High modulus aluminum alloy material and its die casting process

Abstract

The present application belongs to the technical field of aluminum alloy, and particularly relates to a high modulus aluminum alloy material and a die casting process thereof. The present application provides a high modulus aluminum alloy material, raw material composition of which comprises any one or mixture of two of SiC fiber or BN fiber, the length of the SiC fiber and the BN fiber is 0.5-1.5 mm, the diameter is 10-30 mu m, and the elastic modulus is 240-290 GPa. The present application also provides a die casting production method of the high modulus aluminum alloy material, steps of which include, in sequence, batching, smelting, fiber heating, mixing, refining, and die casting, and finally a thin-walled aluminum alloy part with an elastic modulus of greater than or equal to 90 GPa is obtained, which is used in the fields of aerospace, vehicles, buildings and the like.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, and particularly relates to a high-modulus aluminum alloy material and its die-casting process. Background Technology

[0002] Generally, high modulus, without specific definition, refers to a higher elastic modulus. Existing high-modulus aluminum alloys primarily consist of Al, Zn, Mg, and Cu. The typical performance parameters of these alloys are: elastic modulus 70-80 GPa, tensile strength 250-350 MPa, yield strength 180-200 MPa, and elongation ≥5.5%.

[0003] On the other hand, the aluminum alloys mentioned above all refer to die-cast aluminum alloys, which are more suitable for the current aluminum alloy application environment with higher structural complexity and more precise shapes compared to wrought aluminum alloys.

[0004] Common improvement methods for aluminum alloys, from ordinary to high-modulus alloys, mainly include alloying and composite processing. Alloying requires adding new elements to the original raw material composition, including Zr, Sc, and Ni. Composite processing requires adding high-elastic-modulus ceramic particles such as SiC and TiB2.

[0005] Among them, alloying is relatively simple, but its effect on improving elastic modulus is generally not as good as that of composite methods. In composite methods, the newly added high elastic modulus particles are not conducive to the casting of thin-walled aluminum alloy parts. These particles are prone to forming hard spots in aluminum alloys, which in turn reduces the degree of improvement in elastic modulus.

[0006] Furthermore, aluminum alloys prepared through composite methods are essentially various aluminum-based composite materials. These materials have wide applications in aerospace, vehicles, construction, bridges, and military equipment.

[0007] For example, Chinese invention patent CN114032429A, published on February 11, 2022, discloses a high elongation and high modulus TiB2 particle-reinforced aluminum matrix composite material. Using Al-Zn-Mg-Cu-Zr-Sc as the matrix and TiB2 particles as the reinforcement, the process involves the following steps: ① Smelting according to the material composition and obtaining a Ф280mm composite ingot using semi-continuous casting technology; ② Homogenizing the ingot with 400℃ / 6h + 465℃ / 30h annealing; ③ Preheating the homogenized composite material at 420℃ for 2h followed by a first-step hot forging or hot extrusion treatment; ④ Further preheating the first-step deformed composite material at 420℃ for 2h, followed by a second hot deformation along the orthogonal direction, i.e., forging, extrusion, and rolling, to obtain an orthogonally composite hot-deformed TiB2-reinforced aluminum matrix composite material.

[0008] The aluminum-based composite material in this invention patent has good practical value and solves the problem of poor plasticity of TiB2 particle-reinforced aluminum-based composite materials. The composite material has isotropic mechanical properties with high strength, high elongation, and high elastic modulus.

[0009] However, when this aluminum-based composite material is used in structures that are subject to relatively frequent impacts, such as shells and frames, it still has at least the following drawback, which is also the technical problem that this invention aims to solve: Its elastic modulus is still below 80 GPa, so it cannot achieve better impact resistance.

[0010] Therefore, in summary, there is an urgent need for a new type of high-modulus aluminum alloy material based on a composite method, ensuring that its elastic modulus is at least around 90 GPa, so that it can be used in various impact-prone structures in aerospace, vehicle, and construction fields. Summary of the Invention

[0011] This invention provides a high-modulus aluminum alloy material, the raw material composition of which includes any one or a mixture of two of SiC fibers or BN fibers, wherein the SiC fibers and BN fibers have a length of 0.5-1.5 mm, a diameter of 10-30 μm, and an elastic modulus of 240-290 GPa.

[0012] The present invention also provides a die-casting production method for the above-mentioned high-modulus aluminum alloy material, the steps of which include: batching, melting, fiber heating, mixing, refining, and die-casting, to finally obtain thin-walled aluminum alloy parts with an elastic modulus ≥90GPa, for use in aerospace, vehicle, construction and other fields.

[0013] The technical solution adopted by the present invention to solve the above problems is: a high modulus aluminum alloy material, the raw material composition of which includes any one or a mixture of two of SiC fibers or BN fibers, wherein the length of the SiC fibers and BN fibers is 0.5-1.5 mm, the diameter is 10-30 μm, and the elastic modulus is 240-290 GPa.

[0014] In this invention, the SiC fibers and BN fibers mentioned above are selected from commercially available products, or prepared by conventional melt spinning, electrospinning, and chemical vapor deposition methods.

[0015] A further preferred technical solution is that the raw material composition includes the following components by weight: Zn: 1.0-2.5%, Mg: 2.0-2.2%, Cu: 1.5-1.8%, Si: 0.5-0.7%, Fe: 0.1-0.2%, SiC fiber and / or BN fiber: 2.5-3.5%, with the balance being Al and unavoidable impurities.

[0016] In this invention, the amount of Cu added is appropriately higher than the existing level because it can appropriately improve the fluidity of the aluminum alloy liquid, which helps to quickly and sufficiently uniformly disperse the above-mentioned fibers.

[0017] In addition, the amount of the above-mentioned fiber added is less than the existing proportion of granules added, because the elastic modulus gain effect of the above-mentioned fiber per unit weight is significantly higher than that of granules. The continuous shape and performance characteristics of the fiber itself are very beneficial to improving the elastic modulus of aluminum alloy.

[0018] A die-casting process for a high-modulus aluminum alloy material includes the following steps in sequence. S1, Ingredients; S2. Smelting: First, heat and melt aluminum ingots in a smelting furnace, then add Zn, Mg, Cu, Si and Fe, continue smelting, and then keep the temperature to obtain molten liquid; S3. Fiber heating: The SiC fibers and / or BN fibers are heated in a heating furnace to obtain preheated fibers; S4. Mixing: First, add the preheated fiber to the molten liquid, then turn on the electromagnetic stirring function to obtain aluminum alloy liquid; S5. Refining: Add refining agent to the aluminum alloy liquid and fill it with inert gas. At the same time, turn on the electromagnetic stirring function and then perform slag removal operation to obtain the die casting material. S6. Die casting: High-modulus aluminum alloy parts are formed by die casting in a die casting machine through vacuum die casting process.

[0019] A further preferred technical solution is that, in S2, the melting temperature of the aluminum ingot is 740-760℃, the smelting temperature is 780-850℃, the holding temperature is 600-720℃, and the holding time is 30-50 minutes.

[0020] A further preferred technical solution is that, in S3, the temperature of the preheated fiber is 420-480℃.

[0021] In this invention, the above-mentioned fibers at high temperature have better wettability with the molten aluminum alloy compared to the "cold fibers" at room temperature, and the fibers can be dispersed and mixed relatively quickly.

[0022] A further preferred technical solution is that: in S4, the rotation speed of the electromagnetic stirrer is 150-850 r / min, and each 1 kg of SiC fiber and / or BN fiber corresponds to an electromagnetic stirring time of 12-20 min.

[0023] In this invention, the electromagnetic stirring operation described above can further shorten the time required for uniform fiber distribution.

[0024] A further preferred technical solution is that, in S5, the refining agent is a sodium-free refining agent, and the inert gas is nitrogen or argon.

[0025] A further preferred technical solution is that, in step S5, the inert gas is introduced at a rate of 1.5-1.8 m / s. 3 / h, with a continuous charging time of 20-25min.

[0026] In this invention, the values ​​of the filling speed and the continuous filling time are appropriately higher than the existing levels of aluminum alloy refining operations, so as to allow the inert gas to also assist in the uniform dispersion of the fibers.

[0027] Correspondingly, the electromagnetic stirring effect at this time is beneficial to three aspects: slag rising, exhaust gas discharge, and uniform fiber dispersion.

[0028] A further preferred technical solution is that, in S6, the internal temperature of the die-casting machine in the vacuum die-casting process is 740-780℃.

[0029] A further preferred technical solution is that, in S6, the thickness of the high-modulus aluminum alloy part is ≤1.0mm.

[0030] In this invention, the high-modulus aluminum alloy part belongs to a thin-walled aluminum alloy.

[0031] In this invention, the original particles required for composite formation are replaced with fibers. The latter, through its continuous shape and performance characteristics, can better transform its high elastic modulus into the high elastic modulus of the final aluminum alloy product, which is something that the point-distributed particles mentioned above cannot do.

[0032] However, a disadvantage of fibers compared to granules is that fibers are more difficult to distribute evenly. Therefore, the following three methods are used to compensate for this and improve the uniformity of SiC fibers and / or BN fibers in molten aluminum alloy: First, Cu can improve the fluidity of aluminum alloys. By appropriately increasing the amount of Cu used in this invention, the difficulty of uniform fiber distribution can be indirectly reduced, or the time required for uniform distribution can be shortened. Secondly, during the gas refining process, the inert gas injection speed is appropriately increased and the inert gas injection time is appropriately extended, so that the inert gas can be fully stirred and mixed with the above fibers. Third, the above-mentioned fibers are preheated before being added to the aluminum alloy liquid, and their high temperature is also conducive to rapid and uniform distribution.

[0033] On the other hand, since the above-mentioned fibers have a better elastic modulus gain per unit weight than commonly used particles, their addition amount can be further reduced compared to particles such as SiC. Correspondingly, the decrease in the degree of elastic modulus increase caused by the above-mentioned fibers is also reduced, ultimately achieving a beneficial positive feedback effect. Detailed Implementation

[0034] The following description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

[0035] Example 1 A high-modulus aluminum alloy material, the raw material composition of which includes the following components by weight, Zn: 1.2%, Mg: 2.0%, Cu: 1.6%, Si: 0.5%, Fe: 0.1%, SiC fiber: 2.6%, balance Al and unavoidable impurities.

[0036] The SiC fibers have a length of 0.7-1.4 mm, a diameter of 11-27 μm, and an elastic modulus of 266 GPa.

[0037] The die-casting process for the aforementioned high-modulus aluminum alloy materials includes the following steps in sequence: S1, Ingredients; S2. Smelting: First, heat and melt aluminum ingots in a smelting furnace, then add Zn, Mg, Cu, Si and Fe, continue smelting, and then keep the temperature to obtain molten liquid; S3. Fiber heating: The SiC fibers are heated in a heating furnace to obtain preheated fibers; S4. Mixing: First, add the preheated fiber to the molten liquid, then turn on the electromagnetic stirring function to obtain aluminum alloy liquid; S5. Refining: Add refining agent to the aluminum alloy liquid and fill it with inert gas. At the same time, turn on the electromagnetic stirring function and then perform slag removal operation to obtain the die casting material. S6. Die casting: High-modulus aluminum alloy parts are formed by die casting in a die casting machine through vacuum die casting process.

[0038] In S2, the melting temperature of the aluminum ingot is 740℃, the temperature for further melting is 800℃, the holding temperature is 650℃, and the holding time is 50min.

[0039] In S3, the temperature of the preheated fiber is 460°C.

[0040] In S4, the electromagnetic stirring speed is 300 r / min, and each 1 kg of SiC fiber corresponds to 15 min of electromagnetic stirring time.

[0041] In step S5, the refining agent is a sodium-free refining agent, and the inert gas is nitrogen. In step S5, the inert gas is introduced at a rate of 1.6 m / s. 3 / h, with a continuous charging time of 24min.

[0042] In S6, the internal temperature of the die-casting machine in the vacuum die-casting process is 780℃. In S6, the thickness of the high-modulus aluminum alloy part is ≤1.0mm.

[0043] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0044] Example 2 A high-modulus aluminum alloy material, the raw material composition of which includes the following components by weight, Zn: 1.8%, Mg: 2.2%, Cu: 1.8%, Si: 0.5%, Fe: 0.1%, BN fiber: 2.8%, balance being Al and unavoidable impurities.

[0045] The BN fiber has a length of 1.0-1.5 mm, a diameter of 15-25 μm, and an elastic modulus of 281 GPa.

[0046] The die-casting process for the aforementioned high-modulus aluminum alloy materials includes the following steps in sequence: S1, Ingredients; S2. Smelting: First, heat and melt aluminum ingots in a smelting furnace, then add Zn, Mg, Cu, Si and Fe, continue smelting, and then keep the temperature to obtain molten liquid; S3. Fiber heating: The BN fiber is heated in a heating furnace to obtain preheated fiber; S4. Mixing: First, add the preheated fiber to the molten liquid, then turn on the electromagnetic stirring function to obtain aluminum alloy liquid; S5. Refining: Add refining agent to the aluminum alloy liquid and fill it with inert gas. At the same time, turn on the electromagnetic stirring function and then perform slag removal operation to obtain the die casting material. S6. Die casting: High-modulus aluminum alloy parts are formed by die casting in a die casting machine through vacuum die casting process.

[0047] In S2, the melting temperature of the aluminum ingot is 750℃, the temperature for further melting is 800℃, the holding temperature is 680℃, and the holding time is 50 minutes.

[0048] In S3, the temperature of the preheated fiber is 480°C.

[0049] In S4, the electromagnetic stirring speed is 600 r / min, and each 1 kg of BN fiber corresponds to 20 min of electromagnetic stirring time.

[0050] In step S5, the refining agent is a sodium-free refining agent, and the inert gas is nitrogen. In step S5, the inert gas is introduced at a rate of 1.8 m / s. 3 / h, continuous charging time is 25min.

[0051] In S6, the internal temperature of the die-casting machine in the vacuum die-casting process is 780℃. In S6, the thickness of the high-modulus aluminum alloy part is ≤1.0mm.

[0052] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0053] Example 3 A high-modulus aluminum alloy material, the raw material composition of which includes the following components by weight, Zn: 2.0%, Mg: 2.1%, Cu: 1.8%, Si: 0.5%, Fe: 0.2%, SiC fiber and BN fiber: 3.2%, balance Al and unavoidable impurities.

[0054] The SiC fibers and BN fibers have equal weights.

[0055] The SiC and BN fibers have a length of 0.7-1.5 mm and a diameter of 17-29 μm, with elastic moduli of 265 GPa for SiC fibers and 277 GPa for BN fibers.

[0056] The die-casting process for the aforementioned high-modulus aluminum alloy materials includes the following steps in sequence: S1, Ingredients; S2. Smelting: First, heat and melt aluminum ingots in a smelting furnace, then add Zn, Mg, Cu, Si and Fe, continue smelting, and then keep the temperature to obtain molten liquid; S3. Fiber heating: The SiC fibers and BN fibers are heated in a heating furnace to obtain preheated fibers; S4. Mixing: First, add the preheated fiber to the molten liquid, then turn on the electromagnetic stirring function to obtain aluminum alloy liquid; S5. Refining: Add refining agent to the aluminum alloy liquid and fill it with inert gas. At the same time, turn on the electromagnetic stirring function and then perform slag removal operation to obtain the die casting material. S6. Die casting: High-modulus aluminum alloy parts are formed by die casting in a die casting machine through vacuum die casting process.

[0057] In S2, the melting temperature of the aluminum ingot is 760℃, the temperature for further melting is 800℃, the holding temperature is 720℃, and the holding time is 40 minutes.

[0058] In S3, the temperature of the preheated fiber is 480°C.

[0059] In S4, the electromagnetic stirring speed is 650 r / min, and each 1 kg of SiC fiber and BN fiber corresponds to 15 min of electromagnetic stirring time.

[0060] In step S5, the refining agent is a sodium-free refining agent, and the inert gas is nitrogen. In step S5, the inert gas is introduced at a rate of 1.8 m / s. 3 / h, continuous charging time is 20min.

[0061] In S6, the internal temperature of the die-casting machine in the vacuum die-casting process is 770℃. In S6, the thickness of the high-modulus aluminum alloy part is ≤1.0mm.

[0062] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0063] Comparative Example 1 The high-modulus aluminum alloy in this comparative example differs from that in Example 2 in only one aspect, namely, in terms of raw material composition and die-casting process: SiC particles are used to replace BN fibers. The particle diameter is 5-40μm and the elastic modulus is ≥220 GPa.

[0064] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0065] Comparative Example 2 The high-modulus aluminum alloy in this comparative example differs from that in Example 2 in only one aspect, namely, in terms of raw material composition and die-casting process: BN particles are used to replace BN fibers. The particle diameter is 10-40μm and the elastic modulus is ≥250 GPa.

[0066] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0067] Comparative Example 3 The high-modulus aluminum alloy in this comparative example differs from that in Example 2 in only one aspect, namely, in terms of raw material composition and die-casting process: No high-modulus particles or fibers are added to the raw material composition.

[0068] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0069] Comparative Example 4 The high-modulus aluminum alloy in this comparative example differs from that in Example 2 in only one aspect, namely, in terms of raw material composition and die-casting process: In the die-casting process, the "S3, fiber heating" step is eliminated, and BN fibers are added directly at room temperature.

[0070] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0071] Comparative Example 5 The high-modulus aluminum alloy in this comparative example differs from that in Example 2 in only one aspect, namely, in terms of raw material composition and die-casting process: In the die-casting process, the inert gas is introduced at a rate of 0.3 m / s. 3The continuous filling time is 30 minutes, which is basically the same as the existing aluminum alloy die-casting process conditions.

[0072] Finally, the high-modulus aluminum alloy parts in this embodiment were tested for four parameters: elastic modulus, tensile strength, yield strength, and elongation. Each parameter was tested ≥50 times, and the average value was taken. The results are recorded in Table 1 below.

[0073] Table 1 Performance Test Results of High Modulus Aluminum Alloy Parts Summary and Analysis In the first and third embodiments, the aluminum alloy part in embodiment 2 has the best performance, given priority to elastic modulus. This may be because BN fiber has a better effect on improving the elastic modulus of aluminum alloy compared to SiC fiber.

[0074] This is also reflected in the difference in the elastic modulus values ​​between Comparative Example 2 and Comparative Example 1, that is, in terms of elastic modulus values, BN particles in Comparative Example 2 are also superior to SiC particles.

[0075] The second and third embodiments, as well as comparative examples 2, 4, and 5, all meet the basic conditions for high-modulus aluminum alloys, namely, elastic modulus ≥80GPa, tensile strength ≥300MPa, yield strength ≥180MPa, and elongation ≥5.5%. However, when the range of elastic modulus is set to ≥90GPa, only three embodiments are qualified. This also shows that the conditions of the present invention corresponding to the above differences are all indispensable.

[0076] Third, the conditions of the present invention corresponding to the above differences have virtually no impact on the three performance parameters of tensile strength, yield strength, and elongation.

[0077] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various modifications can be made without departing from the spirit of the present invention. These are all non-inventive modifications, and are protected by patent law as long as they fall within the scope of the claims of the present invention.

Claims

1. A high-modulus aluminum alloy material, characterized in that: The raw material composition includes any one or a mixture of two of SiC fibers and BN fibers, wherein the SiC fibers and BN fibers have a length of 0.5-1.5 mm, a diameter of 10-30 μm, and an elastic modulus of 240-290 GPa. The raw material composition includes the following components by weight: Zn: 1.0-2.5%, Mg: 2.0-2.2%, Cu: 1.5-1.8%, Si: 0.5-0.7%, Fe: 0.1-0.2%, SiC fiber and / or BN fiber: 2.5-3.5%, with the balance being Al and unavoidable impurities. The die-casting process for the high-modulus aluminum alloy material includes the following steps in sequence. S1, Ingredients; S2. Smelting: First, heat and melt aluminum ingots in a smelting furnace, then add Zn, Mg, Cu, Si and Fe, continue smelting, and then keep the temperature to obtain molten liquid; S3. Fiber heating: The SiC fibers and / or BN fibers are heated in a heating furnace to obtain preheated fibers; S4. Mixing: First, add the preheated fiber to the molten liquid, then turn on the electromagnetic stirring function to obtain aluminum alloy liquid; S5. Refining: Add refining agent to the aluminum alloy liquid and fill it with inert gas. At the same time, turn on the electromagnetic stirring function and then perform slag removal operation to obtain the die casting material. S6. Die Casting: High-modulus aluminum alloy parts are formed by vacuum die casting in a die casting machine. In S3, the temperature of the preheated fiber is 420-480℃. In S5, the refining agent is a sodium-free refining agent, and the inert gas is nitrogen or argon. In S5, the inert gas is introduced at a rate of 1.5-1.8 m / s. 3 / h, with a continuous charging time of 20-25min.

2. The high-modulus aluminum alloy material according to claim 1, characterized in that: In S2, the melting temperature of the aluminum ingot is 740-760℃, the smelting temperature is 780-850℃, the holding temperature is 600-720℃, and the holding time is 30-50 minutes.

3. The high-modulus aluminum alloy material according to claim 1, characterized in that: In S4, the electromagnetic stirring speed is 150-850 r / min, and the electromagnetic stirring time is 12-20 min for every 1 kg of SiC fiber and / or BN fiber.

4. The high-modulus aluminum alloy material according to claim 1, characterized in that: In S6, the internal temperature of the die-casting machine in the vacuum die-casting process is 740-780℃.

5. The high-modulus aluminum alloy material according to claim 1, characterized in that: In S6, the thickness of the high-modulus aluminum alloy part is ≤1.0mm.

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