Preparation method of high-temperature-resistant die-casting aluminum alloy material for axial flow fan

Abstract

This invention provides a method for preparing a high-temperature resistant die-cast aluminum alloy material suitable for axial flow fans. The formulation of this die-cast aluminum alloy material, by mass percentage, is: Si: ≤1.5%; Fe: ≤0.5%; Cu: 0.35%–0.65%; Mn: 1.5%–3.5%; Mg: 0.05%–0.5%; Zn: ≤0.2%; Ni: 1.9%–5.5%; Ti: ≤0.15%; Zr: 0.1%–0.45%; Pb: ≤0.10%. Sn: ≤0.10%; Cd: ≤0.01%; AlN nanocrystalline seed alloy dosage 1.0%-6.0%; submicron TCB seed alloy dosage 0.3-2.0%; the remainder is Al; the preparation method includes the following steps: adding aluminum ingots; adding manganese additives, copper additives, zirconium nano-alloy additives, and nickel additives; adding AlN nanocrystalline seed alloys; adding sodium-free refining agent; adding magnesium; adding submicron TCB seed alloys; casting alloy aluminum ingots; remelting the alloy aluminum ingots; and die-casting the die castings. The aluminum alloy material prepared by the preparation method provided by this invention has excellent high temperature resistance and strength memory properties, which can meet the application requirements of axial flow fan blades and rotors operating continuously for more than two hours in a high-temperature environment of 400℃.

Description

Technical Field

[0001] This invention belongs to the field of die-cast aluminum alloy technology, specifically relating to a method for preparing high-temperature resistant die-cast aluminum alloy materials that can be used in axial flow fans. Background Technology

[0002] With increasing demands for lightweight and corrosion-resistant properties in subway and other tunnel engineering projects, the blades and rotors of tunnel axial flow fans are now commonly made of die-cast aluminum alloy. Existing technical standards required the fans to pass a heat resistance test involving two hours of hot air circulation at 280°C. The AlSi12CuMnMgFe alloy currently in use meets these performance standards under these conditions.

[0003] However, with the increasing stringent fire prevention and safety standards for tunnels, new standards require fans to operate continuously for more than two hours in a 400°C hot air circulation environment. Traditional heat-resistant aluminum alloys cannot meet this stringent requirement. The currently used AlSi12CuMnMgFe aluminum alloy material is characterized by the following components by mass percentage: Si: 10.4-13%, Fe: ≤1.12%, Cu: 0.4-0.8%, Mn: 0.12-0.72%, Mg: 0.16-0.43%, Zn: ≤0.58%, Ni: ≤0.02%, Pb: ≤0.02%, Sn: ≤0.01%, with the balance being Al. Die-cast parts produced under normal operating conditions (non-laboratory) failed the test at 400°C for two hours. After one hour of operation, the fan blades exhibited significant elongation deformation, leading to collisions with the casing. Clearly, this aluminum alloy material has exceeded its elastic deformation limit during thermal expansion at 400°C, exhibiting significant plastic deformation. The average mechanical properties of die-cast parts made from this material, tested at a high temperature of 400℃, are: tensile strength 52MPa, yield strength 35MPa, and elongation 23%.

[0004] The German GD-AlSi12CuNiMg alloy belongs to the AlSiCuNiMg system and, by mass percentage, comprises the following components: Si: 11.5-12.5%, Fe: ≤0.6%, Cu: 1.5-1.8%, Mg: 0.6-0.8%, Zn: ≤0.2%, Ti: ≤0.1%, Ni: 1.0-1.5%, with the balance being Al. This alloy is currently considered to have relatively good high-temperature resistance below 350℃. Die-cast parts produced under normal working conditions (non-laboratory) tested at 400℃ exhibit the following mechanical properties: tensile strength 57 MPa, yield strength 38 MPa, and elongation 52%. While its tensile strength and yield strength are approximately 10% higher than those of the AlSi12CuMnMgFe aluminum alloy, they still cannot meet the requirements for continuous operation at 400℃ for more than two hours.

[0005] CN118685667A discloses an aluminum-iron-copper based high thermal conductivity aluminum alloy material and its preparation and die-casting methods. The material comprises the following components by mass percentage: Si: ≤0.5%, Fe: 1.0-2.0%, Cu: 0.7-2.0%, Mn: ≤0.05%, Mg: ≤0.05%, Zn: ≤0.05%, Ti: ≤0.05%, Ni: ≤0.05%, TCB seed alloy addition: 0.1-0.6%, Sr: 0.0005-0.06%, Pb: ≤0.05%, Sn: ≤0.01%, Cd: ≤0.01%, single common impurity element: ≤0.05%, total impurity content: ≤0.15%, and the balance is Al. This invention exhibits good thermal conductivity and heat resistance, with a thermal conductivity exceeding 180 W / (mK), and can withstand temperatures up to 500°C. 0 No deformation or discoloration was observed during the 3-hour heat resistance test at C. It belongs to the AlFeCu alloy series, which mainly emphasizes high thermal conductivity. Its die-casting strength at room temperature is relatively low. Its heat resistance test is a qualitative visual inspection method that judges whether there is deformation or discoloration under static conditions without load. This method is also difficult to meet the application requirements of continuous operation for more than two hours in a high-temperature environment of 400℃.

[0006] CN108929975 A discloses an aluminum alloy material and its preparation method, comprising the following components by mass percentage: Si: 2.0-4.5%, Fe: 0.6-1.5%, Cu: <0.3%, Mn: <0.3%, Mg: <0.3%, Zn: <0.3%, Ni: 0.2-1.2%, Pb: ≤0.1%, Sn: ≤0.01%, Cd: ≤0.01%, with the balance being Al. This invention exhibits good thermal conductivity and heat resistance, with a thermal conductivity reaching 178 W / (mK), and can withstand temperatures up to 550°C. 0 In a 3-hour heat resistance test at C, it did not yellow, blacken, deform, or bubble. Belonging to the AlSiFeNi system, its main strength lies in its high thermal conductivity. However, its die-casting strength at room temperature is relatively low. The high-temperature heat resistance test, conducted under static conditions without load, relies on a qualitative visual inspection to determine the presence of yellowing, blackening, deformation, and bubbling. This method is insufficient for applications requiring continuous operation at 400℃ for more than two hours. Furthermore, its die-casting performance is generally poor, and its fluidity is limited.

[0007] Based on the problem of plastic deformation of the blades of axial fans at high temperatures, higher yield strength and its excellent thermal stability have become the key performance indicators to enable continuous operation in a 400°C high-temperature environment. According to the radial centrifugal stress generated by such axial fans at 400°C and considering the factor of high-temperature creep, the maximum can reach nearly 40 MPa. This requires that the yield strength of the aluminum alloy material must be greater than 40 MPa in a 400°C high-temperature environment to meet the requirements. Therefore, there is an urgent need to develop new heat-resistant die-cast aluminum alloy materials to meet the new high-temperature resistance requirements of axial fans for blades and rotors. Achieving this goal can not only meet the new needs of tunnel engineering fans but also be of great significance to the development and application of high-temperature aluminum alloy materials in the fields of transportation, automobile manufacturing, and aerospace. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the present invention provides a preparation method for a high-temperature resistant die-cast aluminum alloy material. The formula of the high-temperature resistant die-cast aluminum alloy material, calculated by mass percentage, is as follows: Si: ≤1.5%; Fe: ≤0.5%; Cu: 0.35% - 0.65%; Mn: 1.5% - 3.5%; Mg: 0.05% - 0.5%; Zn: ≤0.2%; Ni: 1.9% - 5.5%; Ti: ≤0.15%; Zr: 0.1% - 0.45%; Pb: ≤0.10%; Sn: ≤0.10%; Cd: ≤0.01%; the individual content of common impurity elements ≤0.05%, and the total content of common impurity elements: ≤0.15%; the rest is Al; when preparing, AlN nanocrystalline alloy and submicron TCB crystalline alloy are added. The addition amount of the AlN nanocrystalline alloy is 1.0% - 6.0%, and the addition amount of the submicron TCB crystalline alloy is 0.3 - 2.0%.

[0009] To prepare the high-temperature resistant die-cast aluminum alloy material according to the above formula, the preparation method includes the following steps:

[0010] Add aluminum ingots and melt and heat up to between 830°C and 850°C;

[0011] Add manganese additive, copper additive, zirconium nano-alloy additive, nickel additive;

[0012] Cool down to 770°C - 790°C, add the AlN nanocrystalline alloy in two to three batches, stir evenly after adding and let it stand for 5 - 10 minutes;

[0013] When the temperature is at 750°C - 770°C, add a sodium-free refining agent for refining to remove slag and purify;

[0014] Add magnesium and stir evenly;

[0015] Take samples to test the composition and make fine adjustments. After the composition is qualified, proceed to the next step;

[0016] Degas the gas using argon or nitrogen for 20-30 minutes, add submicron TCB seed alloy, and let stand for 5-10 minutes.

[0017] High-temperature die-cast aluminum alloy materials are obtained by casting aluminum alloy ingots at temperatures between 710℃ and 750℃.

[0018] Preferably, the main components of the AlN nanocrystalline seed alloy are: N: 0.8%-1.2%; Si: 9.5%-10.5%; Fe: ≤0.3%; Mn: ≤0.1%; the remainder is Al.

[0019] Preferably, the main components of the AlN nanocrystalline seed alloy are: N: 0.9%-1.1%; Si: 9.9%-10.1%; Fe: ≤0.1%; Mn: ≤0.09%; the remainder is Al.

[0020] Preferably, the AlN nanocrystalline seed alloy contains 1%-5% AlN seeds.

[0021] Preferably, the AlN nanocrystalline seed alloy contains 2%-3% AlN seeds.

[0022] Preferably, the atomic ratio of the AlN seed crystals is 1:1.

[0023] Preferably, in the formulation of the high-temperature die-cast aluminum alloy material, Ni is 2.8%-4%.

[0024] Preferably, the ratio of the AlN nanocrystalline seed alloy to the submicron TCB seed alloy is (2-6):1; the main components of the TCB seed alloy are, by mass percentage: Ti: 4.2-5.2%; C: 0.06-0.12%; B: 0.3-0.5%; RE: 0.5-0.8%; Mn: ≤0.1%; Fe: ≤0.4%; Si: ≤0.3%; V: ≤0.1%; the remainder is Al.

[0025] Preferably, during the casting process, permeable bricks with a pore size of 15-25μm are used to degas the molten aluminum at the bottom of the convection tank or filter box using argon or nitrogen gas.

[0026] Preferably, the amount of the sodium-free refining agent is 0.1%-0.3% of the weight of the molten aluminum.

[0027] The high-temperature die-cast aluminum alloy material prepared by the method of the present invention has high-temperature resistance exceeding that of the German GD-AlSi12CuNiMg alloy, and has excellent strength memory properties, which can meet the application requirements of the fan to operate continuously for more than two hours in a high-temperature environment of 400℃. Attached Figure Description

[0028] The above and other objects, features, and advantages of the invention will become clearer through a more detailed description of the preferred embodiments illustrated in the accompanying drawings. The same reference numerals denote the same parts throughout the drawings, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0029] Figure 1 The aluminum alloy die-casting part of Example 1 was subjected to heat preservation and cooling at different temperatures for two hours, and the resulting curves showed the relationship between strength and heat preservation temperature.

[0030] Figure 2 The graph shows the relationship between the strength and the holding time of the aluminum alloy die-casting part in Example 1 after being held at 400°C for 2 to 16 hours and then cooled.

[0031] Figure 3 The aluminum alloy die-casting part of Example 1 was first subjected to artificial aging treatment at 190℃ for 6 hours, and then subjected to heat preservation and cooling at 400℃ for different durations. The resulting curves show the relationship between strength and heat preservation time. Detailed Implementation

[0032] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0033] This invention provides a method for preparing a high-temperature resistant die-cast aluminum alloy material. The formulation of the high-temperature resistant die-cast aluminum alloy material, by mass percentage, is as follows: Si (silicon): ≤1.5%; Fe (iron): ≤0.5%; Cu (copper): 0.35%-0.65%; Mn (manganese): 1.5%-3.5%; Mg (magnesium): 0.05%-0.5%; Zn (zinc): ≤0.2%; Ni (nickel): 1.9%-5.5%; Ti (titanium): ≤0.15%; Zr (zirconium): 0.1%-0.45%; Pb (lead): ≤0.10%; Sn (tin): ≤0.10%; Cd (cadmium): ≤0.01%; the content of a single common impurity element: ≤0.05%, the total content of common impurity elements: ≤0.15%; the remainder is Al (aluminum). In the preparation of the high-temperature resistant aluminum alloy material of the present invention, AlN seed alloy and TCB seed alloy are added. The amount of AlN nanocrystalline seed alloy added is 1.0%-6.0%, and the amount of TCB seed alloy added is 0.3-2.0%. The TCB seed alloy is a submicron seed alloy. The main composition of the TCB seed alloy, by mass percentage, is: Ti: 4.2-5.2%; C: 0.06-0.12%; B: 0.3-0.5%; RE: 0.5-0.8%; Mn: ≤0.1%; Fe: ≤0.4%; Si: ≤0.3%; V: ≤0.1%; the remainder is Al. The AlN seed alloy is an AlN nanocrystalline seed alloy.

[0034] The high-temperature resistant die-cast aluminum alloy material is prepared according to the described formula. The preparation method includes the following steps:

[0035] S1. Add aluminum ingots, melt them, and heat them to between 830℃ and 850℃.

[0036] S2. Maintaining this temperature range, add manganese additive, copper additive, zirconium nano-alloy additive, and nickel additive in sequence. Each additive is added in 2-6 batches, stirring thoroughly after each addition and letting stand for 5-10 minutes. Allow the temperature to cool naturally after adding the last batch of nickel additive.

[0037] S3. Cool to 770℃-790℃ and add the AlN seed alloy in two to three batches. Stir well after adding and let stand for 5-10 minutes.

[0038] S4. At a temperature of 750℃-770℃, add 0.1%-0.3% of sodium-free refining agent by weight of the molten aluminum for refining, slag removal and purification; add magnesium and stir evenly.

[0039] S5. Take samples to test the components and make minor adjustments. Once the components are qualified, proceed to the next step.

[0040] S6. Degas with argon or nitrogen for 20-30 minutes, add TCB seed alloy, and let stand for 5-10 minutes.

[0041] S7. Casting aluminum alloy ingots at temperatures between 710℃ and 750℃. During the casting process, permeable bricks with 15-25μm pore size are used to degas the molten aluminum in the convection tank or filter box with argon or nitrogen gas to obtain high-temperature resistant aluminum alloy materials.

[0042] The high-temperature resistant die-casting aluminum alloy material prepared by the method provided in this invention is a novel AlCuMnMgNiZr-based multi-element high-temperature resistant aluminum alloy material. Its die-cast parts under normal operating conditions exhibit a yield strength greater than 45 MPa in a 400°C high-temperature environment, meeting the strength requirements of axial flow fans in tunnel engineering for aluminum alloy blades and rotors to operate for at least two hours in a 400°C high-temperature environment. Furthermore, this material has the potential to further improve its strength performance through various process optimizations, and after high-temperature service, it exhibits excellent room-temperature strength memory properties. Moreover, this material has good fluidity and excellent die-casting performance, enabling die-casting molding.

[0043] The high-temperature resistant die-cast aluminum alloy material prepared by the method of this invention is mainly designed with Al-Cu-nMn-Mg-nNi-nAlN-Zr as the basic alloy composition, with Al3Ni phase as the main high-temperature strengthening phase, combined with AlN and Al3Zr nano-strengthening phases, and employs submicron-level TCB microalloying process to refine the matrix structure and delay the coarsening of high-temperature phases, constructing a nano-to-submicron dual-scale strengthening network, exhibiting excellent high-temperature resistance. The heat-resistant die-cast aluminum alloy material provided by this invention can meet the new high-temperature resistance requirements of axial flow fans for blades and rotors. It can not only meet the new requirements of tunnel engineering fans, but also be used in transportation, automotive manufacturing, and aerospace fields.

[0044] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains, by mass percentage, 0.1%-1.0% Si (silicon).

[0045] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains, by mass percentage, Fe (iron): 0.01%-0.5%.

[0046] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains Cu (copper) at a mass percentage of 0.4%-0.6%.

[0047] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains, by mass percentage, Mn (manganese): 1.8%-3.0%.

[0048] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains, by mass percentage, Mg (magnesium): 0.2%-0.3%.

[0049] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains, by mass percentage, Ni (nickel): 2.5%-4.0%.

[0050] In a preferred embodiment, the formulation of the high-temperature die-cast aluminum alloy material contains Zr (zirconium) at a mass percentage of 0.2%-0.4%.

[0051] In a preferred embodiment, the AlN seed alloy content in the formulation of the high-temperature die-cast aluminum alloy material is 3.0%-5.0% by mass percentage.

[0052] In a preferred embodiment, the amount of TCB seed alloy added to the formulation of the high-temperature die-cast aluminum alloy material is 0.6-1.5% by mass percentage.

[0053] In a preferred embodiment, the main composition of the AlN nanocrystalline seed alloy is: N (nitrogen): 0.8%-1.2%, Si (silicon): 9.5%-10.5%, Fe (iron): ≤0.3%, Mn (manganese): ≤0.1%, with the remainder being Al. In a further preferred embodiment, the main composition of the AlN nanocrystalline seed alloy is: N: 0.9%-1.1%; Si: 9.9%-10.1%; Fe: ≤0.1%; Mn: ≤0.09%; with the remainder being Al.

[0054] In a preferred embodiment, the AlN nanocrystalline seed alloy contains 1%-5% AlN seeds. In a further preferred embodiment, the AlN nanocrystalline seed alloy contains 2%-3% AlN seeds. In an even more preferred embodiment, the AlN nanocrystalline seed alloy contains 2.5% AlN seeds. The AlN seeds refer to aluminum nitride nanoparticles synthesized in situ and constructed with a three-dimensional network structure, which can enhance the microstructure and structure of aluminum-based composite materials at high temperatures.

[0055] In a preferred embodiment, the atomic ratio of the AlN seed crystals is 1:1. The AlN has a hexagonal wurtzite crystal structure and a density of 3.26 g / cm³. 3 Its elastic modulus is 310 GPa and its thermal conductivity can reach 320 W / mk.

[0056] In a preferred embodiment, the ratio of AlN nanocrystalline seed alloy to submicron TCB seed alloy is (2-6):1. Through the synergistic effect of the two seed alloys, the yield strength of the die-cast parts of the high-temperature resistant aluminum alloy material under normal working conditions is greater than 45MPa in a 400℃ high-temperature environment, which can meet the strength requirements of axial flow fans in tunnel engineering for aluminum alloy blades and rotors to serve for no less than two hours in a 400℃ high-temperature environment.

[0057] This invention also provides a die-casting method for high-temperature resistant aluminum alloy materials under ordinary working conditions. The method involves die-casting the aluminum alloy material prepared by the preparation method of high-temperature resistant die-cast aluminum alloy materials according to any embodiment of this invention. The die-casting method includes the following steps: a. Before die casting, remelt the aluminum ingots. The remelting temperature of the molten aluminum should be ≤760℃.

[0058] b. Before die casting, degas the aluminum liquid with argon or nitrogen for 20-30 minutes at a temperature of 720℃-740℃, and then remove slag and purify it.

[0059] c. When the aluminum melt temperature is 740℃, microalloying is adjusted using AlN nanomaterials, Zr nanomaterials, and TCB submicron materials.

[0060] The temperature of the molten aluminum during die casting is controlled at 720℃-750℃. The wall thickness of the die casting should be slightly below the lower limit, and slightly above the upper limit for thinner parts. The die casting mold temperature is 100℃-200℃. The wall thickness of the die casting should be slightly below the lower limit, and slightly above the upper limit for thinner parts. The injection speed is 6.0-8.0 m / s. The pressure is 70-90 MPa. No return material is added to the furnace during the die casting process to avoid contamination of the molten aluminum. Iron tools must be coated and dried to prevent the molten aluminum from absorbing air during the die casting process.

[0061] The high-temperature resistant aluminum alloy material prepared by the method of this invention produces a die-cast part with the following mechanical properties at 400℃ under normal die-casting conditions: tensile strength ≥61MPa, yield strength ≥46MPa, and elongation ≥44.5%. Compared with AlSi12CuMnMgFe aluminum alloy, the tensile strength is increased by 17.3%, and the yield strength is increased by 31.4%. This meets the maximum stress load requirements of the blades and rotors of axial flow fans in tunnel engineering, which are subjected to the combined radial centrifugal force and high-temperature creep factors during continuous operation at 400℃ for two hours.

[0062] This invention also provides a die-casting method for high-temperature resistant aluminum alloy materials under optimized die-casting conditions. The aluminum alloy material prepared by the preparation method of the high-temperature resistant die-casting aluminum alloy material according to any embodiment of this invention is then die-cast. The die-casting method is as follows: Vacuum die casting is used. When the mold temperature is greater than 200℃, the vacuum degree is ≤50mbar; when the mold temperature is lower than 200℃, the vacuum degree is ≤30mbar, so as to reduce porosity with a higher vacuum degree.

[0063] A mold temperature controller is used to control the mold temperature between 260-290℃. The wall thickness of the die-casting part is closer to the lower limit for thicker parts and closer to the upper limit for thinner parts.

[0064] The temperature control for die-casting molten aluminum is as follows: When the mold temperature is above 200℃, the molten aluminum temperature is controlled at 720℃-750℃. When the mold temperature is below 200℃, the molten aluminum temperature is controlled at 730℃-760℃ to improve the cooling rate compensation. Injection speed: 5.5-7.5 m / s when the mold temperature is above 200℃. 6.0-8.0 m / s when the mold temperature is below 200℃, to reduce cold shuts through high-speed filling. Pressure: 65-85 MPa when the mold temperature is above 200℃. 70-90 MPa when the mold temperature is below 200℃, to compensate for the low mold temperature with high pressure.

[0065] The vacuum die casting and mold temperature control processes can be optimized separately or simultaneously, depending on the available conditions.

[0066] The high-temperature resistant die-cast aluminum alloy material prepared by the method provided in this invention exhibits significant potential for improvement in the mechanical properties of die-cast parts at 400℃. When die-casting under vacuum conditions ≤50mbar, tensile strength and yield strength can be increased by 20%-25%; when the mold temperature is controlled at 260℃-290℃ using a mold temperature controller, tensile strength and yield strength can be further increased by 5-10%. When these two optimized process conditions are used simultaneously, the improvement in tensile strength and yield strength is cumulative, resulting in an increase of 25%-35%. In other words, excellent high-temperature resistance properties of 76-82MPa tensile strength and 57-62MPa yield strength can be achieved in a 400℃ environment.

[0067] The high-temperature resistant aluminum alloy material prepared by the method of preparing high-temperature die-casting aluminum alloy material provided by the present invention can be used not only for die casting, but also for recasting, liquid forging and other forming methods.

[0068] The high-temperature resistant aluminum alloy material prepared by the method provided in this invention, after artificial aging treatment at 190℃ for 6 hours, exhibits the following mechanical properties in a 400℃ high-temperature environment for die castings under normal working conditions: tensile strength ≥ 66 MPa, yield strength ≥ 50.4 MPa, and elongation ≥ 44.5%. Compared with die castings without artificial aging treatment, the tensile strength increased by 8.2% and the yield strength increased by 9.6% in a 400℃ high-temperature environment; compared with AlSi12CuMnMgFe aluminum alloy, the tensile strength increased by 26.9% and the yield strength increased by 42.9%. This indicates that artificial aging treatment can further improve and stabilize the high-temperature strength performance of this novel heat-resistant aluminum alloy material.

[0069] The high-temperature resistant die-cast aluminum alloy material prepared by the method of the present invention has excellent strength memory properties: after being kept at 400°C for two hours and then cooled, the tensile strength can be restored to the room temperature level, and the yield strength can even be improved.

[0070] The high-temperature resistant aluminum alloy material prepared by the method of the present invention exhibits small strength fluctuations after being held at 400°C for 2 to 16 hours and then cooled, and reaches its peak strength after 12 hours of holding, demonstrating good memory stability.

[0071] The AlSi12CuMnMgFe aluminum alloy commonly used in fans belongs to the Al-Si-Cu system, primarily relying on Al2Cu and Mg2Si strengthening phases. It exhibits stable performance below 300℃, meeting the original technical standards for 280℃ heat resistance in axial fan blades and rotors. However, above 300℃, its strengthening phases begin to coarsen or dissolve, and by 400℃, most have dissolved, losing their coherence. Even with artificial aging treatment before use, the effects of this process will eventually largely fail.

[0072] The German GD-AlSi12CuNiMg aluminum alloy material uses Al-Si eutectic phase, Al2Cu phase, Al3Ni phase, and Mg2Si phase as the main strengthening phases. Among them, the Al3Ni phase has good thermal stability and a melting point greater than 800℃. However, due to the high proportion of Al-Si eutectic phase, Al2Cu phase, and Mg2Si phase, at a high temperature of 400℃, the residual strengthening effect is mainly provided by the Al3Ni phase together with the undissolved Al-Si eutectic phase, Al2Cu phase, and Mg2Si phase. The improvement in heat resistance is limited. Compared with AlSi12CuMnMgFe in a 400℃ environment, the tensile strength and yield strength are only increased by 10%, and the strength memory performance decreases with the extension of high-temperature service time.

[0073] The high-temperature resistant die-cast aluminum alloy material prepared by the method of this invention has Al3Ni phase, Al6Mn phase, nano-Al3Zr phase, nano-AlN phase, and submicron TCB microalloyed dispersion strengthening phase as the main strengthening phases. The Al3Ni phase has a melting point greater than 800℃ and can maintain a dispersed distribution at 400℃, providing continuous dispersion strengthening. The Al3Ni phase can maintain the fine structure and micro-inhomogeneity of the alloy for a long time, which is an important factor in improving heat resistance. The transition metal element Mn nucleates to form Al6Mn by repelling solutes at the solidification front and grain boundaries, subgrain boundaries, or dislocation walls, which helps to improve thermal stability. The nano-Al3Zr strengthening phase is relatively stable, has low mismatch with the matrix, can maintain a coherent relationship with the matrix, can effectively pin dislocations, stabilize the substructure, prevent grain boundary slip, and simultaneously inhibit matrix recrystallization, increasing the matrix recrystallization temperature. Nanoscale AlN phase can refine grains to 20-50 μm, forming a biphase dispersion strengthening with Al3Zr, improving creep resistance, pinning the lattice, and forming a stable strengthening network. TCB can refine the microstructure, delay the coarsening of high-temperature phases, refine the matrix microstructure through heterogeneous nucleation, and reduce microsegregation. Nanoscale Al3Zr + submicron-scale TCB form a dual-scale strengthening network of nanoscale and submicron, improving strength against 400℃. The synergistic effect of these high-temperature strengthening phases effectively pins dislocations and grain boundaries, inhibits high-temperature creep, suppresses recrystallization, hinders grain boundary migration, and delays grain coarsening. This results in a significant improvement in strength compared to AlSi12CuMnMgFe aluminum alloys at 400℃, and maintains excellent strength memory properties even with extended service time at 400℃.

[0074] To provide a better understanding of the technical solution of the present invention, several preferred embodiments are listed below for further detailed description.

[0075] Example 1:

[0076] By mass percentage, Si: 0.217%, Fe: 0.113%, Cu: 0.437%, Mn: 2.05%, Mg: 0.23%, Zn: 0.0297%, Ni: 3.18%, Ti: 0.02%, Zr: 0.32%, AlN nanocrystalline seed alloy: 4.35%, TCB submicron seed alloy: 0.9%, Pb: 0.00056%, Sn: 0.001%, Cd: 0.003%, other impurity elements individually: ≤0.03%, total impurity content: ≤0.12%, the remainder being Al.

[0077] The common impurity elements are metallic elements not mentioned in the above formula. These impurity elements cannot be completely eliminated from aluminum alloys, but the lower the content, the better.

[0078] The main components of the AlN nanocrystalline seed alloy are: N: 1%; Si: 9.8%; Fe: ≤0.3%; Mn: ≤0.1%; the remainder is Al. The AlN nanocrystalline seed alloy contains 2.5% AlN seeds; the atomic ratio of the AlN nanocrystalline seed alloy is 1:1.

[0079] TCB seed alloy is an AlTiCB submicron seed alloy. The main components of the TCB seed alloy, by mass percentage, are: Ti: 4.2-5.2%; C: 0.06-0.12%; B: 0.3-0.5%; RE: 0.5-0.8%; Mn: ≤0.1%; Fe: ≤0.4%; Si: ≤0.3%; V: ≤0.1%; with the remainder being Al.

[0080] The high-temperature resistant aluminum alloy material is prepared according to the above proportions, and the steps are as follows:

[0081] S1. Add aluminum ingots, melt them, and heat them to 840℃.

[0082] S2. Maintaining within this temperature range, add manganese additive, copper additive, zirconium nano-alloy additive, and nickel additive sequentially. Each additive is added in 5 batches, stirring thoroughly after each addition and allowing to stand for 5-10 minutes. After adding the last batch of nickel additive, allow the temperature to cool naturally.

[0083] S3. Cool to 780℃ and add the AlN nanocrystalline seed alloy in two to three batches. Stir well after adding and let stand for 5-10 minutes.

[0084] S4. At 760℃, add 0.2% sodium-free refining agent (by weight of the molten aluminum) for refining, slag removal and purification, add magnesium, and stir evenly.

[0085] S5. Take samples to test the components and make minor adjustments. Once the components are qualified, proceed to the next step.

[0086] S6. Degas the gas using argon or nitrogen for 25 minutes, add TCB submicron seed alloy, and let stand for 8 minutes.

[0087] S7. Casting aluminum alloy ingots at 740℃. During the casting process, 15μm pore size permeable bricks are used to degas the molten aluminum in the flow tank or filter box with argon or nitrogen gas to obtain high-temperature resistant aluminum alloy ingots.

[0088] The high-temperature resistant aluminum alloy ingot prepared under normal die-casting conditions is die-cast to produce die-cast parts. The die-casting method is as follows:

[0089] a. The remelting temperature of the molten aluminum before die casting is 730℃.

[0090] b. Before die casting, the aluminum liquid is degassed with argon gas for 25 minutes starting at 730℃, and then slag is removed and purified after degassed.

[0091] c. Adjustment of microalloying using AlN nanomaterials, Zr nanomaterials, and TCB submicron materials at a temperature of 740℃.

[0092] Die-casting molten aluminum temperature: 720℃-750℃. Lower limit for thicker die-cast parts, upper limit for thinner die-cast parts. Die-casting mold temperature: 100℃-200℃. Lower limit for thicker die-cast parts, upper limit for thinner die-cast parts. Injection speed: 6.0-8.0 m / s. Pressure: 70-90 MPa. No return material is added to the furnace during the die-casting process to avoid contamination of the molten aluminum. Iron tools must be coated and dried to prevent the molten aluminum from absorbing air during the die-casting process.

[0093] Example 2

[0094] Compared with Example 1, the difference is that Mn: 2.12%, Ni: 3.15%, Zr: 0.335%, AlN nanocrystalline seed alloy: 4.15%, and TCB submicron seed alloy: 0.92%. The remaining formulation, preparation method, and die-casting method are the same as in Example 1.

[0095] Example 3

[0096] Compared with Example 1, the difference is that Mn: 2.02%, Ni: 3.02%, Zr: 0.305%, AlN nanocrystalline seed alloy: 4.05%, and TCB submicron seed alloy: 0.88%. The remaining formulation, preparation method, and die-casting method are the same as in Example 1.

[0097] Example 4

[0098] Compared with Example 1, the difference lies in the following: Mn: 1.95%, Ni: 2.97%, Zr: 0.285%, AlN nanocrystalline seed alloy: 3.98%, and TCB submicron seed alloy: 0.86%. The remaining formulation, preparation method, and die-casting method are the same as in Example 1.

[0099] Example 5

[0100] Compared with Example 1, the die casting method in Example 5 adopts optimized die casting conditions. The die casting method is different from that in Example 1, while the other formulations and preparation methods are the same as in Example 1.

[0101] The die-casting method in Example 5 is as follows:

[0102] Vacuum die casting is used. When the mold temperature is greater than 200℃, the vacuum degree is ≤50mbar; when the mold temperature is lower than 200℃, the vacuum degree is ≤30mbar, so as to reduce porosity with a higher vacuum degree.

[0103] A mold temperature controller is used to control the mold temperature between 260-290℃. The wall thickness of the die-casting part is closer to the lower limit for thicker parts and closer to the upper limit for thinner parts.

[0104] The temperature control for die-casting molten aluminum is as follows: When the mold temperature is above 200℃, the molten aluminum temperature is controlled at 720℃-750℃. When the mold temperature is below 200℃, the molten aluminum temperature is controlled at 730℃-760℃ to improve the cooling rate compensation. Injection speed: 5.5-7.5 m / s when the mold temperature is above 200℃. 6.0-8.0 m / s when the mold temperature is below 200℃, to reduce cold shuts through high-speed filling. Pressure: 65-85 MPa when the mold temperature is above 200℃. 70-90 MPa when the mold temperature is below 200℃, to compensate for the low mold temperature with high pressure.

[0105] Comparative Example 1

[0106] The German GD-AlSi12CuNiMg alloy material has the following main components: Si: 11.8%, Fe: 0.327%, Cu: 1.76%, Mn: 0.462%, Mg: 0.73%, Zn: 0.0266%, Ni: 1.45%, Ti: 0.0098%, with the remainder being Al. This alloy material was die-cast using the same method as in Example 1, under normal operating conditions, to produce die-cast parts.

[0107] Comparative Example 2

[0108] Compared with Comparative Example 1, the difference is that Si: 12.2%, Cu: 1.68%, Mg: 0.75%, Ni: 1.41%, while the remaining formula and die-casting method are the same as Comparative Example 1.

[0109] Comparative Example 3

[0110] Compared with Comparative Example 1, the difference is that Si: 12.12%, Cu: 1.65%, Mg: 0.72%, Ni: 1.35%, while the remaining formula and die-casting method are the same as Comparative Example 1.

[0111] Comparative Example 4

[0112] Compared with Comparative Example 1, the difference is that Si: 11.95%, Cu: 1.62%, Mg: 0.79%, Ni: 1.33%, while the remaining formula and die-casting method are the same as Comparative Example 1.

[0113] Comparative Example 5

[0114] The AlSi12CuMnMgFe material has the following main components and processing: Si: 12.1%, Fe: 0.541%, Cu: 0.593%, Mn: 0.275%, Mg: 0.224%, Zn: 0.0955%, Ni: 0.012%, Pb: 0.005%, Sn: 0.001%, with the balance being Al. This alloy material was die-cast using the same method as in Example 1, under normal operating conditions, to produce die-cast parts.

[0115] Comparative Example 6

[0116] Compared with Comparative Example 5, the difference is that Si: 11.8%, Cu: 0.561%, Mn: 0.243%, Mg: 0.229%, while the rest of the formula and die-casting method are the same as Comparative Example 5.

[0117] Comparative Example 7

[0118] Compared with Comparative Example 5, the difference is that Si: 11.9%, Cu: 0.582%, Mn: 0.255%, Mg: 0.226%, while the rest of the formula and die-casting method are the same as Comparative Example 5.

[0119] Comparative Example 8

[0120] Compared with Example 1, Comparative Example 8 did not add AlN nanocrystalline seed alloy, but the rest of the formulation, preparation method and die casting method were the same as in Example 1.

[0121] Comparative Example 9

[0122] Compared with Example 1, the amount of AlN nanocrystalline seed alloy used in Comparative Example 9 was 0.9%, the amount of TCB submicron seed alloy used was 0.2%, and the remaining formulations, preparation methods and die-casting methods were the same as in Example 1.

[0123] Example of effect

[0124] (1) The die castings prepared in Examples 1-5 and Comparative Examples 1-9 were tested and compared in the same environment (400℃ high temperature environment). Specifically, tensile tests were performed in a constant temperature chamber at 400℃, and the data are shown in Table 1.

[0125] Table 1

[0126]

[0127] As can be seen from the data in Table 1, the die-cast parts prepared in the embodiments of the present invention have a tensile strength ≥61MPa and a yield strength ≥46MPa at a high temperature of 400℃, which shows good high-temperature resistance. Compared with existing high-temperature resistant materials such as the German GD-AlSi12CuNiMg alloy and AlSi12CuMnMgFe, it is a very significant breakthrough.

[0128] In Comparative Example 8, the high-temperature resistance was relatively poor when AlN nanocrystalline seed alloy was not added. In Comparative Example 9, the high-temperature resistance was also relatively poor when the content of AlN nanocrystalline seed alloy and TCB submicron seed alloy was outside the scope of this invention. This shows that the high-temperature resistant aluminum alloy material provided by this invention can have its high-temperature resistance significantly enhanced by a reasonable combination of AlN nanocrystalline seed alloy and TCB submicron seed alloy.

[0129] As can be seen from the data in Example 5, the high-temperature die-cast aluminum alloy material prepared by the present invention can further improve its mechanical properties at a high temperature of 400℃ by optimizing the die-casting conditions, and can be applied to a variety of high-temperature fields.

[0130] (2) The die castings of Examples 1-4 and Comparative Examples 1-4 were subjected to artificial aging treatment at 190℃ for 6 hours. The treated die castings were tested and compared in the same environment (400℃ high temperature environment). Specifically, tensile tests were performed in a constant temperature chamber at 400℃. The data are shown in Table 2.

[0131] Table 2

[0132]

[0133] As shown in Table 2, after artificial aging treatment at 190℃ for 6 hours, the die-cast parts under normal working conditions can withstand temperatures up to 400℃. 0 The mechanical properties of C in a high-temperature environment are: tensile strength ≥66MPa, yield strength ≥50MPa, and elongation ≥44.5%. Compared with die-cast parts without artificial aging treatment, the tensile strength increased by 8.2% and the yield strength increased by 9.6% in a high-temperature environment of 400℃. This indicates that artificial aging treatment can further improve and stabilize the high-temperature strength properties of this new heat-resistant aluminum alloy material.

[0134] (3) The strength and elongation of the aluminum alloy die castings of Examples 1-4 and Comparative Examples 1-4 were tested at room temperature before high-temperature service. The test results are shown in Table 3.

[0135] Table 3

[0136]

[0137] The strength and elongation of the aluminum alloy die castings of Examples 1-4 and Comparative Examples 1-4 were tested after the high-temperature service was completed. Specifically, the aluminum alloy die casting samples were kept in a 400°C high-temperature constant temperature chamber for 2 hours and 16 hours, respectively, and then taken out and cooled to room temperature. They were then stretched at room temperature to test their strength and elongation. The test results are shown in Table 4.

[0138] Table 4

[0139]

[0140] As can be seen from the data in Tables 3 and 4, although the strength of the comparative example at room temperature before high-temperature service was significantly higher than that of the embodiment of the present invention, its strength performance decreased significantly after high-temperature service, and continued to decrease with the extension of the service time at 400°C. Its strength memory performance also decreased accordingly. In contrast, after high-temperature service, even for a relatively long period, the tensile strength of the embodiment of the present invention essentially recovered to the level of its pre-service room temperature state, and the yield strength even increased. Both the tensile strength, yield strength, and elongation (which reflects toughness) were significantly higher than those of the comparative example, indicating that the material of the present invention not only exhibited higher high-temperature strength performance compared to the comparative example, but also possessed excellent strength memory stability.

[0141] (4) Multiple samples of the aluminum alloy die-castings from Example 1 were tested. After being held at different temperatures for two hours and then cooled to room temperature, the tensile strength properties were obtained under room temperature conditions. The average values ​​are shown in Table 5 and Appendix. Figure 1 As shown.

[0142] Table 5

[0143]

[0144] As can be seen from Table 5, the alloy material of Example 1 has stable strength after being kept at different temperatures for two hours and then cooled, and the yield strength is even enhanced, indicating that the alloy material provided by the present invention has good resistance to high temperature of 400℃.

[0145] (5) Multiple samples of the aluminum alloy die-cast parts from Example 1 were held at 400℃ for 2 to 16 hours, cooled to room temperature, and then subjected to tensile testing at room temperature. The average values ​​are shown in Table 6 and Appendix. Figure 2 As shown.

[0146] Table 6

[0147]

[0148] As can be seen from the data in Table 6, the high-temperature resistant aluminum alloy material of the present invention exhibits small strength fluctuations after being kept at 400℃ for different durations from 2 to 16 hours and then cooled, and reaches its peak strength after 12 hours of holding, demonstrating good memory stability.

[0149] (6) Multiple samples of the aluminum alloy die-cast parts from Example 1 were first subjected to artificial aging treatment at 190℃ for 6 hours, then held at 400℃ for different durations and cooled to room temperature. The results were tested at room temperature, and the average values ​​are shown in Table 7. Figure 3As shown.

[0150] Table 7

[0151]

[0152] As shown in Table 7, the high-temperature resistant aluminum alloy material of this invention, after undergoing artificial aging treatment at 190℃ for 6 hours, followed by holding at 400℃ for different durations and then cooling, exhibits significantly increased tensile strength and yield strength within 8 hours of holding time, with subsequent stabilization. This indicates that aging treatment can further improve strength performance and enhance high-temperature memory as high-temperature service time is extended.

[0153] In summary, the high-temperature resistant aluminum alloy material provided by this invention exhibits excellent high-temperature resistance. The average mechanical properties of the die-cast parts at 400°C are: tensile strength 63.2 MPa, yield strength 49 MPa, and elongation 50.6%. Compared with the currently used AlSi12CuMnMgFe aluminum alloy material, the tensile strength is increased by 22.31%, and the yield strength is increased by 38.69%. This meets the maximum stress load requirements of the fan blades and rotors of this type of fan, which are subjected to the combined radial centrifugal force and high-temperature creep factors during continuous operation at 400°C for two hours. Furthermore, it retains excellent strength memory properties even with extended service time at 400°C.

[0154] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a high-temperature resistant die-cast aluminum alloy material suitable for axial flow fans, characterized in that, The formula of the high-temperature resistant die-casting aluminum alloy material, by mass percentage, is: Si: 0.1 - 1.5%; Fe: 0.01 - 0.5%; Cu: 0.35% - 0.65%; Mn: 1.5% - 3.5%; Mg: 0.05% - 0.5%; Zn: ≤0.2%; Ni: 1.9% - 5.5%; Ti: ≤0.15%; Zr: 0.1% - 0.45%; Pb: ≤0.10%; Sn: ≤0.10%; Cd: ≤0.01%; The individual content of the commonly existing impurity elements ≤0.05%, and the total content of the commonly existing impurity elements: ≤0.15%; The rest is Al; When preparing, AlN nanocrystalline seed alloy and submicron TCB crystalline seed alloy are added. The addition amount of the AlN nanocrystalline seed alloy is 1.0% - 6.0%, and the addition amount of the submicron TCB crystalline seed alloy is 0.3 - 2.0%; Prepare the high-temperature resistant die-casting aluminum alloy material according to the said formula. The preparation method includes the following steps: Add aluminum ingots and melt and heat up to between 830°C and 850°C; Add manganese additive, copper additive, zirconium nano-alloy additive, nickel additive; Cool down to 770°C - 790°C, add the AlN nanocrystalline seed alloy in two to three batches, stir evenly after adding and let stand for 5 - 10 minutes; When the temperature is at 750°C - 770°C, add a sodium-free refining agent for refining, remove slag and purify; Add magnesium and stir evenly; Take samples to test the composition and make fine adjustments. After the composition is qualified, proceed to the next step; Use argon or nitrogen for degassing for 20 - 30 minutes, add the submicron TCB crystalline seed alloy, and let stand for 5 - 10 minutes; Cast alloy aluminum ingots at a temperature between 710°C and 750°C to obtain the high-temperature resistant die-casting aluminum alloy material; The main component composition of the said AlN nanocrystalline seed alloy is: N: 0.8% - 1.2%; Si: 9.5% - 10.5%; Fe: ≤0.3%; Mn: ≤0.1%; The rest is Al; The dosage ratio of the said AlN nanocrystalline seed alloy and the submicron TCB crystalline seed alloy is (2 - 6):1; The main composition of the TCB crystalline seed alloy, by mass percentage, is Ti: 4.2 - 5.2%; C：0.06-0.12%； B: 0.3 - 0.5%; RE 0.5 - 0.8%; Mn: ≤0.1%; Fe: ≤0.4%; Si: ≤0.3%; 2. The method for preparing high-temperature die-cast aluminum alloy material suitable for axial flow fans as described in claim 1, characterized in that, V: ≤0.1%; The rest is Al.

3. The method for preparing high-temperature die-cast aluminum alloy material suitable for axial flow fans as described in claim 1, characterized in that, The main component composition of the said AlN nanocrystalline seed alloy is: N: 0.9% - 1.1%; Si: 9.9% - 10.1%; Fe: ≤0.1%; Mn: ≤0.09%; The rest is Al.

4. The method for preparing high-temperature die-cast aluminum alloy material suitable for axial flow fans as described in claim 3, characterized in that, The said AlN nanocrystalline seed alloy contains 1% - 5% of AlN seeds.

5. The method for preparing high-temperature die-cast aluminum alloy material suitable for axial flow fans as described in claim 1, characterized in that, The said AlN nanocrystalline seed alloy contains 2% - 3% of AlN seeds; In the said AlN seeds, the atomic ratio is 1:

1.

6. The method for preparing high-temperature die-cast aluminum alloy material suitable for axial flow fans as described in claim 1, characterized in that, In the formula of the said high-temperature resistant die-casting aluminum alloy material, Ni is 2.8% - 4%. The dosage of the said sodium-free refining agent is 0.1% - 0.3% of the weight of the aluminum liquid.

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