A continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating and preparation method thereof

Abstract

The present invention belongs to the field of steel anti-corrosion surface engineering, and specifically relates to a relatively thin continuous hot-dip aluminum-silicon sacrificial anode alloy coating with an iron content of 3-5wt.% and a preparation method thereof. The process steps of the present invention are as follows: pre-treating the surface of the steel; preparing an Al-10Si-Zn alloy solution with an iron content of 3-5wt.%; performing continuous hot-dip plating; performing variable temperature annealing and quenching heat treatment on the steel after continuous hot-dip plating, so that the "long tongue or peak-shaped" η-Fe2Al5, "needle-shaped or fragmented" θ-FeAl3, "needle-shaped" β-Al9Fe2Si2 phase, θ-Al 13 Intermetallic compounds such as Fe4 and Al3FeSi are transformed into the Chinese character-shaped α-Al8Fe2Si phase and a small amount of needle-shaped β-Al9Fe2Si2 phase through peritectic reaction; at the same time, the coating has good bonding with the substrate, the coating is denser, and the ductility is improved, ultimately solving the above-mentioned production problems.

Description

Technical Field

[0001] The invention belongs to the field of steel anti-corrosion surface engineering, and particularly relates to continuous hot-dip aluminum plating and heat treatment technology of steel, and specifically relates to a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating with an iron content of 3-5wt.% and a preparation method thereof. Background Art

[0002] Continuous hot-dip aluminum coating technology is to put the pretreated steel material into a molten aluminum bath, keep it warm for a certain period of time, and then take it out, so that a layer of aluminum alloy solution adheres to the surface of the steel. When the surface aluminum and the steel material are infiltrated, a Fe-Al alloy layer is formed. This layer forms a metallurgical bond through diffusion, with high bonding strength and high mechanical properties. Al-Si eutectic alloy is widely used due to its excellent wear resistance, corrosion resistance, low thermal expansion coefficient and good casting performance. During continuous hot-dip aluminum coating, a certain amount of silicon is usually added to the aluminum alloy molten pool, which can inhibit the growth of Fe-Al intermetallic compounds and improve the fluidity of hot-dip alloy. At the same time, the addition of silicon transforms the tongue-shaped embedded morphology of the silicon-free coating into a flat phase interface, and the thickness of the alloy layer becomes thinner and more resistant to oxidation. It forms intermetallic compounds with other elements, reduces the current efficiency of the anode, and improves the corrosion uniformity of the anode. The addition of zinc can enhance the reaction between the molten alloy and the steel, reduce the hot-dip coating temperature, shorten the hot-dip coating time, and improve the finish of the coating.

[0003] At present, the plating solution in the continuous hot-dip aluminum production line in industry is generally replaced in time, which leads to the saturation of Fe content in the plating solution. During the continuous hot-dip plating process, Al, Fe, and Si will react at different temperatures to form different types of Al-Fe-Si intermetallic compounds. For example, the "long tongue or peak-shaped" η-Fe2Al5, the "needle-shaped or fragmented" θ-FeAl3, the needle-shaped and brittle β-Al9Fe2Si2 phase, and the θ-Al 13 Intermetallic compounds such as Fe4, Al3FeSi, etc. The grains of the above-mentioned metal compounds are relatively coarse, which will seriously damage the sacrificial anode performance and mechanical properties of the continuous hot-dip aluminum plating samples, greatly increasing the production cost and development of continuous hot-dip aluminum plating technology. Summary of the invention

[0004] In view of the problem that in the current industrial continuous hot-dip aluminum production process, the alloy plating solution cannot be replaced in time, which leads to the introduction of a large amount of iron in the coating, forming a large amount of iron-containing intermetallic compounds that reduce the protective performance and mechanical properties of the sacrificial anode, and ultimately affecting the application of continuous hot-dip aluminum products, the present invention realizes the transformation of the iron-containing intermetallic compounds through variable temperature annealing, so that the grain of the aluminum sacrificial anode coating is refined, the sacrificial anode performance and mechanical properties are improved, and the sacrificial anode protection performance of the alloy coating is the same as or better than that of the iron-free coating even in the iron saturation state (3-5wt.%).

[0005] The present invention provides an Al-10Si-xZn sacrificial anode alloy coating with an iron content of 3-5wt.%, wherein the sacrificial anode alloy coating is composed of Si: 10wt.%, Zn: 0-6wt.%, Fe: 3-5wt.%, and the rest is Al and unavoidable impurities in terms of element weight percentage.

[0006] The present invention also provides a method for preparing an Al-10Si-Zn sacrificial anode alloy having an iron content of 3-5wt.%, the specific steps of which are as follows:

[0007] (1) Steel surface pretreatment: After sanding the steel to remove the oxide film on the steel surface, soak it in acetone solution;

[0008] The steel material is commercially available industrial steel with standard composition, preferably Q345 steel.

[0009] (2) Improved Sendzimir process: The steel obtained in step (1) is sent to a direct combustion non-oxidizing heating furnace filled with reducing gas and a high-temperature thermal radiation reduction furnace to remove dirt and residual oxides on the surface of the steel, and to keep the steel warm in preparation for hot dip plating;

[0010] The reducing atmosphere containing reducing gas is composed of 96% by mass of nitrogen and 4% by mass of hydrogen;

[0011] The heating temperature of the heating furnace is 200°C; the heating temperature of the reduction furnace is 720°C, and the heating time is 10 minutes;

[0012] Before the steel enters the molten alloy solution, it is kept warm in a reduction furnace at a temperature of 550°C-700°C. The time from the reduction furnace to entering the alloy solution is negligible, and the temperature loss is negligible.

[0013] (3) Preparation of a continuous hot-dip Al-10Si-Zn alloy solution with an iron content of 3-5wt.%: After completely melting the Al-Si master alloy and removing the slag, heat-treating at 720°C, adding Al particles to prepare an Al-10Si alloy solution; placing an appropriate amount of steel pretreated in step (1) into the molten alloy solution, and keeping it warm until the iron content of the alloy solution reaches 3-5wt.%; then adding Zn particles to control the Zn content in the alloy solution to 0-6wt.%, after it is completely melted, removing the slag, stirring evenly, and keeping the plating solution warm for later use;

[0014] The Al-Si master alloy is an Al-Si master alloy with Si mass percentage greater than 10wt.%, preferably a commercially available Al-12Si master alloy; the Al-Si master alloy is completely melted, slag removed, and kept at 720°C for 1.5 hours;

[0015] The Al particles and Zn particles are pure aluminum and pure zinc, wherein the mass percentages of aluminum and zinc are both greater than 99.99%; when pure zinc is added to the molten alloy solution, it is wrapped with multiple layers of aluminum foil and pressed into the alloy solution to reduce the loss of zinc; the plating solution insulation temperature is 680°C to 720°C.

[0016] (4) Continuous hot-dip aluminum plating: the steel treated in step (2) is placed in the Al-10Si-Zn alloy solution with an iron content of 3-5 wt.% prepared in step (3), and air-cooled; wherein the immersion time is 30 seconds.

[0017] (5) Variable temperature annealing and quenching heat treatment: The steel material that has completed the continuous hot dip coating in step (3) is sequentially annealed and quenched to room temperature.

[0018] Among them, variable temperature annealing is carried out in an annealing furnace, the annealing temperature gradient is 756℃, 658.7℃, and 626℃, and each gradient annealing time is 6 to 9 hours; the temperature drop rate is 50K / s; the quenching treatment is to put the annealed steel directly into water at room temperature for water cooling quenching to room temperature.

[0019] Furthermore, in the above preparation method, step (1) is carried out in a natural air environment, and the remaining steps are carried out in a reducing atmosphere.

[0020] During the variable temperature annealing process, the Al-Fe-Si metal intermediate compound solidifies in a multi-step phase transition sequence, and the phase transition sequence can be described as:

[0021] 756℃ α-Al+θ-Al 13 Fe4+Al3FeSi=α-Al8Fe2Si

[0022] 658.7℃α-Al+Al3FeSi=α-Al8Fe2Si+β-Al9Fe2Si2

[0023] 654.25℃L=(Al)+Al 13 Fe4

[0024] 626℃α-Al+θ-Al 13 Fe4=(Al)+α-Al8Fe2Si

[0025] Beneficial effects of the present invention:

[0026] 1. The silicon added to the alloy plating solution improves the fluidity of the alloy plating solution, changes the diffusion channel of the plating growth, and then changes the phase composition of the plating, thereby reducing the growth rate of the alloy and reducing the content of oxide impurities in the alloy plating solution. Silicon is used in continuous hot-dip aluminum production to improve the adhesion between the plated workpiece and the coating, control the interface reaction of Fe-Al in the inner layer of the coating, improve the unevenness of the iron-aluminum compound layer in the inner layer of the coating, and is beneficial to the bonding of the coating with the base steel. The silicon electrode potential is (-441mV), which is more positive than the other phase potentials in the coating, and becomes the cathode of galvanic corrosion, accelerating the corrosion rate of the coating;

[0027] 2. Add 3-5wt.% iron and 10wt.% silicon to the coating, and the iron-aluminum compound layer is closest to the substrate, and the outer layer is the iron-aluminum-silicon compound layer. The iron-aluminum-silicon compound effectively inhibits the growth of the iron-aluminum compound;

[0028] 3. The addition of zinc can enhance the reaction between the molten alloy and the steel, reduce the hot dip temperature, shorten the hot dip time, and improve the finish of the coating. It also has the effect of negatively shifting the potential of the sacrificial anode coating, uniform anode dissolution, and easy alloying. The addition of zinc also leads to the activation of the anode of the coating, which is due to the transformation of the pure aluminum matrix into an aluminum-zinc solid solution. The aluminum-zinc coating provides stronger sacrificial anode protection for the steel substrate;

[0029] 4. The present invention adopts a heat treatment process of first continuous hot-dip plating, then annealing and quenching, so as to simplify the process flow and realize production by only making minor changes to the existing production equipment; the gradient temperature annealing can accurately realize the formation and elimination of Al-Fe-Si intermetallic compound types by controlling the temperature and annealing time, and can also realize the homogenization and refinement of the organizational morphology, reduce the negative charge of the aluminum-based alloy coating, improve the current efficiency of the aluminum-based sacrificial anode alloy coating, effectively improve the sacrificial anode protection performance of the steel coating, and enhance the corrosion resistance and mechanical properties of the steel;

[0030] 5. The present invention adopts water cooling quenching immediately after annealing, which is simple to operate and widely used. It can retain Al-Fe-Si intermetallic compounds (such as Al8Fe2Si) that are beneficial to improving corrosion resistance and mechanical properties, and can greatly improve the mechanical properties of the coating such as hardness and wear resistance, thereby meeting different use requirements;

[0031] 6. The method of the present invention is simple to operate, low in cost, and can achieve precise control of the generation of Al-Fe-Si intermetallic compound types. At the same time, the structure of the coating will be further homogenized, and the sacrificial anode protection performance and mechanical properties will be greatly improved. It is of great significance to solve the shortcomings of industrial production and promote the use of continuous hot-dip aluminum plating. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Surface morphology of the coating of the continuous hot-dip plated sample obtained in Example 1;

[0033] Figure 2 Surface morphology of the coating of the continuous hot-dip plated sample obtained in Example 2;

[0034] Figure 3 Surface morphology of the coating of the continuous hot-dip plated sample obtained in Example 3;

[0035] Figure 4 Surface morphology of the coating of the continuous hot-dip plated sample obtained in Example 4;

[0036] Figure 5 Surface morphology of the coating of the continuous hot-dip plated sample obtained in Example 5;

[0037] Figure 6 Surface morphology of the coating of the continuous hot-dip galvanized sample prepared in Comparative Example 2;

[0038] Figure 7 Comparative Example 1 Surface morphology of the coating of the continuous hot-dip plated sample;

[0039] Figure 8 XRD comparison diagram before and after heat treatment of Example 4;

[0040] Fig. 9 Polarization curves of continuous hot-dip galvanized samples before and after heat treatment in Example 1 and Example 3;

[0041] Fig.10 Open circuit potential diagrams of continuous hot-dip plating samples of Examples 1, 3, 4, and 5 before and after heat treatment;

[0042] Fig.11 Hardness comparison chart of Examples 1 and 2 and Comparative Examples 1 and 3. DETAILED DESCRIPTION

[0043] The present invention will now be further described in conjunction with specific embodiments. The following embodiments are intended to illustrate the present invention rather than to further limit the present invention.

[0044] Example 1

[0045] Preparation of continuous hot-dip Al-10Si-6Zn sacrificial anode alloy coating with an iron content of 3 wt.%

[0046] The specific steps are as follows:

[0047] (1) The substrate is made of Q345 steel. The steel surface is first coarsely ground with 400-grit sandpaper, and then finely ground with 2000-grit sandpaper. During fine grinding, attention should be paid to the consistent friction direction and light force. The polished sample is immersed in acetone solution;

[0048] (2) The steel samples are placed in a direct combustion non-oxidation heating furnace and a high-temperature thermal radiation reduction furnace filled with reducing gas. The steel samples are first dried in the non-oxidation heating furnace at a heating temperature of 200°C. The steel samples are then heated in the reduction furnace for 10 minutes at a heating temperature of 720°C and a holding temperature of 680°C.

[0049] (3) 4084.97 g of Al-12.24 wt.% Si master alloy was completely melted and kept at 720°C for 1.5 hours, 150 g of industrial Q345 steel plate with deoxidized layer was added, kept warm and melted for 24 hours, 465.03 g of pure aluminum and 300 g of pure zinc particles were added in sequence, and after slag removal, the plating solution temperature was controlled to 720°C;

[0050] (4) placing the ground and reduced Q345 steel in a prepared Al-10Si-6Zn alloy solution with an iron content of 3 wt.% for 30 seconds;

[0051] (5) After cooling, the mixture was placed in an annealing furnace and annealed at 756°C, 658.7°C, and 626°C in sequence. The temperature drop rate was controlled at 50 K / s, and the annealing time at each temperature was 6 hours.

[0052] (6) The annealed steel is immediately placed in water at room temperature for water cooling and quenching to room temperature.

[0053] Example 2

[0054] Preparation of continuous hot-dip Al-10Si-6Zn sacrificial anode alloy coating with an iron content of 5 wt.%

[0055] The specific steps are as follows:

[0056] (1) The substrate is made of Q345 steel, the oxide film on the steel surface is removed by sandpaper polishing, and then immersed in acetone solution;

[0057] (2) The steel samples are sent to a direct combustion non-oxidation heating furnace and a high-temperature thermal radiation reduction furnace filled with reducing gas, and the steel samples are first dried in the non-oxidation heating furnace and then heated in the reduction furnace for 10 minutes;

[0058] (3) 4084.97 g of Al-12.24 wt.% Si master alloy was completely melted and kept at 720°C for 1.5 hours, 250 g of industrial Q345 steel plate with deoxidized layer was added, kept warm and melted for 24 hours, 365.03 g of pure aluminum and 300 g of pure zinc particles were added in sequence, and after slag removal, the plating solution temperature was controlled to 720°C;

[0059] (4) placing the ground and reduced Q345 steel in a prepared Al-10Si-6Zn alloy solution with an iron content of 5 wt.% for 30 seconds;

[0060] (5) After cooling, the mixture is placed in an annealing furnace and annealed at 756°C, 658.7°C, and 626°C in sequence, with each annealing temperature lasting 9 hours;

[0061] (6) The annealed steel is immediately placed in water at room temperature for water cooling and quenching to room temperature.

[0062] Example 3

[0063] Preparation of continuous hot-dip Al-10Si-0Zn sacrificial anode alloy coating with an iron content of 3 wt.%

[0064] The specific steps are as follows:

[0065] (1) The substrate is made of Q345 steel, the oxide film on the steel surface is removed by sandpaper polishing, and then immersed in acetone solution;

[0066] (2) The steel samples are sent to a direct combustion non-oxidation heating furnace and a high-temperature thermal radiation reduction furnace filled with reducing gas, and the steel samples are first dried in the non-oxidation heating furnace and then heated in the reduction furnace for 10 minutes;

[0067] (3) 4084.97 g of Al-12.24 wt.% Si master alloy was completely melted and kept at 720°C for 1.5 hours, 150 g of industrial Q345 steel plate with oxidation layer removed was added, kept melted for 24 hours, 765.03 g of pure aluminum was added in sequence, and after slag removal, the plating solution temperature was controlled to 720°C;

[0068] (4) placing the polished and reduced steel in a prepared Al-10Si-0Zn alloy solution having an iron content of 3 wt.% for 30 seconds;

[0069] (5) After cooling, the mixture is placed in an annealing furnace and annealed at 756°C, 658.7°C, and 626°C in sequence, with each annealing temperature lasting 6 hours;

[0070] (6) The annealed steel is directly placed in water at room temperature for water cooling and quenching to room temperature.

[0071] Example 4

[0072] Preparation of continuous hot-dip Al-10Si-2Zn sacrificial anode alloy coating with 4 wt.% iron content

[0073] The specific steps are as follows:

[0074] (1) The substrate is made of Q345 steel, the oxide film on the steel surface is removed by sandpaper polishing, and then immersed in acetone solution;

[0075] (2) The steel samples are sent to a direct combustion non-oxidation heating furnace and a high-temperature thermal radiation reduction furnace filled with reducing gas, and the steel samples are first dried in the non-oxidation heating furnace and then heated in the reduction furnace for 10 minutes;

[0076] (3) 4084.97 g of Al-12.24 wt.% Si master alloy was completely melted and kept at 720°C for 1.5 hours, 200 g of industrial steel plate with oxidation layer removed was added, and the temperature was kept for 24 hours. 615.03 g of pure aluminum and 100 g of pure zinc particles were added in sequence. After slag removal, the plating solution temperature was controlled to 720°C;

[0077] (4) placing the polished and reduced steel material in a prepared Al-10Si-2Zn alloy solution having an iron content of 4 wt.% for 30 seconds;

[0078] (5) After cooling, the mixture is placed in an annealing furnace and annealed at 756°C, 658.7°C, and 626°C in sequence, with each annealing temperature lasting 9 hours;

[0079] (6) The annealed steel is directly placed in water at room temperature for water cooling and quenching to room temperature.

[0080] Example 5

[0081] Preparation method of continuous hot-dip Al-10Si-4Zn sacrificial anode alloy coating with an iron content of 5wt.%

[0082] The specific steps are as follows:

[0083] (1) The substrate is made of Q345 steel, the oxide film on the steel surface is removed by sandpaper polishing, and then immersed in acetone solution;

[0084] (2) The steel samples are sent to a direct combustion non-oxidation heating furnace and a high-temperature thermal radiation reduction furnace filled with reducing gas, and the steel samples are first dried in the non-oxidation heating furnace and then heated in the reduction furnace for 10 minutes;

[0085] (3) 4084.97 g of Al-12.24 wt.% Si master alloy was completely melted and kept at 720°C for 1.5 hours, 250 g of industrial steel plate with deoxidized layer was added, kept warm and melted for 24 hours, 415.03 g of pure aluminum and 200 g of pure zinc particles were added in sequence, and after slag removal, the plating solution temperature was controlled to 720°C;

[0086] (4) placing the polished and reduced steel material in a prepared Al-10Si-4Zn alloy solution having an iron content of 5 wt.% for 30 seconds;

[0087] (5) After cooling, the mixture is placed in an annealing furnace and annealed at 756°C, 658.7°C, and 626°C in sequence, with each annealing temperature lasting 6 hours;

[0088] (6) The annealed steel is directly placed in water at room temperature for water cooling quenching.

[0089] Comparative Example 1

[0090] Referring to Example 2, an Al-10Si-6Zn alloy solution with an iron content of 5wt.% was prepared, 4084.97g of Al-12.24wt.%Si master alloy was completely melted and kept at 720°C for 1.5 hours, 250g of industrial Q345 steel plate with oxidation layer removed was added, kept warm and melted for 24 hours, 365.03g of pure aluminum and 300g of pure zinc particles were added in sequence, and after slag removal, the plating solution temperature was controlled to 720°C, the substrate was made of Q345 industrial steel, and the immersion plating time was 30 seconds. No variable temperature annealing or water quenching was performed.

[0091] Comparative Example 2

[0092] Prepare an iron-free Al-10Si-6Zn alloy solution, in which 4084.97g of Al-12.24wt.%Si master alloy is completely melted and kept at 720℃ for 1.5 hours, and 615.03g of pure aluminum and 300g of pure zinc particles are added in sequence. The plating solution temperature is controlled to be 720℃, and the substrate is made of Q345 industrial steel. The immersion plating time is 30 seconds. After taking out and cooling, put it into an annealing furnace, and anneal at three temperatures of 756℃, 658.7℃, and 626℃ in sequence, and each annealing temperature is 6 hours. The annealed steel is directly placed in water at room temperature for water cooling quenching.

[0093] Comparative Example 3

[0094] An iron-free Al-10Si-6Zn alloy solution was prepared, wherein 4084.97g of Al-12.24wt.%Si master alloy was completely melted and kept at 720°C for 1.5 hours, 615.03g of pure aluminum and 300g of pure zinc particles were added in sequence, the plating solution temperature was controlled at 720°C, the substrate was made of Q345 industrial steel, and the immersion plating time was 30 seconds. No variable temperature annealing or water quenching was performed.

Claims

1. A continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating, characterized in that: The sacrificial anode alloy coating composition is as follows: Fe: 3-5wt.%, Si: 10wt.%, Zn: 0-6wt.%, and the rest is Al and unavoidable impurities; the continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating is prepared by the following preparation method, which comprises the following steps: (1) Steel surface pretreatment: After sanding the steel to remove the oxide film on the steel surface, soak it in acetone solution; (2) Improved Sendzimir process: The steel treated in step (1) is sent to a direct combustion non-oxidizing heating furnace to dry the steel sample, and then heated in a high-temperature thermal radiation reduction furnace to remove dirt and residual oxides on the surface of the steel, and then kept warm at 550-700°C in the reduction furnace for hot dip plating; (3) Preparation of a continuous hot-dip Al-10Si-Zn alloy solution with an iron content of 3-5wt.%: After completely melting the Al-Si master alloy and removing the slag, heat-treating at 720°C, adding Al particles to prepare an Al-10Si alloy solution; placing the steel pretreated in step (1) in the molten alloy solution, and keeping it warm until the iron content of the alloy solution reaches 3-5wt.%; then controlling the amount of Zn particles added to control the Zn content in the alloy solution to 0-6wt.%, and after it is completely melted, removing the slag, stirring evenly, and keeping the plating solution warm for later use; (4) Continuous hot-dip aluminum plating: placing the steel treated in step (2) in the Al-10Si-Zn alloy solution with an iron content of 3-5 wt.% prepared in step (3), and air cooling; (5) Variable temperature annealing and quenching heat treatment: the steel material that has completed continuous hot dip plating in step (4) is subjected to variable temperature annealing and quenching to room temperature in sequence; the variable temperature annealing is carried out in an annealing furnace, the annealing temperature gradient is 756°C, 658.7°C, 626°C, and the annealing time of each gradient is 6 to 9 hours; the annealing temperature decrease rate is 50K / s; the quenching treatment is to directly put the annealed steel material into water at room temperature for water cooling quenching to room temperature; The steps (2) to (5) are carried out in a reducing atmosphere.

2. A method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating as claimed in claim 1, characterized in that: The steps include: (1) Steel surface pretreatment: After sanding the steel to remove the oxide film on the steel surface, soak it in acetone solution; (2) Improved Sendzimir process: The steel treated in step (1) is sent to a direct combustion non-oxidizing heating furnace to dry the steel sample, and then heated in a high-temperature thermal radiation reduction furnace to remove dirt and residual oxides on the surface of the steel, and then kept warm at 550-700°C in the reduction furnace for hot dip plating; (3) Preparation of a continuous hot-dip Al-10Si-Zn alloy solution with an iron content of 3-5wt.%: After completely melting the Al-Si master alloy and removing the slag, heat-treating at 720°C, adding Al particles to prepare an Al-10Si alloy solution; placing the steel pretreated in step (1) in the molten alloy solution, and keeping it warm until the iron content of the alloy solution reaches 3-5wt.%; then controlling the amount of Zn particles added to control the Zn content in the alloy solution to 0-6wt.%, and after it is completely melted, removing the slag, stirring evenly, and keeping the plating solution warm for later use; (4) Continuous hot-dip aluminum plating: placing the steel treated in step (2) in the Al-10Si-Zn alloy solution with an iron content of 3-5 wt.% prepared in step (3), and air cooling; (5) Variable temperature annealing and quenching heat treatment: the steel material that has completed continuous hot dip plating in step (4) is subjected to variable temperature annealing and quenching to room temperature in sequence; the variable temperature annealing is carried out in an annealing furnace, the annealing temperature gradient is 756°C, 658.7°C, 626°C, and the annealing time of each gradient is 6 to 9 hours; the annealing temperature decrease rate is 50K / s; the quenching treatment is to directly put the annealed steel material into water at room temperature for water cooling quenching to room temperature; The steps (2) to (5) are carried out in a reducing atmosphere.

3. The method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating according to claim 2, characterized in that: The step (1) is carried out in a natural air environment; the steps (2) to (5) are carried out in a reducing atmosphere, wherein the reducing atmosphere is composed of 96% by mass nitrogen and 4% by mass hydrogen.

4. The method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating according to claim 2, characterized in that: In the step (2), the heating temperature of the heating furnace is 200° C.; the heating temperature in the reduction furnace is 720° C., and the heating time is 10 minutes.

5. The method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating according to claim 2, characterized in that: The Al-Si master alloy in step (3) is an Al-Si master alloy with Si mass percentage greater than 10 wt.%.

6. The method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating according to claim 2, characterized in that: The plating solution is kept at a temperature of 680°C to 720°C in step (3).

7. The method for preparing a continuous hot-dip Al-10Si-Zn sacrificial anode alloy coating according to claim 2, characterized in that: The immersion plating time in step (4) is 30 seconds.

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