Aluminum alloy plated steel sheet and method for manufacturing the same

Abstract

The application relates to an aluminum alloy plated steel sheet and a preparation method thereof. The method comprises the following steps: obtaining a first aluminum alloy plated steel sheet, wherein the first aluminum alloy plated steel sheet comprises a steel base body and an aluminum alloy plating layer attached to at least part of the surface of the steel base body, and the chemical composition of the aluminum alloy plating layer comprises Si, Fe, Ti and Al; wherein the content of Si is 5-11% in mass fraction, the content of Fe is 2-10% in mass fraction, and the content of Ti is 0.1-2% in mass fraction; alloying heating the first aluminum alloy plated steel sheet, and setting the process parameters of the alloying heating according to the thickness of the first aluminum alloy plated steel sheet to obtain a second aluminum alloy plated steel sheet; performing tension leveling and finishing on the second aluminum alloy plated steel sheet to obtain a target aluminum alloy plated steel sheet. The application improves the heat absorption performance of the aluminum alloy plating layer by reasonably designing the chemical composition of the aluminum alloy plating layer and the alloying heating treatment of the plating layer.

Description

Technical Field

[0001] This application relates to the field of steel preparation technology, and in particular to an aluminum alloy coated steel sheet and its preparation method. Background Technology

[0002] In the construction industry, improving the utilization rate of solar energy and enhancing the heat absorption performance of materials can better reduce the consumption of fossil fuels and electricity, thus playing a role in energy conservation and emission reduction. Hot-dip galvanizing technology is mature, well-developed, and widely applied. Using hot-dip galvanizing to replace electroplating and other coating processes can achieve mass production of low-cost heat-absorbing coatings.

[0003] Currently, among commonly used hot-dip galvanizing coatings, aluminum alloy coatings offer the best corrosion resistance and heat resistance, making them suitable for heat-absorbing coatings. However, the heat absorption performance of aluminum alloy coatings still needs further improvement. Summary of the Invention

[0004] This application provides an aluminum alloy coated steel sheet and its preparation method to solve the following technical problem: how to improve the heat absorption performance of aluminum alloy coatings.

[0005] In a first aspect, this application provides a method for preparing an aluminum alloy coated steel sheet, the method comprising:

[0006] A first aluminum alloy coated steel sheet is obtained, the first aluminum alloy coated steel sheet comprising a steel substrate and an aluminum alloy coating attached to at least a portion of the surface of the steel substrate, the chemical composition of the aluminum alloy coating comprising: Si, Fe, Ti and Al; wherein, by mass fraction, the content of Si is 5% to 11%, the content of Fe is 2% to 10%, and the content of Ti is 0.1% to 2%.

[0007] The first aluminum alloy coated steel sheet is alloyed and heated, and the alloying heating process parameters are set according to the thickness of the first aluminum alloy coated steel sheet to obtain the second aluminum alloy coated steel sheet.

[0008] Optionally, the chemical composition of the aluminum alloy coating may further include Mg, wherein the content of Mg is 0.1% to 2%.

[0009] Optionally, the Fe content on the coating surface is 35% to 70%; the Fe3O4 content within 0 to 1 μm of the coating surface is ≤30%.

[0010] Optionally, the chemical composition of the steel matrix includes: C, Si, Mn, Nb, Ti, P, S, and Fe; wherein,

[0011] In terms of mass fraction,

[0012] The C content is 0.001%–0.1%, the Si content is 0.001%–0.5%, the Mn content is 0.1%–0.6%, the Nb and Ti mixed element content is 0.1%–0.4%, the P content is ≤0.035%, and the S content is ≤0.035%.

[0013] Optionally, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0014] When the thickness of the first aluminum alloy coated steel plate is ≤0.8mm and ≤0.2mm, the alloying heating process parameters include: temperature 650℃~750℃, time 3min~8min.

[0015] Optionally, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0016] When the thickness of the first aluminum alloy coated steel plate is less than 1.5 mm and less than 0.8 mm, the alloying heating process parameters include: temperature 690℃~800℃, time 5 min~10 min.

[0017] Optionally, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0018] When the thickness of the first aluminum alloy coated steel plate is less than 3.0 mm and less than 1.5 mm, the alloying heating process parameters include: temperature of 750℃~850℃ and time of 8 min~15 min.

[0019] Optionally, the single-sided coating weight of the first aluminum alloy coated steel sheet is 5g / m². 2 ~75g / m 2 The coating thickness of the second aluminum alloy coated steel plate is 8μm to 50μm.

[0020] Optionally, the method further includes: performing tension leveling and finishing on the second aluminum alloy coated steel sheet to obtain the target aluminum alloy coated steel sheet; wherein,

[0021] The finishing process parameters include: finishing roller roughness Ra≥3.5μm, finishing elongation 0.2%~1.0%.

[0022] Secondly, this application provides an aluminum alloy coated steel sheet prepared by the method described in the first aspect, wherein the coating of the aluminum alloy coated steel sheet satisfies the following characteristics:

[0023] The coating color Lab value is L≤30; the coating thermal reflectivity ε≤20% within the operating temperature range of 0-800℃; the coating surface roughness Ra≥1.5μm; and the coating surface Rpc value≥80.

[0024] The technical solutions provided in this application have the following advantages compared with the prior art:

[0025] The method for preparing the aluminum alloy coated steel sheet provided in this application includes: obtaining a first aluminum alloy coated steel sheet, the first aluminum alloy coated steel sheet comprising a steel substrate and an aluminum alloy coating attached to at least a portion of the surface of the steel substrate, the chemical composition of the aluminum alloy coating comprising: Si, Fe, Ti and Al; wherein, by mass fraction, the content of Si is 5% to 11%, the content of Fe is 2% to 10%, and the content of Ti is 0.1% to 2%; alloying heating the first aluminum alloy coated steel sheet, and setting the process parameters of the alloying heating according to the thickness of the first aluminum alloy coated steel sheet to obtain a second aluminum alloy coated steel sheet; and straightening and finishing the second aluminum alloy coated steel sheet to obtain a target aluminum alloy coated steel sheet. Si (Si) ensures uniform thickness of the aluminum alloy coating, resulting in a smaller ΔL value after subsequent alloying and improving the uniformity of the coating's surface heat absorption performance. Fe (Fe) increases the coating's melting point, preventing melting during subsequent alloying and thus improving its integrity and heat absorption after alloying. Ti (Ti) refines the coating's surface grains; due to its high oxygen affinity, Ti accumulates on the coating surface during hot-dip galvanizing and alloying heating, further refining the grains, increasing surface anisotropy, and reducing thermal reflectivity. By alloying the first aluminum alloy coated steel sheet and setting the alloying heating process parameters according to the sheet's thickness, Fe from the steel substrate can diffuse into the coating during alloying, reducing brightness (L value) and increasing surface roughness, further reducing thermal reflectivity and improving heat absorption. In summary, by rationally designing the chemical composition of the aluminum alloy coating and the alloying heating treatment, the heat absorption performance of the aluminum alloy coating is improved. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart illustrating a method for preparing an aluminum alloy coated steel sheet according to some embodiments of this application. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges 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 range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0031] In this application, the terms "comprising," "including," etc., mean "including but not limited to." Relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0032] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0033] Firstly, this application provides a method for preparing an aluminum alloy coated steel sheet. Figure 1 This is a schematic flowchart illustrating a method for preparing an aluminum alloy coated steel sheet according to some embodiments of this application; please refer to [link / reference]. Figure 1 The method includes:

[0034] S1. Obtain a first aluminum alloy coated steel sheet, the first aluminum alloy coated steel sheet comprising a steel substrate and an aluminum alloy coating attached to at least a portion of the surface of the steel substrate, the chemical composition of the aluminum alloy coating comprising: Si, Fe, Ti and Al; wherein, by mass fraction, the content of Si is 5% to 11%, the content of Fe is 2% to 10%, and the content of Ti is 0.1% to 2%.

[0035] In this embodiment, adding Si (Si) makes the coating thickness more uniform, resulting in a smaller ΔL value after subsequent alloying. This improves the uniformity of the heat absorption performance of the coating surface. Si also enhances the fluidity of the plating solution and has good oxidation resistance, reducing oxidation and making it easier to control the coating thickness. If the Si content is too high, the coating plasticity will decrease, making it prone to cracking during subsequent processing, affecting the integrity of the coating and reducing its heat absorption performance. If the Si content is too low, it is difficult to effectively control the coating uniformity, thus reducing the heat absorption effect. For example, the Si content can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, etc.

[0036] Adding Fe to the plating bath is to increase the melting point of the coating, preventing melting and equipment contamination during subsequent alloying processes. Fe also increases the melting point, preventing melting during alloying and ensuring coating integrity, while improving the heat absorption of the alloyed coating. Furthermore, Fe is chosen for its low cost and ease of addition to the plating bath during production. Excessive Fe content leads to the formation of large amounts of iron slag, deteriorating the surface quality of the material after hot-dip galvanizing and causing coating detachment during stamping. The presence of iron slag within the coating also contributes to detachment during subsequent processing, affecting the material's heat absorption performance. Conversely, insufficient Fe content fails to effectively increase the melting point, allowing melting during alloying and impacting heat absorption. For example, the Fe content can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%.

[0037] Adding titanium (Ti) to the plating bath primarily aims to refine the grain size of the coating surface. Due to its high affinity for oxygen, Ti accumulates on the coating surface during hot-dip galvanizing and alloying heating, thus refining the grain size, increasing surface anisotropy, and reducing the thermal reflectivity of the coating. If the Ti content in the plating bath is too high, it significantly increases the coating hardness, making it prone to cracking during subsequent stamping processes and affecting the material's heat absorption properties. Conversely, if the Ti content is too low, it is difficult to effectively refine the coating surface grain size and reduce the material's surface thermal reflectivity. For example, the Ti content can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.3%, 1.5%, 1.7%, 2%, etc.

[0038] In some embodiments, the chemical composition of the aluminum alloy coating further includes Mg, wherein the content of Mg is 0.1% to 2%.

[0039] In this embodiment, the addition of Mg to the plating bath is primarily to improve the corrosion resistance of the coating. When the Mg content is too high, excessive Mg₂Si will be generated within the coating, reducing its plasticity and affecting its performance; when the Mg content is too low, it cannot effectively improve the corrosion resistance of the coating. For example, the Mg content can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.3%, 1.5%, 1.7%, 2%, etc.

[0040] In some embodiments, the Fe content on the coating surface is 35% to 70%; the Fe3O4 content within 0 to 1 μm of the coating surface is ≤30%.

[0041] In this embodiment, the Fe content on the coating surface is limited to ensure that the L value of the coating is ≤30. During heating, Fe diffuses into the coating, thereby reducing the L value. When the Fe content on the coating surface is too high, it significantly reduces the plasticity of the coating, making it prone to microcracks during stamping and affecting the corrosion resistance of the coating. Furthermore, the composition of iron oxides on the coating surface changes with heating temperature and time. Within 0-1 μm of the coating surface, when the Fe3O4 content is too high, it significantly increases the L value of the coating, thus deteriorating its heat absorption performance. For example, the Fe content on the coating surface can be 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, etc.; and the Fe3O4 content within 0-1 μm of the coating surface can be 30%, 28%, 26%, 24%, etc.

[0042] In some embodiments, the chemical composition of the steel matrix includes: C, Si, Mn, Nb, Ti, P, S, and Fe; wherein, by mass fraction,

[0043] The C content is 0.001%–0.1%, the Si content is 0.001%–0.5%, the Mn content is 0.1%–0.6%, the Nb and Ti mixed element content is 0.1%–0.4%, the P content is ≤0.035%, and the S content is ≤0.035%.

[0044] In the embodiments of this application, the performance of the aluminum alloy coated steel sheet can be guaranteed by reasonably controlling the chemical composition of the steel matrix. For example, the content of C can be 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, etc.; the content of Si can be 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc.; the content of Mn can be 0.1%, 0.2%, 0.3%, 0.5%, 0.6%, etc.; the content of the mixed elements of Nb and Ti can be 0.1%, 0.2%, 0.3%, 0.4%, etc.; the content of P can be 0.035%, 0.03%, 0.027%, 0.025%, etc.; and the content of S can be 0.035%, 0.03%, 0.027%, 0.025%, etc.

[0045] S2. The first aluminum alloy coated steel plate is alloyed and heated, and the alloying heating process parameters are set according to the thickness of the first aluminum alloy coated steel plate to obtain the second aluminum alloy coated steel plate.

[0046] In some embodiments, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0047] When the thickness of the first aluminum alloy coated steel plate is ≤0.8mm and ≤0.2mm, the alloying heating process parameters include: temperature 650℃~750℃, time 3min~8min.

[0048] In some embodiments, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0049] When the thickness of the first aluminum alloy coated steel plate is less than 1.5 mm and less than 0.8 mm, the alloying heating process parameters include: temperature 690℃~800℃, time 5 min~10 min.

[0050] In some embodiments, setting the alloying heating process parameters based on the thickness of the first aluminum alloy coated steel plate includes:

[0051] When the thickness of the first aluminum alloy coated steel plate is less than 3.0 mm and less than 1.5 mm, the alloying heating process parameters include: temperature of 750℃~850℃ and time of 8 min~15 min.

[0052] In this embodiment, alloying heating of the coating can reduce the Lab value of the coating, thereby reducing its thermal reflectivity. Using coating alloying instead of traditional painting or electroplating processes can better achieve energy conservation, emission reduction, and environmental protection, and alloying heating offers higher production efficiency and lower production costs. By alloying the coating, Fe elements within the substrate can diffuse into the coating during the alloying process, reducing the coating brightness (L value) and increasing the surface roughness, thus reducing thermal reflectivity and improving heat absorption performance. The alloying heating process parameters are set according to the thickness of the first aluminum alloy coated steel plate. By controlling the alloying time and temperature, the Fe content and roughness of the coating surface can be controlled. Studies have shown that as the heating time increases, the surface roughness of the coating first increases and then decreases. Therefore, to ensure that the surface roughness of the alloyed coating reaches the target range, the alloying heating process parameters are rationally adjusted. For example, when the thickness of the first aluminum alloy coated steel plate is 0.2mm ≤ 0.8mm, the alloying heating process parameters include: temperatures of 650℃, 670℃, 690℃, 710℃, 730℃, 750℃, etc., and times of 3min, 4min, 5min, 6min, 7min, 8min, etc.; when the thickness of the first aluminum alloy coated steel plate is 0.8mm < 1.5mm, the alloying heating process parameters include: temperatures of 690℃, 700℃, 720℃, 740℃, etc. The alloying heating process parameters include: temperatures of 760℃, 780℃, 800℃, etc., and times of 5min, 6min, 7min, 8min, 9min, 10min, etc.; when the thickness of the first aluminum alloy coated steel plate is less than 3.0mm and less than 1.5mm, the alloying heating process parameters include: temperatures of 750℃, 770℃, 790℃, 810℃, 830℃, 850℃, etc., and times of 8min, 9min, 10min, 11min, 12min, 13min, 14min, 15min, etc. The above alloying heating can be performed using three heating methods: salt bath furnace, roller hearth furnace, or radiant tube heating furnace. The atmosphere inside the furnace during heating is air.

[0053] In some embodiments, the single-sided coating weight of the first aluminum alloy coated steel sheet is 5 g / m². 2 ~75g / m 2 The coating thickness of the second aluminum alloy coated steel plate is 8μm to 50μm.

[0054] In this embodiment, the single-sided coating weight of the first aluminum alloy coated steel plate can be 5g / m². 2 10g / m 2 15g / m 2 20g / m2 25g / m 2 30g / m 2 35g / m 2 40g / m 2 45g / m 2 50g / m 2 55g / m 2 60g / m 2 65g / m 2 70g / m 2 75g / m 2 The coating thickness of the aforementioned second aluminum alloy coated steel plate can be 8μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0055] In some embodiments, the method further includes: S3, performing tension leveling and finishing on the second aluminum alloy coated steel sheet to obtain the target aluminum alloy coated steel sheet; wherein,

[0056] The finishing process parameters include: finishing roller roughness Ra≥3.5μm, finishing elongation 0.2%~1.0%.

[0057] In this embodiment, after alloying, tension leveling and finishing processes should be used to improve the material's shape and enhance the surface profile properties of the steel plate, achieving a surface roughness Ra ≥ 1.5 μm and a coating surface Rpc value ≥ 80. By increasing the surface morphology fluctuation of the steel plate, the surface thermal reflectivity can be further reduced, ensuring that the coating thermal reflectivity ε ≤ 20%. For example, the surface roughness Ra of the finishing roller can be 3.5 μm, 3.7 μm, 4.0 μm, 4.5 μm, etc., and the finishing elongation can be 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, etc. The finishing roller can be processed using electrical discharge machining (EDM) to improve the randomness of the coating surface peaks and reduce the processing cost of the grinding roller.

[0058] Secondly, this application provides an aluminum alloy coated steel sheet prepared by the method described in the first aspect, wherein the coating of the aluminum alloy coated steel sheet satisfies the following excellent characteristics:

[0059] The coating color Lab value is L≤30; the coating thermal reflectivity ε≤20% within the operating temperature range of 0-800℃; the coating surface roughness Ra≥1.5μm; and the coating surface Rpc value≥80.

[0060] The aluminum alloy coated steel sheet is realized based on the above-mentioned preparation method of aluminum alloy coated steel sheet. The specific steps of the preparation method of aluminum alloy coated steel sheet can be referred to the above embodiments. Since the aluminum alloy coated steel sheet adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0061] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0062] This application provides a method for preparing an aluminum alloy coated steel sheet. Please refer to Table 1 for the thickness and coating composition of the first aluminum alloy coated steel sheet, Table 2 for the alloying heating process parameters and the coating surface parameters after heating, and Table 3 for the coating thickness and properties after alloying.

[0063] In Examples 1-4 and Comparative Examples 1-4, the steel substrate composition (wt%) was as follows: C: 0.005, Si: 0.025, Mn: 0.5, Nb: 0.05, Ti: 0.15, P: 0.02, S: 0.02, with the remainder being Fe and unavoidable impurities. The aluminum alloy coated steel sheet was processed according to the following steps: steelmaking → hot rolling → cold rolling → annealing → hot-dip aluminum alloy coating → coiling → uncoiling → surface cleaning → alloying heating → tension leveling and finishing → oiling → coiling. Examples 1-4 and Comparative Examples 1-3 used a finishing roller with a roughness of 4.0 μm for finishing, with a finishing elongation of 0.6%. In Comparative Example 3, a finishing roller with a roughness of 2.0 μm was used for finishing, with a finishing elongation of 0.6%.

[0064] The L-value of the alloyed coating was measured using a surface colorimeter at room temperature, and the average value of 10 points was taken as the result. The thermal reflectance of the coating was measured using a reflectance spectrometer at an infrared incident angle of 60° and a test temperature of 800℃, and the average value of 10 measurements was taken as the result. Surface roughness and Rpc value were measured using a surface profilometer at room temperature, and the average value of 10 measurements was taken as the result. The coating thickness and Fe content on the coating surface were measured using a scanning electron microscope, and the average value of 10 measurements was taken as the result. The number of cracks was measured at the bends of the coating within a 1μm length, with a bending angle of 90°, and the number of cracks was determined under a scanning electron microscope. The red rust time was obtained through a neutral salt spray test, conducted according to the national standard GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", with 3 parallel samples used in each group of experiments.

[0065] Table 1 shows the thickness and coating composition (wt%) of the first aluminum alloy coated steel sheet, with the remainder being Al and unavoidable impurities.

[0066]

[0067] Table 2. Process parameters for alloying heating and surface parameters of the coating after heating.

[0068]

[0069] Table 3. Coating thickness and properties after alloying

[0070]

[0071] In summary, by employing a suitable alloying process, the coating achieves a surface thermal reflectivity of ≤20% within an operating temperature range of 0-800℃ without sacrificing plasticity. This aluminum alloy coated steel sheet is suitable for energy storage and heat absorption equipment or working environments. Comparative Example 1 shows that when the Fe content in the plating solution is greater than 10wt%, under the same alloying process, the Fe content on the coating surface exceeds 70wt%, leading to a significant increase in the number of coating cracks and a decrease in the coating's corrosion resistance. Comparative Example 2 shows that compared to Example 3, shortening the heating time resulted in incomplete alloying of the coating, causing the L value and Fe content to exceed the range, and the coating's thermal absorption rate did not meet the usage standards. Comparative Example 3 shows that when the Si content in the plating solution is less than 5wt%, the hot-dip galvanizing process leads to excessively thick coatings, resulting in excessively thick alloyed coatings. Furthermore, due to the excessive thickness, the Fe content on the coating surface decreases under the same alloying process conditions, resulting in a decrease in the thermal reflectivity of the coating. In addition, the excessive thickness of the coating also leads to a decrease in plasticity, thereby increasing the number of coating cracks and reducing corrosion resistance. As can be seen from Comparative Example 4, the roughness of the finishing roller and the finishing elongation in the finishing process are not within the range of the embodiments of this application. When the surface roughness and Rpc value of the alloyed coating are less than the specified range, it will affect the reflectivity of the coating, thereby affecting the heat absorption performance of the coating.

[0072] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this 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 this application. Therefore, this application is not to 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

1. A method for preparing an aluminum alloy coated steel sheet, characterized in that, The method includes: A first aluminum alloy coated steel sheet is obtained, the first aluminum alloy coated steel sheet comprising a steel substrate and an aluminum alloy coating attached to at least a portion of the surface of the steel substrate, the chemical composition of the aluminum alloy coating comprising: Si, Fe, Ti and Al; wherein, by mass fraction, the content of Si is 5%~11%, the content of Fe is 4%~10%, and the content of Ti is 0.1%~2%; The first aluminum alloy coated steel sheet is alloyed and heated, and the alloying heating process parameters are set according to the thickness of the first aluminum alloy coated steel sheet to obtain the second aluminum alloy coated steel sheet. When the thickness is 0.2mm ≤ 0.8mm, the alloying heating temperature is 650℃~750℃ and the time is 3min~8min; When 0.8mm < thickness ≤ 1.5mm, the alloying heating temperature is 690℃~800℃, and the time is 5min~10min; When 1.5mm < thickness ≤ 3.0mm, the alloying heating temperature is 750℃~850℃, and the time is 8min~15min; The second aluminum alloy coated steel sheet is subjected to tension leveling and finishing to obtain an aluminum alloy coated steel sheet; the finishing roller roughness Ra≥3.5μm, the finishing elongation 0.2%~1.0%, and the coating of the aluminum alloy coated steel sheet meets the following characteristics: the coating color Lab value L≤30; the coating heat reflectivity ε≤20% in the operating temperature range of 0-800℃; the coating surface roughness Ra≥1.5μm; and the coating surface Rpc value≥80.

2. The method according to claim 1, characterized in that, The chemical composition of the aluminum alloy coating also includes Mg, and the content of Mg is 0.1% to 2%.

3. The method according to claim 1, characterized in that, The Fe content on the coating surface is 35%~70%; the Fe3O4 content within 0~1μm of the coating surface is ≤30%.

4. The method according to claim 1, characterized in that, The chemical composition of the steel matrix includes: C, Si, Mn, Nb, Ti, P, S, and Fe; wherein, by mass fraction, The content of C is 0.001%~0.1%, the content of Si is 0.001%~0.5%, the content of Mn is 0.1%~0.6%, the content of mixed elements of Nb and Ti is 0.1%~0.4%, the content of P is ≤0.035%, and the content of S is ≤0.035%.

5. The method according to claim 1, characterized in that, The single-sided coating weight of the first aluminum alloy coated steel sheet is 5g / m². 2 ~75 g / m 2 The coating thickness of the second aluminum alloy coated steel plate is 8μm~50μm.

6. An aluminum alloy coated steel sheet prepared by the method according to any one of claims 1 to 5.

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