

First, in the preparation step, a plated steel sheet in which a plating layer containing Al and Si is formed is prepared. The plated steel sheet may be a molten aluminum plated steel sheet. Specifically, the plating layer may include 88 to 90% by weight of Al, 8 to 10% by weight of Si, and 5% by weight or less of Fe based on 100% by weight.

The plating layer may include an Al-Fe-Si alloy layer formed on a steel sheet and an Al-Si layer formed on an Al-Fe-Si alloy layer. The Al-Fe-Si alloy layer may be formed by diffusion of Fe from the plated steel sheet into the plated layer during manufacture of the plated steel sheet.

Next, in the coating step, an Mg coating layer containing Mg is formed on the plating layer. At this time, the coating of Mg may be performed by physical vapor deposition (PVD). Specifically, it may be performed by electromagnetic stimulation physical vapor deposition (EML-PVD). However, the present invention is not limited thereto, and Mg can be coated by employing various methods if deposition of Mg is possible by physical methods such as an electron beam evaporator, a thermal evaporator, a sputtering source, and a cathode arc source.

Next, in the heat treatment step, the plated steel sheet having the Mg coating layer is heat-treated to diffuse Mg into the plating layer. Heat treatment may be performed using an induction heating device. However, the present invention is not limited to this, and other suitable heat treatment means may be employed.

Specifically, heat treatment may be performed at a temperature of 300 to 450°C, and heat treatment may be performed for 5 to 600 seconds.

After diffusing Mg into the plating layer by heat treatment, an Al-Mg-Si alloy layer is formed after heat treatment. The Al-Mg-Si alloy layer may further include at least one of Al-Mg alloy phase and Mg-Si alloy phase.

The Al-Mg alloy phase may include one or more of Al ₃ Mg ₂ and Al ₁₂ Mg ₁₇ , and the Mg-Si alloy phase may include Mg ₂ Si. In the Al-Mg-Si alloy layer, all of Mg may be present in the Al-Mg alloy phase, or may be present in the Mg-Si alloy phase. That is, Mg in a form that is not combined with other elements may not exist.

Next, in the post-treatment step, a post-treatment solution containing an olefin-based resin is applied on the Al-Mg-Si alloy layer formed by diffusion of Mg.

Specifically, a post-treatment layer may be formed by applying a post-treatment solution at 0.5 to 2 g/m ² on the Al-Mg-Si alloy layer.

Accordingly, it may be possible to manufacture an alloy coated steel sheet having excellent cut surface corrosion resistance.

1 is a schematic diagram of a continuous coating device that can be used in the manufacture of alloy coated steel sheet. However, this is only an example according to an embodiment of the present invention and is not limited thereto.

The apparatus disclosed in FIG. 1 is a steel sheet supply device 11 for supplying a molten aluminum plated steel sheet 17 in the atmosphere, an inverse magnetron source 12 capable of pre-processing the steel sheet in vacuum, and Mg after pretreatment. With a physical vapor deposition (PVD) device 13 for coating, and an induction heating device 14 capable of heat-treating the steel sheet discharged to the atmosphere, a steel sheet discharge device 15 for rewinding the heat-treated coated steel sheet again Consists of.

The physical vapor deposition device 13 may be an electromagnetic levitation (EML) source. The reverse magnetron sputtering source 12 and the physical vapor deposition device 13 may be installed and operated in the vacuum container 16.

First, the molten aluminum plated steel sheet 17 is prepared, and alkali degreasing may be performed to remove residual oil, such as rust preventive oil, which is deposited on the surface of the plated steel sheet.

Thereafter, the plated steel sheet is supplied to the vacuum container 16 while being transported through the steel plate supply device 11. Thereafter, power may be applied to the reverse magnetron sputtering source 12 installed in the vacuum container 16 to perform surface cleaning of the plated steel sheet.

After cleaning is completed, Mg may be vacuum coated on the plating layer through the electromagnetic stimulation source 13 installed in the vacuum container 16 while continuously transporting the plated steel sheet.

After the coating is completed, the plated steel sheet is continuously transferred and discharged into the air, and then heat-treated at a constant temperature and time using the induction heating device 14 in the air. After the heat treatment is completed, an alloy-coated steel sheet can be obtained by forming a post-treatment layer by applying a post-treatment solution containing an olefin-based resin on the Al-Mg-Si alloy layer.

Alloy coated steel sheet

When the alloy coated steel sheet according to an embodiment of the present invention is described with reference to FIG. 2, the steel sheet 4, the Al-Mg-Si alloy layer 1 and the Al-Mg-Si located on the steel sheet 4 A post-treatment layer located on the alloy layer 1 is included, and the post-treatment layer contains an olefin-based resin.

The post-treatment layer may further include at least one of a chromium compound, a chromium-free composition, and a zirconium-based chelating agent. The thickness of the post-treatment layer may be 0.1 to 3 μm.

The Al-Mg-Si alloy layer 1 may include at least one of Al-Mg alloy phase and Mg-Si alloy phase. The Al-Mg alloy phase may include one or more of Al ₃ Mg ₂ and Al ₁₂ Mg ₁₇ , and the Mg-Si alloy phase may include Mg ₂ Si.

The Al-Mg-Si alloy layer 1 may include 50 to 90% by weight of Al, 30% by weight or less of Mg, and 1 to 10% by weight of Si based on 100% by weight. In the Al-Mg-Si alloy layer 1, as Mg is contained in an amount of 30% by weight or less, all of Mg may be present in the Al-Mg alloy phase or may be present in the Mg-Si alloy phase. That is, Mg in a form that is not combined with other elements may not exist.

As the Mg coating layer is formed on a plated steel sheet having a plating layer containing Al and Si, and then heat-treated, Fe of the plated steel sheet is partially diffused into the plating layer to form a steel sheet between the steel sheet and the Al-Mg-Si alloy layer 1 In the Al-Fe-Si alloy layer 2 may be located. In addition, the Al-Si alloy layer 3 may be located on the Al-Fe-Si alloy layer 2. The Al-Si alloy layer 3 may be a portion in which Mg is not diffused in the existing plating layer.

In addition, the description of the alloy coated steel sheet will be replaced by the description of the method for manufacturing the alloy coated steel sheet.

Hereinafter, specific examples of the present invention will be described. However, the following examples are only specific examples of the present invention, and the present invention is not limited to the following examples.

Example

(1) Preparation of alloy coated steel sheet

[Example 1] A Mg coating layer having a thickness of 1 µm was formed on a hot-dip aluminum plated steel sheet having a plating layer containing Al and Si using physical vapor deposition (PVD), followed by heat treatment for 600 seconds based on a heat treatment temperature of 400°C. It was carried out to form an Al-Mg-Si alloy layer on the plated steel sheet. Thereafter, a post-treatment solution was applied on the Al-Mg-Si alloy layer at 1.0 g/m ² to form a post-treatment layer. The post-treatment solution included olefinic resin.

[Example 2] A Mg coating layer having a thickness of 1 µm was formed on a hot-dip aluminum plated steel sheet having a plating layer containing Al and Si using physical vapor deposition (PVD), followed by heat treatment for 300 seconds based on a heat treatment temperature of 400°C. It was carried out to form an Al-Mg-Si alloy layer on the plated steel sheet. Thereafter, a post-treatment solution was applied on the Al-Mg-Si alloy layer at 1.0 g/m ² to form a post-treatment layer. The post-treatment solution included olefinic resin.

(2) Microstructure observation of alloy coated steel sheet

3 and 4, the composition of the alloy layer formed on the alloy coated steel sheet was investigated using an X-ray diffraction machine.

For Example 1, Al and Al ₃ Mg ₂ and Mg ₂ Si were observed. In addition, looking at the diffraction angle between 35° and 37°, it was found that there was no peak, and it was found that Mg alone was not present.

In the case of Example 2, Al ₃ Mg ₂ , Mg ₂ Si and Al ₁₂ Mg ₁₇ including Mg, Al, and Si were observed. In addition, it was confirmed that a peak corresponding to Mg appeared between the diffraction angles of 35° and 37°.

(3) Evaluation of corrosion resistance of alloy coated steel sheet

A salt spray test was performed on the alloy coated steel sheets according to Examples 1 and 2 to evaluate corrosion resistance of the cut. The salt spray test is a test for comparing discoloration and white rust of a specimen after spraying salt water for 120 hours using a salt water tester, and was performed according to ASTM B-117.

As shown in Figure 5, after 120 hours of salt spray, in the case of Example 1, white rust of about 4 mm was generated from the cut portion to the surface side. In the case of Example 2, about 15 mm of white rust was generated from the cut portion to the surface side.

In view of this, Example 1, in which Al was present in both the Al-Mg-Si alloy layer and Al-Mg alloy phase and Mg-Si alloy phase, was superior in corrosion resistance to Example 2 in which only Mg was present. Could confirm.

The present invention is not limited to the above embodiments and/or embodiments, but may be manufactured in various different forms, and those skilled in the art to which the present invention pertains may change the technical spirit or essential features of the present invention. It will be understood that it may be practiced in other specific forms without. Therefore, it should be understood that the above-described embodiments and/or embodiments are illustrative in all respects and not restrictive.

Claims (14)

Grater;
Al-Mg-Si alloy layer located on the steel sheet; And
It includes; a post-processing layer located on the Al-Mg-Si alloy layer,
The post-treatment layer is an alloy coated steel sheet containing an olefin-based resin. According to claim 1,
The post-treatment layer,
An alloy coated steel sheet further comprising at least one of a chromium compound, a chromium-free composition and a zirconium-based chelating agent. According to claim 1,
The Al-Mg-Si alloy layer,
Alloy coated steel sheet containing less than 30% by weight of Mg, based on 100% by weight. According to claim 3,
The Al-Mg-Si alloy layer,
Alloy-coated steel sheet containing at least one of Al-Mg alloy phase and Mg-Si alloy phase. According to claim 4,
The Al-Mg alloy phase,
Alloy coated steel sheet comprising at least one of Al ₃ Mg ₂ and Al ₁₂ Mg ₁₇ . According to claim 4,
The Mg-Si alloy phase,
Alloy coated steel sheet containing Mg ₂ Si. According to claim 4,
In the Al-Mg-Si alloy layer, the Mg is present as the Al-Mg alloy phase, or an alloy coated steel sheet present as the Mg-Si alloy phase. According to claim 1,
And an Al-Fe-Si alloy layer positioned between the steel sheet and the Al-Mg-Si alloy layer. A preparation step of preparing a plated steel sheet on which a plating layer containing Al and Si is formed;
A coating step of forming an Mg coating layer containing Mg on the plating layer;
A heat treatment step of diffusing the Mg into the plating layer by heat-treating the plated steel sheet on which the Mg coating layer is formed; And
Including the post-treatment step of applying a post-treatment solution on the Al-Mg-Si alloy layer formed by the diffusion of Mg;
The post-treatment solution is a method of manufacturing an alloy coated steel sheet containing an olefin-based resin. The method of claim 9,
In the preparation step,
The plated steel sheet is a method of manufacturing an alloy coated steel sheet which is a hot-dip aluminum plated steel sheet. The method of claim 9,
In the coating step,
Method for manufacturing an alloy coated steel sheet to form the Mg coating layer by using physical vapor deposition (PVD). The method of claim 9,
In the heat treatment step,
Method for manufacturing an alloy coated steel sheet heat-treated at a temperature of 300 to 450°C. The method of claim 9,
In the heat treatment step,
Method for manufacturing an alloy coated steel sheet heat-treated for 5 to 600 seconds. The method of claim 9,
In the post-processing step,
Method for manufacturing an alloy coated steel sheet to apply the post-treatment solution at 0.5 to 2 g/m ² on the Al-Mg-Si alloy layer.

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