CN-118621247-B - Zinc-aluminum-magnesium alloy coating, zinc-aluminum-magnesium alloy coating steel plate and preparation method thereof

Abstract

The application relates to a zinc-aluminum-magnesium alloy coating, a zinc-aluminum-magnesium alloy coated steel plate and a preparation method thereof, wherein the zinc-aluminum-magnesium alloy coating comprises the chemical components of Mg, al and Zn, the content of Mg is 1.5% -3% and the content of Al is 3% -4% in percentage by mass, and the area percentage of a surface eutectic structure of the zinc-aluminum-magnesium alloy coating is not less than 80%. The application improves the filiform corrosion resistance of the zinc-aluminum-magnesium alloy plating layer.

Inventors

• Jiang guangrui
• SHANG TING
• HAN ZHIGANG
• WANG SONGTAO
• LI YAN
• LIU GUANGHUI
• YU WEI
• TENG HUAXIANG
• HAN BIN
• PAN MING
• ZHENG YANKUN

Assignees

• 首钢集团有限公司

Dates

Publication Date

20260512

Application Date

20240607

Claims (6)

1. 1. The zinc-aluminum-magnesium alloy coating is characterized by comprising the following chemical components: Mg, al and Zn, wherein, in mass fraction, The content of Mg is 1.5-3%, and the content of Al is 3-3.9%; The area fraction of the surface eutectic structure of the zinc-aluminum-magnesium alloy coating is not less than 80 percent so as to avoid forming a filiform corrosion form; the content of Mg and the content of Al satisfy the following relation: -0.5≤[Mg]-[Al]*0.7≤0.5; wherein [ Mg ] represents a mass fraction of Mg and [ Al ] represents a mass fraction of Al; the surface eutectic structure comprises a ternary eutectic structure, and the area fraction of the ternary eutectic structure is not less than 40%.
2. 2. Zinc-aluminium-magnesium alloy coating according to claim 1, characterized in that the Mg content is 2.5% and the Al content is 3.7%.
3. 3. A zinc-aluminum-magnesium alloy coated steel sheet, characterized in that the zinc-aluminum-magnesium alloy coated steel sheet comprises a steel substrate and the zinc-aluminum-magnesium alloy coating according to any one of claims 1-2 attached to at least part of the surface of the steel substrate.
4. 4. A method of producing a zinc-aluminum-magnesium alloy coated steel sheet according to claim 3, comprising: Carrying out hot dip galvanizing on a steel matrix by using a plating solution, and then sequentially carrying out first-stage cooling and second-stage cooling to obtain a zinc-aluminum-magnesium alloy plated steel plate, wherein the final temperature of the first-stage cooling is obtained according to the content of Mg and the content of Al in the plating solution; the cooling speed of the first-stage cooling is 10K/s-20K/s, and the cooling speed of the second-stage cooling is 0.1K/s-5K/s.
5. 5. The method according to claim 4, wherein the obtaining the end point temperature of the first stage cooling based on the Mg content and the Al content in the plating solution comprises: When the content of Al is less than or equal to 3.5 percent and the content of Mg is less than or equal to 1.5 percent and less than or equal to 2.5 percent in the plating solution, the end temperature of the first stage cooling meets the following relation that T0=400-10 [ Al ] -8 [ Mg ]; Wherein T0 represents the end temperature of the first stage cooling, [ Mg ] represents the mass fraction of Mg, and [ Al ] represents the mass fraction of Al.
6. 6. The method according to claim 4 or 5, wherein the obtaining the end point temperature of the first stage cooling based on the Mg content and the Al content in the plating solution comprises: When the content of 3.5 percent < Al and 2.5 percent < Mg in the plating solution is less than or equal to 4 percent, and the content of the plating solution is less than or equal to 3 percent, the end temperature of the first stage cooling satisfies the following relation that T0=400-5 [ Al ] -4 [ Mg ]; Wherein T0 represents the end temperature of the first stage cooling, [ Mg ] represents the mass fraction of Mg, and [ Al ] represents the mass fraction of Al.

Description

Zinc-aluminum-magnesium alloy coating, zinc-aluminum-magnesium alloy coating steel plate and preparation method thereof Technical Field The application relates to the technical field of steel preparation, in particular to a zinc-aluminum-magnesium alloy coating, a zinc-aluminum-magnesium alloy coating steel plate and a preparation method thereof. Background Hot dip galvanizing is the process of reacting molten metal with an iron matrix to produce an alloy layer, thereby bonding both the matrix and the coating. The hot dip galvanized steel has the advantages of uniform coating, strong adhesive force, long service life, simple manufacturing process, low product price and the like, and is widely used for manufacturing automobile bodies, household appliances and the like. At present, in order to improve the protection effect of a hot dip galvanized coating on the notch position of a steel plate and improve the plane corrosion resistance, a proper amount of Mg is added into the hot dip coating to obtain a zinc-aluminum-magnesium alloy coating, the corrosion resistance can be further improved by more than 20%, and the corrosion resistance of the notch position is improved. However, after magnesium element is added into the hot dip galvanizing coating, the zinc-aluminum-magnesium alloy coating can generate filiform corrosion under an organic film under certain conditions. The filiform corrosion can form an extended corrosion morphology in a specific direction, and can influence the appearance quality of the organic film and the corrosion resistance of the plating layer in severe cases. Disclosure of Invention The application provides a zinc-aluminum-magnesium alloy coating, a zinc-aluminum-magnesium alloy coating steel plate and a preparation method thereof, which aim to solve the technical problem of how to improve the filiform corrosion resistance of the zinc-aluminum-magnesium alloy coating. In a first aspect, the application provides a zinc-aluminum-magnesium alloy coating, which comprises the following chemical components: Mg, al and Zn, wherein, in mass fraction, The content of Mg is 1.5-3%, and the content of Al is 3-4%; the area fraction of the surface eutectic structure of the zinc-aluminum-magnesium alloy coating is not less than 80%. Alternatively, the Mg content is 2.5% and the Al content is 3.7%. Optionally, the content of Mg and the content of Al satisfy the following relation: -0.5≤[Mg]-[Al]*0.7≤0.5 wherein [ Mg ] represents the mass fraction of Mg and [ Al ] represents the mass fraction of Al. Optionally, the surface eutectic structure includes a ternary eutectic structure, and an area fraction of the ternary eutectic structure is not less than 40%. In a second aspect, the present application provides a zinc-aluminum-magnesium alloy coated steel sheet comprising a steel substrate and a zinc-aluminum-magnesium alloy coating according to the first aspect attached to at least part of the surface of the steel substrate. In a third aspect, the present application provides a method for preparing the zinc-aluminum-magnesium alloy coated steel sheet according to the second aspect, the method comprising: and carrying out hot dip galvanizing on the steel matrix by using a plating solution, and then sequentially carrying out first-stage cooling and second-stage cooling to obtain a zinc-aluminum-magnesium alloy plated steel plate, wherein the final temperature of the first-stage cooling is obtained according to the content of Mg and the content of Al in the plating solution. Optionally, the obtaining the end point temperature of the first stage cooling according to the Mg content and the Al content in the plating solution includes: When the content of Al is less than or equal to 3.5 percent and the content of Mg is less than or equal to 1.5 percent and less than or equal to 2.5 percent in the plating solution, the end temperature of the first stage cooling meets the following relation that T0=400-10 [ Al ] -8 [ Mg ]; Wherein T0 represents the end temperature of the first stage cooling, [ Mg ] represents the mass fraction of Mg, and [ Al ] represents the mass fraction of Al. Optionally, the obtaining the end point temperature of the first stage cooling according to the Mg content and the Al content in the plating solution includes: When the content of 3.5 percent < Al and 2.5 percent < Mg in the plating solution is less than or equal to 4 percent, and the content of the plating solution is less than or equal to 3 percent, the end temperature of the first stage cooling satisfies the following relation that T0=400-5 [ Al ] -4 [ Mg ]; Wherein T0 represents the end temperature of the first stage cooling, [ Mg ] represents the mass fraction of Mg, and [ Al ] represents the mass fraction of Al. Optionally, the cooling speed of the first stage cooling is 5K/s-20K/s. Optionally, the cooling speed of the second stage cooling is 0.1K/s-5K/s. Compared with the prior art, the technical scheme provided by the embodiment of