CN116005094A - Zinc coating, zinc coating steel sheet and preparation method thereof - Google Patents

Abstract

The present application relates to the technical field of metal alloys, in particular to a zinc coating, a zinc coating steel plate and a preparation method thereof. The chemical composition of the coating includes: Zn, Mg, Si, Sr, Al; wherein, the content of Si is 0.04% by weight to 0.1% by weight, the content of Mg is 0.5% by weight to 2.5% by weight, and the content of Sr is 0.5% by weight % to 0.8% by weight. The content of the present application solves the problem of poor corrosion resistance of zinc-coated steel sheets in the prior art.

Description

Zinc coating, zinc coating steel sheet and preparation method thereof

technical field

The present application relates to the technical field of metal alloys, in particular to a zinc coating, a zinc coating steel plate and a preparation method thereof.

Background technique

Galvanizing is currently the main anti-corrosion method for steel materials, but in some areas with high corrosion resistance, the corrosion resistance of zinc-coated steel sheets cannot meet the requirements of the service life, resulting in structural corrosion, affecting structural safety and causing waste. Therefore, within the hot-dip galvanizing industry, the goal of improving the corrosion resistance of zinc-coated steel sheets has been pursued.

Contents of the invention

The present application provides a zinc-coated layer, a zinc-coated steel sheet and a preparation method thereof, so as to solve the problem of poor corrosion resistance of the zinc-coated steel sheet in the prior art.

In the first aspect, the application provides a zinc coating, the chemical composition of the coating includes:

Zn, Mg, Si, Sr, Al, among them,

The content of Si is 0.04% by weight to 0.1% by weight, the content of Mg is 0.5% by weight to 2.5% by weight, and the content of Sr is 0.5% by weight to 0.8% by weight.

Optionally, in the chemical composition of the coating, the content of Si is 0.08% to 0.1% by weight, the content of Mg is 2.0% to 2.5% by weight, and the content of Sr is 0.6% to 0.8% by weight.

Optionally, in the chemical composition of the coating, the content of Zn is 84% by weight to 98% by weight.

In the second aspect, based on the same inventive concept, the present application provides a zinc-coated steel sheet, the steel sheet comprising:

The coating described in the first aspect, and

A steel plate base, the coating is at least attached to at least part of the surface of the steel plate base.

In the third aspect, based on the same inventive concept, the present application provides a method for preparing a zinc-coated steel sheet, which is used to prepare the zinc-coated steel sheet described in the second aspect, the method comprising:

Under the condition of setting the annealing temperature, anneal the cleaned plate, and then cool it, so that the cleaned plate after annealing reaches the first temperature, and obtain the steel plate matrix;

Under the condition of setting the coating thickness, galvanizing is performed on the steel plate substrate to obtain a zinc-coated steel plate.

Optionally, the set annealing temperature is 520°C-760°C.

Optionally, the first temperature is 420°C-460°C.

Optionally, the set coating thickness is 30g/m ² -450g/m ² .

Optionally, under the condition of setting the coating thickness, the steel plate substrate is galvanized to obtain a zinc-coated steel plate, including:

Under the condition of setting the coating thickness, galvanize the steel plate substrate, and then cool it in stages, so that the galvanized steel plate substrate reaches the second temperature, and obtain the zinc-coated steel sheet.

Optionally, under the condition of setting the thickness of the coating, galvanize the steel plate substrate, and then cool it in stages, so that the galvanized steel plate substrate reaches the second temperature to obtain a zinc-coated steel sheet, including:

Under the condition of setting the coating thickness, galvanizing the steel plate base, and then performing mobile air cooling, and or fixed air cooling, so that the galvanized steel plate base reaches a third temperature;

water-cooling the galvanized steel sheet substrate having a third temperature, so that the galvanized steel sheet substrate reaches a second temperature to obtain a zinc-coated steel sheet;

The second temperature is 35°C-50°C, and the third temperature is 110°C-90°C.

Compared with the prior art, the above-mentioned technical solutions provided by the embodiments of the present application have the following advantages:

The zinc coating provided in the embodiment of the present application improves the corrosion resistance of the coating by designing the chemical composition of the coating. The addition of magnesium improves the corrosion resistance of the coating and reduces the friction coefficient; the addition of strontium refines the grains, increases the wettability of the strip steel and the zinc solution, improves the ductility of the coating, and further improves the resistance of the coating. corrosion; the addition of silicon inhibits the reaction between aluminum and iron, ensuring the processing performance of the coating. The steel sheet containing this zinc coating also has further improved corrosion resistance.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the application and together with the description serve to explain the principles of the application.

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, In other words, other drawings can also be obtained from these drawings without paying creative labor.

Fig. 1 is the schematic flow sheet of the preparation method of a kind of galvanized steel sheet that the embodiment of the present application provides;

Fig. 2 is the surface topography figure of a kind of galvanized steel plate that the embodiment of the present application provides;

Fig. 3 is a cross-sectional view of a zinc-coated steel sheet provided in an embodiment of the present application.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, but not all of them. Based on the embodiments in the present application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present application.

Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the application; therefore, the described range should be regarded as The description has specifically disclosed all possible subranges as well as individual values within that range. For example, a description of a range from 1 to 6 should be considered to have specifically disclosed subranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and Single numbers within the stated ranges, eg 1, 2, 3, 4, 5 and 6, apply regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

In the present application, unless otherwise stated, the used orientation words such as "upper" and "lower" specifically refer to the direction of the drawings in the drawings. In addition, in the description of the specification of the present application, the terms "including" and "comprising" mean "including but not limited to". In this document, relational terms such as "first" and "second", etc., are only used to distinguish one entity or operation from another, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or sequence. In this article, "and/or" describes the association relationship of associated objects, indicating that there may be three kinds of relationships, for example, A and/or B, which can mean: A exists alone, A and B exist simultaneously, and B exists alone . Among them, A and B can be singular or plural. Herein, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, "at least one item (unit) of a, b, or c", or "at least one item (unit) of a, b, and c" can mean: a, b, c, a-b( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

In the first aspect, the application provides a zinc coating, the chemical composition of the coating includes:

Zn, Mg, Si, Sr, Al, among them,

The content of Si is 0.04% by weight to 0.1% by weight, the content of Mg is 0.5% by weight to 2.5% by weight, and the content of Sr is 0.5% by weight to 0.8% by weight.

In the embodiment of the present application, the corrosion resistance of the coating is improved by designing the chemical composition of the coating. Add Mg, Si and Sr on the basis of Zn and Al; the addition of magnesium improves the corrosion resistance of the coating and reduces the friction coefficient; the addition of strontium refines the grains and increases the wettability of the strip steel and the zinc solution , improve the ductility of the coating, and further improve the corrosion resistance of the coating; the addition of silicon inhibits the reaction between aluminum and iron, reduces the generation of slag, makes the composition of the plating solution more pure, and further improves the corrosion resistance of the coating sex.

The positive effect of controlling the Si content to 0.04% to 0.1% by weight: the reaction between aluminum and iron is inhibited, the generation of slag is reduced, the components of the plating solution are purer, and the corrosion resistance of the coating is further improved. If the content of Si is too high, it will lead to the increase of silicon-rich phase in the coating to a certain extent, which will affect the processing performance of the coating; if the content of Si is too low, it will not be able to inhibit the aluminum-iron reaction to a certain extent.

The positive effect of controlling the content of Mg to 0.5% to 2.5% by weight: the corrosion resistance of the coating is improved and the coefficient of friction is reduced. If the content of Mg is too high, to a certain extent, it will lead to the increase of oxides on the surface of the plating solution, which will increase the failure rate of the product; purpose of corrosion resistance.

Positive effects of controlling the Sr content to 0.5% to 0.8% by weight: the crystal grains are refined, the wettability of the steel strip and the zinc solution is increased, the ductility of the coating is improved, and the corrosion resistance of the coating is further improved. If the content of Sr is too high, the grain refinement will not increase obviously to a certain extent; if the content of Sr is too low, the grain refinement will not be realized to a certain extent.

Specifically, the content of Si can be 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, etc.; the content of Mg can be 0.5 wt%, 0.8 wt%, 1.1% by weight, 1.4% by weight, 1.7% by weight, 2.1% by weight, 2.4% by weight, etc.; the content of Sr can be 0.5% by weight, 0.6% by weight, 0.7% by weight, 0.8% by weight, etc.

In some embodiments, in the chemical composition of the coating, the content of Si is 0.08% to 0.1% by weight, the content of Mg is 2.0% to 2.5% by weight, and the content of Sr is 0.6% to 0.8% by weight.

Preferably, the content of Si is 0.08 wt%, 0.09 wt%, 0.1 wt%, etc.; the content of Mg is 2.0 wt%, 2.3 wt%, 2.5 wt% etc.; the content of Sr is 0.6 wt%, 0.7 wt%, 0.8 wt% % by weight etc.

In some embodiments, in the chemical composition of the plating layer, the content of Zn is 84% by weight to 98% by weight.

In this embodiment, zinc is the main element in the plating solution, and the positive effect of controlling the Zn content to 84% to 98% by weight is to ensure the corrosion resistance of the steel plate, and at the same time, the process can be stably controlled. If the content of Zn is too high, the corrosion resistance will be reduced to a certain extent; if the content of Zn is too low, the process control will be unstable to a certain extent, and the failure rate of the product will be increased. Specifically, the content of Zn may be 84% by weight, 86% by weight, 88% by weight, 90% by weight, 92% by weight, 94% by weight or the like.

In the second aspect, based on the same inventive concept, the present application provides a zinc-coated steel sheet, the steel sheet comprising:

The coating described in the first aspect, and

A steel plate base, the coating is at least attached to at least part of the surface of the steel plate base.

In this embodiment, the zinc-coated steel sheet uses the above-mentioned zinc-coated layer, so that the corrosion resistance of the zinc-coated steel sheet is improved. Please refer to Figure 2 for the surface morphology of the zinc-coated steel sheet. The coating is mainly composed of Zn-MgZn ₂ binary eutectic structure and Zn-Al-MgZn ₂ ternary eutectic structure; the cross-sectional morphology of the zinc-coated steel sheet is shown in See Figure 3.

The zinc-coated steel sheet is realized based on the above-mentioned zinc-coated layer. The specific composition design of the zinc-coated layer can refer to the above-mentioned embodiments. The zinc-coated steel sheet has improved corrosion resistance due to the zinc-coated layer. Part or all of the technical solutions, therefore at least have all the beneficial effects brought by the technical solutions of the above embodiments, and will not be repeated here.

In the third aspect, based on the same inventive concept, the present application provides a method for preparing a zinc-coated steel sheet, which is used to prepare the zinc-coated steel sheet described in the second aspect, please refer to Figure 1, the method includes:

S1. Under the condition of setting the annealing temperature, anneal the cleaned plate, and then cool it, so that the cleaned plate after annealing reaches the first temperature, and obtain a steel plate substrate;

S2. Under the condition of setting the coating thickness, galvanizing the steel plate substrate to obtain a zinc-coated steel plate.

In some embodiments, the set annealing temperature is 520°C-760°C.

The positive effect of controlling and setting the annealing temperature at 520°C-760°C: stable physical properties of the strip. If the annealing temperature is set too high, the yield strength and tensile strength of the strip will be unqualified to a certain extent; if the annealing temperature is set too low, the elongation of the strip after breaking will be unqualified to a certain extent. Specifically, the set annealing temperature may be 520° C., 540° C., 560° C., 580° C., 600° C., 620° C., 640° C., 660° C. or the like.

In some embodiments, the first temperature is 420°C-460°C.

"First temperature" means the temperature of the cleaned plate after cooling, and the positive effect of controlling the first temperature to 420°C-460°C is to stabilize the temperature of the zinc pot and prepare for the galvanizing process. If the first temperature is too high, the temperature of the zinc pot will be increased to a certain extent, and the quality of the board surface will be unstable; Zinc problem. Specifically, the first temperature may be 420°C, 430°C, 440°C, 450°C, 460°C and so on.

In some embodiments, the set coating thickness is 30g/m ² -450g/m ² .

The positive effect of controlling and setting the thickness of the coating to 30g/m ² -450g/m ² is that it has good anti-corrosion performance and the process can be stably controlled. If the coating thickness is set too high, the coating control will be unstable to a certain extent, and the coating thickness will be uneven; if the coating thickness is set too low, the corrosion resistance of the strip will be affected to a certain extent. Specifically, the set coating thickness can be 30g/m ² , 80g/m ² , 130g/m 2 , 180g/m ² , 230g/ ^{m 2 ,} 280g/m ² , 330g/m ² , 380g/m ² , 430g /m ² etc.

In some embodiments, under the condition of setting the coating thickness, the steel plate substrate is galvanized to obtain a zinc-coated steel plate, including:

Under the condition of setting the coating thickness, galvanize the steel plate substrate, and then cool it in stages, so that the galvanized steel plate substrate reaches the second temperature, and obtain the zinc-coated steel sheet.

Positive effect of staged cooling: the strip is cooled to the target temperature in stages to prevent black spots or round spot defects on the plate surface caused by extreme cold or slow cooling.

In some embodiments, under the condition of setting the thickness of the coating, the steel plate substrate is galvanized, and then cooled in stages, so that the galvanized steel plate substrate reaches the second temperature, and the zinc-coated steel sheet is obtained, including :

Under the condition of setting the coating thickness, galvanizing the steel plate base, and then performing mobile air cooling, and or fixed air cooling, so that the galvanized steel plate base reaches a third temperature;

water-cooling the galvanized steel sheet substrate having a third temperature, so that the galvanized steel sheet substrate reaches a second temperature to obtain a zinc-coated steel sheet;

The second temperature is 35°C-50°C, and the third temperature is 110°C-90°C.

Positive effect of moving air cooling, and/or stationary air cooling: the strip is cooled in a controlled gradient according to the cooling curve.

Positive effect of water cooling: the strip cools down quickly.

The "third temperature" indicates the temperature of the zinc-coated steel sheet after air cooling, and the positive effect of controlling the third temperature to 110°C-90°C is to obtain a stable strip surface. If the third temperature is too high, to a certain extent, it will cause the friction between the unsolidified coating and the top roller to form black spot defects; defect. Specifically, the third temperature may be 110°C, 90°C, 100°C, 95°C, 105°C and so on.

"Second temperature" means the temperature of the zinc-coated steel sheet after water cooling, and the positive effect of controlling the second temperature to 35°C-50°C is to prepare for the skin pass process. If the second temperature is too high, to a certain extent, it will cause color difference defects on the surface of the strip after skinning; if the second temperature is too low, to a certain extent, it will cause bright spot defects on the surface of the strip after skinning. Specifically, the second temperature may be 35°C, 40°C, 45°C, 50°C and so on.

The zinc-coated steel sheet is realized based on the production method of the above-mentioned zinc-coated steel sheet. The specific steps of the production method of the zinc-coated steel sheet can refer to the above-mentioned embodiments. Since the zinc-coated steel sheet adopts some or all of the technical solutions of the above-mentioned embodiments, therefore It has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described here one by one.

The present application will be further described below in conjunction with specific embodiments. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods not indicating specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, proceed according to general international standards, conventional conditions, or the conditions suggested by the manufacturer.

Manufacturing method of galvanized steel sheet:

First, the hot-rolled or hard-rolled coils are welded, and then the welded steel plates enter the cleaning section through the production line, so that the cleaned steel plates have a certain surface cleanliness; second, the steel plates are then processed in the annealing furnace Annealing and cooling; third, put the cooled steel plate into the plating solution for galvanizing, and use an air knife to control the thickness of the alloy coating; fourth, cool the galvanized steel plate through moving air cooling, fixed air cooling and water cooling; Fifth, the cooled zinc-coated steel plate is passed through skinning and tension leveling to eliminate the yield platform and control the shape of the plate.

Table 1 Example 1-5 Chemical composition (wt%) of zinc coating, the rest is Al and unavoidable impurities.

serial number Zn Mg Si Sr Example 1 98 0.5 0.04 0.5 Example 2 90 2 0.08 0.6 Example 3 84 2.5 0.1 0.8 Example 4 88 2.3 0.09 0.7 Example 5 94 1.5 0.06 0.55

Table 2 Comparative Example 1-2 The chemical composition (wt%) of the coating, the rest is Zn and unavoidable impurities.

serial number Al Comparative example 1 0.2 Comparative example 2 0.2

Table 3 Process parameters for preparing zinc-coated steel sheets in Examples 1-5 and Comparative Examples 1-2.

Neutral salt spray test and coating hardness test (Vickers hardness) were respectively carried out on the zinc-coated steel sheets obtained in Examples 1-5 and Comparative Examples 1-2 above. The properties of the steel sheets including the hot-dip coating were thus evaluated, and the results are shown in Tables 4 and 5 below. The neutral salt spray test is carried out in accordance with GB/T10125-2012, through which the time for 5% red rust to appear on the zinc-coated steel sheet is measured.

Table 4 The results of the neutral salt spray test on the zinc-coated steel sheets of Examples 1-5 and Comparative Examples 1-2.

Table 5 The coating hardness test (Vickers hardness) results of the zinc-coated steel sheets of Examples 1-5 and Comparative Examples 1-2.

serial number Coating Hardness (Vickers) Example 1 110 Example 2 130 Example 3 122 Example 4 125 Example 5 118 Comparative example 1 80 Comparative example 2 82

As can be seen from Table 4, the time for 5% red rust to appear in the zinc-coated steel sheets of Examples 1-5 is all much longer than that of Comparative Examples 1 and 2, indicating that the alloying elements added in the present invention can greatly improve the corrosion resistance of the zinc-coated steel sheets .

As can be seen from Table 5, the Vickers hardness of the zinc-coated steel sheets of Examples 1-5 is greater than that of Comparative Examples 1 and 2, indicating that the hardness of the coating obtained by the present invention is higher than that of the traditional zinc-coated coating, which can reduce the friction of the subsequent use of the galvanized steel sheet. Increase formability.

The above descriptions are only specific implementation manners of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the present application will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims (10)

1. a zinc coating, is characterized in that, the chemical composition of described coating comprises: Zn, Mg, Si, Sr, Al, among them, The content of Si is 0.04% by weight to 0.1% by weight, the content of Mg is 0.5% by weight to 2.5% by weight, and the content of Sr is 0.5% by weight to 0.8% by weight. 2. The coating according to claim 1, characterized in that, in the chemical composition of the coating, the content of Si is 0.08% by weight to 0.1% by weight, the content of Mg is 2.0% by weight to 2.5% by weight, and the content of Sr It is 0.6 weight% - 0.8 weight%. 3. The coating according to claim 1 or 2, characterized in that, in the chemical composition of the coating, the content of Zn is 84% by weight to 98% by weight. 4. A galvanized steel plate, characterized in that, said steel plate comprises: The coating according to any one of claims 1-3, and A steel plate base, the coating is at least attached to at least part of the surface of the steel plate base. 5. a preparation method for zinc-coated steel sheet, is characterized in that, for preparing the zinc-coated steel sheet according to claim 4, said method comprises: Under the condition of setting the annealing temperature, anneal the cleaned plate, and then cool it, so that the cleaned plate after annealing reaches the first temperature, and obtain the steel plate matrix; Under the condition of setting the coating thickness, galvanizing is performed on the steel plate substrate to obtain a zinc-coated steel plate. 6. The method according to claim 5, wherein the set annealing temperature is 520°C-760°C. 7. The method according to claim 5, wherein the first temperature is 420°C-460°C. 8 . The method according to claim 5 , wherein the set coating thickness is 30g/m ² -450g/m ² . 9. The method according to claim 5, characterized in that, under the condition of setting the coating thickness, the steel plate substrate is galvanized to obtain a zinc-coated steel plate, comprising: Under the condition of setting the coating thickness, galvanize the steel plate substrate, and then cool it in stages, so that the galvanized steel plate substrate reaches the second temperature, and obtain the zinc-coated steel sheet. 10. The method according to claim 9, characterized in that, under the condition of setting the coating thickness, the steel plate base is galvanized, and then cooled in stages, so that the steel plate base after galvanizing reaches the first Two temperatures, to obtain zinc-coated steel sheets, including: Under the condition of setting the coating thickness, galvanizing the steel plate base, and then performing mobile air cooling, and or fixed air cooling, so that the galvanized steel plate base reaches a third temperature; water-cooling the galvanized steel sheet substrate having a third temperature, so that the galvanized steel sheet substrate reaches a second temperature to obtain a zinc-coated steel sheet; The second temperature is 35°C-50°C, and the third temperature is 110°C-90°C.

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