Anodic oxidizable die-cast aluminum alloy, preparation method and application thereof

Abstract

The present application provides anodizable die-casting aluminum alloy, its preparation method and application. The anodizable die-casting aluminum alloy comprises Mn 2.0-5.0%, Si 1.5-3.0%, Fe≤0.2%, Mg≤4.0%, Zn≤4.0%, the sum of Mg and Zn content≥3.0%, Ni 0.6-1.2%, Ti 0.02-0.04%, the balance being Al and inevitable impurities, by weight percentage. The ingot of the anodizable die-casting aluminum alloy is melted and kept at 700-740 DEG C, and then the molten is sprayed with a silicon-free release agent, and then the die-casting is carried out using a mold at 160-250 DEG C, the die-casting temperature is 420-500 DEG C higher than the mold temperature, and the anodizable die-casting aluminum alloy is obtained by demolding. The present application can take into account good die-casting yield and anodizing effect, and is suitable for die-casting products with high surface quality requirements.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy, in particular to an anodizable die-casting aluminum alloy, a preparation method and application thereof. BACKGROUND

[0002] The anodizable die-casting aluminum alloy with high surface quality is mainly produced by die-casting, and can be used for producing 3C product accessories, decorative parts, household appliance buttons, television supports and the like. Compared with conventional die-casting alloys, the anodizable die-casting aluminum alloy has good anodization effect and can be colored in various colors; compared with traditional deformed alloys, the anodizable die-casting aluminum alloy shortens traditional hot rolling, cold rolling and annealing processes into one die-casting process, greatly improves production efficiency and reduces production cost.

[0003] In order to ensure the anodization characteristics of the die-casting alloy, the composition of the die-casting alloy is quite different from that of conventional die-casting alloys, especially the Si and Fe contents are low, so that the die-casting alloy is prone to problems such as poor filling property, poor demolding property and easy thermal cracking, which are not prone to occur in conventional die-casting alloys. This is because the Si and Fe contents of conventional die-casting alloys are high, which can effectively improve the fluidity, demolding property and thermal cracking resistance of the alloy. However, these two elements are prone to cause black spots and cracks on the surface of the oxide film during anodization. Therefore, the Si and Fe contents in the anodizable die-casting alloy product with high anodization surface quality requirement are low. This will cause the anodizable die-casting alloy to have poor fluidity, poor demolding property and easy thermal cracking during die-casting production, resulting in low product yield and increased production cost. SUMMARY

[0004] The main purpose of the present application is to provide an anodizable die-casting aluminum alloy, a preparation method and application thereof, so as to solve the problem that the anodizable die-casting alloy in the prior art cannot balance the die-casting yield and anodization effect.

[0005] In order to achieve the above object, according to one aspect of the present invention, a method for preparing an anodized die-cast aluminum alloy is provided, wherein the anodized die-cast aluminum alloy comprises, by weight percentage: Mn 2.0-5.0%, Si 1.5-3.0%, Fe≤0.2%, Mg≤4.0%, Zn≤4.0%, the sum of Mg and Zn content ≥3.0%, Ni The invention discloses an anodizable die-cast aluminum alloy having an anodizable die-casting aluminum alloy and an aluminum alloy having an anodizable die-casting aluminum alloy content of 0.6 to 1.2%, Ti of 0.02 to 0.04%, and a balance of Al and inevitable impurities, wherein the inevitable impurities are ≤ 0.1% and Al ≥ 87.0%. The preparation method comprises the following steps: step S1, melting an ingot of an anodizable die-casting aluminum alloy and keeping the ingot warm at 700 to 740° C. to obtain a melt; step S2, spraying a silicon-free mold release agent on the surface of the melt to obtain a sprayed melt; step S3, die-casting the sprayed melt using a mold, and demolding the mold to obtain an anodizable die-casting aluminum alloy; wherein the temperature of the mold is 160 to 250° C., the die-casting temperature is greater than the mold temperature, and the difference between the die-casting temperature and the mold temperature is 420 to 500° C.

[0006] Furthermore, the anodizable die-cast aluminum alloy includes, by weight percentage: Mn 2.1-3.5%, Si 1.6-2.4%, Fe≤0.1%, Mg≤1.0%, Zn≤3.0%, the sum of Mg and Zn content ≥3.0%, Ni 0.6-0.8%, Ti0.02-0.04%, the balance being Al and unavoidable impurities, unavoidable impurities ≤0.1%, and Al≥90.0%.

[0007] Furthermore, in step S1, melting and heat preservation are performed in a crucible; preferably, the crucible is a graphite crucible or a ceramic crucible.

[0008] Furthermore, in step S2, the spraying time is 2 to 4 seconds.

[0009] Furthermore, in step S3, the temperature of the mold is 180-220°C.

[0010] Furthermore, in step S3, the difference between the die-casting temperature and the mold temperature is 420-480°C.

[0011] Furthermore, in step S3, the sprayed melt is die-casted using a mold and then cooled for 3 to 6 seconds for demolding.

[0012] Furthermore, the surface average grain size of the anodized die-cast aluminum alloy is ≤30 μm, the maximum grain size is ≤60 μm, and the wall thickness is ≥1.8 mm.

[0013] According to another aspect of the present invention, there is provided an anodizable die-cast aluminum alloy, which is obtained using the above-mentioned preparation method of the present invention.

[0014] According to another aspect of the present application, there is provided an anodized die-cast alloy, obtained by anodizing the above-mentioned anodizable die-cast aluminum alloy of the present application; preferably, the anodized die-cast alloy has a surface color difference ≤0.3 and a white brightness ≥80.

[0015] By applying the technical solution of the present application, on the one hand, the flowability of the melt during die casting is improved by controlling the alloy composition and the melt temperature, thereby solving the problem of insufficient flowability of low-Si die-cast aluminum alloy in the case of low Si and Fe elements, and improving the die casting production efficiency and yield; on the other hand, the grain size of the die-cast aluminum alloy is effectively refined by the synergistic control of the melt temperature, the mold temperature, and the difference between the mold and the die-casting temperature, so that the surface grains of the die-cast aluminum alloy are fine and uniform, which is conducive to improving the surface quality during anodizing and reducing problems such as anodizing black spots and cracks. In summary, the method of the present application can significantly improve the flowability of the anodizable die-cast aluminum alloy during die casting and the quality after anodizing, reduce problems such as deformation during die casting and black spots during anodizing, greatly improve the production efficiency of the anodized die-cast aluminum alloy, and can balance good die-cast yield and anodizing effect, which is suitable for die-cast products with high requirements for surface quality. DETAILED DESCRIPTION

[0016] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments.

[0017] As described in the background art of the present application, there is a problem in the prior art that the anodized die-cast alloy cannot balance the die-cast yield and the anodizing effect. In order to solve the above-mentioned problem, in a typical embodiment of the present application, a preparation method of an anodizable die-cast aluminum alloy is provided, which comprises, by weight percentage: Mn 2.0-5.0%, Si 1.5-3.0%, Fe ≤0.2%, Mg ≤4.0%, Zn ≤4.0%, the sum of Mg and Zn content ≥3.0%, Ni 0.6-1.2%, Ti 0.02-0.04%, the balance being Al and unavoidable impurities, the unavoidable impurities ≤0.1%, and Al ≥87.0%; the preparation method comprises the following steps: step S1, melting the ingot of the anodizable die-cast aluminum alloy and heat preserving at 700-740℃ to obtain a melt; step S2, spraying a silicon-free release agent on the surface of the melt to obtain a sprayed melt; step S3, using a mold to die-cast the sprayed melt and demolding to obtain the anodizable die-cast aluminum alloy; wherein the temperature of the mold is 160-250℃, the temperature of the die-casting is higher than the temperature of the mold, and the difference between the temperature of the die-casting and the temperature of the mold is 420-500℃. The unavoidable impurities include one or more of Ca, Na, Cl, K, etc.

[0018] During the research process, the inventors unexpectedly discovered that in the above-mentioned anodizable die-cast aluminum alloy, when the Si content exceeds 3%, the anodizing effect will be seriously affected, and black spots will easily appear on the surface of the oxide film; when the Si content is low, the alloy fluidity is poor. Therefore, the present invention limits the Si content to 1.5-3.0% to achieve a balance between the alloy processing performance and anodizing performance. At the same time, in order to better solve the common problems of insufficient fluidity and difficulty in die-casting filling of low-Si die-casting alloys, the present invention also increases the alloy melt temperature (i.e., the holding temperature during smelting) to improve the fluidity of the melt, and raises the melt temperature to above 700°C to ensure the die-casting filling effect; but it is not too high, which will cause the grain size on the alloy surface to increase and affect the anodizing effect.

[0019] During the research process, the inventors unexpectedly discovered that in the above-mentioned anodizable die-cast aluminum alloy, when the Fe content exceeds 0.2%, surface cracks and black spots are likely to appear after anodization, reducing the surface quality of the oxide film; at the same time, in order to better solve the common demolding problem of low-Fe die-casting alloys, the present invention also adds an appropriate amount of Mn instead of Fe to assist in demolding, thereby improving the die-casting yield of the anodizable alloy.

[0020] During their research, the inventors unexpectedly discovered that the Ni element in the aforementioned anodizable die-cast aluminum alloy releases latent heat of solidification during die-casting solidification, significantly improving the alloy's fluidity and alleviating the lack of fluidity caused by low Si content. Furthermore, the appropriate addition of Ni effectively enhances the brightness of the subsequent anodized film, making the die-cast surface glossier and more aesthetically pleasing. Ti, added in the form of a refiner, AlTiB wire, refines the alloy's grain size, enhances the anodizing effect, and reduces surface color variation.

[0021] In addition, adding Zn and Mg to the die-casting alloy can significantly improve the strength of the alloy without negatively affecting the anodizing effect. However, the addition of Zn and Mg will increase the solid-liquid phase interval, resulting in reduced fluidity. At the same time, excessive Zn or Mg elements will increase the alloy's tendency to hot cracking. Therefore, in order to reduce the hot cracking tendency of die-castings, especially thin-walled die-castings, and ensure higher fluidity to achieve the preparation of complex structural parts, thereby improving the yield of die-castings, Zn and Mg elements should not be added too much. Mg≤4.0%, Zn≤4.0%, and the sum of Mg and Zn content ≥3.0%. Within the above range, the above elements can play a relatively good role in improving the performance of the alloy of the present invention. The aluminum content in the alloy should be above 87.0% to ensure that the alloy has good fluidity.

[0022] Mold temperature is an important parameter in the anodizing die-casting process. When the mold temperature is too low, thermal cracking is likely to occur; when the mold temperature is too high, mold sticking is likely to occur. The present invention limits the temperature of the mold to 160-250°C. This mold temperature can make the grains on the surface of the die-casting finer, which is beneficial to improving the uniformity of the surface color after anodizing. The difference between the die-casting temperature and the mold temperature is controlled at 420-500°C to prevent excessive stress in the die-casting due to excessive temperature difference, resulting in cracks, and at the same time extending the service life of the mold. At the same time, the use of a silicon-free release agent can prevent elements that need to be controlled, such as Si, from being mixed into the melt or adhering to the surface through the release agent during the die-casting production process, reducing the generation of black spots or cracks in the oxide film after anodizing, and effectively improving the yield of anodized parts.

[0023] The above method of the present invention can effectively improve the problems of poor fluidity and difficulty in filling the mold of anodized die-casting alloys, improve the surface quality of anodized die-casting alloys, and is suitable for die-casting products with high surface quality requirements. Compared with the prior art, the method of the present invention can significantly improve the fluidity and anodizing quality of the alloy, reduce deformation during the die-casting process, and reduce the problems of black spots after anodizing. First, the method of the present invention improves the fluidity of the melt during die-casting, solves the problem of insufficient fluidity of low-Si die-casting alloys, and thus greatly improves the die-casting production efficiency and yield rate; second, the method of the present invention effectively refines the grain size of the die-casting by controlling the melt temperature, mold temperature and the temperature difference between the two, and controlling the mold opening time, so that the grains on the surface of the die-casting are small and uniform, which is conducive to improving the subsequent anodizing quality, reducing the problems of anodizing black spots, material lines, etc., making this type of alloy and method suitable for products with high surface quality requirements. In summary, the present invention improves the die-casting production yield rate while improving the anodizing effect through reasonable composition regulation and die-casting process optimization, and facilitates the mass production of anodized die-casting alloy products.

[0024] In order to better improve the effect after anodizing and at the same time improve the yield of die-casting production, in a preferred embodiment, the anodizable die-casting aluminum alloy includes, by weight percentage: Mn 2.1-3.5%, Si 1.6-2.4%, Fe≤0.1%, Mg≤1.0%, Zn≤3.0%, the sum of Mg and Zn content ≥3.0%, Ni 0.6-0.8%, Ti0.02-0.04%, the balance is Al and unavoidable impurities, unavoidable impurities ≤0.1%, Al ≥90.0%; preferably, in the anodizable die-casting aluminum alloy, the sum of Si and Fe content is 1.55-3.05%; the sum of Mg and Zn content is 3.0-7.0%, thereby better reducing surface black spots after anodizing and further improving surface quality.

[0025] In a preferred embodiment, in step S1, melting and heat preservation are carried out in a crucible; preferably, the crucible is a graphite crucible or a ceramic crucible, which has a smooth surface and is easier to clean, thereby reducing the furnace cleaning step before each die-casting and further improving production efficiency; at the same time, the surface of the graphite crucible or the ceramic crucible is generally coated, which can further effectively prevent the Fe element from entering and contaminating the melt under high temperature conditions, thereby further improving production efficiency and yield.

[0026] To further improve the uniformity of the melt surface spraying, in a preferred embodiment, the spraying time in step S2 is 2 to 4 seconds, thereby achieving a more complete and uniform spraying. The silicon-free release agent can be sprayed on the melt surface or coated on the mold surface, which is well understood by those skilled in the art and will not be further described here.

[0027] During the die-casting process, the mold can be cooled by a cooling water pipe. In a preferred embodiment, in step S3, the temperature of the mold is 180-220°C, which can better prevent the mold from thermal cracking or sticking during the die-casting process, further refine the alloy grains, and improve the surface quality after anodizing.

[0028] In a preferred embodiment, in step S3, the difference between the die casting temperature and the mold temperature is 420-480° C. This can extend the mold life while preventing the alloy part from having an excessively high surface temperature, thereby further improving the grain distribution of the alloy part and enhancing the anodizing effect.

[0029] In a preferred embodiment, in step S3, after the sprayed melt is die-cast using a mold, it is cooled for 3 to 6 seconds for demolding, which can further prevent the die-cast part from being kept warm in the mold for too long, causing the surface grain size to grow and affecting the anodizing effect.

[0030] The present invention further improves the surface quality of the alloy after anodization by regulating the surface grain size. In a preferred embodiment, the surface average grain size of the anodized die-cast aluminum alloy is ≤30 μm, the maximum grain size is ≤60 μm, and the wall thickness is ≥1.8 mm. The smaller the surface grain size of the die-cast alloy and the more uniform the grain size, the better the anodization effect. When the grain size in some areas is too large, grain defects may occur after anodization. When the wall thickness of the die-cast alloy is thicker, the filling performance of the alloy during the die-casting process can be further improved, making the alloy preparation more convenient.

[0031] In another typical embodiment of the present invention, an anodizable die-cast aluminum alloy is provided, which is obtained using the above-mentioned preparation method of the present invention. The anodized aluminum alloy has a more reasonable grain distribution, a high die-casting yield, and a high surface quality after anodization.

[0032] In another exemplary embodiment of the present invention, an anodized die-cast alloy is provided, obtained by anodizing the anodizable die-cast aluminum alloy described above. Preferably, the anodized die-cast alloy has a surface color difference of ≤0.3 and a white brightness of ≥80, meaning that the surface color is uniform and easily colored in various bright colors, making it suitable for various die-cast products requiring high surface quality. Conventional methods in the art can be used for the anodization process, which is readily understood by those skilled in the art and will not be further elaborated upon here.

[0033] Typical, but not limiting, anodizable die casting aluminum alloys include, by weight percentage, Mn of 2.0%, 2.1%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0% or a range consisting of any two of them; Si of 1.5%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0% or a range consisting of any two of them; Fe of 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2% or a range consisting of any two of them; Mg of 1.0%, 1.5%, 2.0%, 2.5% or a range consisting of any two of them , 3.0%, 3.5%, 4.0% or a range consisting of any two of them; Zn is 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0% or a range consisting of any two of them; Ni is 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2% or a range consisting of any two of them; Ti is 0.02%, 0.03%, 0.04% or a range consisting of any two of them; Al is 87.0%, 88.0%, 89.0%, 90.0%, 91.0%, 92.0%, 93.0% or a range consisting of any two of them.

[0034] Typically but not limitatively, in step S1, the holding temperature of the ingot of the anodizable die-casting aluminum alloy after melting is 700°C, 705°C, 710°C, 715°C, 720°C, 725°C, 730°C, 735°C, 740°C or a range consisting of any two of them.

[0035] Typically but not limitatively, in step S3, the temperature of the mold is 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, or a range consisting of any two of them; the difference between the die-casting temperature and the mold temperature is 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, or a range consisting of any two of them.

[0036] The present application is further described in detail below with reference to specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in this application.

[0037] Unless otherwise specified, the silicone-free release agent used in the following examples and comparative examples is KZY690 silicone-free release agent.

[0038] The aluminum alloy compositions of the following examples and comparative examples are shown in Table 1.

[0039] Example 1

[0040] (1) Melting: The melting and holding of the anodized die-cast alloy ingots are carried out in a graphite crucible at a holding temperature of 700°C;

[0041] (2) Spraying of silicone-free release agent: Use silicone-free release agent, spraying time 4s;

[0042] (3) Die casting: cooling water is used for mold temperature control, the mold temperature is 220℃, and the difference between the die casting temperature and the mold temperature is 480℃;

[0043] (4) Demolding: After die casting, open the mold after cooling for 3 seconds and take out the die casting with a wall thickness of 2mm.

[0044] Example 2

[0045] (1) Melting: The melting and holding of the anodized die-cast alloy ingots are carried out in a graphite crucible at a holding temperature of 740°C.

[0046] (2) Spraying silicone-free release agent: Use silicone-free release agent, spraying time 3.5s;

[0047] (3) Die casting: Use cooling water to control the mold temperature, the mold temperature is 250℃, and the difference between the die casting temperature and the mold temperature is 490℃; (4) Demolding: After the die casting is completed, open the mold after cooling for 4s and take out the die casting. The wall thickness is 2mm.

[0048] Example 3

[0049] (1) Melting: The melting and holding of the anodized die-cast alloy ingots are carried out in a graphite crucible at a holding temperature of 730°C.

[0050] (2) Spraying of silicone-free release agent: Use silicone-free release agent, spraying time 2s;

[0051] (3) Die casting: Use cooling water to control the mold temperature, the mold temperature is 230℃, and the difference between the die casting temperature and the mold temperature is 500℃; (4) Demolding: After the die casting is completed, open the mold after cooling for 4s and take out the die casting. The wall thickness is 2mm.

[0052] Example 4

[0053] (1) Melting: The melting and holding of the anodized die-casting alloy ingot were carried out in a graphite crucible, and the holding temperature was 730°C;

[0054] (2) Spraying silicon-free release agent: A silicon-free release agent was used, and the spraying time was 3 s;

[0055] (3) Die casting: Cooling water was used for mold temperature control, and the mold temperature was 200°C. The difference between the die casting temperature and the mold temperature was 450°C;

[0056] Examples 5 to 9

[0057] Examples 5 to 9 differ from Example 4 in that the aluminum alloy composition is different.

[0058] Example 10

[0059] Example 10 differs from Example 4 in that the mold temperature during die casting was 160°C.

[0060] Example 11

[0061] Example 11 differs from Example 4 in that the mold temperature during die casting was 180°C.

[0062] Example 12

[0063] Example 12 differs from Example 4 in that the difference between the die casting temperature and the mold temperature was 420°C.

[0064] Comparative Example 1

[0065] (1) Melting: The melting and holding of the anodized die-casting alloy ingot were carried out in a graphite crucible, and the holding temperature was 720°C;

[0066] (2) Spraying silicon-free release agent: A silicon-free release agent was used, and the spraying time was 3 s;

[0067] (3) Die casting: Cooling water was used for mold temperature control, and the mold temperature was 220°C. The difference between the die casting temperature and the mold temperature was 500°C;

[0068] (4) Demolding: After die casting, the mold was opened after cooling for 4 s, and the die casting was removed.

[0069] Comparative Example 2

[0070] (1) Melting: The melting and holding of the anodized die-casting alloy ingot were carried out in a graphite crucible, and the holding temperature was 690°C;

[0071] (2) Spraying silicon-free release agent: A silicon-free release agent was used, and the spraying time was 3 s;

[0072] (3) Die casting: cooling water is used for mold temperature control, the mold temperature is 140°C, and the difference between the die casting temperature and the mold temperature is 550°C;

[0073] (4) Demolding: After die casting is completed, open the mold after cooling for 3 seconds and take out the die casting.

[0074] Comparative Example 3

[0075] (1) Melting: The melting and holding of the anodized die-cast alloy ingots are carried out in a graphite crucible at a holding temperature of 760°C.

[0076] (2) Spraying of silicone-free release agent: Use silicone-free release agent, spraying time 2s;

[0077] (3) Die casting: Use cooling water for mold temperature control, the mold temperature is 230℃, and the difference between the die casting temperature and the mold temperature is 530℃;

[0078] (4) Demolding: After die casting is completed, open the mold after cooling for 5 seconds and take out the die casting.

[0079] The die castings of the above embodiments and comparative examples were ground and polished before being anodized using a conventional anodizing process comprising ash removal, neutralization, chemical polishing, anodizing, dyeing, and sealing, with water washing between each step.

[0080] The alloy die castings of the above examples and comparative examples were subjected to performance tests, and the measured performance data are shown in Table 2.

[0081] Test method:

[0082] Fluidity (relative to ADC12 aluminum alloy): Alloy melts were poured into spiral fluidity test molds. After solidification, the molds were opened and samples were removed. The lengths were measured with a tape measure and recorded. The average of the three castings was used as the fluidity value for the alloy. The test results for all alloy compositions were compared with those of the ADC12 alloy, and the relative values ​​were used as the fluidity value for the alloy.

[0083] Hot cracking tendency: visual observation.

[0084] Whether the mold is sticking: Use the die-casting machine to test and observe whether demolding is difficult.

[0085] Average grain size: GB / T 6394-2017 Metal average grain size determination method.

[0086] Maximum grain size: GB / T 6394-2017 Metal average grain size determination method. This national standard method is used to count the grains and select the maximum value as the maximum grain size.

[0087] Color difference value: GB / T 12967.6-2022 Aluminum and aluminum alloy anodic oxidation film and organic polymer film test method Part 6: color difference and appearance quality.

[0088] White brightness: GB / T 12967.6-2022 Aluminum and aluminum alloy anodic oxidation film and organic polymer film test method Part 6: color difference and appearance quality of color difference measurement method, taking the average value of L value as the numerical value of white brightness.

[0089] Table 1

[0090]

[0091] Table 2

[0092]

[0093]

[0094] From Table 2, compared with the comparative example, the alloy fluidity of each embodiment of the present application is more than 60% of ADC12, reaching the requirements of die casting filling; there is no tendency of thermal cracking; it is not easy to stick to the mold during die casting; the color difference value is less than or equal to 0.3, the white brightness is greater than or equal to 80, reaching the appearance requirements of anodic oxidation products; the average grain size is less than or equal to 30um, the maximum grain size is less than or equal to 60um, and the surface organization is uniform and fine.

[0095] From the above, the method of the present application can significantly improve the fluidity of the anodizable die casting aluminum alloy during the die casting process and the quality after anodizing, reduce the problems of deformation during die casting and black spots during anodizing, and greatly improve the production efficiency of the anodizable die casting aluminum alloy. Good die casting yield and anodizing effect can be considered. In addition, it can be seen that when each process parameter is within the scope of the present application, the comprehensive performance of the alloy is better

[0096] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing anodizable die-cast aluminum alloy, characterized in that: The anodizable die-cast aluminum alloy comprises, by weight percentage, Mn 2.1-3.5%, Si 1.5-3.0%, Fe≤0.2%, Mg≤4.0%, Zn≤4.0%, the sum of Mg and Zn content ≥3.0%, Ni 0.6-1.2%, Ti 0.02-0.04%, the balance being Al and unavoidable impurities, unavoidable impurities ≤0.1%, and Al ≥87.0%. The preparation method comprises the following steps: Step S1, melting an ingot of anodizable die-cast aluminum alloy and keeping the temperature at 730-740° C. to obtain a melt; Step S2, spraying a silicon-free release agent on the surface of the melt to obtain a sprayed melt; Step S3, die-casting the sprayed melt using a mold, and demolding to obtain the anodizable die-cast aluminum alloy; The temperature of the mold is 160-250° C., the die-casting temperature is greater than the temperature of the mold, and the difference between the die-casting temperature and the mold temperature is 420-500° C. The surface average grain size of the anodizable die-cast aluminum alloy is ≤30 μm, the maximum grain size is ≤60 μm, and the wall thickness is ≥1.8 mm.

2. The preparation method according to claim 1, characterized in that The anodizable die-cast aluminum alloy comprises, by weight percentage, Mn 2.1-3.5%, Si 1.6-2.4%, Fe≤0.1%, Mg≤1.0%, Zn≤3.0%, the sum of Mg and Zn content ≥3.0%, Ni 0.6-0.8%, Ti 0.02-0.04%, the balance being Al and unavoidable impurities, unavoidable impurities ≤0.1%, and Al≥90.0%.

3. The preparation method according to claim 1 or 2, characterized in that In the step S1, the melting and the heat preservation are performed in a crucible.

4. The preparation method according to claim 3, characterized in that The crucible is a graphite crucible or a ceramic crucible.

5. The preparation method according to claim 1 or 2, characterized in that In step S2, the spraying time is 2 to 4 seconds.

6. The preparation method according to claim 1 or 2, characterized in that In step S3, the temperature of the mold is 180-220°C.

7. The preparation method according to claim 1 or 2, characterized in that In step S3, the difference between the die-casting temperature and the mold temperature is 420-480°C.

8. The preparation method according to claim 1 or 2, characterized in that In the step S3, the sprayed melt is die-casted using the mold, and then cooled for 3 to 6 seconds to perform the demolding.

9. An anodizable die-cast aluminum alloy, characterized in that: The method according to any one of claims 1 to 8 is used.

10. An anodic oxidation die-casting alloy, characterized in that: The anodizable die-cast aluminum alloy according to claim 9 is used for anodization.

11. The anodic oxidation die-casting alloy according to claim 10, characterized in that: The surface color difference of the anodized die-casting alloy is ≤0.3, and the white brightness is ≥80.

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