Aluminum alloy and preparation method and application thereof

Abstract

The invention provides an aluminum alloy as well as a preparation method and application thereof. The aluminum alloy comprises the following components in percentage by mass: 7%-10% of Si, 0-1% of Ni, 0.5%-0.7% of Mn, 0.3%-0.6% of Mg, 0.1%-0.45% of Fe, 0.05%-0.15% of Cr, less than or equal to 0.1% of Cu, less than or equal to 0.1% of V, less than or equal to 0.1% of Zr, 0.08%-0.15% of Ti, 0.016%-0.03% of B, 0.005%-0.025% of Sr and 0.05%-0.35% of RE. Wherein RE comprises at least one of La and Ce. The aluminum alloy provided by the invention has relatively high strength and toughness.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal materials and their preparation technology, specifically to an aluminum alloy, its preparation method, and its application. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the use of high-vacuum die casting technology to produce large, thin-walled, integrated vehicle body structural components has become an important way to achieve vehicle lightweighting. Against this backdrop, improving the recycling rate of aluminum alloy materials and reducing production costs and carbon emissions have become urgent industry needs.

[0003] Currently, aluminum alloys are widely used in integrated aluminum alloy castings for automobiles. These materials must simultaneously meet core mechanical property requirements such as high yield strength, high elongation, and high fatigue strength, while also possessing excellent die-casting fluidity, dimensional stability, and high specific stiffness. However, to achieve these properties, existing aluminum alloys typically impose extremely strict limitations on their alloy composition, particularly the content of impurity elements such as Fe. This is because Fe readily forms brittle, needle-like or lamellar iron-rich phases in alloys, severely impairing the material's toughness and elongation. This compositional constraint makes it difficult to use recycled aluminum in large proportions during production, and it is also incompatible with mixed recycled materials from multiple sources and of different grades. Often, high-purity virgin aluminum ingots must be relied upon, thus limiting the material's cost advantage and environmental benefits.

[0004] Furthermore, in alloy composition design, there are often mutual constraints between elements that ensure fluidity (such as Si), elements that achieve as-cast strength (such as solid solution strengthening elements such as Mg and Mn), and elements that maintain high toughness (such as suppressing harmful second phases and controlling lattice distortion). This makes it difficult to improve strength and toughness simultaneously, becoming a technical bottleneck for the further development of existing aluminum alloys. Summary of the Invention

[0005] This invention provides an aluminum alloy, its preparation method, and its application. The aluminum alloy is suitable for high-vacuum die casting and can achieve both high strength and toughness.

[0006] This invention provides an aluminum alloy comprising, by mass percentage: Si 7%–10%, Ni 0–1%, Mn 0.5%–0.7%, Mg 0.3%–0.6%, Fe 0.1%–0.45%, Cr 0.05%–0.15%, Cu≤0.1%, V≤0.1%, Zr≤0.1%, Ti 0.08%–0.15%, B 0.016%–0.03%, Sr 0.005%–0.025%, and RE 0.05%–0.35%; wherein RE includes at least one of La and Ce.

[0007] Optionally, the mass ratio of Si to Ni is greater than or equal to 10:1; and / or, the mass ratio of Mn to Cr is greater than or equal to 4; and / or, the mass ratio of La to Ce is 1:(3-5); and / or, the aluminum alloy further includes impurity elements, which include one or more of P, Ca, and Zn.

[0008] The present invention provides a method for preparing the aluminum alloy as described above, comprising: providing raw materials for forming the aluminum alloy and performing refining treatment to obtain the aluminum alloy.

[0009] Optionally, the raw materials for the aluminum alloy include a first raw material and recycled aluminum alloy material. The first raw material includes at least one of aluminum material, silicon material, and Al-X master alloy, wherein X includes Ni, Mn, Mg, Cr, Cu, V, Zr, Ti, B, Sr, and RE. The recycled aluminum alloy material includes Fe, and the mass percentage of the recycled aluminum alloy material in the raw materials of the aluminum alloy is 0-50%, preferably 30%-50%, more preferably 40%-50%. Preferably, the Al-X master alloy includes one or more of Al-Ni master alloy, Al-Mn master alloy, Al-Mg master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-V master alloy, Al-Zr master alloy, Al-Ti-B master alloy, Al-Sr master alloy, and Al-RE master alloy.

[0010] Optionally, the refining process includes: melting and refining the raw materials of the aluminum alloy to obtain the aluminum alloy; preferably, the process of melting and refining the raw materials of the aluminum alloy to obtain the aluminum alloy specifically includes: first melting a first raw material system including aluminum materials and recycled aluminum alloy materials, and then performing a first refining to obtain a first material; mixing the first material with a second raw material system including silicon materials, Al-Ni master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-Zr master alloy, Al-Ti-B master alloy, and Al-RE master alloy, and performing a second melting of the second raw material system to obtain a second material; mixing the second material with a third raw material system including Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy, and performing a third melting of the Al-Mg master alloy, and then performing a second refining to obtain the aluminum alloy.

[0011] Optionally, the temperature of the second refining is 700℃~730℃; and / or, the second refining is followed by deep refining, wherein the deep refining includes a powder spraying refining process, wherein the powder spraying refining process is carried out by introducing an inert gas carrying a refining agent into the melt using a rotary spraying device; wherein the degassing speed of the powder spraying refining process is 280r / min~500r / min, the degassing time is 8min~15min, and the pressure of the gas source during degassing is 0.25±0.05MPa; the refining agent includes at least one of magnesium chloride and calcium chloride.

[0012] The present invention provides an aluminum alloy structural component, the aluminum alloy structural component comprising the aluminum alloy as described above or the aluminum alloy obtained by the aluminum alloy preparation method described above.

[0013] Optionally, the aluminum alloy structural component includes an aluminum alloy casting.

[0014] This invention provides a method for preparing an aluminum alloy casting, comprising: casting an aluminum alloy to obtain the aluminum alloy casting; wherein the aluminum alloy includes the aluminum alloy described above or the aluminum alloy obtained according to the method for preparing the aluminum alloy described above.

[0015] Optionally, before casting the aluminum alloy, the molten aluminum alloy is kept at a temperature within the casting temperature range, and then casting is performed to obtain the aluminum alloy casting; preferably, the density equivalent of the molten aluminum alloy is ≤2%, and the K-modulus value is ≤0.1; and / or, the casting process parameters meet the following: injection speed of 4m / s~6m / s, mold temperature of 180℃~240℃, and casting pressure of 25MPa~80MPa; wherein, a release agent diluted with water is sprayed onto the mold, and the volume ratio of the release agent to water is 1:(20~100); the temperature of the cooling medium in the point cooling channel of the mold is 5℃~15℃.

[0016] This invention provides an aluminum alloy, its preparation method, and its application, which has at least the following beneficial effects: the aluminum alloy achieves a synergistic improvement in mechanical and casting properties through multi-element synergistic regulation. Specifically, on the one hand, by introducing elements such as Ni, Mn, Cr, and RE, a composite precipitate phase is constructed to replace the traditional Fe-based brittle phase, reducing the negative impact of Fe on the elongation of the aluminum alloy and increasing the upper limit of Fe tolerance. On the other hand, by regulating the precipitation morphology of impurities (such as P, Ca, and Zn) through elements such as Sr and RE, they exist in a dispersed, non-brittle phase form, avoiding the deterioration of the mechanical properties of the aluminum alloy. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In a first aspect, embodiments of the present invention provide an aluminum alloy comprising, by mass percentage: Si 7%–10%, Ni 0–1%, Mn 0.5%–0.7%, Mg 0.3%–0.6%, Fe 0.1%–0.45%, Cr 0.05%–0.15%, Cu≤0.1%, V≤0.1%, Zr≤0.1%, Ti 0.08%–0.15%, B 0.016–0.03%, Sr 0.005%–0.025%, and RE 0.05%–0.35%; wherein RE includes at least one of La and Ce.

[0019] According to research and analysis, the aluminum alloy in this embodiment of the invention achieves a synergistic improvement in mechanical and casting properties through multi-element synergistic regulation. Specifically, on the one hand, by introducing elements such as Ni, Mn, Cr, and RE, a composite precipitate phase is constructed to replace the traditional Fe-based brittle phase, reducing the negative impact of Fe on the elongation of the aluminum alloy and increasing the upper limit of Fe tolerance. On the other hand, by regulating the precipitation morphology of impurities (such as P, Ca, and Zn) through elements such as Sr and RE, they exist in a dispersed, non-brittle phase form, avoiding the deterioration of the mechanical properties of the aluminum alloy. Furthermore, by introducing an appropriate amount of B, stable borides are formed with transition elements (especially Ti, V, and Cr), thereby refining the grains, improving the casting structure, and significantly enhancing the mechanical properties of the material.

[0020] Therefore, the aluminum alloy of the present invention can have both excellent strength and toughness, achieving a synergistic improvement in its mechanical properties and casting properties.

[0021] The aluminum alloy of this invention, after being cast (such as die casting), does not require a special heat treatment process and can directly meet the mechanical properties and usage requirements of the final product in the as-cast state.

[0022] In aluminum alloys, the mass percentage of Si is 7% to 10%, for example, 7%, 8%, 9%, 10%, or any combination thereof.

[0023] When the mass percentage of silicon (Si) meets the above range, it can improve the casting fluidity of aluminum alloys and enhance the performance of aluminum alloy castings.

[0024] In aluminum alloys, the mass percentage of Ni is 0% to 1%, for example, 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any combination thereof.

[0025] When the mass percentage of Ni (nickel) meets the above range, it can improve the high-temperature stability of aluminum alloys, enhance their performance under high-temperature conditions, and extend their service life.

[0026] In some embodiments, the mass ratio of Si to Ni is greater than or equal to 10:1.

[0027] For example, the mass ratio of Si to Ni can be a range of 10:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, or any combination thereof.

[0028] When the mass ratio of Si to Ni meets the above range, the precipitation of brittle phases in aluminum alloys can be suppressed, which is beneficial to improving the toughness of aluminum alloys.

[0029] In aluminum alloys, the mass percentage of Mn is 0.5% to 0.7%, for example, 0.5%, 0.6%, 0.7%, or any combination thereof.

[0030] When the mass percentage of Mn (manganese) meets the above range, it is beneficial to the solid solution strengthening of aluminum (Al) lattice and the refinement of its grain boundary structure, and it inhibits the formation of acicular second phase by high iron content, thereby improving the strength and toughness of aluminum alloys.

[0031] In aluminum alloys, the mass percentage of Mg is 0.3% to 0.6%, for example, 0.3%, 0.4%, 0.5%, 0.6%, or any combination thereof.

[0032] When the mass percentage of Mg (magnesium) meets the above range, it is beneficial to the solid solution strengthening of aluminum (Al) lattice and the refinement of its grain boundary structure, thereby improving the strength of aluminum alloys.

[0033] In aluminum alloys, the mass percentage of Fe is 0.1% to 0.45%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or any combination thereof.

[0034] The aluminum alloy system of this invention significantly improves the upper limit of tolerance (0.45%) for Fe (iron) mass content, thus making it possible to produce aluminum alloys with high iron content while maintaining excellent strength and toughness. Furthermore, since high proportions of recycled aluminum alloys introduce high iron content in practical applications, this invention also expands the application scenarios for high proportions of recycled aluminum alloys.

[0035] In aluminum alloys, the mass percentage of Cr is 0.05% to 0.15%, for example, 0.05%, 0.1%, 0.15%, or any combination thereof.

[0036] When the mass percentage of chromium (Cr) meets the above range, it can work synergistically with magnesium and manganese to promote solid solution strengthening of the aluminum (Al) lattice and refine the grain boundary structure. It also inhibits the formation of acicular second phase from high iron content, thereby improving the strength and toughness of aluminum alloys.

[0037] In some embodiments, the mass ratio of Mn to Cr can be greater than or equal to 4.

[0038] For example, the mass ratio of Mn to Cr can be 4 to 14, such as 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1 or any combination thereof.

[0039] When the mass ratio of Mn to Cr meets the above range, it is beneficial for the two to work together better, which is beneficial for the solid solution strengthening of the aluminum (Al) lattice and the refinement of its grain boundary structure, and further improves the strength and toughness of the aluminum alloy.

[0040] In aluminum alloys, the mass percentage of Cu is ≤0.1%. When the mass percentage of Cu, i.e. copper element, meets the above range, it can avoid the formation of brittle copper-containing phases and improve the toughness of aluminum alloys.

[0041] In aluminum alloys, the mass percentage of vanadium (V) is ≤0.1%. When the mass percentage of vanadium (V) meets the above range, it can refine the grains of aluminum (a single crystal region in a crystalline material where the internal atomic arrangement is consistent but the orientation of its adjacent regions is different), thereby improving the strength of the aluminum alloy.

[0042] In aluminum alloys, the mass percentage of Zr is ≤0.1%. The mass percentage of Zr, i.e. zirconium, within the above range is beneficial for refining the grains of aluminum and improving the strength of the aluminum alloy.

[0043] In aluminum alloys, the mass percentage of Ti is 0.08% to 0.15%, for example, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, or any combination thereof.

[0044] When the mass percentage of titanium (Ti) meets the above range, it helps to refine the grains of aluminum, inhibits the formation of needle-like second phases from high-content iron, and improves the strength and toughness of aluminum alloys.

[0045] In aluminum alloys, the mass percentage of boron is 0.016% to 0.03%, for example, 0.016%, 0.021%, 0.026%, 0.030%, or any combination thereof.

[0046] The mass percentage of boron (B) within the above range improves the strength and toughness of aluminum alloys.

[0047] In aluminum alloys, the mass percentage of Sr is 0.005% to 0.025%, for example, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, or any combination thereof.

[0048] When the mass percentage of Sr meets the above range, it helps to suppress the formation of acicular second phase by high iron content, thereby improving the strength and toughness of aluminum alloys.

[0049] In this embodiment of the invention, RE includes at least one of La and Ce.

[0050] In aluminum alloys, the mass percentage of RE is 0.05% to 0.35%, for example, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, or any combination thereof.

[0051] When the mass percentage of RE meets the above range or type, it helps to suppress the formation of needle-like second phase by high iron content, thereby improving the strength and toughness of aluminum alloys.

[0052] In some specific implementations, the mass ratio of La to Ce can be 1:(3 to 5), for example, 1:3, 1:4, 1:5 or any combination thereof.

[0053] When the mass ratio of La (lanthanum) and Ce (cerium) meets the above-mentioned range, it helps to suppress the formation of needle-like second phases by high iron content, thereby further improving the strength and toughness of aluminum alloys.

[0054] The aforementioned aluminum alloys achieve a synergistic improvement in mechanical properties (strength and toughness) and casting performance through multi-element synergistic regulation.

[0055] In practice, the aluminum alloy also includes impurity elements, which include one or more of P, Ca, and Zn.

[0056] The monomer content of the above-mentioned impurity elements can be less than or equal to 0.05% of the total mass of the aluminum alloy, and the total content can be less than or equal to 0.25% of the total mass of the aluminum alloy.

[0057] These impurity elements can originate primarily from contamination of recycled materials, furnace lining erosion, tool wear, or trace elements present in raw materials.

[0058] It is understood that the elements in the aluminum alloy of the present invention form a homogeneous solid solution with metallic properties, rather than a physically stacked mixture.

[0059] Secondly, embodiments of the present invention provide a method for preparing the above-mentioned aluminum alloy, comprising: providing raw materials for forming the aluminum alloy and performing refining treatment to obtain the aluminum alloy.

[0060] In practice, raw materials for forming aluminum alloys can be provided according to the expected elemental composition of the aluminum alloy; then the raw materials for forming aluminum alloys are preheated and then refined to obtain aluminum alloys.

[0061] The above preheating treatment can be carried out by drying to ensure that the raw materials are free of moisture and avoid absorbing hydrogen, thereby further improving the density and mechanical properties of the aluminum alloy, and helping to improve the strength and toughness of the aluminum alloy.

[0062] In some specific embodiments, the preheating temperature can be between 150°C and 200°C, for example, a range of 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any combination thereof. Controlling the preheating temperature to meet these ranges helps ensure the raw materials are free of moisture and avoids hydrogen absorption, thereby further improving the density and mechanical properties of the aluminum alloy, and contributing to improved strength and toughness.

[0063] In some embodiments, the raw materials for the aluminum alloy include a first raw material and recycled aluminum alloy material. The first raw material includes at least one of aluminum material, silicon material, and Al-X master alloy, wherein X includes Ni, Mn, Mg, Cr, Cu, V, Zr, Ti, B, Sr, and RE. The recycled aluminum alloy material includes Fe, and the mass percentage of recycled aluminum alloy material in the raw materials for the aluminum alloy is 0-50%, preferably 30%-50%, and more preferably 40%-50%.

[0064] The above preparation method uses recycled aluminum alloy materials to prepare the aluminum alloy with excellent strength and toughness. In this aluminum alloy system, through multi-element synergistic regulation, the formation of needle-like second phase of iron can be suppressed, thereby achieving a synergistic improvement in the mechanical properties and casting properties of the aluminum alloy.

[0065] In this embodiment of the invention, recycled aluminum alloy material refers to aluminum alloy material that is recycled and reused during the production and manufacturing process of aluminum alloy.

[0066] In practical applications, iron inevitably gets mixed into aluminum alloy recycled materials. Specifically, the sources of iron (Fe) mainly include two aspects: one is the iron inherent in the raw materials, which comes from the iron impurities contained in the primary aluminum ingots (aluminum materials) and the iron carried by various aluminum alloy recycled materials (in-plant remelting materials and purchased scrap materials); the other is the iron introduced by the process, which is the iron that inevitably dissolves when the melt comes into contact with iron tools (such as crucibles and iron spoons) during the smelting and transfer process.

[0067] This invention optimizes the elemental composition and process control of aluminum alloys to transform harmful needle-like iron-rich phases into relatively harmless rounded morphologies, thereby achieving compatible use of high-proportion iron-containing recycled materials while ensuring material strength and toughness.

[0068] In some specific embodiments, recycled aluminum alloy materials may also include one or more of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series and 6000 series.

[0069] Specifically, 1000 series recycled materials are aluminum alloys with an aluminum content of 99% or higher; 2000 series recycled materials include aluminum alloys with copper as the main element; 3000 series recycled materials include aluminum alloys with manganese as the main element; 4000 series recycled materials include aluminum alloys with silicon as the main element; 5000 series recycled materials include aluminum alloys with magnesium as the main element; and 6000 series recycled materials include aluminum alloys with magnesium and silicon as the main elements.

[0070] The mass percentage of recycled aluminum alloy in the raw materials of aluminum alloy can be 0% to 50%, for example, 0, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any combination thereof; preferably 30% to 50%, more preferably 40% to 50%.

[0071] The percentage of recycled aluminum alloy materials in aluminum alloy raw materials has been significantly increased, greatly improving the resource recycling rate. While ensuring the mechanical properties and process stability of aluminum alloy materials, this technology has achieved a breakthrough over existing constraints, effectively reducing production costs and making significant progress in resource conservation and carbon emission reduction, thus possessing outstanding economic, environmental, and social benefits.

[0072] The first raw material includes at least one of aluminum material, silicon material, and Al-X master alloy, where X includes Ni, Mn, Mg, Cr, Cu, V, Zr, Ti, B, Sr, and RE.

[0073] In practice, the composition and content of recycled aluminum alloy can be tested first, and then the first raw material can be prepared according to the expected elemental composition of the aluminum alloy to ensure that the elemental composition of the obtained aluminum alloy meets the expectations.

[0074] In some specific embodiments, the Al-X master alloy may include one or more of the following: Al-Ni master alloy, Al-Mn master alloy, Al-Mg master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-V master alloy, Al-Zr master alloy, Al-Ti-B master alloy, Al-Sr master alloy, and Al-RE master alloy.

[0075] RE includes at least one of La and Ce, therefore Al-RE master alloys may include at least one of Al-La master alloys and Al-Ce master alloys.

[0076] Since different types of Al-X master alloys have different melting temperatures and loss temperatures, in order to improve the utilization rate of each raw material, the above-mentioned process of melting and refining aluminum alloy raw materials to obtain aluminum alloys can specifically include: firstly melting a first raw material system including aluminum materials and recycled aluminum alloy materials, and then refining it to obtain a first material; mixing the first material with a second raw material system including silicon materials, Al-Ni master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-V master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-RE master alloy, and then melting the second raw material system to obtain a second material; mixing the second material with a third raw material system including Al-Mg master alloy, and then melting the Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy to obtain a third material, and then refining it to obtain an aluminum alloy.

[0077] In some specific embodiments, after obtaining the first material, its composition can be tested first, and then the added components and dosage of the intermediate alloy can be adjusted based on the test results. The testing methods for the composition of the first material may include direct-reading spectroscopy, etc.

[0078] The first melting temperature can be 745℃~765℃, for example, 745℃, 750℃, 755℃, 760℃, 765℃ or any combination thereof.

[0079] The temperature for the first refining can be 730°C to 750°C, for example, 730°C, 735°C, 740°C, 745°C, 750°C, or any combination thereof.

[0080] In some specific embodiments, the process of mixing a first material with a second raw material system including silicon material, Al-Ni master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-V master alloy, Al-Zr master alloy, Al-Ti-B master alloy, and Al-RE master alloy, and then subjecting the second raw material system to a second melting to obtain a second material, may specifically include: mixing the first material sequentially with Al-Ni master alloy, Al-Ti-B master alloy, Al-Cu master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Zr master alloy, Al-RE master alloy, and silicon material, and then subjecting the mixture to a second melting to obtain the second material.

[0081] The second melting temperature can be 745℃~765℃, for example, 745℃, 750℃, 755℃, 760℃, 765℃ or any combination thereof.

[0082] In some specific embodiments, the second material is mixed with a third raw material system including Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy, and the Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy are subjected to a third melting and then a second refining to obtain an aluminum alloy.

[0083] The above process may specifically include: after the second material is cooled down, the second material is mixed with a third raw material system including Al-Mg master alloy, Al-V master alloy and Al-Sr master alloy, and the Al-Mg master alloy, Al-V master alloy and Al-Sr master alloy are (pressed) into the bottom of the melt for a third melting, and then a second refining is carried out to obtain an aluminum alloy.

[0084] The temperature of the second material after cooling can be 680℃~700℃, for example, 680℃, 685℃, 690℃, 695℃, 700℃ or any combination thereof.

[0085] In some specific embodiments, the temperature of the second refining can be 700°C to 730°C, for example, 700°C, 705°C, 710°C, 715°C, 720°C, 725°C, 730°C or any combination thereof.

[0086] The second refining temperature meets the above range, which can improve degassing efficiency, promote composition homogenization, reduce magnesium loss, facilitate the aggregation and flotation of impurities, prepare for subsequent deep refining, and further improve the purity of aluminum alloy.

[0087] The second refining process includes a deep refining process, which may include a powder spraying refining process, which is carried out by introducing an inert gas carrying a refining agent into the melt using a rotary spraying device.

[0088] The deep refining process may specifically include: using a rotary jetting device to pass Ar containing refining agent powder into the melt material after the third melting for powder spraying refining, after slag removal and degassing treatment, standing for 10 min to 15 min, and then slag removal treatment to obtain aluminum alloy.

[0089] Specifically, the settling time after the above degassing treatment can be 10 min to 15 min, for example, 10, 11, 12, 13, 14, 15 min or any combination thereof.

[0090] The degassing speed for powder spraying refining can be 280 r / min to 500 r / min, for example, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500 r / min or any combination thereof.

[0091] The degassing speed of the powder spraying refining process meets the above range, which is beneficial for shearing and breaking the introduced Ar gas into a large number of small, uniform bubbles, so that they can come into more full contact with the melt, and the efficiency of adsorbing hydrogen and inclusions is higher, which is conducive to obtaining a pure aluminum alloy.

[0092] The degassing time for powder spraying refining can be 8 min to 15 min, for example, 8, 9, 10, 11, 12, 13, 14, 15 min or any combination thereof.

[0093] The degassing time of the powder spraying refining process meets the above range, which provides sufficient assurance for the diffusion and mass transfer process of hydrogen atoms from the interior of the melt to the surface of the bubble.

[0094] The pressure of the gas source during degassing can be 0.25±0.05MPa, for example, 0.20, 0.25, 0.30MPa or any combination thereof.

[0095] If the pressure of the gas source meets the above range, it can ensure that Ar gas can be smoothly ejected from below the rotor and form bubbles, while avoiding excessive disturbance that would reduce refining efficiency and further improve the purity of the aluminum alloy.

[0096] Refining agents may include at least one of magnesium chloride and calcium chloride, which helps to improve the purity of the melt material after deep refining, thereby obtaining a high-purity aluminum alloy.

[0097] This invention also provides an aluminum alloy structural component, which comprises the above-described aluminum alloy or an aluminum alloy prepared according to the above-described aluminum alloy preparation method.

[0098] Based on this aluminum alloy, the aluminum alloy structural component has both high strength and toughness, which will not be elaborated here.

[0099] In some embodiments, the aluminum alloy structural component includes an aluminum alloy casting.

[0100] This invention also provides a method for preparing an aluminum alloy casting, comprising: casting an aluminum alloy to obtain an aluminum alloy casting; wherein the aluminum alloy structural component comprises the above-mentioned aluminum alloy or an aluminum alloy obtained according to the above-mentioned method for preparing aluminum alloy.

[0101] Based on this aluminum alloy, the aluminum alloy casting has both high strength and toughness, which will not be elaborated here.

[0102] In some specific embodiments, before casting the aluminum alloy, the molten aluminum alloy is kept at a temperature within the casting temperature range, and then casting is carried out to obtain an aluminum alloy casting.

[0103] Specifically, the aluminum alloy obtained after deep refining can be left to stand for 10 to 15 minutes, and then its temperature can be adjusted to 680℃ to 720℃ to obtain the aluminum alloy melt. Then, the aluminum alloy melt is kept at a casting temperature range, such as 680℃ to 720℃, to obtain the aluminum alloy melt.

[0104] For example, the settling time can be 10, 11, 12, 13, 14, 15 minutes or any combination thereof.

[0105] The insulation temperature can be 680℃~720℃, for example, 680, 690, 700, 710, 720℃ or any combination thereof, preferably 690℃~710℃.

[0106] The insulation temperature meets the above range, which can ensure that the aluminum alloy remains in a molten state and achieve lower energy consumption.

[0107] Aluminum alloy materials held at 680℃~720℃ are in a fully molten state, which can be called aluminum alloy melt. After cooling the melt to room temperature and solidifying it through a corresponding casting process, a solid aluminum alloy casting or material with a cast structure can be obtained.

[0108] Preferably, the density equivalent of the aluminum alloy melt is ≤2% and the K modulus value is ≤0.1; the density equivalent is used to measure the dissolved hydrogen content in the melt, which characterizes the "gas saturation" of the melt.

[0109] A density equivalent of ≤2% for aluminum alloys indicates that the aluminum alloy melt has undergone extremely thorough and effective degassing and refining, approaching the ideal state of "hydrogen-free", which is beneficial to improving the tensile strength, elongation and fatigue life of aluminum alloy castings.

[0110] The K-modulus value is used to measure the content of solid non-metallic inclusions (mainly alumina) in a melt, and it characterizes the "cleanliness" of the melt.

[0111] A K-modulus value ≤ 0.1 indicates that the melt has undergone deep purification and efficient filtration, resulting in extremely low inclusion content, which can significantly improve the fracture toughness (K-value) and impact performance of aluminum alloy castings.

[0112] In practice, the casting mentioned above may include die casting or squeeze casting.

[0113] Compared with traditional casting, the aluminum alloy casting process of the above-mentioned aluminum alloy castings uses a lower temperature of aluminum alloy melt, such as 690℃~710℃, which ensures the uniformity of the internal structure and the stability of the grain size of the aluminum alloy castings to a greater extent, and greatly improves the defects such as shrinkage cavities, hot cracks and internal stress caused by high temperature cooling of aluminum alloys in the existing technology.

[0114] The above-mentioned aluminum alloy castings have excellent mechanical properties. In particular, the yield strength of the aluminum alloy castings in the embodiments of the present invention can be greater than 135 MPa and the elongation can be less than or equal to 10%.

[0115] The above casting process parameters can meet the following requirements: injection speed can be 4m / s~6m / s, mold temperature can be 180℃~240℃, and casting pressure can be 25MPa~80MPa; wherein, a diluted release agent can be used to spray the mold, and the volume ratio of the release agent to water can be 1:(20~100); the temperature of the cooling medium in the point cooling channel of the mold can be 5℃~15℃.

[0116] The injection velocity can be 4 m / s to 6 m / s, for example, 4, 5, 6 m / s or any combination thereof.

[0117] The mold temperature can be 180℃~240℃, for example, 180, 190, 200, 210, 220, 230, 240℃ or any combination thereof.

[0118] The casting pressure can be 25MPa to 80MPa, for example, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80MPa or any combination thereof.

[0119] The volume ratio of the release agent to water can be 1:(20~100), for example, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, 1:100 or any combination thereof.

[0120] The temperature of the cooling medium in the point cooling channel of the mold (point cooling temperature) can be 5℃~15℃, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15℃ or any combination thereof.

[0121] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0122] Example 1

[0123] This embodiment provides a method for preparing an aluminum alloy, including the following steps:

[0124] A first raw material system comprising aluminum and recycled aluminum alloy is first melted, then first refined to obtain a first material; wherein the first refining temperature is 740℃; and the mass percentage of recycled aluminum alloy in the aluminum alloy raw material is 50%.

[0125] The first material is mixed with a second raw material system including silicon, Al-Ni master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-Zr master alloy, Al-Ti master alloy, and Al-RE master alloy, and the second raw material system is subjected to a second melting to obtain the second material; wherein, the temperature of the second melting is 750℃.

[0126] The second material is mixed with a third raw material system including Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy. After the Al-Mg master alloy, Al-V master alloy, and Al-Sr master alloy undergo a third melting, a second refining and a deep refining are performed to obtain an aluminum alloy. The third melting temperature is 740℃, the second refining temperature is 720℃, and the deep refining process specifically includes: using a rotary jetting device to introduce Ar containing magnesium chloride powder into the melt material after the second refining for powder spraying refining. After slag removal and degassing treatment, the mixture is allowed to stand for 10 minutes, and then slag removal treatment is performed to obtain the aluminum alloy.

[0127] The elemental composition of the aluminum alloy in Example 1 is shown in Table 1:

[0128] Table 1

[0129]

[0130] The aluminum alloys of the following examples and comparative examples were prepared according to the preparation method of Example 1. The specific elemental composition is shown in the following content.

[0131] Example 2

[0132] This embodiment provides an aluminum alloy, the elemental composition of which is shown in Table 2:

[0133] Table 2

[0134]

[0135] Example 3

[0136] This embodiment provides an aluminum alloy, the elemental composition of which is shown in Table 3:

[0137] Table 3

[0138]

[0139] Example 4

[0140] This embodiment provides an aluminum alloy, the elemental composition of which is shown in Table 4:

[0141] Table 4

[0142]

[0143] Comparative Example 1

[0144] The elemental composition of aluminum alloys is shown in Table 5:

[0145] Table 5

[0146]

[0147] Comparative Example 2

[0148] The elemental composition of aluminum alloys is shown in Table 6:

[0149] Table 6

[0150]

[0151] Comparative Example 3

[0152] The elemental composition of aluminum alloys is shown in Table 7:

[0153] Table 7

[0154]

[0155] Comparative Example 4

[0156] The elemental composition of aluminum alloys is shown in Table 8:

[0157] Table 8

[0158]

[0159] Comparative Example 5

[0160] The elemental composition of aluminum alloys is shown in Table 9:

[0161] Table 9

[0162]

[0163] Test case

[0164] The aluminum alloys of the above embodiments and comparative examples were held at 690°C to obtain aluminum alloy melt. The aluminum alloy melt was then die-cast to obtain aluminum alloy castings. The injection speed was 5 m / s, the mold temperature was 200°C, and the casting pressure was 60 MPa. A diluted release agent (Trennex W3351-16) was sprayed onto the mold, with a release agent to water volume ratio of 1:60. The temperature of the cooling medium in the mold's point cooling channel was 10°C. The aluminum alloy melts of the embodiments and comparative examples met the requirements of density equivalent ≤2% and K-modulus value ≤0.1. The following parameters of the aluminum alloy castings were then tested:

[0165] Tensile strength test method: The test shall be conducted in accordance with the requirements of GB / T 15114-2023.

[0166] Yield strength test method: The test shall be conducted in accordance with the requirements of GB / T 15114-2023.

[0167] Elongation calculation method: Test according to the requirements of GB / T 15114-2023.

[0168] The mechanical property tests of the examples and comparative examples are shown in Table 10.

[0169] Table 10

[0170]

[0171] Conclusion Analysis:

[0172] As can be seen from Table 10, the aluminum alloys prepared using the present invention (Examples 1-4) all meet the following requirements: tensile strength ≥ 260 MPa, yield strength ≥ 125 MPa, and elongation ≥ 10%.

[0173] In Comparative Example 1, when the Si and Mg contents were relatively low, the aluminum alloy tended to have low strength and high elongation. In Comparative Example 2, as the Mg content increased, it enhanced the strength of the aluminum alloy, but the elongation showed a decreasing trend. In Comparative Example 3, Fe significantly reduced the strength and elongation of the aluminum alloy. Therefore, under these conditions, the mechanical properties of the sample were the lowest, with a tensile strength of 237.8 MPa, a yield strength of 108.2 MPa, and an elongation of 6.7%. In Comparative Example 4, the low Si / Ni ratio (Si / Ni=7.2) increased the risk of brittle phases and reduced the elongation of the aluminum alloy to 8.8%. In Examples 1-4, the strength of the aluminum alloy increased with the addition of strengthening elements (Si, Mg). However, the addition of Si weakened the problem of reduced elongation caused by the strengthening phase alloy. By increasing the fluidity of the alloy, the alloy was guaranteed to have low macroscopic defects. Therefore, to ensure the mechanical properties of the alloy, the content of alloying elements must be controlled within the requirements of this invention.

[0174] In summary, the heat-treatable strengthened aluminum alloy adapted to high-recycle materials prepared by this invention has significant industrial application value. This heat-treatable strengthened aluminum alloy, under die-cast conditions, can achieve excellent properties such as a yield strength of 125MPa~140MPa, a tensile strength of 260MPa~290MPa, and an elongation of 10%~15% (compared to traditional AlSi). 10 MnMg alloys have a cast tensile strength of 200MPa~220MPa and an elongation of 5%~8%, and can achieve good die-casting performance, meeting the application requirements of large thin-walled body structural parts in the new energy vehicle industry. Compared with existing heat-treatable aluminum alloys, aluminum alloy castings made from aluminum alloys can reduce heat treatment processes, improve the qualification rate of castings, and reduce the cost of castings.

[0175] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An aluminum alloy, characterized in that, The aluminum alloy comprises, by mass percentage, Si 7%–10%, Ni 0–1%, Mn 0.5%–0.7%, Mg 0.3%–0.6%, Fe 0.1%–0.45%, Cr 0.05%–0.15%, Cu≤0.1%, V≤0.1%, Zr≤0.1%, Ti 0.08%–0.15%, B 0.016%–0.03%, Sr 0.005%–0.025%, and RE 0.05%–0.35%; wherein RE includes at least one of La and Ce.

2. The aluminum alloy according to claim 1, characterized in that, The mass ratio of Si to Ni is greater than or equal to 10:1; And / or, the mass ratio of Mn to Cr is greater than or equal to 4; And / or, the mass ratio of La to Ce is 1:(3-5); And / or, the aluminum alloy further includes impurity elements, including one or more of P, Ca, and Zn.

3. A method for preparing the aluminum alloy according to claim 1 or 2, characterized in that, include: The raw materials used to form the aluminum alloy are subjected to refining treatment to obtain the aluminum alloy.

4. The method for preparing the aluminum alloy according to claim 3, characterized in that, The raw materials for the aluminum alloy include a first raw material and recycled aluminum alloy material. The first raw material includes at least one of aluminum material, silicon material, and Al-X master alloy, wherein X includes Ni, Mn, Mg, Cr, Cu, V, Zr, Ti, B, Sr, and RE. The recycled aluminum alloy material includes Fe, and the mass percentage of the recycled aluminum alloy material in the raw materials of the aluminum alloy is 0-50%, preferably 30%-50%, and more preferably 40%-50%. Preferably, the Al-X master alloy includes one or more of the following: Al-Ni master alloy, Al-Mn master alloy, Al-Mg master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-V master alloy, Al-Zr master alloy, Al-Ti-B master alloy, Al-Sr master alloy, and Al-RE master alloy.

5. The method for preparing the aluminum alloy according to claim 3 or 4, characterized in that, The refining process includes: melting and refining the raw material of the aluminum alloy to obtain the aluminum alloy; Preferably, the process of smelting and refining the raw material of the aluminum alloy to obtain the aluminum alloy specifically includes: The first raw material system, including aluminum material and recycled aluminum alloy, is first melted and then first refined to obtain the first material. The first material is mixed with a second raw material system comprising silicon material, Al-Ni master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-Cu master alloy, Al-Zr master alloy, Al-Ti-B master alloy, and Al-RE master alloy, and the second raw material system is subjected to a second melting to obtain the second material. The second material is mixed with a third raw material system including Al-Mg master alloy, Al-V master alloy and Al-Sr master alloy, and the Al-Mg master alloy is subjected to a third melting and then a second refining to obtain the aluminum alloy.

6. The method for preparing the aluminum alloy according to claim 5, characterized in that, The second refining temperature is 700℃~730℃; And / or, the second refining process further includes deep refining, wherein the deep refining includes a powder spraying refining process, wherein the powder spraying refining process is carried out by introducing an inert gas carrying a refining agent into the melt using a rotary spraying device; wherein the degassing speed of the powder spraying refining process is 280 r / min to 500 r / min, the degassing time is 8 min to 15 min, and the pressure of the gas source during degassing is 0.25 ± 0.05 MPa; wherein the refining agent includes at least one of magnesium chloride and calcium chloride.

7. An aluminum alloy structural component, characterized in that, The aluminum alloy structural component comprises the aluminum alloy as described in claim 1 or 2, or the aluminum alloy prepared according to the method described in any one of claims 3-6.

8. The aluminum alloy structural component according to claim 7, characterized in that, The aluminum alloy structural components include aluminum alloy castings.

9. A method for preparing an aluminum alloy casting, characterized in that, include: The aluminum alloy is cast to obtain the aluminum alloy casting; wherein the aluminum alloy includes the aluminum alloy according to claim 1 or 2 or the aluminum alloy obtained by the preparation method of the aluminum alloy according to any one of claims 3-6.

10. The method for preparing aluminum alloy castings according to claim 9, characterized in that, Before casting the aluminum alloy, the molten aluminum alloy is kept at a temperature within the casting temperature range, and then casting is performed to obtain the aluminum alloy casting; preferably, the density equivalent of the molten aluminum alloy is ≤2% and the K modulus value is ≤0.

1. And / or, the casting process parameters satisfy: injection speed of 4m / s~6m / s, mold temperature of 180℃~240℃, and casting pressure of 25MPa~80MPa; wherein, a release agent diluted with water is used to spray the mold, and the volume ratio of the release agent to water is 1:(20~100); the temperature of the cooling medium in the point cooling channel of the mold is 5℃~15℃.

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