A kind of die-casting aluminum alloy and preparation method thereof

Abstract

In order to overcome the problems of high dependence on molding conditions and high molding defect rate of existing die-casting aluminum alloys, the present invention provides a die-casting aluminum alloy, characterized in that it includes the following components in mass percentage: Si content is 9-11%, Cu content is 1.8-3%, Mg content is 1-1.5%, Zn content is 0.5-1.3%, Mn content is 0.15-0.55%, Ti content is 0.03-0.1%, Sr content is 0.01-0.1%, The content of Mo is 0.0015-0.015%, the content of Hf is 0.02-0.45%, the content of Fe is 0.1-0.4%, the content of Cr is 0.001-0.4%, the content of Ga is 0.01-0.05%, the content of Ca is 0.01-0.15%, and the content of B is 0.001-0.02%; the content of N is 1ppm-50ppm, the content of Al is 80.47-87.36%, and the total amount of other elements is ≤0.5%. At the same time, the present invention also discloses a preparation method of the above-mentioned die-casting aluminum alloy. The present invention improves the mechanical properties of the aluminum alloy after die-casting and meets different die-casting requirements.

Description

Technical Field

[0001] The invention belongs to the technical field of alloy materials and relates to a die-casting aluminum alloy and a preparation method thereof. Background Art

[0002] Die-cast aluminum alloys have unparalleled advantages over other processed parts, such as high dimensional accuracy, high production efficiency, and excellent economic effects, which makes them widely used in industry. The processing steps of traditional die-cast aluminum alloys include: first stamping to obtain a die-cast aluminum alloy substrate, then surface treatment after cleaning, then CNC processing to form a die-cast aluminum alloy part, and finally a die-cast aluminum finished product that meets the appearance requirements through a specific anodizing process. Aluminum alloys as die-casting materials have high requirements for their mechanical properties, such as yield strength, tensile strength, elongation, and melt fluidity. Existing die-cast aluminum alloy materials themselves are difficult to take into account the strength requirements, elongation requirements, and fluidity requirements of die-casting. Therefore, when performing die-casting, the control conditions of the molding process are highly dependent on accuracy, and are greatly affected by small fluctuations in process parameters. It is easy to produce cracks or internal bubbles, deformation, and other problems during the die-casting process. Summary of the invention

[0003] In view of the problems that the existing die-casting aluminum alloys are highly dependent on molding conditions and have a high molding defect rate, the present invention provides a die-casting aluminum alloy and a preparation method thereof.

[0004] The technical solution adopted by the present invention to solve the above technical problems is as follows:

[0005] In one aspect, the present invention provides a die-casting aluminum alloy, comprising the following components in percentage by mass:

[0006] The Si content is 9-11%, the Cu content is 1.8-3%, the Mg content is 1-1.5%, the Zn content is 0.5-1.3%, the Mn content is 0.15-0.55%, the Ti content is 0.03-0.1%, the Sr content is 0.01-0.1%, the Mo content is 0.0015-0.015%, the Hf content is 0.02-0.45%, the Fe content is 0.1-0.4%, the Cr content is 0.001-0.4%, the Ga content is 0.01-0.05%, the Ca content is 0.01-0.15%, and the B content is 0.001-0.02%; the N content is 1ppm-50ppm, the Al content is 80.47-87.36%, and the total amount of other elements is ≤0.5%.

[0007] Optionally, the die-casting aluminum alloy includes the following components in percentage by mass:

[0008] The Si content is 9-11%, the Cu content is 2.35-2.6%, the Mg content is 1.15-1.4%, the Zn content is 0.52-1.17%, the Mn content is 0.15-0.45%, the Ti content is 0.06-0.08%, the Sr content is 0.01-0.03%, the Mo content is 0.005-0.015%, the Hf content is 0.025-0.045%, the Fe content is 0.1-0.4%, the Cr content is 0.2-0.3%, the Ga content is 0.01-0.035%, the Ca content is 0.01-0.15%, and the B content is 0.01-0.02%; the N content is 15ppm-30ppm, the Al content is 81.8-86.4%, and the total amount of other elements is ≤0.5%.

[0009] Optionally, in the die-cast aluminum alloy, the mass percentage content of Cu and Mg meets the following conditions: 1.8 <Cu:Mg<2。

[0010] Optionally, in the die-cast aluminum alloy, the mass percentage content of Zn and Mg meets the following conditions: 0.5 <Zn:Mg<0.9。

[0011] Optionally, in the die-cast aluminum alloy, the mass percentage contents of Sr, Mo and Si satisfy the condition: (Sr+Mo):Si=(3-8):2000.

[0012] Optionally, in the die-cast aluminum alloy, N and B are derived from the addition of AlN / BN multiphase nanoceramics, wherein the mass ratio of AlN and BN meets the condition: 1≤AlN:BN≤1.5; the mass percentage content of Hf and N meets the condition: 12.5 <Hf:N<22.5。

[0013] Optionally, in the die-cast aluminum alloy, the mass percentage contents of Ti and N satisfy the condition: Ti:N=(20-45):1.

[0014] Optionally, in the die-cast aluminum alloy, the mass percentage contents of Mn and Cr satisfy the condition: Mn+2.98Cr>0.6.

[0015] Optionally, in the die-cast aluminum alloy, the mass percentage contents of Mn, Cr and Ga satisfy the condition: (Mn+2.98Cr):Ga≥22.5:1.

[0016] Optionally, the other elements include one or more of Ba, Be, Bi, Cd, Ce, Co, Pb, Sn, Li, and Na, wherein the mass percentage of a single element is less than or equal to 0.002%.

[0017] Optionally, the die-cast aluminum alloy has a yield strength greater than or equal to 280 MPa, a tensile strength greater than or equal to 380 MPa, and an elongation at break greater than or equal to 3%.

[0018] On the other hand, the present invention provides a method for preparing the die-cast aluminum alloy as described above, comprising the following steps:

[0019] According to the ratio of elements in the aluminum alloy, Al agent, Si agent, Cu agent, Mn agent, Fe agent, Cr agent, Ti agent, Ga agent, Zn agent and excess Ca agent are weighed in required proportions, and added into a smelting furnace for smelting to obtain a melt;

[0020] Refining the melt with a refining agent to remove the Ca agent, introducing an inert gas, and scraping off the scum;

[0021] Weigh the required proportion of Mg agent and add it into the smelting furnace;

[0022] Weigh the required proportions of Sr agent and Mo agent respectively for modification treatment;

[0023] Adding Al-AlN / BN composite nano-ceramics and Hf agent in required proportions, performing refinement treatment, and casting to obtain an aluminum alloy ingot;

[0024] The aluminum alloy ingot is die-casted.

[0025] Optionally, the Ca element added in the Ca agent during the smelting process has an added mass of 0.1% to 0.5%.

[0026] Optionally, the method for removing the Ca agent includes:

[0027] Add AlF3 to remove Ca agent;

[0028] Alternatively, chlorine or carbon tetrachloride is introduced with the inert gas as a carrier to remove the Ca agent.

[0029] Optionally, the aluminum alloy after die-casting is subjected to artificial aging treatment, and is placed at room temperature for 1 to 2 days before being hot-pressed at a temperature of 250° C.-270° C. After hot-pressing, the aluminum alloy is placed at room temperature for 1 to 3 days.

[0030] According to the die-casting aluminum alloy provided by the present invention, the yield strength, tensile strength, elongation at break and other properties of the aluminum alloy are enhanced by limiting the ratio of each element composition, thereby further expanding the application field of the aluminum alloy after die-casting. At the same time, the improvement of its mechanical strength and fluidity has an important improvement on the adaptability of the aluminum alloy to different die-casting conditions, and reduces the sensitivity of the aluminum alloy to the die-casting conditions, so that it can form a die-casting molded part with good continuity, smooth surface and few internal defects under the control of different pressures, temperatures, molding thickness conditions and other die-casting parameters. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] An embodiment of the present invention provides a die-casting aluminum alloy, comprising the following components in percentage by mass:

[0033] The Si content is 9-11%, the Cu content is 1.8-3%, the Mg content is 1-1.5%, the Zn content is 0.5-1.3%, the Mn content is 0.15-0.55%, the Ti content is 0.03-0.1%, the Sr content is 0.01-0.1%, the Mo content is 0.0015-0.015%, the Hf content is 0.02-0.45%, the Fe content is 0.1-0.4%, the Cr content is 0.001-0.4%, the Ga content is 0.01-0.05%, the Ca content is 0.01-0.15%, and the B content is 0.001-0.02%; the N content is 1ppm-50ppm, the Al content is 80.47-87.36%, and the total amount of other elements is ≤0.5%.

[0034] In the die-cast aluminum alloy, the yield strength, tensile strength, elongation at break and other properties of the aluminum alloy are enhanced by limiting the ratio of each element composition, thereby further expanding the application field of the aluminum alloy after die-casting. At the same time, the improvement of its mechanical strength and fluidity has an important effect on the adaptability of the aluminum alloy to different die-casting conditions, reducing the sensitivity of the aluminum alloy to die-casting conditions, so that it can form die-cast parts with good continuity, smooth surface and few internal defects under different pressures, temperatures, molding thickness conditions and other die-casting parameters.

[0035] In a preferred embodiment, the die-casting aluminum alloy includes the following components in mass percentage:

[0036] The Si content is 9-11%, the Cu content is 2.35-2.6%, the Mg content is 1.15-1.4%, the Zn content is 0.52-1.17%, the Mn content is 0.15-0.45%, the Ti content is 0.06-0.08%, the Sr content is 0.01-0.03%, the Mo content is 0.005-0.015%, the Hf content is 0.025-0.045%, the Fe content is 0.1-0.4%, the Cr content is 0.2-0.3%, the Ga content is 0.01-0.035%, the Ca content is 0.01-0.15%, and the B content is 0.01-0.02%; the N content is 15ppm-30ppm, the Al content is 81.8-86.4%, and the total amount of other elements is ≤0.5%.

[0037] In other specific embodiments, the Si content may be selected from 9.0%, 9.2%, 9.5%, 9.9%, 10.2%, 10.5%, 10.7% or 11.0%; the Cu content may be selected from 1.8%, 1.9%, 2.0%, 2.2%, 2.4%, 2.5%, 2.7%, 2.9% or 3.0%; the Mg content may be selected from 1%, 1.1%, 1.3%, 1.4% or 1.5%; the Zn content may be selected from 0.53%, 0.6%, 0.65%, 0.72%, 0.76%, 0.79%, 0. 83%, 0.88%, 0.9%, 1.1%, 1.2% or 1.3%; the Mn content may be selected from 0.15%, 0.2%, 0.24%, 0.3%, 0.36%, 0.4%, 0.45% or 0.5%; the Ti content may be selected from 0.03%, 0.05%, 0.07%, 0.09% or 0.1%; the Sr content may be selected from 0.01%, 0.03%, 0.05%, 0.07%, 0.09% or 0.1%; the Mo content may be selected from 0.0015%, 0.005%, 0.006%, 0.01% or 0.02%; .008%, 0.010%, 0.012% or 0.015%; the Hf content can be selected from 0.025%, 0.05%, 0.15%, 0.2%, 0.24%, 0.3%, 0.36%, 0.4% or 0.45%, the Fe content is 0.10%, 0.15%, 0.2%, 0.24%, 0.3%, 0.36% or 0.4%, the Cr content is 0.0001%, 0.0005%, 0.01%, 0.10%, 0.15%, 0.2%, 0.24%, 0.3%, 0.36% or 0.4%, the Ga content is 0.010%, 0.15%, 0.2%, 0.24%, 0.3%, 0.36% or 0.4%, the The content of Ni is 0.01%, 0.02%, 0.03%, 0.04% or 0.05%, the content of Ca is 0.015%, 0.03%, 0.05%, 0.07%, 0.09%, 0.1% or 0.15%, the content of B is 0.0015%, 0.005%, 0.006%, 0.008%, 0.010%, 0.012%, 0.015% or 0.02%; the content of N is 1ppm, 5ppm, 9ppm, 12ppm, 20ppm, 25ppm, 31ppm, 36ppm, 42ppm or 50ppm.

[0038] It should be noted that, in the die-cast aluminum alloy, each element does not act alone, but has a related effect. The increase or decrease of any element may lead to a change in the effect of other elements, thereby causing a change in the overall performance of the die-cast aluminum alloy. The following is an explanation of the relationship between the elements in the present invention through specific embodiments:

[0039] The Si content is 9-11%, the Mg content is 1-1.5wt%, the Cu content is 1.8-3%, and the Zn content is 0.5-1.3%. By adding the above-mentioned elements, Mg2Si, Al2Cu and Al4Mg5Si4Cu4 phases can be generated interactively, which is helpful to improve the strength of the aluminum alloy material, among which the strengthening effect of the Al4Mg5Si4Cu4 phase is the best. The obtained die-cast aluminum alloy has good heat resistance, can withstand high temperatures of 250-300°C, and is suitable for use at higher temperatures.

[0040] In some embodiments, the mass percentage content of Cu and Mg in the die-cast aluminum alloy satisfies the following conditions: 1.8 <Cu:Mg<2。

[0041] When Cu and Mg are added in the above-mentioned proportion, less Mg2Si phase is generated in the aluminum alloy structure, and more Al4Mg5Si4Cu4 and Al2Cu phases are generated, which can enhance the toughness while maintaining the strength of the material.

[0042] In a preferred embodiment, the mass percentage content of Zn and Mg in the die-cast aluminum alloy meets the following conditions: 0.5 <Zn:Mg<0.9。

[0043] Further limiting the ratio range of Zn and Mg within the above-mentioned Cu and Mg addition range will promote the formation of MgZn2 phase and further improve the strength of aluminum alloy.

[0044] In some embodiments, in the die-cast aluminum alloy, the mass percentage contents of Sr, Mo and Si satisfy the condition: (Sr+Mo):Si=(3-8):2000.

[0045] In the die-cast aluminum alloy, the morphology of Si can be improved by the composite modification treatment of Sr+Mo. The coarse needle-like structure of eutectic silicon that is distributed in the alloy will split the matrix and become fibrous or densely branched to improve the performance of the alloy. The combined modification of Sr+Mo has the effect of continuously blocking the twin grooves, prompting the silicon phase to change the growth direction, and making the silicon phase branch, refine and spheroidize. The best effect is achieved when the mass percentage content of Sr, Mo and Si satisfies (Sr+Mo):Si=(3-8):2000. At this time, the eutectic silicon is fibrous and the ductility of the material is improved.

[0046] In some embodiments, in the die-cast aluminum alloy, N and B are derived from the addition of AlN / BN multiphase nanoceramics, wherein the mass ratio of AlN and BN satisfies the condition: 1≤AlN:BN≤1.5; the mass percentage content of Hf and N satisfies the condition: 12.5 <Hf:N<22.5。

[0047] During the solidification of molten metal, Hf, Ti, AlN / BN composite nanoceramics, etc. can provide heterogeneous nuclei such as Hf3Al and AlTi3. The AlN / BN composite nanoceramics play a role in providing nucleation sites, hindering grain growth, and enhancing the refinement of the alloy microstructure.

[0048] Among them, when 1 ≤ AlN:BN ≤ 1.5, the composite refinement effect produced by the AlN / BN composite nanoceramics is the best. At this time, the formation of clusters at the grain boundaries can be inhibited through the interaction, and the AlN / BN composite nanoceramics can provide more nucleation sites.

[0049] When the mass percentage content of Hf and N satisfies the condition: 12.5 < Hf:N < 22.5, the distribution of the reinforcing phase is more uniform, and the microtopography is mostly within 100 nm. It can promote the refinement of grains, prevent the deposition of N, B, and Hf in the aluminum melt due to the interaction at high temperatures, and at the same time avoid the weakening of the refinement and modification effects caused by the excessive addition of B reacting with Sr.

[0050] Due to the interaction between N and Ti, in the preferred embodiment, in the die-cast aluminum alloy, the mass percentage content of Ti and N needs to satisfy the condition: Ti:N = (20 - 45):1, which is beneficial to improving the strength and toughness simultaneously.

[0051] In the die-cast aluminum alloy, Fe, Mn, and Cr can improve the fluidity of the material and prevent sticking to the mold. However, when the content of Fe is added too much, needle-shaped Al9Fe2Si2 phases are likely to appear, which is not conducive to the improvement of the strength of the aluminum alloy. Therefore, the content of Fe needs to be controlled. Elements such as Cr and Mn can be used to replace Fe, but the content of Fe cannot be lower than 0.1%. Adding 0.2% of Mn and Cr each can improve the strength of the alloy. The Mn and Cr elements can promote the phase transformation of the Fe-containing impurity phase at high temperatures and can basically transform the Al9Fe2Si2 phase into Al 12 Fe3Si, further weakening the harm caused by Fe, and by adding Mn and Cr elements, an intermetallic compound layer that is not easy to cause sticking to the mold can be formed on the surface of the die steel, such as Al 12 Cr3Si, FeSiAlCrMnCu, etc., form a smooth interface on the surface of the die steel, and the size of the formed intermetallic compound layer is smaller, which can improve the problem of sticking of the aluminum alloy to the mold. Specifically, in some embodiments, in the die-cast aluminum alloy, the mass percentage content of Mn and Cr satisfies the condition: Mn + 2.98Cr > 0.6, which is beneficial to improving the anti-sticking performance of the aluminum alloy at this time.

[0052] In the preferred embodiment, in the die-cast aluminum alloy, the mass percentage content of Mn, Cr, and Ga satisfies the condition: (Mn + 2.98Cr):Ga ≥ 22.5:1.

[0053] When Mn and Cr are within the above-mentioned addition range, the enrichment of Ga at the grain boundary can be reduced, and Ga is dispersedly distributed without segregation. At the same time, the enrichment of Fe element is reduced at the α-Al grain boundary, the tendency of aluminum alloy to produce Rehbinder effect is reduced, the structure of the alloy is improved, and the material properties are improved.

[0054] It should be noted that the above is only a theoretical speculation based on the interaction between elements. In most cases, it is necessary to obtain die-cast aluminum alloys with specific element ratios through specific experiments in order to know the actual mechanical properties under their ratios.

[0055] In some embodiments, the other elements include one or more of Ba, Be, Bi, Cd, Ce, Co, Pb, Sn, Li, and Na, wherein the mass percentage of a single element is less than or equal to 0.002%.

[0056] In some embodiments, the die-cast aluminum alloy has a yield strength greater than or equal to 280 MPa, a tensile strength greater than or equal to 380 MPa, and an elongation at break greater than or equal to 3%.

[0057] It should be noted that the mechanical properties of the above-mentioned die-cast aluminum alloy are measured after artificial aging.

[0058] Another embodiment of the present invention provides a method for preparing the die-cast aluminum alloy as described above, comprising the following steps:

[0059] According to the ratio of elements in the aluminum alloy, Al agent, Si agent, Cu agent, Mn agent, Fe agent, Cr agent, Ti agent, Ga agent, Zn agent and excess Ca agent are weighed in required proportions, and added into a smelting furnace for smelting to obtain a melt;

[0060] Refining the melt with a refining agent to remove the Ca agent, introducing an inert gas, and scraping off the scum;

[0061] Weigh the required proportion of Mg agent and add it into the smelting furnace;

[0062] Weigh the required proportions of Sr agent and Mo agent respectively for modification treatment;

[0063] Adding Al-AlN / BN composite nano-ceramics and Hf agent in required proportions, performing refinement treatment, and casting to obtain an aluminum alloy ingot;

[0064] The aluminum alloy ingot is die-casted.

[0065] In the present invention, Al agent, Si agent, Cu agent, Mn agent, Fe agent, Cr agent, Ti agent, Ga agent, Zn agent, Ca agent, Mg agent, Sr agent, Mo agent and Hf agent are materials that can provide various elements required for preparing the die-casting aluminum alloy of the present invention, and can be intermediate alloys, metal compounds or pure metals containing the above elements, as long as the composition of the aluminum alloy obtained after smelting the added aluminum alloy raw material is within the above range.

[0066] In the preparation method provided by the present invention, an excess amount of Ca agent is first added during the smelting process, a refining agent is then added to refine and remove the Ca agent, and then an Mg agent is added, and then an Sr agent and a Mo agent are added for modification treatment, and the aluminum alloy provided by the present invention is obtained by casting and die-casting. The present invention finds through a large number of experiments that the introduction of an excess amount of Ca agent can effectively increase the smelting speed of elements with relatively high melting points such as Cu, Mn and Ti, shorten energy consumption, and improve efficiency. The efficiency is improved by about 30% in the smelting stage, and at the same time, the excess Ca agent introduced can be removed by the refining agent without introducing excess impurities.

[0067] The addition of AlN / BN composite nanoceramics can maximize the grain refinement effect and more accurately control the content of B element in the alloy, while also preventing the reaction between B and Sr and affecting the grain refinement effect.

[0068] Since Mg is easily oxidized during the smelting process and easily removed during the refining process, Mg is added after refining to accurately control the content of Mg in the aluminum alloy and improve the utilization efficiency of raw materials.

[0069] In some embodiments, during the smelting process, Al and Si agents are added first, then Ca agent is added, and then Cu, Mn, Fe, Cr, Ti, Ga, and Zn agents are added. This is beneficial for improving the melting efficiency of the subsequently added elements with the Ca agent and shortening the smelting time.

[0070] In some embodiments, during the modification process, Sr agent is first added for modification, and then Mo agent is added, which can effectively improve the modification effect of the aluminum liquid.

[0071] In some embodiments, the Ca element added in the Ca agent during the smelting process is 0.1% to 0.5% by mass.

[0072] In some embodiments, the method of removing the Ca agent comprises:

[0073] Add AlF3 to remove Ca agent;

[0074] Alternatively, chlorine or carbon tetrachloride is introduced with the inert gas as a carrier to remove the Ca agent.

[0075] By introducing AlF3, chlorine or carbon tetrachloride to react with the Ca agent to generate CaF2, the Ca agent can be effectively removed without introducing new impurities.

[0076] In some embodiments, the refining agent includes one or both of hexafluoroethane and aluminum refining agent ZS-AJ01C, and the inert gas includes nitrogen and / or argon.

[0077] More preferably, the inert gas is nitrogen.

[0078] In some embodiments, the refining temperature is 730-750°C, and the modification temperature is 700-740°C.

[0079] More preferably, the temperature of the modification treatment is 720°C.

[0080] In some embodiments, during the die-casting of the aluminum alloy ingot, the die-casting temperature is 680-720° C., the die-casting machine speed is 1.6-2 m / s, and the holding time is 1-3 s.

[0081] In some embodiments, the aluminum alloy after die-casting is artificially aged, and then hot-pressed after being placed at room temperature for 1 to 2 days. The hot-pressing temperature is 250°C-270°C, and the aluminum alloy is placed at room temperature for 1 to 3 days after hot-pressing.

[0082] The die-cast aluminum alloy is hot-pressed to improve the flatness due to the stability of the aluminum alloy performance.

[0083] The present invention is further described below by way of examples.

[0084] Table 1 shows the mass percentage (%) of the aluminum alloy components of various embodiments and comparative examples of the present invention. The total mass of the aluminum alloy is 100%, and the mass percentage of the remaining components except the components listed in Table 1 is Al.

[0085] Table 1

[0086]

[0087]

[0088]

[0089]

[0090]

[0091] Example 1

[0092] This embodiment is used to illustrate the aluminum alloy and the preparation method thereof disclosed in the present invention, and includes the following steps:

[0093] Step 1, weigh and prepare the raw materials according to the aluminum alloy composition shown in Table 1;

[0094] Step 2: During the smelting process, 80% pure aluminum is first put into a smelting furnace, and when the temperature is raised to about 700°C, Al-Si master alloy and Al-Ca master alloy are added;

[0095] Step 3, when the furnace temperature reaches above 800°C, add Al-Cu, Al-Mn, Al-Cr, Al-Ti, Al-Ga master alloys, and single element Zn, stir once every 10 minutes, each stirring time is 3 minutes, and stand for about 8 minutes after stirring;

[0096] Step 4: Add the remaining pure Al and adjust the melting temperature to 760°C;

[0097] Step 5, refining the melt with a refining agent, the refining agent is sprayed into the melt together with an inert gas to remove excess Ca elements, the temperature is 730-750°C, and the surface slag is scraped off after refining;

[0098] Step 6: After the added alloy is completely melted, the temperature is lowered to 760°C and pure Mg is added;

[0099] Step 7, at a temperature of 720° C., adding Al-10% Sr alloy to modify the melt, and then adding Al-8% Mo master alloy to modify the melt;

[0100] Step 8: Add Al-AlN / BN nano-ceramic phase and Al-10.45% Hf master alloy at a melting temperature of 720°C for refinement. After being fully melted, stir thoroughly and let stand for 1 minute. The melt temperature is controlled at 720°C. Degassing and pouring are performed after component testing.

[0101] Step 9: After crushing the material, vacuum die-casting is performed, and the die-casting temperature is set to 680-720°C, the die-casting machine speed is 1.6-2m / s, and the holding time is 1-3s.

[0102] Step 10: Place the die-cast samples at room temperature for 1-2 days, then hot-press them with a metal mold and take out the samples. The hot-pressing temperature is 250-270°C, and place them at room temperature for 1-3 days.

[0103] Embodiments 2 to 66

[0104] Examples 2 to 66 are used to illustrate the aluminum alloy and the preparation method thereof disclosed in the present invention, and include most of the operating steps in Example 1, except that:

[0105] The aluminum alloy compositions shown in Examples 2 to 66 in Table 1 were used, and the other operating steps were the same as those in Example 1.

[0106] Comparative Examples 1 to 26

[0107] Comparative Examples 1 to 26 are used to compare and illustrate the aluminum alloy and the preparation method thereof disclosed in the present invention, and include most of the operating steps in Example 1, except that:

[0108] The aluminum alloy compositions shown in Comparative Examples 1 to 26 in Table 1 were used, and the other operating steps were the same as those in Example 1.

[0109] Performance Testing

[0110] The aluminum alloys prepared in the above Examples 1 to 66 and Comparative Examples 1 to 26 were subjected to the following performance tests:

[0111] The tensile strength, yield strength and elongation of the material are tested using "GB / T 228.1-2010 Tensile test of metallic materials Part 1: Room temperature test method".

[0112] The aluminum alloy die-casting prepared from the above components formed a tensile test bar (diameter 6.4mm*gauge length 50mm), and the tensile properties were tested using an electronic universal testing machine model CMT5105 with a gauge length of 50mm and a loading rate of 2mm / min. The measurement data were recorded, and six samples were tested at each formulation point, where the yield strength, tensile strength and elongation were the average values ​​of the six data, the relative standard deviation of the yield strength was the percentage ratio of the standard deviation of the six yield strength data to the average value, and the relative standard deviation of the tensile strength was the percentage ratio of the standard deviation of the six tensile strength data to the average value.

[0113] Fluidity test: Use mosquito coil mold die casting, crush the material and then perform vacuum die casting, set the die casting temperature to 680-720℃, the die casting machine speed to 1.5-1.8m / s, and the holding time to 1-3s.

[0114] The test results obtained are entered in Table 2.

[0115] Table 2

[0116]

[0117]

[0118]

[0119]

[0120] It can be seen from the test results in Table 2 that the die-casting aluminum alloy provided by the present invention has excellent yield strength and tensile strength, and also has good elongation and fluidity while ensuring strength, and can meet different die-casting conditions.

[0121] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A die-cast aluminum alloy, characterized in that: The components include the following mass percentages: The content of Si is 9-11%, the content of Cu is 1.8-3%, the content of Mg is 1-1.5%, the content of Zn is 0.5-1.3%, the content of Mn is 0.15-0.55%, the content of Ti is 0.03-0.1%, the content of Sr is 0.01-0.1%, the content of Mo is 0.0015-0.015%, the content of Hf is 0.02-0.45%, the content of Fe is 0.1-0.4%, the content of Cr is 0.001-0.4%, the content of Ga is 0.01-0.05%, the content of Ca is 0.01-0.15%, the content of B is 0.001-0.02%, the content of N is 1ppm-50ppm, the content of Al is 80.47-87.36%, and the total amount of other elements is ≤0.5%; the mass percentage content of Mn and Cr meets the condition: Mn+2.98Cr>0.

6.

2. The die-cast aluminum alloy according to claim 1, characterized in that: The die-casting aluminum alloy includes the following components in percentage by mass: The Si content is 9-11%, the Cu content is 2.35-2.6%, the Mg content is 1.15-1.4%, the Zn content is 0.52-1.17%, the Mn content is 0.15-0.45%, the Ti content is 0.06-0.08%, the Sr content is 0.01-0.03%, the Mo content is 0.005-0. 015%, the Hf content is 0.025-0. 045%, the Fe content is 0.1-0.4%, the Cr content is 0.2-0.3%, the Ga content is 0.01-0.035%, the Ca content is 0.01-0.15%, the B content is 0.01-0.02%, the N content is 15ppm-30ppm, the Al content is 81.8-86.4%, and the total amount of other elements is ≤0.5%.

3. The die-cast aluminum alloy according to claim 1, characterized in that: In the die-cast aluminum alloy, the mass percentage content of Cu and Mg meets the following conditions: 1.8 <Cu:Mg<2。 4. The die-cast aluminum alloy according to claim 3, characterized in that: In the die-cast aluminum alloy, the mass percentage content of Zn and Mg meets the following conditions: 0.5 <Zn:Mg <0.9。 5. The die-cast aluminum alloy according to claim 1, characterized in that: In the die-cast aluminum alloy, the mass percentage contents of Sr, Mo and Si satisfy the following conditions: (Sr+Mo):Si=(3-8):2000.

6. The die-cast aluminum alloy according to claim 1, characterized in that: In the die-cast aluminum alloy, N and B are derived from the addition of AlN / BN multiphase nano-ceramics, wherein the mass ratio of AlN and BN meets the condition: 1≤AlN:BN≤1.5; the mass percentage content of Hf and N meets the condition: 12.5 <Hf:N<22.5。 7. The die-cast aluminum alloy according to claim 6, characterized in that: In the die-cast aluminum alloy, the mass percentage contents of Ti and N satisfy the condition: Ti:N=(20-45):

1.

8. The die-cast aluminum alloy according to claim 1, characterized in that: In the die-cast aluminum alloy, the mass percentage contents of Mn, Cr and Ga satisfy the condition: (Mn+2.98Cr):Ga≥22.5:

1.

9. The die-cast aluminum alloy according to claim 1, characterized in that: The other elements include one or more of Ba, Be, Bi, Cd, Ce, Co, Pb, Sn, Li, and Na, wherein the mass percentage of a single element is less than or equal to 0.002%.

10. The die-cast aluminum alloy according to any one of claims 1 to 9, characterized in that: The die-cast aluminum alloy has a yield strength greater than or equal to 280 MPa, a tensile strength greater than or equal to 380 MPa, and an elongation at break greater than or equal to 3%.

11. The method for preparing a die-cast aluminum alloy according to any one of claims 1 to 10, characterized in that: The steps include: According to the ratio of elements in the aluminum alloy, Al agent, Si agent, Cu agent, Mn agent, Fe agent, Cr agent, Ti agent, Ga agent, Zn agent and excess Ca agent are weighed in required proportions, and added into a smelting furnace for smelting to obtain a melt; Refining the melt with a refining agent to remove the Ca agent, introducing an inert gas, and scraping off the scum; Weigh the required proportion of Mg agent and add it into the smelting furnace; Weigh the required proportions of Sr agent and Mo agent respectively for modification treatment; Adding Al-AlN / BN composite nano-ceramics and Hf agent in required proportions, performing refinement treatment, and casting to obtain an aluminum alloy ingot; The aluminum alloy ingot is die-casted.

12. The method for preparing a die-cast aluminum alloy according to claim 11, characterized in that: The Ca element added in the Ca agent during the smelting process has an added mass of 0.1%~0.5%.

13. The method for preparing a die-cast aluminum alloy according to claim 11, characterized in that: Methods for removing Ca agents include: Add AlF3 to remove Ca agent; Alternatively, chlorine or carbon tetrachloride is introduced with the inert gas as a carrier to remove the Ca agent.

14. The method for preparing a die-cast aluminum alloy according to claim 11, characterized in that: The aluminum alloy after die-casting is artificially aged, and then hot-pressed after being placed at room temperature for 1 to 2 days. The temperature of the hot-pressing treatment is 250°C-270°C. After hot-pressing, the aluminum alloy is placed at room temperature for 1 to 3 days.

Images