Anodic oxidation aluminum alloy die casting and preparation method and application thereof

Abstract

The invention provides an anodized aluminum alloy die casting and a preparation method and application thereof. The preparation method comprises the steps that raw materials are prepared, specifically, the anodic oxidation aluminum alloy die casting comprises, by weight, 1.6%-2.4% of Mn, 1.0%-2.0% of Si, 0-0.3% of Fe, 1.0%-2.0% of Ni, 0.08%-0.2% of Ti, 0.05%-0.3% of Zr, Mg and Zn with the total amount being 5.0%-7.0% and Zn / Mg being 1.6%-1.8, 0-0.2% of inevitable impurity elements and not containing Cu, V and Cr, and the balance Al; smelting is conducted; refining and degassing; die casting; and anodizing. The composition formula of the anodized aluminum alloy die casting is designed, meanwhile, the die casting technology is accurately regulated and controlled, and the anodized aluminum alloy die casting with high mechanical performance and surface performance is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an anodized aluminum alloy die casting, a preparation method thereof and an application thereof. Background Art

[0002] As people's demand for the aesthetics of daily necessities gradually increases, a large number of products are facing the need for material upgrades, such as automotive interior parts, armrests, medical devices and other products, which are converted from original plastic and steel materials to aluminum alloy products that can be anodized on the surface. However, the shape of aluminum alloy profiles in the current industry is single, and the cost is extremely high if they need to be processed into different types of products. Therefore, many companies choose to use anodized die-casting alloys for fine-shaped product production. However, the mechanical properties of anodized die-casting alloys on the market are significantly different from those of commonly used 6xxx series aluminum alloy profiles, and it is difficult to meet the requirements of mechanical properties. For example, the tensile strength of commonly used 6061 profiles is above 200MPa, the yield strength is about 110MPa, and the hardness is above 100HV. The tensile strength of anodized die-casting alloys is generally between 120 and 180MPa, the yield strength is generally between 60 and 80MPa, and the hardness is below 80HV. For example, patent CN115522104B introduces a high-strength anodized die-casting alloy, but it is difficult to achieve both strength and anodized film effect, especially light-colored oxide film, while meeting the performance requirements of the profile.

[0003] In the prior art, the mechanical properties of die-casting alloys are generally improved by dissolving a large amount of elements in the matrix, thereby playing a role of solid solution strengthening. However, a large amount of elements dissolved in the matrix will increase the viscosity of the melt, thereby affecting its fluidity, resulting in difficulties in die-casting. Improving the molding performance is generally achieved by adding a large amount of Si and Fe elements, but these two elements will have an extremely adverse effect on anodization, resulting in black spots or darkening on the surface. Therefore, high-strength anodized die-casting alloys must not only take into account the balance between die-casting molding performance and anodizing performance, but also consider the improvement of strength, which makes development difficult.

[0004] Based on this, how to coordinate the composition ratio of die-cast aluminum alloy and the corresponding preparation process conditions to provide an anodized aluminum alloy die-casting with excellent performance, so that it can take into account the three performance requirements of high formability, high surface quality and high mechanical properties, is one of the important technical problems that need to be solved in this field. Summary of the invention

[0005] The main purpose of the present invention is to provide an anodized aluminum alloy die-casting, a preparation method and application thereof, so as to solve the problem that anodized aluminum alloy die-castings in the prior art are difficult to meet the three performance requirements of high formability, high surface quality and high mechanical properties.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing an anodized aluminum alloy die casting, comprising: preparing raw materials: in terms of weight percentage, the composition of the anodized aluminum alloy die casting includes 1.6% to 2.4% Mn, 1.0% to 2.0% Si, 0 to 0.3% Fe, 1.0% to 2.0% Ni, 0.08% to 0.2% Ti, 0.05% to 0.3% Zr, 5.0% to 7.0% Mg and Zn with a Zn / Mg ratio of 1.6 to 1.8, and 0 to 0.2% of unavoidable impurity elements, and It does not contain Cu, V and Cr, and the balance is Al. The raw materials are prepared according to the composition of the aluminum alloy material; smelting: after the raw materials are smelted, a first melt is obtained; refining and degassing: the first melt is subjected to refining treatment and degassing treatment in sequence to obtain a second melt; die casting: the second melt is subjected to die casting treatment at a temperature of 710°C to 718°C to obtain an aluminum alloy die casting; anodizing: the aluminum alloy die casting is subjected to anodizing surface treatment to obtain an anodized aluminum alloy die casting; the die casting treatment is carried out using a die casting mold with a coating on the surface, the draft angle of the die casting mold is 4° to 5°, and the corner is greater than R2.

[0007] Further, the temperature of the die-casting mold is 180° C. to 200° C.; preferably, the coating is selected from one or more of aluminum nitride coating, titanium aluminum nitride coating and chromium aluminum nitride coating.

[0008] Furthermore, before the die-casting process is performed, a mold release agent is sprayed onto the surface of the die-casting mold, and the spraying time is 8s to 12s.

[0009] Furthermore, the die-casting thickness of the die-casting process is 2.5 mm to 4.0 mm, and the holding time is 40 s to 60 s.

[0010] Furthermore, the smelting includes: adding Al, Zn, Al-Mn master alloy, Al-Ni master alloy and Fe into a smelting furnace for a first melting at a temperature of 770°C to 800°C to obtain a mixture; when the temperature of the mixture is reduced to 750°C to 759°C, adding Mg and Al-Zr master alloy to the mixture for a second melting to obtain a first melt.

[0011] Furthermore, the refining and degassing comprises adding a refining agent and a refiner into the first melt, stirring for 3 minutes to 5 minutes, and obtaining a second melt after degassing and standing.

[0012] A second aspect of the present invention provides an anodized aluminum alloy die casting, which is prepared by the above-mentioned preparation method.

[0013] Furthermore, the phase structure of the anodized aluminum alloy die-casting includes a matrix phase and a second phase, and the area proportion of the second phase in the phase structure is less than 7.0%; preferably, the second phase is selected from one or more of Al6Mn phase, MgZn2 phase and AlFeMnZr phase, and the Al6Mn phase also includes a second phase composed of one or more of Fe element, Si element and Ni element.

[0014] Furthermore, the Vickers hardness of the anodized aluminum alloy die casting is 75HV to 96HV, and the tensile strength is 210MPa to 260MPa; preferably, the white brightness of the anodized aluminum alloy die casting is 70 to 90, and the color difference value is ≤0.40.

[0015] A third aspect of the present invention provides an application of the above-mentioned anodized aluminum alloy die casting as a part in the fields of aerospace, automobile manufacturing and electronic equipment.

[0016] By applying the technical solution of the present invention, the composition formula of the anodized aluminum alloy die casting is comprehensively designed, and the die casting process is precisely controlled, thereby overcoming the problem that it is difficult to take into account the melt fluidity, mechanical properties and surface morphology properties obtained by anodization during the preparation process of the anodized aluminum alloy die casting. The obtained anodized aluminum alloy die casting not only exhibits high mechanical properties and surface properties, but also has excellent processing properties, thereby being able to meet the material requirements of various fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 This is a SEM photo of the anodized aluminum alloy die casting obtained in Example 1;

[0019] Figure 2 This is a metallographic photograph of the anodized aluminum alloy die casting obtained in Example 1. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0021] As described in the background technology, the anodized aluminum alloy die castings in the prior art have the problem of difficulty in taking into account the three performance requirements of high formability, high surface quality and high mechanical properties. In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing an anodized aluminum alloy die casting, comprising: preparing raw materials: in terms of weight percentage, the composition of the anodized aluminum alloy die casting includes 1.6% to 2.4% Mn, 1.0% to 2.0% Si, 0 to 0.3% Fe, 1.0% to 2.0% Ni, 0.08% to 0.2% Ti, 0.05% to 0.3% Zr, 5.0% to 7.0% Mg and Zn in total, Zn / Mg of 1.6 to 1.8, and 0 to 0.2% of unavoidable impurity elements. , and does not contain Cu, V and Cr, the balance is Al, and the raw materials are prepared according to the composition of the aluminum alloy material; smelting: after the raw materials are smelted, a first melt is obtained; refining and degassing: the first melt is successively subjected to refining treatment and degassing treatment to obtain a second melt; die casting: the second melt at a temperature of 710-718°C is subjected to die casting treatment to obtain an aluminum alloy die casting; anodizing: the aluminum alloy die casting is subjected to anodizing surface treatment to obtain anodized aluminum alloy die casting; the die casting treatment is carried out using a die casting mold with a coating on the surface, the draft angle of the die casting mold is 4°-5°, and the corner is greater than R2.

[0022] To avoid ambiguity, the "anodized aluminum alloy die casting" in the present invention means a die casting prepared using anodized die-casting aluminum alloy, and the two are collectively referred to as anodized die-casting alloy materials.

[0023] By applying the technical solution of the present invention, the composition formula of the anodized aluminum alloy die casting is comprehensively designed, and the die casting process is precisely controlled, thereby overcoming the problem that it is difficult to take into account the melt fluidity, mechanical properties and surface morphology properties obtained by anodization during the preparation process of the anodized aluminum alloy die casting. In the design process of the above alloy composition, the inventor controls the sum of the Mg and Zn contents within 5-7% through a large number of experiments, so that during the rapid cooling process of the die casting process, the strengthening elements are dissolved in the matrix to the maximum extent to form a supersaturated solid solution, thereby achieving the purpose of solid solution strengthening. At the same time, further controlling Zn / Mg=1.6-1.8 can control the precipitation phase to precipitate as much as possible, so that the MgZn2 phase that plays a strengthening effect can play a role as much as possible. In particular, compared with a higher Zn / Mg, the MgZn2 phase obtained under this content relationship can be more significantly dissolved in the oxide film, reducing the impact on the anodized color.

[0024] In the above alloy formula, Mn and Fe elements in the alloy mainly play the role of promoting demolding, but excessive Fe content will lead to the formation of Fe-containing phase in the melt. The Fe-containing phase is insoluble in the oxide film and will cause defects such as black spots on the surface of the oxide film. Therefore, it is controlled below 0.3%.

[0025] The Si content within 1-2% can improve the fluidity of the melt, while ensuring that the effect on anodizing is within an acceptable range; the Ni element can replace Si to a certain extent, releasing latent heat of crystallization during solidification and improving the fluidity of the alloy, but adding a large amount of Ni will increase the size and amount of the second phase, which is not conducive to the improvement of mechanical properties. Taking this into consideration, it is controlled to 1.0%-2.0%.

[0026] The addition of 0.08% to 0.2% Ti and 0.05% to 0.3% Zr elements can increase nucleation points in the melt, refine the grains, make the surface and subsurface grain structures more uniform and fine, and enable the die casting to obtain a larger surface grinding thickness.

[0027] In particular, the anodized aluminum alloy die casting provided by the present invention does not include Cu, V and Cr. After a large number of experiments and comparisons, the inventors found that if the above-mentioned metal elements are added individually or in combination on the basis of the alloy composition formula provided by the present invention, while complicating the alloy composition and the corresponding preparation process, the performance of the obtained anodized aluminum alloy die casting will not be improved, and may even cause certain deterioration, as follows:

[0028] On the one hand, the addition of Cu element will reduce the fluidity of the melt and affect the die-casting molding. On the other hand, the addition of Cu will affect the overall electrochemical activity of the material, which is not conducive to the stability of the anodizing process. The addition of V element is easy to form a large-sized AlFeMnVZr second phase with Fe, Mn and Zr. On the one hand, it will significantly reduce the beneficial effect of Zr. On the other hand, the large-sized second phase is not conducive to anodizing and will increase the risk of black spots on the surface after anodizing. A large amount of Mg and Zn elements are added in this product, and the fluidity is low. The addition of Cr element has a greater impact on the fluidity, which will greatly increase the melt viscosity and further reduce the alloy filling capacity.

[0029] Due to the need to strengthen the alloy, a large amount of Mg and Zn elements are added to the alloy, and the degree of alloying is high, so the fluidity of the alloy melt is significantly reduced and the tendency to stick to the film is increased. Therefore, when designing the mold, the preparation method provided by the present invention controls the draft angle to be 4° to 5°, and the corners are all greater than R2, which is beneficial to improving the filling capacity and demolding performance of the alloy. At the same time, the temperature during die casting is strictly controlled to be 710℃ to 720℃ in order to obtain die castings with fewer defects. The anodized aluminum alloy die castings prepared according to the above method not only show high mechanical properties and surface properties, but also have excellent processing properties, so that they can meet the material requirements of various fields.

[0030] The above steps in the method for preparing anodized aluminum alloy die-castings provided by the present invention, in addition to the advantages of improving the performance of the alloy itself, are more importantly designed based on the above-mentioned specific metal element formula, and the steps can cooperate with each other, that is, as an overall solution, to achieve performance improvement for the aluminum alloy, especially balancing its formability during the preparation process and the comprehensive performance of the resulting material. It should be additionally explained that for the high Mg and high Zn alloys provided by the present invention, it is particularly necessary to use a die-casting mold with a coating on the surface to achieve die-casting, because the anodized die-casting alloy has the need for anodization, so the Fe and Si content cannot be too high, resulting in the inability to compensate for the increase in melt viscosity caused by the excessively high Mg and Zn content, resulting in the problem of sticking to the film, which will result in the inability to demold during die-casting. Therefore, a coated mold is used to assist in demolding.

[0031] In several typical embodiments, in order to further reduce the problem of thermal cracking, the temperature of the die-casting mold is preferably 180°C to 200°C to reduce the cooling rate of the die-casting and reduce the temperature drop caused by the rapid mold opening to produce thermal cracks. And in order to further solve the problem of thermal cracking that may occur during the die-casting process, the coating on the surface of the die-casting mold is preferably selected from one or more of aluminum nitride coating, titanium aluminum nitride coating and chromium aluminum nitride coating. The above-mentioned coatings have high temperature resistance and can still maintain the original hardness and chemical properties at high temperatures. They can be well applied to high-temperature die-casting processes, especially with the aluminum alloy formula provided by the present invention. It can be well compatible and further reduce the sticking tendency of the alloy. These coatings are more compatible with the alloy components and are not easy to increase the impurity elements in the melt.

[0032] Furthermore, in order to improve the demoulding effect and enhance the surface quality of the obtained aluminum alloy material, before the die-casting process, a mold release agent is sprayed on the surface of the die-casting mold, and the spraying time is 8s to 12s. In order to minimize the adverse effects on anodization, the mold release agent is preferably selected from Si-free mold release agent and / or low-Si mold release agent, and the specific type can be selected from the types commonly used in the art.

[0033] As mentioned above, a large amount of Mg and Zn elements are added to the alloy, so the alloy's tendency to hot cracking and sticking film also increases accordingly, so higher requirements are also put forward for its preparation process. In order to reduce the hot cracking problem caused by the high degree of alloying, the preferred holding time of die casting is 40s to 60s. At the same time, in order to further reduce the cooling rate of the die casting, reduce the hot cracking defects caused by the sudden temperature change during the die casting process, and improve the forming rate of the die casting, the inventor has preferably selected the thickness of the die casting to be 2.5mm to 4mm after a large number of experiments, thereby effectively suppressing the problems of too fast cooling and insufficient fluidity caused by too thin wall thickness.

[0034] In several typical embodiments, smelting includes: adding Al, Zn, Al-Mn master alloy, Al-Ni master alloy and Fe into a smelting furnace for a first melting at a temperature of 770°C to 800°C to obtain a mixture; when the temperature of the mixture is reduced to 750°C to 759°C, adding Mg and Al-Zr master alloy to the mixture for a second melting to obtain a first melt. The preparation of aluminum alloy by each raw material according to the above-mentioned feeding sequence and process conditions can more effectively obtain a melt with a purer phase structure, which is conducive to the subsequent improvement of comprehensive mechanical properties and formability. The temperature points of the two stages are preferably as above, which can enable each alloy ingot to melt into the melt at a more suitable speed without increasing the risk of entrainment and reducing energy consumption. In particular, for the first melting, if the temperature is lower than 770°C, it is difficult to achieve sufficient melting of the raw materials, which is not conducive to the subsequent steps.

[0035] Furthermore, in order to reduce impurities to a greater extent, it is preferred that refining and degassing include adding a refining agent and a refiner to the first melt, stirring for 3 to 5 minutes, and obtaining a second melt after degassing and standing. The refining time is particularly optimized to be 3 to 5 minutes, thereby suppressing the removal of effective elements in the alloy and excessive temperature reduction caused by too long a refining time, and effectively reducing the problem that the gas and impurities in the alloy cannot be completely removed due to too short a refining time, thereby making the strength and surface quality of the alloy substandard and affecting the product quality, and finally obtaining an anodized aluminum alloy die casting with better mechanical properties.

[0036] And, in the actual preparation process, the degassing time can be 10 minutes to 15 minutes, and the standing time can be 15 minutes to 20 minutes. The refiner is Al-Ti-B refiner.

[0037] The second aspect of the present invention provides an anodized aluminum alloy die casting, which is prepared by the above preparation method. The obtained anodized aluminum alloy die casting exhibits excellent solid solution strengthening effect, and also has good processability and surface quality.

[0038] Furthermore, the phase structure of the anodized aluminum alloy die casting includes a matrix phase and a second phase, and the area ratio of the second phase in the phase structure is less than 7.0%, and more preferably 6.0% to 7.0%. The above-mentioned aluminum alloy material obtained by the present invention has a matrix mainly of α-Al, and it is inevitable that there is a second phase. After a large number of experiments, the inventors preferably prefer that the area ratio of the second phase in the metallographic structure is 6.0 to 7.0%, so as to better balance the relationship between processability, mechanical strength and corrosion resistance. Preferably, the second phase is selected from one or more of Al6Mn (FeSiNi) phase, MgZn2 phase and AlFeMnZr phase. Among them, Al6Mn (FeSiNi) phase represents Al6Mn phase, and includes a second phase composed of one or more of Fe element, Si element and Ni element.

[0039] In several typical implementations, the Vickers hardness of the anodized aluminum alloy die casting is 75HV to 96HV, and the tensile strength is 210MPa to 260MPa; preferably, the white brightness of the anodized aluminum alloy die casting is 70 to 90, and the color difference value is ≤0.40. The comprehensive performance is comprehensively improved compared with the existing anodized aluminum alloy die castings in the art.

[0040] The third aspect of the present invention provides an application of the above-mentioned anodized aluminum alloy die casting as a part in the fields of aerospace, automobile manufacturing and electronic equipment. The above-mentioned anodized aluminum alloy die casting has high mechanical properties and surface properties, especially excellent processability during the die-casting process, and is easy to demold, so it can be well used as a part in various fields.

[0041] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0042] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0043] Example 1

[0044] A method for preparing anodized aluminum alloy die castings:

[0045] S1. Prepare raw materials: use industrial pure aluminum, pure zinc, pure iron, pure magnesium, Al-Mn master alloy, Al-Ni master alloy and Al-Zr master alloy raw materials; prepare alloy composition as follows: Mn=1.6%, Si=1.0%, Fe=0.21%, Ni=1.0%, Ti=0.08%; Zr=0.05%, Zn=3.5%, Mg=2.0% (Zn / Mg is 1.75, Zn+Mg=5.5%), inevitable impurities=0.14%, and the balance Al (see Table 1);

[0046] S2, smelting: adding Al, Zn, Al-Mn master alloy, Al-Ni master alloy and Fe into a smelting furnace and heating to 800°C for first melting, and obtaining a mixture after the raw materials are completely melted; cooling the mixture to 755°C, adding Mg and Al-Zr master alloy thereto for second melting, until all the raw materials are completely melted, to obtain a first melt.

[0047] S3, refining and degassing: 3.0‰ of the weight of the feed as the refining agent and 0.02% of the weight of the feed as the Al-Ti-B refiner are used as the refining agent and the refiner respectively, and the two are added to the first melt, slowly stirred for 4 minutes, and degassed for 10 minutes with inert gas as Ar gas. After degassing, let it stand for 15 minutes, and skim off the slag to obtain the second melt.

[0048] S4, Die casting: Select a die casting mold with aluminum nitride coating on the surface, set its draft angle to 4°, and the corner to R3. Before die casting, use Si-free mold release agent to spray the die casting mold for 10 seconds. When the melt temperature reaches 710℃, start die casting, control the die casting mold temperature at 180℃, set the die casting thickness to 3mm, and hold the pressure for 40s.

[0049] S5. Anodizing: The die castings obtained by die casting are sequentially subjected to ash removal, neutralization, chemical polishing, anodizing and sealing treatments, and 1 to 2 water washings are performed between each step to obtain anodized aluminum alloy die castings.

[0050] The phase structure of the obtained anodized aluminum alloy die casting includes a matrix phase and a second phase mainly composed of Al6Mn(FeSiNi), MgZn2, and AlFeMnZr, and the area proportion of the second phase is 4%.

[0051] The SEM images of the anodized aluminum alloy die castings are shown in Figure 1 , where the dark part is the matrix phase and the light part is the second phase mentioned above.

[0052] The metallographic photographs of the anodized aluminum alloy die castings are shown in Figure 2 .

[0053] The difference between Example 2 and Example 3 and Example 1 is only the different amounts of elements in the alloy, see Table 1 for details.

[0054] Example 4

[0055] A method for preparing anodized aluminum alloy die castings:

[0056] The only difference between this embodiment and embodiment 1 is that the temperature of the die-casting mold used in step S4 is changed to 160° C., and the other conditions remain unchanged.

[0057] Example 5

[0058] A method for preparing anodized aluminum alloy die castings:

[0059] The only difference between this embodiment and embodiment 1 is that the temperature of the die-casting mold used in step S4 is changed to 220° C., and the other conditions remain unchanged.

[0060] Example 6

[0061] A method for preparing anodized aluminum alloy die castings:

[0062] The only difference between this embodiment and the first embodiment is that in step S4, a die-casting mold with a graphite coating on the surface is selected.

[0063] Example 7

[0064] A method for preparing anodized aluminum alloy die castings:

[0065] The only difference between this embodiment and embodiment 1 is that the time for spraying the release agent on the die-casting mold in step S4 is changed to 5 seconds, and the other conditions remain unchanged.

[0066] Example 8

[0067] A method for preparing anodized aluminum alloy die castings:

[0068] The only difference between this embodiment and embodiment 1 is that the time for spraying the release agent on the die-casting mold in step S4 is changed to 15 seconds, and the other conditions remain unchanged.

[0069] Example 9

[0070] A method for preparing anodized aluminum alloy die castings:

[0071] The difference between this embodiment and embodiment 1 is only in step S2, specifically: Al, Zn, Al-Mn master alloy, Al-Ni master alloy and Fe are added into a smelting furnace and heated to 820°C for a first melting, and a mixture is obtained after the raw materials are completely melted; the mixture is cooled to 765°C, and Mg and Al-Zr master alloy are added thereto for a second melting, until all the raw materials are completely melted to obtain a first melt.

[0072] The difference between Comparative Examples 1 to 7 and Example 1 is only the different amounts of each element in the alloy, see Table 1 for details.

[0073] Comparative Example 8

[0074] A method for preparing anodized aluminum alloy die castings:

[0075] The only difference between this comparative example and Example 1 is that in step S4, die casting is started when the melt temperature reaches 700°C instead of 710°C.

[0076] Comparative Example 9

[0077] A method for preparing anodized aluminum alloy die castings:

[0078] The only difference between this comparative example and Example 1 is that in step S4, die casting is started when the melt temperature reaches 725°C instead of 710°C.

[0079] Comparative Example 10

[0080] A method for preparing anodized aluminum alloy die castings:

[0081] The difference between this comparative example and Example 1 is that the setting of the die-casting mold in step S4 is changed, specifically, the draft angle is set to 3° and the corner is set to R2.

[0082] Comparative Example 11

[0083] A method for preparing anodized aluminum alloy die castings:

[0084] The difference between this comparative example and Example 2 is that in step S4, a die-casting mold without any coating on the surface is selected, and no release agent spraying treatment is performed on it. That is, in the case of a high-Zn and high-Mg alloy element formula, a die-casting mold with a coating is not used, so it is difficult to demold and obtain a sample smoothly because the Fe and Si contents in the alloy cannot make up for the melt viscosity caused by high Mg and high Zn.

[0085] Test Method

[0086] Second phase area ratio: tested using an optical microscope, and its evaluation and calculation are based on GB / T 13298-2015 "Methods for Examination of Metal Microstructures".

[0087] Vickers hardness: Tested in accordance with GB / T 4340.1-2009 "Vickers hardness test for metals - Part 1: Test method".

[0088] Tensile strength: tested in accordance with GBT 228.1-2021 national standard.

[0089] White brightness: tested in accordance with national standard GB / T 12967.6-2022. The higher the value, the better, but it is considered that 74 to 82 can meet the requirements.

[0090] Table 1

[0091]

[0092]

[0093] The examples and comparative examples not shown in Table 1 all have the same amount of each element as in Example 1. Based on Table 1, Comparative Example 5 additionally adds 0.5% Cu, Comparative Example 6 additionally adds 0.08% V, and Comparative Example 7 additionally adds 0.5% Cr.

[0094] Table 2

[0095]

[0096]

[0097] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the preparation of anodized aluminum alloy die-castings with high mechanical properties and surface properties, and the material exhibits excellent processing properties during the preparation process.

[0098] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an anodized aluminum alloy die casting, characterized in that: The preparation method comprises: Prepare raw materials: by weight percentage, the composition of the anodized aluminum alloy die casting includes 1.6% to 2.4% Mn, 1.0% to 2.0% Si, 0 to 0.3% Fe, 1.0% to 2.0% Ni, 0.08% to 0.2% Ti, 0.05% to 0.3% Zr, a total of 5.0% to 7.0% Mg and Zn with a Zn / Mg ratio of 1.6 to 1.8, 0 to 0.2% of inevitable impurity elements, and does not contain Cu, V and Cr, the balance is Al, and the raw materials are prepared according to the composition of the anodized aluminum alloy die casting; Melting: Melting the raw materials to obtain a first melt; Refining and degassing: refining and degassing the first melt in sequence to obtain a second melt; Die casting: performing die casting on the second melt at a temperature of 710° C. to 718° C. to obtain an aluminum alloy die casting; Anodizing: performing anodizing surface treatment on the aluminum alloy die casting to obtain the anodized aluminum alloy die casting; The die-casting process is performed using a die-casting mold with a coating on the surface. The die-casting mold has a draft angle of 4° to 5°, and a corner>R2.

2. The preparation method according to claim 1, characterized in that: The temperature of the die-casting mold is 180°C to 200°C; Preferably, the coating is selected from one or more of an aluminum nitride coating, a titanium aluminum nitride coating and a chromium aluminum nitride coating.

3. The preparation method according to claim 1 or 2, characterized in that: Before the die-casting process is performed, a mold release agent is sprayed onto the surface of the die-casting mold, and the spraying time is 8s to 12s.

4. The preparation method according to any one of claims 1 to 3, characterized in that The die-casting thickness of the die-casting process is 2.5 mm to 4.0 mm, and the holding time is 40 s to 60 s.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The smelting comprises: Adding Al, Zn, Al-Mn master alloy, Al-Ni master alloy and Fe into a smelting furnace for first melting at a temperature of 770° C. to 800° C. to obtain a mixture; When the temperature of the mixture is reduced to 750° C. to 759° C., Mg and Al—Zr master alloy are added to the mixture for a second melting to obtain the first melt.

6. The preparation method according to any one of claims 1 to 5, characterized in that The refining and degassing comprises adding a refining agent and a refiner into the first melt, stirring for 3 minutes to 5 minutes, and obtaining the second melt after degassing and standing.

7. An anodized aluminum alloy die casting, characterized in that: The anodized aluminum alloy die casting is prepared by the method for preparing anodized aluminum alloy die casting according to any one of claims 1 to 6.

8. The anodized aluminum alloy die casting according to claim 7, characterized in that: The phase structure of the anodized aluminum alloy die casting includes a matrix phase and a second phase, and the area proportion of the second phase in the phase structure is less than 7.0%; Preferably, the second phase is selected from one or more of Al6Mn phase, MgZn2 phase and AlFeMnZr phase, and the Al6Mn phase also includes a second phase composed of one or more of Fe element, Si element and Ni element.

9. The anodized aluminum alloy die casting according to claim 7 or 8, characterized in that: The Vickers hardness of the anodized aluminum alloy die casting is 75HV to 96HV, and the tensile strength is 210MPa to 260MPa; Preferably, the white brightness of the anodized aluminum alloy die casting is 70-90, and the color difference value is ≤0.

40.

10. Use of the anodized aluminum alloy die casting according to any one of claims 7 to 9 as a part in the fields of aerospace, automobile manufacturing and electronic equipment.

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