A die-cast aluminum alloy and its preparation method, structural components and equipment

Abstract

This application provides a die-cast aluminum alloy, its preparation method, structural components, and equipment. The die-cast aluminum alloy, by mass percentage, comprises 7%–11.5% silicon, 0.3%–0.8% manganese, 0.1%–0.7% magnesium, 0.005%–1.7% copper, and 0.01%–0.6% iron; the hydrogen (H) content is 44%–105%, and the sulfur (S) content is 39%–100%. The H and S content are calculated based on the matching relationships between the aforementioned elements. By limiting the content of each element in the die-cast aluminum alloy as described above, its deformation resistance and the controllability of deformation are effectively improved, thereby ensuring the safety and reliability of the die-cast aluminum alloy in application.

Description

Technical Field

[0001] This application relates to the field of materials, and more particularly to a die-cast aluminum alloy and its preparation method, structural components, and equipment. Background Technology

[0002] Aluminum alloys, with their excellent specific strength and lightweight benefits, have become key materials for achieving weight reduction and efficiency improvement in the automotive, aerospace, and consumer electronics industries. Among aluminum alloy processing technologies, wrought aluminum alloys and die-cast aluminum alloys are two main types. Die-casting, with its high efficiency, high material utilization, and ability to integrally form complex components, demonstrates significant advantages in lightweight structural manufacturing, especially suitable for the mass production of parts with intricate structures.

[0003] In fields with stringent safety requirements, such as automobiles, the performance of die-cast aluminum alloys used in critical load-bearing structures must meet a range of comprehensive requirements. Firstly, the material should exhibit good impact toughness in collision scenarios, effectively absorbing impact energy through controlled plastic deformation to ensure occupant safety. Secondly, as structural components requiring reliable connections with other parts via bolts, the material must also possess sufficient resistance to deformation at the connection points to maintain the stability and long-term reliability of the connection system. Both of these performance aspects place clear and high demands on the microstructure and mechanical properties of die-cast aluminum alloys.

[0004] Currently, the performance of conventional die-cast aluminum alloys often falls short of ideal levels in both of the aforementioned aspects. This, to some extent, limits the further widespread application of die-cast aluminum alloys in critical structural components where both collision safety and connection reliability are extremely demanding. Therefore, it is necessary to systematically improve the overall performance of die-cast aluminum alloys through material composition optimization to meet increasingly stringent engineering application requirements. Summary of the Invention

[0005] This application provides a die-cast aluminum alloy that, by limiting its special elemental composition, effectively improves its resistance to deformation and the controllability of deformation, thereby giving it the advantage of safety and reliability in application.

[0006] This application also provides a method for preparing a die-cast aluminum alloy, used to prepare the aforementioned die-cast aluminum alloy.

[0007] This application also provides a structural component comprising the aforementioned die-cast aluminum alloy, thus providing the advantage of safety and reliability.

[0008] This application also provides a device including the above-mentioned structural components, thus the device has the advantage of long-term safety and stability.

[0009] This application provides a die-cast aluminum alloy, which, by mass percentage, comprises 7%~11.5% silicon, 0.3%~0.8% manganese, 0.1%~0.7% magnesium, 0.005%~1.7% copper, and 0.01%~0.6% iron; the hydrogen (H) content of the die-cast aluminum alloy is 44%~105%, and the sulfur (S) content is 39%~100%; wherein, H is calculated using Formula 1, and S is calculated using Formula 2.

[0010] H = 4.5 × Wa + 21 × Wb + 27 × Wc + 11.1 × Wd + 3 × We (Equation 1);

[0011] S = 0.0504 / (0.5 × Wa + 2.5 × Wb + 4.5 × Wc + Wd + 3.5 × We) Equation 2;

[0012] In Formulas 1 and 2, Wa represents the mass percentage of silicon in the die-cast aluminum alloy (in units of %), Wb represents the mass percentage of manganese in the die-cast aluminum alloy (in units of %), Wc represents the mass percentage of magnesium in the die-cast aluminum alloy (in units of %), Wd represents the mass percentage of copper in the die-cast aluminum alloy (in units of %), and We represents the mass percentage of iron in the die-cast aluminum alloy (in units of %).

[0013] In the die-cast aluminum alloy described above, H is 47.3% to 90%; and / or, S is 44% to 91%.

[0014] In the die-cast aluminum alloy described above, Wa is 8.0%~9.5%; preferably, Wa is 8.3%~9.3%; and / or, Wb is 0.35%~0.7%; preferably, Wb is 0.35%~0.65%; and / or, Wc is 0.18%~0.65%; preferably, Wc is 0.2%~0.65%; and / or, Wd is 0.005%~1.3%; and / or, We is 0.05%~0.4%.

[0015] The die-cast aluminum alloy described above further includes titanium; the mass percentage (Wf) of titanium in the die-cast aluminum alloy is 0.03%~0.13%; preferably, the Wf is 0.06%~0.13%; and / or, the die-cast aluminum alloy further includes hafnium; the mass percentage (Wg) of hafnium in the die-cast aluminum alloy is 0.01%~0.1%; preferably, the Wg is 0.01%~0.08%; and / or, the die-cast aluminum alloy further includes nickel; the mass percentage (Wh) of nickel in the die-cast aluminum alloy is 0.0015%~0.18%; preferably, the Wh is 0.002%~0.15%.

[0016] In the die-cast aluminum alloy described above, Wf, Wg, and Wh satisfy 0.1% ≥ Wf + Wg + Wh ≥ 0.25%.

[0017] The die-cast aluminum alloy as described above further includes strontium with a mass percentage of 0.005% to 0.05%; preferably, the mass percentage of strontium in the die-cast aluminum alloy is 0.01% to 0.04%.

[0018] The die-cast aluminum alloy as described above further includes boron at a mass percentage of 0.0005%-0.005%; and / or, the die-cast aluminum alloy further includes carbon at a mass percentage of 0.0005%~0.05%.

[0019] This application also provides a method for preparing the die-cast aluminum alloy described in any of the above claims, comprising the following steps: smelting and die-casting raw materials including silicon source, manganese source, magnesium source, iron source and copper source according to the expected mass percentage content of the corresponding elements in the die-cast aluminum alloy, to obtain the die-cast aluminum alloy.

[0020] In the preparation method described above, a grain refiner is added during the smelting process, and the grain refiner includes Al-Ti-B and / or Al-Ti-C.

[0021] This application also provides a structural component comprising the die-cast aluminum alloy described in any of the above claims, or the die-cast aluminum alloy obtained by the above preparation method.

[0022] The structural component described above has a thickness of 1.5mm to 6mm.

[0023] This application also provides an apparatus including the above-described structural components.

[0024] The die-cast aluminum alloy provided in this application, by limiting the mass percentage content of silicon, manganese, magnesium, iron and copper elements and ensuring their mutual matching, effectively improves the deformation resistance and deformation controllability of the die-cast aluminum alloy, thereby enhancing its safety and reliability in application. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a bolt connection test for die-cast aluminum alloy according to this application;

[0026] Figure 2 This is a schematic diagram of an impact collapse test for die-cast aluminum alloys according to this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] To improve the safety performance of die-cast aluminum alloys in collision scenarios, the inventors focused on the material's resistance to deformation and the controllability of deformation. The study found that die-cast aluminum alloys typically contain high levels of alloying elements to ensure good casting fluidity. Combined with the inherent rapid solidification characteristics of the die-casting process, this easily leads to the segregation of brittle phases at grain boundaries or in localized areas. This inhomogeneity in the microstructure makes the material's collapse behavior during collisions unpredictable, and the deformation mode difficult to determine, thus posing a safety hazard.

[0029] The inventors initially attempted to improve the problem by controlling the content of single elements (such as silicon, manganese, and magnesium), but found that the consistency of product performance remained unsatisfactory. Further research revealed that the proportions of different alloying elements significantly affected their solid solubility and the distribution morphology of precipitated phases in the aluminum matrix, leading to large fluctuations in alloy properties. Therefore, the inventors realized that it was necessary to start with the synergistic mechanism of multiple elements and systematically analyze the precipitation behavior and interactions of each element under die-casting conditions. Ultimately, it was determined that only through precise proportioning and synergistic control of multiple key alloying components could the material's resistance to deformation and the consistency of deformation be optimized simultaneously, thereby systematically solving the core problem of collision safety and reliability in die-cast aluminum alloys.

[0030] Based on this, this application provides a die-cast aluminum alloy, which, according to mass percentage, comprises 7%~11.5% silicon, 0.3%~0.8% manganese, 0.1%~0.7% magnesium, 0.005%~1.7% copper, and 0.01%~0.6% iron; the H content of the die-cast aluminum alloy is 44%~105%, and the S content is 39%~100%; wherein, H is calculated using Formula 1, and S is calculated using Formula 2;

[0031] H = 4.5 × Wa + 21 × Wb + 27 × Wc + 11.1 × Wd + 3 × We (Equation 1);

[0032] S = 0.0504 / (0.5 × Wa + 2.5 × Wb + 4.5 × Wc + Wd + 3.5 × We) Equation 2;

[0033] In Equations 1 and 2, Wa represents the mass percentage of silicon in the die-cast aluminum alloy (in units of %), Wb represents the mass percentage of manganese in the die-cast aluminum alloy (in units of %), Wc represents the mass percentage of magnesium in the die-cast aluminum alloy (in units of %), Wd represents the mass percentage of copper in the die-cast aluminum alloy (in units of %), and We represents the mass percentage of iron in the die-cast aluminum alloy (in units of %).

[0034] This application systematically regulates the microstructure and mechanical properties of die-cast aluminum alloys by optimizing the composition and proportion of multiple elements, thereby effectively solving the combined problem of bolt connection performance and controllable impact deformation.

[0035] Specifically, by precisely controlling the content range of each alloying element, the stability of the metallographic structure and the consistency of quality of the die-cast aluminum alloy are essentially guaranteed. For example, within the above range, silicon balances the casting fluidity and matrix strength of the alloy and refines the grains through eutectic action; manganese and magnesium synergistically promote precipitation strengthening while inhibiting harmful segregation; iron forms stable intermetallic compounds, improving the toughness of the material; and copper enhances strength through solid solution strengthening.

[0036] It is worth noting that the main element in die-cast aluminum alloys is aluminum. However, during the preparation process, due to limitations in raw material purity and the cleanliness of the preparation environment, trace amounts of other impurity elements may be introduced. These other impurity elements are elements other than those mentioned above, such as at least one of the following: V, Ga, Sn, Pb, Zn, Ba, Na, Zr, Ca, Y, Cr, Ag, P, and Li. The composition design of this scheme has fully considered this factor to ensure that impurities are within a controllable range.

[0037] Meanwhile, the inventors discovered that the rapid solidification characteristic of the die-casting process makes it easy for die-cast aluminum alloys to form a significant gradient in microstructure and properties from the surface to the core, and this gradient is extremely sensitive to the wall thickness of the component. This wall thickness dependence leads to drastically different failure risks: for thin-walled parts, the cross-section cools rapidly and uniformly, forming an ultra-fine-grained dense layer on the surface, while the internal α-Al solid solution has a higher proportion, exhibiting the characteristics of "brittle on the surface and tough on the inside"; for thick-walled parts, due to the large temperature difference in the cross-section, coarse and continuous brittle compound bands are easily formed on the inner side of the surface, while the core exhibits coarse grains and shrinkage porosity due to slow cooling, exhibiting the characteristics of "tough on the surface and brittle on the inside".

[0038] To overcome the aforementioned wall thickness sensitivity and coordinate the performance requirements of die-cast aluminum alloys under different strain rates, such as static connections (bolt preload) and dynamic collisions (high-speed impacts), the inventors, based on in-depth modeling and analysis of the synergistic effects of specific element combinations, constructed quantitative relationships (Equations 1 and 2) between parameters H and S. These formulas scientifically quantify the contributions of key elements such as silicon, manganese, magnesium, copper, and iron to the comprehensive mechanical properties of die-cast aluminum alloys, particularly ensuring the reliability of bolted connections under collision conditions, by assigning optimized specific weight coefficients to these elements.

[0039] By precisely controlling the H and S values ​​within the aforementioned ranges, the microstructure and phase distribution of the alloy can be effectively regulated. This results in smaller intrusion and a controllable fragmentation mode in the die-cast aluminum alloy after bolting, demonstrating its excellent resistance to plastic deformation under assembly torque and meeting the connection design requirements of high-strength bolts. Simultaneously, the controllable fragmentation mode effectively absorbs impact energy, achieving a balance between connection point strength and overall energy absorption. Especially under typical working conditions with wall thicknesses of 1.5–6 mm and impact speeds below 32 km / h, this solution further enhances the reliability of bolted connections while maintaining the lightweight advantages of die-cast aluminum alloys.

[0040] It is worth noting that when calculating the H and S values, the percentage units of each element must be substituted into Equations 1 and 2. For example, when Wa=11.5%, Wb=0.65%, Wc=0.55%, Wd=1.7%, and We=0.25%, simply substitute 11.5%, 0.65%, 0.55%, 1.7%, and 0.25% into the calculation.

[0041] Through the synergistic effect of the aforementioned elements, this die-cast aluminum alloy effectively suppresses the regional segregation of brittle phases during the die-casting process, enabling the material to exhibit controllable plastic deformation behavior under impact conditions while ensuring sufficient deformation resistance at the bolted connection. This characteristic stems from the effective control of precipitates through compositional design: on the one hand, fine-grained strengthening and solid solution strengthening ensure the required strength and deformation resistance of the bolted connection; on the other hand, through microstructure homogenization and optimization of brittle phase morphology, it ensures that the die-cast aluminum alloy can undergo stable plastic deformation in a predetermined sequence during impact, achieving efficient energy absorption.

[0042] In summary, the die-cast aluminum alloy of this application, through multi-element synergistic fine composition design, simultaneously optimizes the microstructure uniformity and mechanical property matching, ultimately achieving an organic unity of connection reliability (high resistance to deformation) and collision safety (controllable plastic deformation), providing an efficient solution for the lightweight design of key load-bearing structural components.

[0043] Specifically, the content of each element in die-cast aluminum alloys can be determined using methods such as direct-reading spectrometers and ICP chemical detection, in accordance with GB / T 7999, GB / T 15114, and GB / T 20975.2 standards.

[0044] Furthermore, when the H content of the die-cast aluminum alloy is 47.3%~90%, the die-cast aluminum alloy has a more superior resistance to plastic deformation under the local high pressure stress of bolt pre-tightening, thereby ensuring that the connection surface maintains tightness under long-term vibration and load, enhancing the local load-bearing integrity of the connection thread area, effectively avoiding early connection failure modes such as thread stripping, peeling or matrix cracking caused by local structural defects (such as coarse brittle phases), and achieving a further improvement in the reliability of bolt connections.

[0045] Furthermore, when the S content of die-cast aluminum alloy is 44%~91%, the structural components of die-cast aluminum alloy exhibit higher stability under collision conditions and can absorb and dissipate impact kinetic energy in a more controllable manner, thereby providing safer protection for passengers in extreme collision scenarios.

[0046] Furthermore, when Wa is 8.0%~9.5%, the casting fluidity and mechanical strength of the die-cast aluminum alloy achieve a better balance. The eutectic structure formed by silicon and aluminum can be sufficiently refined, ensuring the integrity of the mold filling during the die-casting process for thin-walled complex components, while avoiding the precipitation of coarse primary silicon crystals due to excessive silicon content. This optimized eutectic silicon morphology effectively reduces the cutting effect on the matrix, providing a more uniform and dense microstructure for subsequent bolted connections, and laying a more favorable microstructural foundation for stable deformation under impact conditions. When Wa is 8.3%~9.3%, the structural stability of the die-cast aluminum alloy is even better.

[0047] Furthermore, when Wb is 0.35%~0.7%, the neutralization and refinement effect of harmful iron phases in die-cast aluminum alloys is better. Manganese and iron can form fine, dispersed compounds, effectively inhibiting the formation of coarse, needle-like brittle phases, thereby improving the dynamic toughness of die-cast aluminum alloys. This allows them to distribute stress more evenly when subjected to impact loads, avoiding early cracking caused by local concentration of brittle phases, and further improving the stability and predictability of the impact collapse process. When Wb is 0.35%~0.65%, the structural stability of die-cast aluminum alloys is even better.

[0048] Furthermore, when Wc is between 0.18% and 0.65%, the age-hardening potential of the die-cast aluminum alloy is more fully realized. Magnesium can form a sufficient number of fine reinforcing phases with silicon, improving the yield strength and tensile strength of the matrix while ensuring good die-casting formability. This directly translates into higher crush resistance and creep resistance in bolted connections, ensuring the connection surface remains stable under high preload torque, thus providing a more favorable guarantee for the long-term reliability of key structural components. When Wc is between 0.2% and 0.65%, the structural stability of the die-cast aluminum alloy is even better.

[0049] Furthermore, when Wd is 0.005%~1.3%, the solid solution strengthening effect and precipitation strengthening effect of die-cast aluminum alloy achieve better synergy. Copper can not only fully dissolve in the aluminum matrix to cause lattice distortion and improve the basic strength, but also form fine strengthening phases under appropriate conditions, further enhancing the load-bearing capacity of die-cast aluminum alloy. At the same time, it avoids grain boundary segregation and hot cracking tendency caused by excessive copper, so that it can still have good plastic deformation ability while maintaining high strength characteristics, thereby obtaining higher toughness.

[0050] Furthermore, when We is 0.05%~0.4%, the hot crack resistance and demolding properties of the die-casting alloy are further optimized. Iron can effectively reduce the tendency of the alloy to stick to the mold during the die-casting process, extend the mold life and improve production efficiency. At the same time, through the synergistic effect with manganese, iron exists in a fine and dispersed compound form, avoiding the tearing of the matrix by coarse and brittle elements. This allows it to maintain good casting processability while still ensuring the dynamic toughness required under impact conditions, achieving a better balance between process performance and mechanical properties.

[0051] In one specific embodiment, the die-cast aluminum alloy further includes titanium; the mass percentage (Wf) of titanium in the die-cast aluminum alloy is 0.03% to 0.13%.

[0052] In detail, when the mass percentage of titanium is within the above range, the grain refinement effect of titanium is more fully realized. The TiAl3 compound formed by titanium and aluminum can provide sufficient and uniformly distributed heterogeneous nucleation sites, effectively refining the α-Al primary phase and obtaining a dense equiaxed grain structure. This grain refinement strengthening effect effectively improves the yield strength of the material and significantly improves the uniformity of the structure, providing a more uniform local load-bearing capacity for bolted connections.

[0053] Furthermore, when Wf is between 0.06% and 0.13%, the grain refinement effect of titanium reaches an even better state, and the strength and plasticity of the die-cast aluminum alloy achieve a better match. Under impact conditions, this microstructure makes the crack propagation path more tortuous and further increases the proportion of transgranular fracture, thereby achieving higher energy absorption efficiency while ensuring connection reliability.

[0054] In one specific embodiment, the mass percentage (Wg) of hafnium in the die-cast aluminum alloy is 0.01% to 0.1%.

[0055] In detail, when the mass percentage of hafnium is within the above-mentioned range, hafnium can partially dissolve in the aluminum matrix to produce lattice distortion strengthening, and at the same time, it forms composite nucleation particles with titanium, which have higher thermal stability. These composite particles can continuously play a refining role in the high-temperature melt, resulting in a more uniform and finer grain structure than when titanium is added alone, thereby further improving the microstructure consistency and high-temperature stability of the die-cast aluminum alloy during the die-casting process.

[0056] Furthermore, when Wg is 0.01%~0.08%, the synergistic refining effect of hafnium reaches its optimal state. The composite precipitate formed by hafnium and titanium is more dispersed and uniformly distributed, which not only further refines the grains but also effectively inhibits abnormal grain growth during solidification. This highly uniform fine-grained structure makes the stress distribution of the die-cast aluminum alloy more uniform under dynamic impact loads, significantly reducing local stress concentration, thereby further improving the stability and controllability of the impact collapse process.

[0057] In one specific embodiment, the die-cast aluminum alloy further includes nickel; the mass percentage (Wh) of nickel in the die-cast aluminum alloy is 0.0015% to 0.18%.

[0058] In detail, when the mass percentage of nickel is within the above range, the solid solution strengthening effect of nickel is more fully exerted. Nickel dissolves in the aluminum matrix, causing lattice distortion, which improves the basic strength of the die-cast aluminum alloy. At the same time, fine Al3Ni intermetallic compounds begin to form, laying the foundation for subsequent precipitation strengthening, which in turn helps to improve the deformation resistance of bolted connections.

[0059] Furthermore, when Wh is between 0.002% and 0.15%, the solid solution strengthening and precipitation strengthening effects of nickel achieve a better balance. Nickel can both fully strengthen the matrix through solid solution and uniformly precipitate within the grains and at grain boundaries in the form of finely dispersed Al3Ni compounds. These nanoscale strengthening phases effectively hinder dislocation movement and avoid stress concentration, enabling the die-cast aluminum alloy to absorb energy through uniform micro-plastic deformation when subjected to dynamic impacts. This further improves the fracture toughness and energy absorption efficiency under impact conditions, achieving a synergistic improvement in connection strength and impact toughness.

[0060] In one specific implementation, Wf, Wg, and Wh satisfy 0.1% ≥ Wf + Wg + Wh ≥ 0.25%.

[0061] In detail, when the content of each element in the die-cast aluminum alloy meets the above-mentioned range, the elements are more well-matched. For example, the grain refinement and precipitate control effects of high-melting-point elements are further synergistic, improving the mechanical strength and microstructure uniformity of the die-cast aluminum alloy. Simultaneously, under impact conditions, this die-cast aluminum alloy exhibits a more pronounced tendency for transgranular fracture, thereby maximizing the absorption of impact kinetic energy, effectively buffering impacts, and further enhancing the impact safety of the die-cast aluminum alloy.

[0062] In one specific embodiment, the die-cast aluminum alloy further includes strontium at a mass percentage of 0.005% to 0.05%.

[0063] In detail, when the mass percentage of strontium is within the above range, strontium, as a highly efficient modifier, can more effectively improve the morphology and distribution of eutectic silicon. Coarse, plate-like or needle-like eutectic silicon is transformed into fine, fibrous or granular forms, effectively reducing its cutting effect on the aluminum matrix. This microstructure optimization not only improves the static mechanical properties of the die-cast aluminum alloy, but more importantly, enhances the continuity of the matrix, reduces stress concentration sources, and provides a more uniform and dense microstructure for bolted connections. Simultaneously, it enables the die-cast aluminum alloy to more effectively transfer and disperse impact energy during collisions.

[0064] Furthermore, when the mass percentage of strontium in the die-cast aluminum alloy is 0.01%~0.04%, it ensures that the eutectic silicon is sufficiently and uniformly refined, while avoiding incomplete modification due to excessively low content or over-modification (such as increased porosity) due to excessively high content. This significantly improves the dynamic toughness of the die-cast aluminum alloy, thereby maximizing the absorption and dissipation of energy. At the same time, the homogenized microstructure ensures the consistency of performance in regions with different wall thicknesses, making the deformation mode of the structural components more stable and controllable, and further improving connection reliability and collision energy absorption efficiency.

[0065] In one specific embodiment, the die-cast aluminum alloy further includes boron in a mass percentage of 0.0005%-0.005%.

[0066] In detail, as the thickness of die-cast aluminum alloys increases (especially for thicknesses greater than 4 mm), the core cooling rate slows down, easily leading to coarse grains and decreased mechanical properties. Adding a certain amount of boron-containing grain refiner (such as Al5TiB) during the die-casting process can effectively increase the number of heterogeneous nucleation sites, refine the overall grain structure, and thus further improve the mechanical properties of the die-cast aluminum alloy. The boron in this type of grain refiner will remain in the die-cast aluminum alloy, forming the elemental composition described above. Other impurity elements are those not mentioned above.

[0067] In another specific embodiment, the die-cast aluminum alloy also includes carbon elements with a mass percentage of 0.0005% to 0.05%.

[0068] As mentioned earlier, with the increase of the thickness of die-cast aluminum alloys (especially those thicker than 4 mm), the core cooling rate slows down, which can easily lead to coarse grains and decreased mechanical properties. Adding a certain amount of carbon-containing grain refiner (such as Al5TiC) during the smelting process of die-cast aluminum alloys can effectively increase the number of heterogeneous nucleation sites, refine the overall grain structure, and thus further improve the mechanical properties of the die-cast aluminum alloys. The carbon element in this type of grain refiner will remain in the die-cast aluminum alloy, forming the elemental composition described above. Other impurity elements are elements other than those mentioned above.

[0069] This application also provides a method for preparing the aforementioned die-cast aluminum alloy, comprising the following steps: smelting and die-casting raw materials including silicon source, manganese source, magnesium source, iron source and copper source according to the expected mass percentage content of the corresponding elements in the die-cast aluminum alloy, to obtain the die-cast aluminum alloy.

[0070] Specifically, the silicon source, manganese source, magnesium source, iron source, and copper source mentioned above can be elemental or alloy. For example, when other elements need to be introduced, the elemental can be silicon, manganese, magnesium, iron, copper, titanium, strontium, nickel, hafnium, and aluminum, and the alloy can be aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-titanium alloy, aluminum-titanium alloy, aluminum-strontium alloy, aluminum-hafnium alloy, aluminum-iron alloy, aluminum-nickel alloy, etc. This application does not limit them.

[0071] It is worth noting that the mass percentage of the corresponding elements mentioned in the preparation method of this application refers to the element content in the die-cast aluminum alloy. In specific preparation, the raw materials can be selected according to the designed element content of the die-cast aluminum alloy. The smelting process melts all the raw materials into a liquid state at high temperature, and then solidifies them through die casting to obtain the die-cast aluminum alloy.

[0072] In specific preparation, preheating can be used to ensure the dryness of the raw materials. For example, in one specific preparation process, raw materials can be selected according to the elemental proportions of the target die-cast aluminum alloy. Adjustments can be made during preparation based on measured data of the elements in the melt. Specifically, pure aluminum can be added to a melting furnace and heated to 700°C to 800°C to fully melt the pure aluminum and obtain the first melt. Aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-titanium alloy, aluminum-iron alloy, and aluminum-nickel alloy are added sequentially to the first melt, and melting and stirring are continued to obtain the second melt. Aluminum-strontium alloy and aluminum-hafnium alloy are added to the second melt for refinement and modification treatment, with the temperature controlled at 700°C to 720°C. Then, a degassing rotor is used to introduce high-purity argon gas into the bottom of the second aluminum alloy liquid. Stir clockwise for 10-20 minutes to remove impurities and degas, then remove the aluminum slag from the furnace to obtain the third melt. Reduce the temperature of the third melt to 720℃-760℃, then press pure magnesium and a refining agent (if added) into the second melt. After the pure magnesium melts, stir evenly to obtain the fourth melt. Cast the fourth melt into aluminum ingots and transport them to a die-casting equipment for remelting. Then fill the ingots into a die-casting insulation equipment, or transport them directly to the equipment for die-casting. Control the cooling rate at 300-800 k / s, with a low-speed filling rate of 0.15-0.35 m / s and a high-speed filling rate of 3.5-7.0 m / s. The casting pressure is 25-60 MPa. Solidify to obtain a die-cast aluminum alloy. During the preparation process, when the second melt, third melt, and fourth melt are obtained, the element content in each melt is analyzed by direct reading spectrometer, and the corresponding elements of the above-mentioned alloy or monomer are supplemented to address the differences in elements with the target die-cast aluminum alloy.

[0073] In one specific embodiment, a grain refiner is added during the smelting process. The grain refiner includes Al-Ti-B and / or Al-Ti-C.

[0074] As mentioned above, the grain refiner can effectively increase the number of heterogeneous nucleation sites and refine the overall grain structure, making it more suitable for thicker die-cast aluminum alloys, thereby further improving their mechanical properties.

[0075] This application also provides a structural component, including the aforementioned die-cast aluminum alloy.

[0076] The structural components provided in this application can be any structural component with collision safety requirements, such as automotive energy-absorbing box structural components or automotive anti-collision beam structural components. They can maintain high mechanical strength and fully absorb the energy during the impact according to the expected crumple mode, effectively ensuring the safety of passengers.

[0077] In one specific implementation, the thickness of the structural component is 1.5mm to 6mm.

[0078] In detail, when the thickness of the structural component is controlled within the aforementioned range, it is more compatible with the specific composition system and rapid solidification process characteristics of the die-cast aluminum alloy. This thickness range ensures good formability during the die-casting filling process while allowing the alloy to form a microstructure gradient beneficial to its performance during solidification. Under these conditions, the synergistic effect of each element in the composition design is fully utilized, thereby achieving effective control over the material's strength, toughness, and microstructure uniformity. Therefore, this thickness range enables die-cast structural components to exhibit more stable collapse behavior and higher bolt connection performance during impacts, ultimately achieving superior safety and reliability.

[0079] This application also provides an apparatus including the aforementioned structural components.

[0080] The equipment described in this application can be, for example, automobiles, mobile phones, or aerospace vehicles; this application does not specifically limit it. Any equipment that simultaneously requires lightweight design, high strength, stable crumple zone deformation under impact, and bolted connections can utilize the structural components described in this application. This equipment can effectively improve problems such as unstable collision behavior and poor bolted connections, thereby significantly enhancing safety and reliability under unexpected impact conditions.

[0081] The die-cast aluminum alloy provided in this application will be described in detail below through specific embodiments.

[0082] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0083] Example 1

[0084] The preparation method of die-cast aluminum alloy in this embodiment includes the following steps:

[0085] 1) Select raw materials according to the mass percentage of each element in the target die-cast aluminum alloy (11.5% silicon, 0.65% manganese, 0.55% magnesium, 0.25% iron, 1.7% copper, 0.15% titanium, 0.12% strontium, 0.15% nickel, 0.1% hafnium, with the balance being aluminum); First, put aluminum into a melting furnace and heat it to 800℃ to melt it into the first melt; then add aluminum-silicon alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-titanium alloy, aluminum-iron alloy, and aluminum-nickel alloy to the first melt in sequence and continue to melt and stir evenly to obtain the second melt; then add aluminum-strontium alloy and aluminum-hafnium alloy to the second melt and adjust the temperature to 700℃, then use a degassing rotor to introduce argon gas into the bottom of it, stir clockwise for 15 minutes, and then remove the aluminum slag from the furnace to obtain the third melt;

[0086] 2) After the temperature of the third melt is reduced to 750℃, magnesium metal is pressed into it. After the magnesium metal melts, it is stirred evenly to obtain the fourth melt. The fourth melt is filled into the die-casting heat preservation equipment at a low filling speed of 0.25m / s and a high filling speed of 5m / s. The cooling temperature is controlled at 500K / s and the casting pressure is 30Mpa. After solidification, the die-cast aluminum alloy is obtained.

[0087] During the preparation process, when the second melt, third melt, and fourth melt are obtained, the element content in each melt is analyzed by direct reading spectrometer, and the corresponding elements of the above-mentioned alloy or monomer are supplemented to address the differences in elements with the target die-cast aluminum alloy.

[0088] Examples 2-56 and Comparative Examples 1-15 differ from Example 1 in that the amount of each element added to the corresponding monomer or alloy is different, and can be adjusted according to the mass percentage of each element in the target die-cast aluminum alloy; wherein, step 2) of Example 54 further includes adding a grain refiner (Al-Ti) to the third melt. - B), the grain refiner is added at a mass of 0.015% of the third melt mass, introducing element B corresponding to the elemental composition of the target die-cast aluminum alloy. Step 2) of Example 55 also includes adding a grain refiner (Al-Ti-C) to the fourth melt, the grain refiner being added at a mass of 0.015% of the third melt mass, introducing element C corresponding to the elemental composition of the target die-cast aluminum alloy.

[0089] Experimental Example 1

[0090] The elemental content in the die-cast metals of all examples and comparative examples was determined (the balance was Al element), and Wf+Wg+Wh was statistically analyzed. The H value and S value were calculated according to Equations 1 and 2, respectively. The results are shown in Table 1. The elemental content was determined by direct-reading spectrometer.

[0091] Table 1

[0092]

[0093]

[0094]

[0095] Experimental Example 2

[0096] Bolt connection tests and impact collapse tests were performed on all examples and comparative examples of die-cast aluminum alloys, and the test results are shown in Table 2; among them,

[0097] Bolt connection test: A flat plate with a thickness of 3mm was made from die-cast aluminum alloy (e.g., ...). Figure 1As shown in the figure, a through hole is left on the plate, through which the nut is passed and a torque wrench is used to apply a fixed torque of 115 N·m to tighten it to the 10.8 grade bolt; the maximum deformation of the plate in the thickness direction before and after tightening is measured. If the maximum deformation exceeds 1 mm, the sample is deemed unqualified. The experiment is repeated 20 times and the pass rate is calculated, which is the connection target achievement rate.

[0098] Impact collapse test: Die-cast aluminum alloy is made as follows Figure 2 The test sample shown (72mm long, 55mm wide, 50mm high, with an edge and middle crossbeam thickness of 2.6mm and a middle crossbeam height of 38mm) has a hollow support structure at the bottom. The middle crossbeam is located in the middle of the hollow structure, with a space of 36mm between the two. An electronic universal testing machine was used for testing, with the punch force applied along the F direction to the middle crossbeam. The indenter was set to compress at a constant speed of 200mm / min. If the maximum downward pressure recorded during the entire compression process was greater than 30KN, and the corresponding compression displacement was greater than 8mm, and the bulge in the deformation area of ​​the bottom plate was less than 11mm, it was considered to meet the design requirements (i.e., qualified). The experiment was repeated 50 times for each die-cast aluminum alloy, and the percentage of qualified products was statistically analyzed, representing the collision target achievement rate.

[0099] Among them, when the connection target achievement rate is 60% or higher and the collision target achievement rate is 70% or higher, the requirements for collision safety and connection reliability can be met simultaneously; preferably, the collision target achievement rate is greater than 80%; more preferably, the connection target achievement rate is greater than 70%; further preferably, the connection target achievement rate is greater than 80%; further preferably, the collision target achievement rate is greater than 90%; further preferably, the connection target achievement rate is greater than 90%; further preferably, both the connection target achievement rate and the collision target achievement rate are greater than 95%.

[0100] Table 2

[0101]

[0102]

[0103]

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 therein. Such 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 this application.

Claims

1. A die-cast aluminum alloy, characterized in that, According to mass percentage, the die-cast aluminum alloy comprises 7%~11.5% silicon, 0.3%~0.8% manganese, 0.1%~0.7% magnesium, 0.005%~1.7% copper, and 0.01%~0.6% iron; the hydrogen (H) of the die-cast aluminum alloy is 44%~105%, and the sulfur (S) of the die-cast aluminum alloy is 39%~100%; wherein, H is calculated using Formula 1, and S is calculated using Formula 2. H = 4.5 × Wa + 21 × Wb + 27 × Wc + 11.1 × Wd + 3 × We (Equation 1); S = 0.0504 / (0.5 × Wa + 2.5 × Wb + 4.5 × Wc + Wd + 3.5 × We) Equation 2; In Formulas 1 and 2, Wa represents the mass percentage of silicon in the die-cast aluminum alloy (in units of %), Wb represents the mass percentage of manganese in the die-cast aluminum alloy (in units of %), Wc represents the mass percentage of magnesium in the die-cast aluminum alloy (in units of %), Wd represents the mass percentage of copper in the die-cast aluminum alloy (in units of %), and We represents the mass percentage of iron in the die-cast aluminum alloy (in units of %).

2. The die-cast aluminum alloy according to claim 1, characterized in that, The H value is 47.3%~90%; and / or, The value of S is 44% to 91%.

3. The die-cast aluminum alloy according to claim 1 or 2, characterized in that, The Wa content is 8.0%~9.5%; preferably, the Wa content is 8.3%~9.3%; and / or, The Wb content is 0.35%~0.7%; preferably, the Wb content is 0.35%~0.65%; and / or, The Wc is 0.18%~0.65%; preferably, the Wc is 0.2%~0.65%; and / or, The Wd is 0.005%~1.3%; and / or, The value of We is 0.05% to 0.4%.

4. The die-cast aluminum alloy according to any one of claims 1-3, characterized in that, The die-cast aluminum alloy further includes titanium; the mass percentage (Wf) of titanium in the die-cast aluminum alloy is 0.03%~0.13%; preferably, the Wf is 0.06%~0.13%; and / or, The die-cast aluminum alloy further includes hafnium, and the mass percentage (Wg) of hafnium in the die-cast aluminum alloy is 0.01%~0.1%; preferably, the Wg is 0.01%~0.08%; and / or, The die-cast aluminum alloy also includes nickel; the mass percentage (Wh) of nickel in the die-cast aluminum alloy is 0.0015% to 0.18%; preferably, the Wh is 0.002% to 0.15%.

5. The die-cast aluminum alloy according to claim 4, characterized in that, The Wf, Wg, and Wh satisfy 0.1% ≥ Wf + Wg + Wh ≥ 0.25%.

6. The die-cast aluminum alloy according to any one of claims 1-5, characterized in that, The die-cast aluminum alloy further includes strontium at a mass percentage of 0.005% to 0.05%; preferably, the mass percentage of strontium in the die-cast aluminum alloy is 0.01% to 0.04%.

7. The die-cast aluminum alloy according to any one of claims 1-6, characterized in that, The die-cast aluminum alloy further includes boron at a mass percentage of 0.0005%-0.005%; and / or, The die-cast aluminum alloy also includes carbon elements with a mass percentage of 0.0005% to 0.05%.

8. A method for preparing the die-cast aluminum alloy according to any one of claims 1-7, characterized in that, Includes the following steps: The raw materials, including silicon, manganese, magnesium, iron, and copper sources, are smelted and die-cast according to the expected mass percentage of the corresponding elements in the die-cast aluminum alloy to obtain the die-cast aluminum alloy.

9. The preparation method according to claim 8, characterized in that, A grain refiner is added during the smelting process, the grain refiner comprising Al-Ti-B and / or Al-Ti-C.

10. A structural component, characterized in that, Includes the die-cast aluminum alloy according to any one of claims 1-6, or the die-cast aluminum alloy obtained by the preparation method according to claim 8 or 9.

11. The structural component according to claim 10, characterized in that, The thickness of the structural component is 1.5mm to 6mm.

12. A device, characterized in that, Includes the structural component described in claim 10 or 11.

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