WO2021120334A1

WO2021120334A1 - Steel plate comprising zinc-aluminum-magnesium coating and manufacturing method therefor

Info

Publication number: WO2021120334A1
Application number: PCT/CN2019/130630
Authority: WO
Inventors: 王新东; 李建新; 齐建军; 孙力; 张鹏; 梅淑文; 张�杰; 张启富; 宋志岗; 杨士弘; 江社明; 李文田; 弓俊杰; 曹宏玮; 梁爱国; 王学慧; 戚振南; 蔡啸; 孙恺; 杨丽芳
Original assignee: 河钢股份有限公司; 唐山钢铁集团有限责任公司; 河钢股份有限公司唐山分公司; 新冶高科技集团有限公司
Priority date: 2019-12-19
Filing date: 2019-12-31
Publication date: 2021-06-24
Also published as: EP4079920A1; CN111074187A; EP4079920A4; CN111074187B

Abstract

A steel plate comprising a zinc-aluminum-magnesium coating and a manufacturing method therefor. The method may comprise: pretreating a cold-rolled steel plate; immersing the pretreated steel plate in a plating solution containing zinc, aluminum and magnesium as main components for immersion plating treatment, so that the plating solution is coated on at least one of the two surfaces of the steel plate to form a plating solution layer; using an air knife to control the thickness of the plating solution layer on the at least one surface of the steel plate; and cooling the steel plate coated with the plating solution layer. The plating solution may comprise the following components in percentage by mass: 1.5-2.3% of Al, 1.2-1.8% of Mg, 0.01-0.08% of La and Ce, and 0.01-0.08% of at least one of Cu, Cr and Ni, with the balance being Zn and inevitable impurities, wherein the mass ratio of Al to Mg is 1.2 to 1.4, and the mass ratio of La to Ce is 2:1.

Description

Steel plate including zinc-aluminum-magnesium coating and manufacturing method thereof

Technical field

The invention relates to a steel plate including a zinc-aluminum-magnesium coating and a manufacturing method thereof.

Background technique

Steel components are generally degraded due to the environment in which they are used. For example, steel components are easily corroded by air in a low-temperature and humid environment, and are easily oxidized in a high-temperature environment, and problems such as a faster corrosion rate in an acidic environment will occur. Therefore, the above-mentioned problems are usually solved by forming a plating layer on the steel member.

Zinc has excellent corrosion resistance, electrical conductivity and thermal conductivity, is easy to process, and can be used as a sacrificial anode to protect steel components, thereby greatly extending the service life of steel components. Therefore, galvanizing is one of the earliest, most widely used, and most cost-effective surface treatment methods for steel components used to protect steel components such as steel plates or steel wires.

At present, ordinary galvanizing has become increasingly unable to meet industrial development and social needs, and people have begun to explore adding other trace elements to improve the corrosion resistance and compression and deformation resistance of the coating. In the past few decades, new coatings with higher corrosion resistance have been developed successively. Steel components including zinc-aluminum-magnesium coatings have received widespread attention because their corrosion resistance is 3-18 times higher than that of steel components including pure zinc coatings. However, the current zinc-aluminum-magnesium coatings have problems such as high brittleness, poor formability, and poor surface quality. Therefore, a large number of studies are being carried out on zinc-aluminum-magnesium coatings to solve the above problems while ensuring their corrosion resistance.

Summary of the invention

technical problem

An object of the present invention is to provide a steel sheet including a zinc-aluminum-magnesium coating and a manufacturing method thereof.

The object of the present invention is to provide a steel sheet including a zinc-aluminum-magnesium coating and a manufacturing method thereof that can solve at least one of the above problems.

Technical solutions

The method for manufacturing a steel sheet including a zinc-aluminum-magnesium coating layer according to the present invention may include: pre-treating the cold-rolled steel sheet; immersing the pre-treated steel sheet in a plating solution containing zinc-aluminum-magnesium as a main component for dipping treatment to make The plating solution is plated on at least one of the two surfaces of the steel plate to form a plating solution layer; an air knife is used to control the thickness of the plating solution layer on the at least one surface of the steel plate; The layer of steel plate undergoes cooling treatment. The plating solution may include the following components by mass percentage: 1.5-2.3% of Al, 1.2-1.8% of Mg, total of 0.01-0.08% of La and Ce, total of 0.01-0.08% of Cu, At least one element of Cr and Ni, and the balance of Zn and inevitable impurities, wherein the mass ratio of Al to Mg is 1.2 to 1.4, and the mass ratio of La to Ce is 2:1.

In an embodiment according to the present invention, in the step of the immersion plating treatment, the immersion plating time may be 2-6 seconds.

In an embodiment according to the present invention, the step of pretreatment may include: placing the cold-rolled steel sheet in a solution tank to chemically degrease the cold-rolled steel sheet using the solution in the solution tank, wherein the solution is solid alkali The mass percentage is 1 to 2%, the solution temperature is 70 to 90 ℃, and the degreasing time is 10 to 15s; the steel plate after chemical degreasing treatment is placed in the electrolytic cell to use the electrolyte in the electrolytic cell to electrolyze the steel plate Degreasing treatment, in which the mass percentage of solid alkali in the electrolyte is 2 to 3%, the electrolyte temperature is 70 to 90 ℃, and the degreasing time is 4 to 8 s; and the steel plate after electrolytic degreasing is heat treated. The heat treatment step includes: annealing the steel plate after electrolytic degreasing treatment, wherein the annealing temperature is 680-850°C, and the annealing time is 30-90s.

In the embodiment according to the present invention, in the step of controlling the thickness of the plating solution layer of the steel sheet, the quality of the plating solution layer on the at least one surface of the steel sheet may be controlled to be 30-300 g/m ² , and the thickness is controlled It is 4-43μm.

In the embodiment according to the present invention, the step of cooling the steel plate coated with the plating solution layer may include: the first stage, cooling at a cooling rate of 10-20°C/s; the second stage, cooling at a cooling rate of 30-100 Fast cooling is performed at a cooling rate of ℃/s; and in the third stage, slow cooling is performed at a cooling rate of 5-10 ℃/s.

In an embodiment according to the present invention, the method may further include: using a smoothing machine to perform smoothing treatment on the cooled steel plate; using a tension and straightening machine to perform stretching and straightening treatment on the smoothed steel plate; The chemical coating machine performs passivation treatment on the steel sheet after drawing and straightening; and performs drying treatment on the passivation treatment steel sheet, so as to obtain the steel sheet including the zinc-aluminum-magnesium coating.

In an embodiment according to the present invention, in the passivation treatment, the passivation amount may be 0.02-1.0 g/m ² .

According to an embodiment of the present invention, a steel sheet including a zinc-aluminum-magnesium coating layer is provided. The zinc-aluminum-magnesium coating layer is formed on at least one surface of the steel sheet. In the steel sheet including the zinc-aluminum-magnesium coating layer, the zinc-aluminum-magnesium coating layer may include The following components are calculated: 1.5-2.3% Al, 1.2-1.8% Mg, 0.01-0.08% La and Ce, 0.01-0.08% Cu, Cr and Ni at least one element , And the balance of Zn and unavoidable impurities. The mass ratio of Al to Mg may be 1.2 to 1.4, and the mass ratio of La to Ce may be 2:1.

In an embodiment according to the present invention, the thickness of one side of the zinc-aluminum-magnesium coating may be 4-43 μm.

In an embodiment according to the present invention, the mass percentage of Al may be 1.5-2.0%.

Beneficial effect

The zinc-aluminum-magnesium coating and the steel sheet including the zinc-aluminum-magnesium coating according to the above-mentioned embodiments of the present invention ensure the corrosion resistance of the steel member including the zinc-aluminum-magnesium coating, and can also avoid the increase in brittleness and the decrease in formability due to the high Al content. The problem of black spots on the surface of the coated steel plate is solved.

Description of the drawings

These and/or other aspects will become clearer and easier to understand through the following description of the exemplary embodiments in conjunction with the accompanying drawings. In the accompanying drawings:

FIG. 1 is a diagram showing the surface morphology of a steel sheet including a zinc aluminum magnesium coating layer according to an exemplary embodiment of the inventive concept;

FIG. 2 is a diagram illustrating a cross-sectional morphology of a steel sheet including a zinc-aluminum-magnesium plating layer according to an exemplary embodiment of the inventive concept;

3 is a diagram showing a cross-sectional topography of a steel sheet including a zinc-aluminum-magnesium coating layer after an OT bending test according to an exemplary embodiment of the inventive concept; and

Fig. 4 is a cross-sectional topography diagram of a steel sheet including a zinc-aluminum-magnesium coating according to a comparative example after an 0T bending test.

Detailed ways

The principle of the present invention will be described in further detail below in conjunction with the accompanying drawings and exemplary embodiments, so as to make the technical solution of the present invention clearer.

The zinc-aluminum-magnesium coating can be plated on the surface of the steel component as a corrosion-resistant layer of the steel component to improve the corrosion resistance of the steel component. The Al content in the traditional zinc-aluminum-magnesium coating is usually high, which leads to a decrease in the forming performance of the final product. In addition, the high content of Al and Mg in the zinc-aluminum-magnesium coating can cause surface quality defects due to oxidation. In order to solve the above problems, it is necessary to control the content of Al and Mg in the coating, and at the same time, it is necessary to avoid the influence on the corrosion resistance of the coating.

In an embodiment according to the present invention, the zinc-aluminum-magnesium plating layer may include zinc (Zn), aluminum (Al), magnesium (Mg), lanthanum (La), and cerium (Ce), and may also include copper (Cu), chromium At least one element of (Cr) and nickel (Ni). In addition to the above elements, inevitable impurities may also be included in the zinc-aluminum-magnesium coating. Specifically, according to an embodiment of the present invention, the zinc-aluminum-magnesium coating may include the following chemical components in terms of mass percentage: Al 1.5-2.3%, Mg 1.2-1.8%, and the total mass percentage of La and Ce is 0.01-0.08%, The total mass percentage of at least one element of Cu, Cr and Ni is 0.01-0.08%, and the rest is Zn and inevitable impurities. Among them, the mass ratio of Al to Mg in the zinc-aluminum-magnesium coating is controlled to be 1.2-1.4 and Control the mass ratio of La to Ce to 2:1.

In the embodiment according to the present invention, the mass percentage of the chemical composition in the zinc-aluminum-magnesium coating is intended to include any sub-range or any specific value in the above range. Specifically, in the zinc-aluminum-magnesium coating, the mass percentage of Al is preferably 1.5 to 2.0%, more preferably 1.5 to 1.8%; the mass percentage of Mg is preferably 1.2 to 1.7%, and more preferably 1.2 to 1.5 %; the total mass percentage of La and Ce is preferably 0.01-0.07%, more preferably 0.03-0.05%; the total mass percentage of at least one element of Cu, Cr and Ni is preferably 0.01-0.07%, and further Preferably it is 0.01 to 0.05%.

In the embodiment according to the present invention, the mass percentage of Al in the zinc-aluminum-magnesium coating is controlled to be 1.5-2.3%, and the mass percentage of Mg is controlled to be 1.2-1.8%. In this case, the content of Al and Mg in the zinc-aluminum-magnesium coating can be controlled at a relatively low level, thereby avoiding the increase in brittleness and the decrease in formability due to the high content of Al, and solving the problems caused by Al and Mg. The high content of Mg causes a serious problem of oxidation on the surface of steel components containing zinc-aluminum-magnesium coatings. In addition, in order to ensure the corrosion resistance of the steel components containing the zinc-aluminum-magnesium coating, in the embodiment of the present invention, the mass ratio of Al to Mg is controlled to 1.2-1.4, and a certain content is added to the zinc-aluminum-magnesium coating. La and Ce with a mass ratio of 2:1. The addition of La and Ce can not only further improve the corrosion resistance of the zinc-aluminum-magnesium coating, but also prevent the surface oxidation of the immersion bath during immersion and improve the surface quality. However, excessive La and Ce will cause the composition of the dipping bath to be complicated and increase the difficulty of zinc pot management. In addition, the addition of La and Ce alone and the combined addition have different effects on the corrosion resistance of the zinc-aluminum-magnesium coating. The inventor of the present application has found through research that the combined addition of La and Ce can better improve the resistance of the zinc-aluminum-magnesium coating. Corrosive. Therefore, in an embodiment according to the present invention, the zinc-aluminum-magnesium plating layer may include La and Ce in a total mass percentage of 0.01% to 0.08%, and the mass ratio of La to Ce is 2:1.

In addition to the above elements, in order to further improve the corrosion resistance and other properties of the zinc-aluminum-magnesium coating, the zinc-aluminum-magnesium coating may also include other trace elements. For example, in an embodiment according to the present invention, the zinc-aluminum-magnesium plating layer may further include at least one element of Cu, Cr, and Ni. Among the above-mentioned trace elements, Cu can refine the grains of the zinc-aluminum-magnesium coating, increase the strength of the coating, improve the surface friction resistance of the coating, and improve the corrosion resistance of the coating; Cr can increase the hardness of the coating, improve the surface quality, and increase Corrosion resistance of the coating; Ni can improve the corrosion resistance of the coating and inhibit surface oxidation. In order to exert the effects of these several elements and avoid the influence of the above-mentioned elements on the performance of the plating solution due to excessive amounts of the above-mentioned elements, the total mass percentage of the above-mentioned trace elements can be controlled to 0.01-0.08%.

Hereinafter, the steel member including the zinc-aluminum-magnesium coating and the preparation method thereof according to the present invention will be described in more detail in conjunction with specific embodiments. In the following description, a steel plate will be used as an example of a steel member. However, the embodiment according to the present invention is not limited thereto, for example, the steel member may also be a steel wire or the like.

In the embodiment according to the present invention, the steel sheet including the zinc-aluminum-magnesium coating is manufactured through the following steps.

First, the steel plate is pretreated as follows. Specifically, the cold-rolled steel sheet is placed in a solution tank to chemically degrease the cold-rolled steel sheet using the solution in the solution tank, wherein the mass percentage of solid alkali in the solution is 1 to 2%, and the solution temperature is 70 to 90℃, the degreasing time is 10-15s; then, the steel plate after the chemical degreasing treatment is placed in the electrolytic cell to use the electrolyte in the electrolytic cell to perform the electrolytic degreasing treatment on the steel plate. The mass percentage is 2～3%, the solution temperature is 70～90℃, and the degreasing time is 4～8s; then, the steel plate after electrolytic degreasing treatment is annealed using a continuous annealing furnace, where the annealing temperature is 680～850 ℃, the annealing time is 30-90s.

Next, the pre-treated steel sheet is immersed in a zinc-aluminum-magnesium plating solution having the chemical composition of the above content, so that the plating solution is uniformly plated on at least one of the two surfaces of the steel sheet after the annealing treatment. A plating solution layer is formed, wherein the immersion plating time is 2-6s.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-coated steel sheet, so that the quality of the plating solution layer on the at least one surface is 30-300 g/m ² (corresponding thickness: 4- 43μm), where the air knife pressure is 0.1～0.5MPa.

Next, the above-mentioned hot-dip-plated steel sheet with the plating solution layer is subjected to a post-plating cooling treatment using a fan. In the cooling process, the post-plating cooling process has a greater impact on the coating structure, and the improper cooling process will easily lead to the formation of Mg ₂ Zn ₁₁ phases in the coating, and then the formation of black spots on the surface of the coating. Therefore, in order to avoid this defect, use The cooling process of staged cooling, the specific process is: cooling at a cooling rate of 10-20°C/s in the first stage, rapid cooling at a cooling rate of 30-100°C/s in the second stage, and then in the third stage The stage is slowly cooled at a cooling rate of 5-10°C/s.

Then, for example, the steel plate including the zinc-aluminum-magnesium coating after the cooling treatment is subjected to a finishing treatment using a finishing machine, wherein the finishing pressure is 100 to 200 tons (T).

Next, the steel sheet including the zinc-aluminum-magnesium coating after finishing is subjected to a tension-straightening treatment with a tension-straightening machine, wherein the tension is 10-15 tons.

Then, using a passivation coating machine to passivate the steel sheet including the zinc-aluminum-magnesium coating after stretching and straightening, wherein the passivation amount is 0.02-1.0 g/m ² (double-sided);

Finally, the passivation-treated steel sheet including the zinc-aluminum-magnesium coating is dried, wherein the drying temperature is 50-100° C., and the drying time is 10-15 seconds.

The steel sheet including the zinc-aluminum-magnesium coating according to the present invention is finally obtained through the above-mentioned method.

Hereinafter, the steel sheet including the zinc-aluminum-magnesium coating of the present invention will be described with reference to specific embodiments.

Example 1

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 1%, the solution temperature is 70°C, and the degreasing time is 15s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2.0%, the solution temperature is 70°C, and the degreasing time is 4s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 750°C and the annealing time is 80s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 1 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 1, the mass of the single-sided plating solution layer is 70 g/m ² (corresponding thickness: 10 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling treatment, the specific process is: cooling at a cooling rate of 20°C/s in the first stage, rapid cooling at a cooling rate of 70°C/s in the second stage, and then at 7°C/s in the third stage The cooling rate is slow cooling.

Then, the steel plate is subjected to subsequent finishing treatment, stretching treatment, passivation treatment and drying treatment.

Example 2

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 1%, the solution temperature is 75°C, and the degreasing time is 14s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2%, the solution temperature is 75°C, and the degreasing time is 5s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 680°C and the annealing time is 90s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 2 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 2, the mass of the single-sided plating solution layer is 30 g/m ² (corresponding thickness: 4 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling process, the specific process is: cooling at a cooling rate of 10°C/s in the first stage, rapid cooling at a cooling rate of 100°C/s in the second stage, and then at 5°C/s in the third stage The cooling rate is slow cooling.

Example 3

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 3 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 3, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 4

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 1%, the solution temperature is 80°C, and the degreasing time is 13s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2%, the solution temperature is 80°C, and the degreasing time is 6s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 30s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 4 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 4, the mass of the single-sided plating solution layer was 300 g/m ² (corresponding thickness: 43 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling process, the specific process is: cooling at a cooling rate of 20°C/s in the first stage, rapid cooling at a cooling rate of 50°C/s in the second stage, and then at 10°C/s in the third stage The cooling rate is slow cooling.

Example 5

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 5 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 5, the mass of the single-sided plating solution layer is 70 g/m ² (corresponding thickness: 10 μm).

Example 6

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 1%, the solution temperature is 85°C, and the degreasing time is 12s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2%, the solution temperature is 85°C, and the degreasing time is 7s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 750°C and the annealing time is 80s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 6 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 6, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 7

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 1%, the solution temperature is 90°C, and the degreasing time is 11s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2%, the solution temperature is 90°C, and the degreasing time is 8s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 750°C and the annealing time is 80s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 7 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 7, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 8

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 1.5%, the solution temperature is 70°C, and the degreasing time is 14s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2.5%, the solution temperature is 70°C, and the degreasing time is 5s; the steel plate after electrolytic degreasing treatment is annealed, wherein the annealing temperature is 750°C and the annealing time is 80s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 8 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 8, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 9

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 1.5%, the solution temperature is 80°C, and the degreasing time is 12s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2.5%, the solution temperature is 75°C, and the degreasing time is 6s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 9 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 9, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling treatment, the specific process is: cooling at a cooling rate of 20°C/s in the first stage, rapid cooling at a cooling rate of 100°C/s in the second stage, and then at 10°C/s in the third stage The cooling rate is slow cooling.

Example 10

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 1.5%, the solution temperature is 85°C, and the degreasing time is 11s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2.5%, the solution temperature is 80°C, and the degreasing time is 7s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 10 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 10, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 11

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 1.5%, the solution temperature is 90°C, and the degreasing time is 10s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2.5%, the solution temperature is 85°C, and the degreasing time is 8s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 11 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 11, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling treatment, the specific process is: cooling at a cooling rate of 10°C/s in the first stage, rapid cooling at a cooling rate of 50°C/s in the second stage, and then at 5°C/s in the third stage The cooling rate is slow cooling.

Example 12

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 2%, the solution temperature is 70°C, and the degreasing time is 13s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 3%, the solution temperature is 70°C, and the degreasing time is 6s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 12 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 12, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 13

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, in which the mass percentage of solid alkali in the solution is 2%, the solution temperature is 80°C, and the degreasing time is 11s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 3%, the solution temperature is 75°C, and the degreasing time is 7s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 13 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 13, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Example 14

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 2%, the solution temperature is 85°C, and the degreasing time is 10s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 3%, the solution temperature is 80°C, and the degreasing time is 8s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Example 14 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Example 14, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Comparative example 1-5

First, the steel plate is pretreated as follows: the cold-rolled steel plate is subjected to chemical degreasing treatment, wherein the mass percentage of solid alkali in the solution is 2%, the solution temperature is 90°C, and the degreasing time is 15s; the steel plate is subjected to electrolytic degreasing treatment, where , The mass percentage of solid alkali in the electrolyte is 2%, the solution temperature is 90°C, and the degreasing time is 8s; the steel plate after the electrolytic degreasing treatment is annealed, wherein the annealing temperature is 820°C and the annealing time is 70s.

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Comparative Examples 1-5 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Comparative Examples 1-5, the mass of the single-sided plating solution layer is 70 g/m ² (corresponding thickness: 10 μm).

Comparative example 6

Next, the steel sheet subjected to the above pretreatment was immersed in a zinc-aluminum-magnesium plating solution having a chemical composition of the content shown in Comparative Example 6 in Table 1 below, and a plating solution layer was formed on the front and back surfaces of the steel sheet.

Then, an air knife is used to control the thickness of the plating solution layer of the hot-dip-treated steel sheet. In Comparative Example 6, the mass of the single-sided plating solution layer was 70 g/m ² (corresponding thickness: 10 μm).

Next, the steel sheet is subjected to post-plating cooling treatment. In the cooling treatment, the specific process is: cooling at a cooling rate of 10°C/s in the first stage, rapid cooling at a cooling rate of 10°C/s in the second stage, and then at 5°C/s in the third stage The cooling rate is slow cooling.

Table 1

Evaluation example

A neutral salt spray test and a coating formability test (0T bending test) were performed on the steel plates including the hot-dip coating obtained by the above-mentioned Examples 1 to 14 and Comparative Examples 1 to 6, respectively. Thus, the performance of the steel sheet including the hot-dip coating was evaluated, and the results are shown in Tables 2 and 3 below. The neutral salt spray test was carried out in accordance with GB/T10125-2012. Through this experiment, the time for the steel plate including the hot-dip coating to appear 5% red rust was measured.

Table 2

It can be seen from Table 2 that the 5% red rust time of the steel plate including the hot-dip coating of Examples 1-14 is much longer than that of Comparative Example 1 (GI coating composition), and the time for the steel plate with the same coating weight to appear 5% red rust is It is 8.05 times or more than that of Comparative Example 1. When the coating weight in Example 2 is only 30g/m ^{2 on} one side, the time for 5% red rust on the coated steel sheet is that of Comparative Example 1 (70g/m ^{2 on} one side) About 3.6 times, and the time for 5% red rust to appear on the coated steel plate after adding Cu, Cr, and Ni elements in Examples 2-14 is longer than that without adding Cu, Cr, and Ni elements. Therefore, it can be seen from Table 2 that by adding La and Ce and a small amount of Cu, Cr, and/or Ni to the Zn-Al-Mg-RE composition, the corrosion resistance of the steel sheet including the hot-dip coating can be improved. Comparative Examples 2 and 3 respectively show that the coating does not include La and Ce and only includes La. From the results shown in Table 2, it can be seen that the coating with La and Ce added with a mass ratio of 2:1 Can have better corrosion resistance. Comparative Examples 4 and 5 show that the content and mass ratio of Al and Mg in the hot-dip coating do not satisfy the above numerical range, and the content of Al and Mg in the hot-dip coating shown in Examples 1 to 14 is lower than that of the comparative example In the case of 4 and 5, it can be seen from Table 2 that by adding RE, Cu, Cr, Ni and other elements, the time for the coated steel sheets of Examples 1 to 14 to appear 5% red rust is close to that of Comparative Examples 4 and 5. This indicates that the hot-dip coating according to the present invention can provide the same corrosion resistance as a coating with a higher Al content.

table 3

序号Serial number	镀层表面质量Surface quality of coating	0T弯曲测试结果0T bending test result
实施例1Example 1	○○	○○
实施例2Example 2	○○	○○
实施例3Example 3	○○	○○
实施例4Example 4	○○	○○
实施例5Example 5	○○	○○
实施例6Example 6	○○	○○
实施例7Example 7	○○	○○
实施例8Example 8	○○	○○
实施例9Example 9	○○	○○
实施例10Example 10	○○	○○
实施例11Example 11	○○	○○
实施例12Example 12	○○	○○
实施例13Example 13	○○	○○
实施例14Example 14	○○	○○
比较例1Comparative example 1	○○	○○
比较例2Comparative example 2	○○	○○
比较例3Comparative example 3	○○	○○
比较例4Comparative example 4	○○	XX
比较例5Comparative example 5	○○	XX
比较例6Comparative example 6	XX	○○

Note: ○ means the surface quality is good; X means the surface quality is poor, and there are black spots on the surface of the steel plate

In the 0T bending test, ○ means that the 0T bending coating has no cracking and no peeling (that is, the surface quality is acceptable), and X indicates that the 0T bending coating has cracks or peeling (the surface quality is unqualified). It can be seen from Table 3 that after the 0T bending test is performed, the zinc-aluminum-magnesium-coated steel sheets with higher Al content of Comparative Examples 4 and 5 will have cracks in the coating. In addition, although Comparative Example 6 and Example 9 have the same coating composition, different cooling processes are used in Comparative Example 6 and Example 9, resulting in poorer coating surface quality of the zinc-aluminum-magnesium-coated steel sheet of Comparative Example 6 And there is a black spot defect. It can be seen from the above table that the steel sheets including the hot-dip coating layer according to the present invention all exhibit excellent surface quality and improved formability.

Hereinafter, the above-mentioned experimental results will be further explained through FIGS. 1 to 4.

1 is a diagram showing the surface morphology of a steel sheet including a zinc-aluminum-magnesium coating layer according to an exemplary embodiment of the inventive concept, and FIG. 2 is a diagram showing a steel sheet including a zinc-aluminum-magnesium coating layer according to an exemplary embodiment of the inventive concept Fig. 3 is a diagram showing the cross-sectional morphology of a steel plate including a zinc-aluminum-magnesium coating according to an exemplary embodiment of the inventive concept after the 0T bending test, and Fig. 4 is a diagram showing Comparative Example 5. The cross-sectional morphology of the steel plate including the zinc-aluminum-magnesium coating after the 0T bending test.

It can be seen from Fig. 1 that the steel sheet including the hot-dip coating according to the present invention has an excellent surface morphology, with few or no surface defects on the surface. In addition, it can be seen from FIG. 2 that the section of the steel sheet including the hot-dip coating layer according to the present invention includes a zinc-rich phase and a eutectic structure. In addition, it can be seen from FIG. 3 that the steel sheet including the hot-dip coating layer according to the present invention did not show the phenomenon of coating cracking after the 0T bending test, but it can be seen from FIG. 4 that the steel sheet including the zinc-aluminum-magnesium coating layer of Comparative Example 5 After the 0T bending test, the steel showed the phenomenon of cracking of the coating (as shown in area A in Figure 4).

Although the present invention has been specifically shown and described with reference to exemplary embodiments of the present invention, those of ordinary skill in the art will understand that without departing from the spirit and scope of the present invention as defined by the claims and their equivalents Under circumstances, various changes in form and details can be made here. The embodiments should be considered in a descriptive sense only and not for the purpose of limitation. Therefore, the scope of the present invention is defined not by the specific embodiments of the present invention but by the claims, and all differences within the scope will be construed as being included in the present invention.

Claims

A method of manufacturing a steel plate including a zinc-aluminum-magnesium coating, the method comprising the following steps:

Pretreatment of cold-rolled steel sheets;

Immersing the pretreated steel sheet in a plating solution containing zinc, aluminum and magnesium as a main component for immersion plating treatment, so that the plating solution is plated on at least one of the two surfaces of the steel sheet to form a plating solution layer;

Using an air knife to control the thickness of the plating solution layer on the at least one surface of the steel plate; and

Cooling the steel plate coated with the plating solution,

Wherein, the plating solution includes the following components by mass percentage: 1.5-2.3% of Al, 1.2-1.8% of Mg, total of 0.01-0.08% of La and Ce, total of 0.01-0.08% of Cu At least one element of Cr and Ni, as well as the balance of Zn and unavoidable impurities, wherein the mass ratio of Al to Mg is 1.2-1.4, and the mass ratio of La to Ce is 2:1.
The method according to claim 1, wherein in the step of the immersion plating treatment, the immersion plating time is 2-6 seconds.
The method according to claim 1, wherein the step of preprocessing comprises:

The cold-rolled steel sheet is placed in a solution tank to chemically degrease the cold-rolled steel sheet with the solution in the solution tank. The mass percentage of solid alkali in the solution is 1 to 2%, and the solution temperature is 70 to 90°C, degreasing The time is 10～15s;

The steel plate after chemical degreasing treatment is placed in an electrolytic cell to use the electrolyte in the electrolytic cell to perform electrolytic degreasing treatment on the steel plate. The mass percentage of solid alkali in the electrolyte is 2 to 3%, and the temperature of the electrolyte is 70. ～90℃, degreasing time is 4～8s; and

Heat treatment is performed on the steel plate after electrolytic degreasing treatment, wherein the step of heat treatment includes: annealing the steel plate after electrolytic degreasing treatment, the annealing temperature is 680-850°C, and the annealing time is 30-90s.
The method according to claim 1, wherein, in the step of controlling the thickness of the plating solution layer of the steel sheet, the quality of the plating solution layer on the at least one surface of the steel sheet is controlled to 30-300 g/m 2 , and the thickness is controlled It is 4～43μm.
The method according to claim 1, wherein the step of cooling treatment comprises:

In the first stage, cooling is performed at a cooling rate of 10-20°C/s;

In the second stage, rapid cooling is performed at a cooling rate of 30-100°C/s; and

In the third stage, slow cooling is performed at a cooling rate of 5-10°C/s.
The method according to claim 1, further comprising the following steps:

Use the finishing machine to finish the steel plate after the cooling treatment;

Utilize the tension and straightening machine to carry out tension and straightening treatment on the steel plate after finishing;

Use a passivation coating machine to passivate the drawn steel plate; and

The passivation-treated steel sheet is dried to obtain the steel sheet including the zinc-aluminum-magnesium coating.
The method according to claim 6, wherein, in the step of passivation treatment, the amount of passivation is 0.02-1.0 g/m 2 .
A steel sheet comprising a zinc-aluminum-magnesium coating layer formed on at least one surface of the steel sheet, wherein the zinc-aluminum-magnesium coating layer comprises the following components by mass percentage: 1.5-2.3% Al, 1.2 ~1.8% of Mg, 0.01~0.08% of La and Ce in total, 0.01~0.08% of at least one element of Cu, Cr and Ni in total, and the balance of Zn and unavoidable impurities,

Among them, the mass ratio of Al to Mg is 1.2～1.4, and

Among them, the mass ratio of La to Ce is 2:1.
The steel sheet according to claim 8, wherein the thickness of the zinc-aluminum-magnesium plating layer formed on the at least one surface of the steel sheet is 4-43 μm.
The steel sheet according to claim 8, wherein the mass percentage of Al is 1.5 to 2.0%.