CN115522104B - Anodic oxidation die-casting aluminum alloy and preparation method thereof - Google Patents

Abstract

The invention discloses an anodic oxidation die-casting aluminum alloy and a preparation method thereof, wherein the aluminum alloy comprises the following components in percentage by mass: 2.0 to 7.0 percent of Si, 2.0 to 7.0 percent of Zn, 1.5 to 3.5 percent of Mn, 0 to 2.0 percent of Mg, 0.1 to 0.2 percent of Ti, 0.05 to 0.2 percent of RE and less than or equal to 0.3 percent of the sum of the mass percent of all impurities, wherein the mass percent of the impurity Fe is less than 0.2 percent, and the balance is Al; the RE element is La and Ce. The anodic oxidation die-casting aluminum alloy has high mechanical strength, excellent surface quality and good fluidity, and can meet the technical requirements of complex structural parts with low appearance color and luster and higher requirements on color difference.

Description

Anodic oxidation die-casting aluminum alloy and preparation method thereof

Technical Field

The invention relates to the technical field of aluminum alloy and casting thereof, in particular to an anodic oxidation die-casting aluminum alloy and a preparation method thereof.

Background

Along with the improvement of the living standard of people, the demand of the anodized decoration product is gradually increased, and the requirements on color and appearance are gradually diversified, such as an intelligent door lock, a beauty instrument, a household appliance accessory and the like, but the anodized aluminum product is mainly machined by an aluminum section machine at present, so that the problems of long flow, low yield, long CNC machining time and the like are solved, and the aluminum alloy decoration product has no cost competitive advantage. The die-casting product has the advantages of short flow, suitability for mass production, low production cost and suitability for market development, but in order to obtain excellent casting performance, the existing die-casting aluminum alloy mainly takes Si as a main alloy element, the problems of surface graying, discontinuous oxide film and the like can occur after the traditional Al-Si alloy is anodized, the existing die-casting aluminum alloy can only be used for black anodizing, other colors are difficult to realize, and the existing die-casting aluminum alloy product cannot be used as an anodized decorative part.

The anodic oxidation die-casting aluminum alloy developed at home and abroad at present is mainly Al-Mn series alloy, and although the anodic oxidation effect is better, the Al-Mn series alloy has extremely low fluidity and is difficult to be applied to complex die-casting products; and because the alloying degree is low, the strength of the alloy is far lower than that of Al-Si alloy and wrought alloy, and the alloy is difficult to replace the wrought alloy to be applied to actual products.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the anodic oxidation die-casting aluminum alloy with high strength and good die-casting performance and the preparation method thereof.

The invention is realized by the following technical scheme.

An anodic oxidation die-casting aluminum alloy is characterized in that the aluminum alloy comprises the following components in percentage by mass: 2.0 to 7.0 percent of Si, 2.0 to 7.0 percent of Zn, 1.5 to 3.5 percent of Mn, 0 to 2.0 percent of Mg, 0.1 to 0.2 percent of Ti, 0.05 to 0.2 percent of RE and less than or equal to 0.3 percent of the sum of the mass percent of all impurities, wherein the mass percent of the impurity Fe is less than 0.2 percent, and the balance is Al; the RE element is La and Ce.

Further, the area ratio of a second phase of a metallurgical structure of the cast ingot prepared from the aluminum alloy with the components is 8-25%; the size of the second phase of the metallographic structure of the die casting prepared by adopting the aluminum alloy with the components is less than 20 microns, and the size of the second phase of the metallographic structure of the ingot prepared by adopting the aluminum alloy with the components is less than 40 microns.

Further, the second phase comprises: alFeMnSi phase, al₆ Mn phase, alSi eutectic phase.

Further, the secondary dendrite arm spacing of the metallographic structure of the ingot prepared by using the aluminum alloy with the components is less than 30 micrometers.

Further, the tensile strength of the cast rod prepared by adopting the aluminum alloy with the components is more than 180MPa.

Further, the aluminum alloy comprises the following components in percentage by mass: 2.0 to 5.0 percent of Si, 2.0 to 5.0 percent of Zn, 1.6 to 2.3 percent of Mn, 0.7 to 1.5 percent of Mg, 0.1 to 0.2 percent of Ti, 0.1 to 0.2 percent of RE and less than or equal to 0.1 percent of the sum of the mass percent of all impurities, wherein the impurity Fe is less than 0.05 percent, and the balance of Al.

The preparation method of the anodic oxidation die-casting aluminum alloy is characterized by comprising the following steps of:

(1) Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot, an Al-Mn intermediate alloy and an Al-Si intermediate alloy into a smelting furnace, heating to 780-800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, pressing pure Mg into the smelting furnace until the pure Mg is completely melted, keeping the temperature for 30min, pressing rare earth elements into the smelting furnace and completely melting to obtain a melted material;

(2) Adding a refining agent and a refiner into the smelting furnace, stirring and degassing for 15-20 min, standing for 15-20 min, and skimming to obtain a skimmed sample;

(3) When the temperature of the slag-removed sample reaches 680-720 ℃, casting to obtain an anodic oxidation die-casting aluminum alloy casting blank; wherein the temperature of the casting mould is 180-220 ℃;

(4) Carrying out die-casting forming, CNC (computer numerical control) processing and surface sand blasting on the obtained aluminum alloy casting blank, and then carrying out anodic oxidation treatment, wherein the anodic oxidation treatment comprises the following steps: primary washing, anodic oxidation, secondary washing, dyeing and hole sealing.

Further, the adding amount of the refining agent in the step (2) is 1.5-3 per mill of the sum of the mass of the raw materials (namely, the raw materials comprise industrial pure Al ingots, industrial pure Zn ingots, al-Mn intermediate alloys, al-Si intermediate alloys, pure Mg and rare earth elements) added in the step (1); the addition amount of the refiner is 1-3 per mill of the sum of the mass of the raw materials added in the step (1).

Further, the refining agent in the step (2) is a blocky or granular sodium-free refining agent.

Further, in the step (2), the refiner is Al-Ti-B or Al-Ti-C wire.

Further, the cooling rate of the casting in the step (4) in the compression casting process is more than 200 ℃/s.

The invention has the beneficial technical effects that:

(1) The mechanical property of the aluminum material is improved. The die-casting aluminum alloy capable of being anodized is added with Zn, mg, mn, si and RE elements, and the addition of a large amount of Zn elements effectively improves the solid solution strengthening effect of the alloy and improves Al₆ The size and distribution of the Mn coarse phase obviously improve the strength and the elongation of the alloy.

(2) The die casting performance of the alloy is improved. The addition of a proper amount of Si element is matched with rare earth elements for modification, so that the size and the appearance of eutectic silicon can be effectively improved, the strength and the elongation of the alloy are ensured, the fluidity of the alloy is greatly improved, the alloy can be applied to a complex structural member, the size of a Si-containing phase is controlled, and the influence on anodic oxidation is reduced.

(3) The anodic oxidation process is simple, and the surface quality is uniform. The die-casting aluminum alloy does not need acid washing and alkali washing before anodic oxidation, the process is simplified, the operation is convenient, fine grain structures and fine dispersed second phases are formed on the surface, compared with other high-Si anodic oxidation die-casting alloys, an oxide film which is uniform and continuous and has the color difference value delta E smaller than 0.5 can be formed after anodic oxidation, a finished product is easy to dye, but the color is dark, and the die-casting aluminum alloy can be applied to appearance decorating parts with low requirements on surface color.

(4) The anodic oxidation die-casting aluminum alloy has high mechanical property, good surface quality and excellent die-casting property, and can well meet the technical requirements of appearance structural members on aluminum materials. The method is simple to operate and easy for large-scale production.

Drawings

FIG. 1 is a metallographic image of the microstructure of an ingot of the aluminum alloy of example 2;

FIG. 2 is a metallographic image of the microstructure of an aluminum alloy ingot of comparative example 1;

FIG. 3 is a metallographic image of the microstructure of an aluminum alloy die cast part of example 3.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

The invention relates to an anodic oxidation die-casting aluminum alloy which comprises the following components in percentage by mass: 2.0 to 7.0 percent of Si, 2.0 to 7.0 percent of Zn, 1.5 to 3.5 percent of Mn, 0 to 2.0 percent of Mg, less than 0.2 percent of Fe, 0.1 to 0.2 percent of Ti, 0.05 to 0.2 percent of RE (La, ce), less than or equal to 0.3 percent of the sum of all impurities including Fe by mass, and the balance of Al.

The area proportion of the second phase of the metallographic structure of the ingot prepared by the aluminum alloy with the components is 8-25%, the size of the second phase of the metallographic structure of the die casting prepared by the aluminum alloy with the components is less than 20 mu m, the size of the second phase of the metallographic structure of the ingot prepared by the aluminum alloy with the components is less than 40 mu m, and the second phase comprises AlFeMnSi phase and Al phase₆ Mn phase, alSi eutectic phase. The secondary dendrite arm spacing of the metallurgical structure of the cast ingot prepared by the aluminum alloy with the components is less than 30 μm. The tensile strength of the cast rod prepared by the aluminum alloy with the components is more than 180MPa. Preferably, the anodic oxidation die-casting aluminum alloy comprises the following components in percentage by mass: 2 to 5 percent of Si, 2 to 5 percent of Zn, 1.6 to 2.3 percent of Mn, 0.7 to 1.5 percent of Mg, less than 0.05 percent of Fe, 0.1 to 0.2 percent of Ti, 0.1 to 0.2 percent of RE (La, ce), less than or equal to 0.1 percent of the sum of all impurities including Fe in percentage by mass, and the balance of Al. The cooling rate of the aluminum alloy in the die casting process is more than 200 ℃/s. The area ratio of the second phase of the cast ingot structure prepared by the aluminum alloy with the components is 8-15%, the size of the second phase of the die casting metallographic structure prepared by the aluminum alloy with the components is less than 20 mu m, the maximum size of the second phase of the cast ingot structure prepared by the aluminum alloy with the components is less than 30 mu m, and the secondary dendrite spacing of the cast ingot structure prepared by the aluminum alloy with the components is less than 25 mu m. The tensile strength of the casting prepared from the aluminum alloy with the components is more than 180MPa. The color difference value delta E is less than 0.3. The strength of the alloy is improved by controlling the area ratio of the second phase structure of the alloy; the maximum size of the second phase is controlled, the elongation of the alloy is ensured, the color difference between the second phase and the matrix is reduced, and the uniform color difference of the alloy after anodic oxidation is ensured.

The preparation method of the anodic oxidation die-casting aluminum alloy comprises the following steps:

(1) Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot, an Al-Mn intermediate alloy and an Al-Si intermediate alloy into a smelting furnace, heating to 780-800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, pressing pure Mg into the smelting furnace until the pure Mg is completely melted, preserving heat for 30min, pressing rare earth elements into the smelting furnace and fully melting to obtain a melted material;

(2) Adding a refining agent and a refiner into the smelting furnace, stirring and degassing for 15-20 min, standing for 15-20 min, and skimming to obtain a skimmed sample;

(3) When the temperature of the slag removed sample reaches 680-720 ℃, casting to obtain an anodic oxidation die-casting aluminum alloy casting blank; the temperature of the casting mould is 180-220 ℃. The refining agent is a blocky or granular sodium-free refining agent, and the refiner is Al-Ti-B/Al-Ti-C wire and the like. The addition amount of the refining agent is 1.5-3 per mill of the sum of the mass of the raw materials added in the step (1); the addition amount of the refiner is 1-3 per mill of the total mass of the raw materials added in the step (1).

(4) After die-casting forming, CNC processing and surface sand blasting are carried out on an aluminum alloy casting blank, anodic oxidation treatment is carried out, and the anodic oxidation treatment step comprises the following steps: primary washing, anodic oxidation, secondary washing, dyeing and hole sealing.

The anodic oxidation die-casting aluminum alloy material provided by the invention optimizes chemical components and a second phase, and a proper amount of Mn, zn, mg, si, ti and RE elements are added into the aluminum alloy, so that the alloy obtains a fine and uniformly distributed second phase structure, and has good die-casting performance, anodic oxidation performance and mechanical property. The mass percentage of Zn element is controlled to be 2.0-7.0%, the mass percentage of Mg element is controlled to be 0-2.0%, the cooling rate is more than 200 ℃/s in the die-casting process, zn and Mg can be completely dissolved in the matrix under the die-casting condition, the solid solution strengthening effect is achieved, and the mechanical property and the anodic oxidation effect are improved; meanwhile, the Zn element is controlled to be less than 7.0 percent, the Zn is ensured to be completely dissolved in the matrix, and a coarse second phase cannot be precipitated to influence the mechanical property; on the other hand, the addition of Zn and Mg can effectively change Al₆ The size of the Mn phase is changed from a coarse rhombohedral phase to a fine spherical phase, which is beneficial to improving the elongation and the strength of the alloy. The mass percentage content of Si element is controlled to be 2.0-7.0%, so that large-size primary crystal silicon phase is prevented from being formed in the die-casting process, the anodic oxidation effect is prevented from being influenced, the fluidity of the alloy can be effectively improved by proper amount of Si, the die-casting temperature of the alloy is reduced, and the die-casting performance of the alloy is obviously improved; meanwhile, with the increase of the content of the Si element, the strength of the alloy is gradually improved, a small amount of Al-Si eutectic phase is still generated in the die-casting process, and a proper amount of rare earth element is added, so that the Al-Si eutectic phase is deteriorated and is changed into a fine spherical phase from a coarse rodlike second phase, and the deterioration effect of the Al-Si relative to the anodic oxidation effect is favorably reduced. By regulating and controlling the components and the casting process, the area ratio of the second phase of the ingot casting structure of the aluminum alloy is 8-25%, the size of the second phase of the die casting structure is less than 20 microns, and the size of the second phase of the ingot casting structure is less than 40 microns, so that on one hand, the deterioration effect of the large-size second phase on the mechanical property of the alloy is reduced, and the alloy has higher strength, and on the other hand, the diamond-shaped large-size Al-Mn phase and the rod-shaped large-size Al-Si phase are not easy to generate in the die casting process of the alloy, so that the second phase in the die casting is distributed more finely and uniformly, the elongation of the alloy is improved, and simultaneously, the potential difference between the second phase and a matrix in the die casting is reduced, the produced oxide film is more uniform and continuous, the color difference value is lower, and the anodic oxidation performance is improved. The secondary dendrite spacing of the ingot casting structure of the alloy is less than 30 micrometers, and the main purpose is to control the grain size and prevent the increase of chromatic aberration caused by uneven grain size of a die casting product and the influence on the anodic oxidation effect. Because Fe can seriously affect the strength and the anodic oxidation effect of the alloy, mn is added to replace Fe, so that the die-casting alloy has better demolding property, and meanwhile, the content of Mn is controlled to be near a eutectic point, so that the fluidity of the alloy is ensured. The addition of Ti is beneficial to grain refinement, and can improve the flow property and the anodic oxidation property of the alloy. The invention reduces the generation of impurity phase in the alloy and ensures the uniformity and continuity of the anodic oxide film by controlling the content of total impurities in the alloy to be less than or equal to 0.3 percent. The anodic oxidation die-casting aluminum alloy material provided by the invention is added withA large amount of Zn elements fully embody the solid solution strengthening effect, and simultaneously play a role in refining the Al-Mn phase, so that the alloy strength and the anodic oxidation effect are simultaneously improved; by adding a proper amount of Si element and rare earth element, the Al-Si phase can be refined while the alloy strength and the die-casting performance are improved, the adverse effects of the coarse Al-Si on the anodic oxidation and the elongation are reduced, and the strength, the elongation, the anodic oxidation performance and the die-casting performance of the anodic oxidation die-casting alloy are improved.

The present invention will be described in detail below with reference to examples and comparative examples.

Example 1

Placing raw materials of industrial pure Al ingot, industrial pure Zn ingot, al-Mn intermediate alloy and Al-Si intermediate alloy into a smelting furnace, heating to 800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, then pressing pure Mg into the smelting furnace until the pure Mg is completely melted, keeping the temperature for 30min, pressing rare earth elements into the smelting furnace and fully melting to obtain the melted materials.

And adding a sodium-free refining agent and an Al-Ti-B refiner into the smelting furnace, stirring and degassing for 15min, standing for 15min after degassing is finished, and slagging off to obtain a slagging-off sample. The addition amount of the sodium-free refining agent is 2 per mill of the mass sum of the raw materials, and the addition amount of the Al-Ti-B refiner is 3 per mill of the mass sum of the raw materials.

When the temperature of the slag-removed sample reaches 720 ℃, casting to obtain a die-casting aluminum alloy casting blank, wherein the temperature of a casting die is 200 ℃;

carrying out die-casting forming, CNC (computerized numerical control) treatment and surface sand blasting on an aluminum alloy casting blank obtained by casting, and then carrying out anodic oxidation treatment, wherein the anodic oxidation treatment comprises the following steps: and carrying out primary washing, anodic oxidation, secondary washing, dyeing and hole sealing to obtain the anodic oxidation die-casting aluminum alloy.

The anodic oxidation die-casting aluminum alloy comprises the following components in percentage by mass: si 2.19%, zn 2.84%, mn 1.67%, mg 0.82%, fe 0.04%, ti 0.11%, RE 0.18%, the total amount of all impurities including Fe 0.11%, and the balance of Al.

Example 2

Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot, an Al-Mn intermediate alloy and an Al-Si intermediate alloy into a smelting furnace, heating to 780 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, pressing pure Mg into the smelting furnace until the pure Mg is completely melted, keeping the temperature for 30min, pressing rare earth elements into the smelting furnace, and fully melting to obtain a melted material.

And adding a sodium-free refining agent and an Al-Ti-C refiner into the smelting furnace, stirring and degassing for 17min, standing for 20min after degassing is finished, and slagging off to obtain a slagging-off sample. The addition amount of the sodium-free refining agent is 3 per mill of the mass sum of the raw materials, and the addition amount of the Al-Ti-C refiner is 2 per mill of the mass sum of the raw materials.

When the temperature of the slag-removed sample reaches 700 ℃, casting to obtain an anodic oxidation die-casting aluminum alloy casting blank, wherein the temperature of a casting die is 220 ℃;

carrying out die-casting forming, CNC (computerized numerical control) treatment and surface sand blasting on an aluminum alloy casting blank obtained by casting, and then carrying out anodic oxidation treatment, wherein the anodic oxidation treatment comprises the following steps: and carrying out primary washing, anodic oxidation, secondary washing, dyeing and hole sealing to obtain the anodic oxidation die-casting aluminum alloy.

The anodic oxidation die-casting aluminum alloy comprises the following components in percentage by mass: 4.33% of Si, 3.52% of Zn, 1.56% of Mn, 0.77% of Mg, 0.08% of Fe, 0.13% of Ti, 0.16% of RE, 0.13% of the total amount of all impurities including Fe and the balance of Al. FIG. 1 is a gold phase diagram of the microstructure of an anodized die cast aluminum alloy ingot of example 2.

Example 3

Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot, an Al-Mn intermediate alloy and an Al-Si intermediate alloy into a smelting furnace, heating to 790 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, pressing a pure Mg alloy into the smelting furnace until the pure Mg is completely melted, keeping the temperature for 30min, pressing rare earth elements into the smelting furnace and fully melting to obtain a melted material.

And adding a sodium-free refining agent and an Al-Ti-B refiner into the smelting furnace, stirring and degassing for 20min, standing for 17min after degassing is finished, and slagging off to obtain a slagging-off sample. The addition amount of the sodium-free refining agent is 3 per mill of the mass sum of the raw materials, and the addition amount of the Al-Ti-B refiner is 3 per mill of the mass sum of the raw materials.

When the temperature of the slag-removed sample reaches 680 ℃, casting to obtain an anodic oxidation die-casting aluminum alloy casting blank, wherein the temperature of a casting mold is 180 ℃;

carrying out die-casting forming, CNC (computerized numerical control) treatment and surface sand blasting on an aluminum alloy casting blank obtained by casting, and then carrying out anodic oxidation treatment, wherein the anodic oxidation treatment comprises the following steps: and carrying out primary washing, anodic oxidation, secondary washing, dyeing and hole sealing to obtain the anodic oxidation die-casting aluminum alloy.

The anodic oxidation die-casting aluminum alloy comprises the following components in percentage by mass: 6.13% of Si, 6.34% of Zn, 1.52% of Mn, 1.79% of Mg, 0.05% of Fe, 0.13% of Ti, 0.19% of RE, 0.23% of the total amount of all impurities including Fe and the balance of Al.

Comparative example 1

Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot and an Al-Mn intermediate alloy into a smelting furnace, heating to 800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, and pressing pure Mg alloy into the smelting furnace until the pure Mg is completely melted to obtain the melted material.

And adding a sodium-free refining agent and Al-Ti-B/Al-Ti-C and other refiners into the smelting furnace, stirring and degassing for 15min, standing for 15min after degassing is finished, and slagging off to obtain a slagging-off sample. The addition amount of the sodium-free refining agent is 3 per mill of the mass of the raw materials, and the addition amount of the refiner such as Al-Ti-B/Al-Ti-C is 3 per mill of the mass of the raw materials.

When the temperature of the sample after slagging off reaches 740 ℃, casting, wherein the temperature of a casting mold is 200 ℃, and the anodized die-cast aluminum alloy is obtained after casting, and comprises the following components in percentage by mass: 1.95% of Zn, 1.90% of Mn, 0.75% of Mg, 0.06% of Fe, 0.13% of Ti and the balance of Al. FIG. 2 is a metallographic gold image of the microstructure of an aluminum alloy ingot of comparative example 1.

Comparative example 2

Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot and an Al-Mn intermediate alloy into a smelting furnace, heating to 800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, and pressing pure Mg alloy into the smelting furnace until the pure Mg is completely melted to obtain the melted material.

And adding a sodium-free refining agent and Al-Ti-B/Al-Ti-C and other refiners into the smelting furnace, stirring and degassing for 15min, standing for 15min after degassing is finished, and slagging off to obtain a slagging-off sample. The addition amount of the sodium-free refining agent is 2 per mill of the mass of the raw materials, and the addition amount of the refiner such as Al-Ti-B/Al-Ti-C is 3 per mill of the mass of the raw materials.

When the temperature of the sample after slagging off reaches 740 ℃, casting, wherein the temperature of a casting mold is 200 ℃, and the anodized die-cast aluminum alloy is obtained after casting, and comprises the following components in percentage by mass: 0.83% of Zn, 1.80% of Mn, 0.30% of Mg, 0.13% of Fe, 0.13% of Ti, 0.05% of Si and the balance of Al.

The measured performance data for the alloys of examples 1-3 and comparative examples 1-2 are shown in table 1.

TABLE 1 measured Performance data for the alloys of examples 1-3 and comparative examples 1-2

As can be seen from Table 1, the alloy of comparative example 1 has good anodic oxidation performance, but the second phase area ratio in the ingot structure is low, so that the alloy strength is lower than 180MPa, and the alloy is difficult to be applied to products with high strength requirements, and the alloy has poor fluidity and is difficult to be applied to products with complex structures. The alloy of the comparative example 2 has better die casting performance, but has larger secondary dendrite spacing, so that the color difference value of the alloy is increased, the anodic oxidation effect is influenced, and the strength is lower, so that the alloy is difficult to apply to actual products. The alloy of the embodiment 1-3 has very high strength and excellent flow property, can meet the requirements of products with higher strength and structure, has wider application range, is easier to produce by die casting, has good anodic oxidation effect, uniform and continuous oxidation film, small color difference value and less than 0.5 of delta E, and is easy to dye uniformly.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention. It should be noted that those skilled in the art, on the basis of the teachings provided herein, may make other modifications equivalent to those already described, and should be considered within the scope of the present invention.

Claims (10)

1. An anodic oxidation die-casting aluminum alloy is characterized in that the aluminum alloy comprises the following components in percentage by mass: si 2.0-7.0%, zn 2.0-7.0%, mn 1.5-3.5%, mg 0-2.0%, ti 0.1-0.2%, RE 0.05-0.2%, and the sum of the mass percentages of all impurities is less than or equal to 0.3%, wherein the impurity Fe is less than 0.2%, and the balance is Al; the RE element is La and Ce; the second phase area proportion of the cast ingot metallographic structure prepared by the aluminum alloy with the components is 8-25%; the size of the second phase of the metallographic structure of the die casting prepared from the aluminum alloy with the components is less than 20 micrometers, and the size of the second phase of the metallographic structure of the ingot prepared from the aluminum alloy with the components is less than 40 micrometers.

2. The anodized die cast aluminum alloy of claim 1, wherein the second phase comprises: alFeMnSi phase, al6Mn phase and AlSi eutectic phase.

3. An anodized die cast aluminum alloy according to claim 1 wherein the ingot has a metallographic structure with a secondary dendrite arm spacing of less than 30 μm prepared from an aluminum alloy having the composition according to claim 1.

4. An anodized die-cast aluminum alloy according to claim 1 wherein the tensile strength of the cast bar produced from the aluminum alloy of claim 1 is greater than 180MPa.

5. The anodized die-cast aluminum alloy according to claim 1, wherein the aluminum alloy comprises the following components in percentage by mass: 2.0 to 5.0 percent of Si, 2.0 to 5.0 percent of Zn, 1.6 to 2.3 percent of Mn, 0.7 to 1.5 percent of Mg, 0.1 to 0.2 percent of Ti, 0.1 to 0.2 percent of RE and less than or equal to 0.1 percent of the sum of the mass percent of all impurities, wherein the impurity Fe is less than 0.05 percent, and the balance of Al.

6. A method for producing an anodized aluminum die-cast alloy according to any of claims 1 to 5, comprising the steps of:

(1) Placing raw materials of an industrial pure Al ingot, an industrial pure Zn ingot, an Al-Mn intermediate alloy and an Al-Si intermediate alloy into a smelting furnace, heating to 780-800 ℃, cooling the smelting furnace to 760-770 ℃ after the raw materials in the smelting furnace are melted, pressing pure Mg into the smelting furnace until the pure Mg is completely melted, keeping the temperature for 30min, pressing rare earth elements into the smelting furnace and completely melting to obtain a melted material;

(2) Adding a refining agent and a refiner into the smelting furnace, stirring and degassing for 15-20 min, standing for 15-20 min, and skimming to obtain a skimmed sample;

(3) When the temperature of the slag-removed sample reaches 680-720 ℃, casting to obtain an anodic oxidation die-casting aluminum alloy casting blank; wherein the temperature of the casting mould is 180-220 ℃;

(4) Carrying out die-casting forming, CNC (computerized numerical control) treatment and surface sand blasting on the obtained aluminum alloy casting blank, and then carrying out anodic oxidation treatment, wherein the anodic oxidation treatment comprises the following steps: primary washing, anodic oxidation, secondary washing, dyeing and hole sealing.

7. The preparation method according to claim 6, characterized in that the adding amount of the refining agent in the step (2) is 1.5-3% o of the sum of the mass of the raw materials added in the step (1); the addition amount of the refiner is 1-3 per mill of the sum of the mass of the raw materials added in the step (1).

8. The method according to claim 6, wherein the refining agent in the step (2) is a lump or granular sodium-free refining agent.

9. The method according to claim 6, wherein the refiner in the step (2) is Al-Ti-B or Al-Ti-C wire.

10. The method for preparing a casting according to claim 6, wherein the cooling rate of the casting during the die casting in the step (4) is more than 200 ℃/s.

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