Aluminum alloy material and preparation method and application thereof

Abstract

The invention provides an aluminum alloy material and a preparation method and application thereof. The preparation method comprises the following steps: preparing raw materials; furnace washing is conducted, specifically, an aluminum ingot is added into the smelting furnace and heated, so that the aluminum ingot is molten, then the molten aluminum ingot is poured out, and furnace washing melt is obtained; smelting to obtain a first melt; refining to obtain a second melt; casting: casting the second melt to obtain a casting; the casting comprises casting and cooling which are carried out in sequence, and the cooling is carried out within 0.5-2.0 minutes after the casting is completed; and aging is conducted, specifically, the casting is subjected to aging treatment at the temperature of 250-300 DEG C for 1.5-2.5 h, and the aluminum alloy material is obtained. The preparation method provided by the invention not only has the advantages of simple process flow and low production cost, and can well balance the manufacturing cost and performance expression, but also can obtain the aluminum alloy material with comprehensive performance requirements such as high formability, mechanical property and conductivity.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy material, a preparation method and application thereof. Background Art

[0002] The asynchronous motor for new energy vehicles is mainly composed of two basic parts: the stator and the rotor. The function of the stator is to generate a magnetic field, and the function of the rotor is to cut the stator's rotating magnetic field to generate an induced electromotive force and current, and form an electromagnetic torque to rotate the motor. When the current passes through the rotor, it will generate heat due to resistance loss, reducing the efficiency of the motor. At the same time, the heat transferred to other components will also cause the motor temperature to rise (i.e., temperature rise). Once the heat cannot be dissipated in time, stress will be generated between the various parts of the rotor due to different thermal expansion coefficients. In order to improve the efficiency of the motor and achieve a higher speed, on the one hand, the rotor is required to have a higher conductivity to reduce resistance loss and reduce temperature rise; on the other hand, the rotor is also required to have a higher strength to withstand the centrifugal force generated by high-speed rotation (proportional to the square of the speed). Therefore, high-speed motors have increasingly higher requirements for the comprehensive performance of rotor materials.

[0003] Prior art 1 (CN112853160A, a motor rotor casting aluminum alloy and its preparation method) relates to a motor rotor casting aluminum alloy and its preparation method, the aluminum alloy includes 0.01wt%-0.04wt% titanium, boron less than 0.05wt%, silicon <0.1wt%, iron <0.2wt%, copper less than 0.1wt%, magnesium less than 0.1wt%, zinc less than 0.1wt%, other impurities less than 0.05wt%, the final balance is aluminum content greater than 99.6wt%, and provides a preparation method of the motor rotor casting aluminum alloy. The casting aluminum alloy using this technology can meet the requirements of high strength and high conductivity, and is suitable for the manufacture of high-strength and high-conductivity motor rotors. However, this solution mainly obtains highly conductive materials (33.5-36MS / m) by refining AlTiB grains on the basis of pure aluminum. However, the strengthening effect of fine grains alone is limited. Therefore, the overall strength of the alloy is relatively low, and the yield strength is only in the range of 38-35MPa. It is not suitable for use in high-speed motors above 14000rpm, and it is easy to break bars, posing a safety hazard.

[0004] Prior art 2 (CN116875859B, an aluminum alloy material and a preparation method thereof, a motor rotor aluminum alloy, an induction AC asynchronous motor and a vehicle) relates to an aluminum alloy material and a preparation method thereof, a motor rotor aluminum alloy, an induction AC asynchronous motor and a vehicle. The aluminum alloy material comprises: 0.8-1.0 weight % Si, 0.3-0.5 weight % Mg, 0.03-0.05 weight % Zr, 0.03-0.05 weight % Sr, 0.15-0.25 weight % Sb, 0-0.1 weight % Fe, 0-0.05 weight % Ti, 0-0.005 weight % Mn, 0-0.08 weight % or less of other impurity elements and the balance Al. The aluminum alloy material has a yield strength of more than 80 MPa at 25°C, a tensile strength of more than 100 MPa, and an electrical conductivity of more than 50 IACS, preliminarily taking into account the high yield strength and high electrical conductivity of the aluminum alloy material. However, this scheme is mainly based on Al-Si-Mg alloy, and improves strength and refines grains by introducing Zr element to form Al3Zr high temperature stable phase. However, the addition amount of Mg element is relatively high (0.3-0.5%). Due to its high solubility in Al (0.24%) and the large difference in atomic radius between Mg and Al, Mg element is dissolved in Al matrix, which has a great influence on the degree of lattice distortion and significantly reduces the conductivity. On the other hand, since grain boundary as a surface defect will also increase the probability of free electron scattering, grain refinement will also have an adverse effect on the conductivity. In addition, the Si content in the alloy is only in the range of 0.8-1.0%, and Sr and Sb also play the role of modifying silicon phase. The addition of both at the same time and the addition amount is above 0.06%, so it is easy to cause excessive modification of silicon phase, and excessive Sr will also increase the tendency of hydrogen absorption of melt, which ultimately leads to poor conductivity performance.

[0005] Prior art 3 (CN114875255A, a high-strength motor rotor aluminum alloy and its preparation process) relates to a high-strength motor rotor aluminum alloy and its preparation process, which belongs to the technical field of new energy vehicle motor rotor materials. The high-strength motor rotor aluminum alloy includes the following components: Sb 0.5-1.5wt%, Mg 0.3-0.7wt%, Si 0.3-0.7wt% and the balance Al. The performance of the high-strength motor rotor aluminum alloy meets the following requirements: the casting porosity is 2-6%, the yield strength is 80-100MPa, the tensile strength is 150-180MPa, and the conductivity is 32.5-34MS / m. This solution mainly includes three added elements: Si, Mg, and Sb. The Mg content is also relatively high (0.3-0.7%). In order to improve the comprehensive performance of the alloy, this solution adopts a solid solution + aging heat treatment process to further improve the electrical conductivity. The solid solution system is 500-550°C, and the temperature is kept for 3-8 hours; the aging system is 160-200°C, and the temperature is kept for 12-20 hours. The above-mentioned solid solution aging process will not only increase the number of processes, extend the working hours, and increase the production cost, but more importantly, due to the centrifugal casting process, some pores will inevitably remain inside the rotor parts, which will easily cause the parts to blister and deform at high temperatures (>350°C), which is not conducive to its practical application.

[0006] Based on this, how to coordinate the composition ratio of aluminum alloy and the corresponding preparation process conditions to provide an aluminum alloy material with excellent performance, so that it can take into account both high mechanical properties and high electrical conductivity, so as to better meet the use requirements of aluminum alloy for new energy vehicle motor rotors, is one of the important technical problems that need to be solved in this field. Summary of the invention

[0007] The main purpose of the present invention is to provide an aluminum alloy material, a preparation method and application thereof, so as to solve the problem that the aluminum alloy material in the prior art is difficult to achieve both high mechanical properties and high electrical conductivity.

[0008] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for preparing an aluminum alloy material, comprising: preparing raw materials: in terms of weight percentage, the components of the aluminum alloy material include 0.8% to 1.2% Si element, 0.02% to 0.1% Mg element, 0% to 0.02% impurity elements, the remainder is Al, and the weight ratio of Si element to Mg element is (15 to 30): 1, and the impurity elements include Mn element, Cr element and V element; preparing raw materials according to the components of the aluminum alloy material; furnace washing: adding aluminum ingots to the smelting furnace; And heating to melt the aluminum ingot, then pouring out the molten aluminum ingot to obtain a furnace-washing melt; smelting: melting the raw materials and adding them into a smelting furnace to obtain a first melt after smelting; refining: refining the first melt to obtain a second melt; casting: casting the second melt to obtain a casting; casting includes casting and cooling in sequence, and cooling is carried out within 0.5min to 2.0min after the casting is completed; aging: aging the casting at a temperature of 250℃ to 300℃ for 1.5h to 2.5h to obtain an aluminum alloy material.

[0009] Furthermore, the weight sum of Si element and Mg element is 0.8% to 1.2%; preferably, when the aluminum ingot is used for furnace washing, the furnace washing step is ended when the total weight of Mn element, Cr element and V element in the furnace washing melt is 0% to 0.02%.

[0010] Furthermore, the smelting process includes first adding Al element and Si element into the smelting furnace, obtaining an initial melt through a first smelting, and then adding Mg element into the initial melt, obtaining a first melt through a second smelting; preferably, when the Mg element is added, the temperature of the initial melt is 720°C to 730°C.

[0011] Furthermore, the refining temperature is 720°C to 730°C, and the density of the second melt is 2.65 g / cm 3 ~2.70g / cm 3 .

[0012] Furthermore, during casting, the heating temperature of casting is 730°C to 740°C, and the mold temperature is 150°C to 200°C.

[0013] Further, the casting is centrifugal casting or gravity casting; preferably, the casting is centrifugal casting, and the casting speed of the centrifugal casting is 200 rpm to 400 rpm.

[0014] Furthermore, the internal defect size of the casting is 0.2 mm to 1.0 mm, and the porosity is 0.02% to 0.50%.

[0015] A second aspect of the present invention provides an aluminum alloy material, which is prepared by the above-mentioned method for preparing the aluminum alloy material.

[0016] Furthermore, the aluminum alloy material has a tensile strength of 110 MPa to 130 MPa, a yield strength of 65 MPa to 80 MPa, an elongation of 18% to 24%, and an electrical conductivity of 31.5 MS / m to 35.0 MS / m.

[0017] The third aspect of the present invention provides an application of the above-mentioned aluminum alloy material as a rotor material in the motor system of a new energy vehicle; preferably, the aluminum alloy material is processed into a profile and used as a rotor; more preferably, the working environment of the rotor is a temperature of -40°C to 320°C and a humidity of 25RH% to 95RH%.

[0018] By applying the technical solution of the present invention, through comprehensive alloy composition design and production process matching, and strictly limiting the content of each element and impurity therein, and coordinating a specific aging process, an aluminum alloy material with uniform structure, high density and few defects is prepared. The preparation method provided by the present invention not only has the advantages of simple process flow and low production cost, but also balances the manufacturing cost and performance well, and can also obtain an aluminum alloy material that takes into account the comprehensive performance requirements such as high forming performance, mechanical properties, and electrical conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 This is a metallographic structure photograph of the aluminum alloy material obtained in Example 1. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0022] As described in the background technology, the aluminum alloy materials in the prior art have the problem of being difficult to balance high mechanical properties and high electrical conductivity. In order to solve the above technical problems, the first aspect of the present invention provides a method for preparing an aluminum alloy material, comprising: preparing raw materials: in terms of weight percentage, the composition of the aluminum alloy material includes 0.8% to 1.2% Si element, 0.02% to 0.1% Mg element, 0% to 0.02% impurity elements, the balance is Al, and the weight ratio of Si element to Mg element is (15 to 30): 1, and the impurity elements include Mn element, Cr element and V element; preparing raw materials according to the composition of the aluminum alloy material; furnace washing: adding aluminum to the smelting furnace; Ingot and heating to melt the aluminum ingot, then pouring out the molten aluminum ingot to obtain a furnace-washing melt; smelting: melting the raw materials and adding them into a smelting furnace to obtain a first melt after smelting; refining: refining the first melt to obtain a second melt; casting: casting the second melt to obtain a casting; casting includes casting and cooling in sequence, and cooling is performed within 0.5min to 2.0min after the casting is completed; aging: aging the casting at a temperature of 250℃ to 300℃ for a time of 1.5h to 2.5h to obtain an aluminum alloy material.

[0023] In the technical solution provided by the present invention, the content of Si and Mg in the alloy components is first controlled, and the content relationship between the two is strictly limited, that is, Si / Mg=15-30, and an aluminum alloy with extremely high resistivity and excellent mechanical properties is prepared under this optimally matched element content condition. Specifically, for the Al-Mg-Si alloy provided by the present invention to which only Si and Mg functional elements are added, the precipitation sequence of the precipitates at different stages of the aging process is: supersaturated solid solution (sss) → cluster / GP zone → β" phase → β' phase → steady-state β phase. In the early stage of aging, spherical solute atom clusters and GP zones with a high number density are precipitated, and the peak aging state mainly precipitates β" phase. Different types and distribution states of precipitates directly determine the electrical conductivity and mechanical properties of the alloy. When solute atoms exist in the form of solid solution or in the form of coherent GP zones, the strength of the alloy can be improved, but due to the increased degree of lattice distortion, the electrical conductivity of the alloy will be affected. The β″ phase belongs to the polygonal monoclinic system and has a significant strengthening effect, but it also maintains a highly coherent relationship with the Al matrix. The steady-state β phase is in a non-coherent relationship with the matrix, and is most beneficial to the electrical conductivity of the alloy when distributed in a dispersed state, but is not conducive to the strengthening effect. Therefore, based on the above mechanism, the present invention has found through a large number of experimental studies that by reasonably designing the absolute content and relative content relationship of Si and Mg as above, combined with an aging treatment process with a temperature of 250°C to 300°C and a time of 1.5h to 2.5h, the crystal structure, size, number density, morphology and distribution state of the precipitation strengthening phase are effectively regulated, thereby achieving the best match between the electrical conductivity and mechanical properties of the alloy, and finally obtaining an aluminum alloy material that can take into account both high electrical conductivity and mechanical properties.

[0024] And, except for the Si and Mg elements matched in a specific relationship, the present invention has not added expensive metals such as rare earth, and strictly controlled the impurity elements in the alloy composition, that is, in the above alloy formula provided by the present invention, the weight percentage of the impurity elements of Mn, Cr and V is less than 0.02%. Among them, it is generally believed in the technical field that the Mn element can improve the strength of the aluminum alloy, so that it has better mechanical properties, and can also improve its processing performance; the Cr element can also improve the hardness, strength and corrosion resistance of the aluminum alloy; the V element can improve the thermal stability of the aluminum alloy. However, for the Al-Mg-Si alloy with the above-mentioned component content provided by the present invention, the addition of the Mn element may reduce the plasticity of the aluminum alloy material, thereby affecting its elongation, and also easily cause its stress corrosion; the Cr element and the V element, in addition to weakening the plasticity of the aluminum alloy material provided by the present invention, are also very likely to cause the brittleness of the obtained aluminum alloy material, affecting its reliability under impact load. Therefore, the present invention strictly controls the impurity content of the above three elements, thereby more significantly reducing defects and improving mechanical properties and processing properties, and improving the overall performance of the obtained aluminum alloy material. Especially for conductivity, due to the interaction between Mn, Cr and V impurity atoms and aluminum alloy matrix atoms, local defects may be formed. The difference in their size and the size of the alloy matrix atoms will affect the lattice structure of the obtained aluminum alloy material, and their charge state may also affect the electronic structure of the aluminum alloy material, and ultimately affect the electronic transmission and electrical conductivity of the aluminum alloy material. Therefore, when the impurity content is strictly controlled to be ≤0.02wt% in the preparation method provided by the present invention, the electronic structure and lattice structure of the aluminum alloy can be optimized, thereby significantly improving its electrical conductivity. As for the method for controlling the impurity content, the present invention introduces a furnace washing process in the preparation method provided to significantly reduce impurities in the subsequent preparation process, and ultimately make the impurity content in the obtained aluminum alloy material ≤0.02wt%.

[0025] In particular, as mentioned above, the preparation method provided by the present invention is not only designed for the content of alloy components, but more importantly, the specific alloy formula is matched with the specific preparation process, especially the aging process, so as to successfully achieve the regulation of the metallographic structure of the aluminum alloy, and finally obtain an aluminum alloy material with excellent comprehensive performance. What is more worth mentioning is that in the casting process of the above-mentioned aluminum alloy material, the present invention strictly controls the interval time between casting and cooling during the casting process, that is, the cooling is carried out within 0.5min to 2.0min after the casting is completed, thereby effectively improving the cooling rate of the melt, refining its organizational grains and reducing segregation, and finally making it exhibit superior mechanical properties and extremely high electrical conductivity.

[0026] Furthermore, in order to better balance the strengthening relationship brought about by the synergistic effect of Si and Mg, the inventors have optimized the weight sum of Si and Mg elements to be 0.8% to 1.2% through a large number of experiments, and obtained an aluminum alloy material with superior electrical conductivity and mechanical properties under this dosage relationship.

[0027] In several typical implementations, in order to more effectively control and reduce the impurity content in the aluminum alloy material, thereby improving its electrical conductivity and various mechanical properties, it is preferred to use aluminum ingots for furnace washing until the total weight of Mn elements, Cr elements and V elements in the furnace washing melt is 0% to 0.02%, and then the furnace washing step is ended.

[0028] It should be noted that the three impurities of Mn, Cr and V involved in the present invention come from the residues in the smelting furnace on the one hand and the inevitable inherent impurities of the Al raw material on the other hand. The furnace washing process of the present invention mainly targets the residual impurities in the smelting furnace, deeply removes them, and thus improves the various properties of the obtained aluminum alloy material.

[0029] Furthermore, in order to make the compatibility and dispersion of the elements more uniform during the smelting process, and obtain an aluminum alloy material with fewer defects and higher comprehensive performance, the smelting process preferably includes first adding Al and Si elements to the smelting furnace, obtaining an initial melt through a first smelting, and then adding Mg elements to the initial melt, and obtaining a first melt through a second smelting. Preferably, when adding the Mg element, the temperature of the initial melt is 720°C to 730°C, and the raw materials are alloyed according to the above-mentioned feeding sequence and process conditions, which is more inclined to obtain an aluminum alloy melt with a purer phase structure, and adding the Mg element to the melt at 720°C to 730°C can promote it to melt into the first melt containing Al and Si at a more suitable speed, thereby improving the uniformity of the composition and structure.

[0030] It should be noted that, in the actual preparation process, the Al element used in the present invention is provided by industrial pure Al, and its purity is ≥99.7%; the Si element is provided by industrial pure Si, and its purity is ≥99.9%; the Mg element is provided by industrial pure Mg, and its purity is ≥99.8%. At the same time, the Si element can also be added in the form of Al-Si master alloy.

[0031] In several typical implementations, in order to further optimize the purity and microstructure of the aluminum alloy and make it exhibit higher electrical conductivity, the inventors have optimized the refining temperature to be 720°C to 730°C after a large number of experiments. At the same time, in order to improve the distribution uniformity of each component, reduce pores and inclusions, and thus improve the comprehensive performance of the obtained aluminum alloy material, the density of the second melt is preferably 2.65g / cm 3 ~2.70g / cm 3.

[0032] In order to obtain castings with less internal component segregation, fewer defects, higher density and lower porosity, thereby further improving the electrical conductivity and mechanical properties of the resulting aluminum alloy material, the preferred heating temperature for casting is 730°C to 740°C and the mold temperature is 150°C to 200°C.

[0033] In several typical embodiments, the casting is centrifugal casting or gravity casting. In order to further improve the compactness and reduce the resistivity of the obtained aluminum alloy material, the casting is preferably centrifugal casting. At the same time, the inventor further preferred the casting speed of the centrifugal casting to be 200rpm to 400rpm after a large number of experiments, so as to provide a more suitable centrifugal force for the second melt, so that the pressure borne by the melt in the casting mold is more suitable, thereby significantly improving the compactness of the casting obtained by casting, and finally making the obtained aluminum alloy material show better comprehensive performance.

[0034] Furthermore, the castings obtained by casting were tested, and in several typical implementations, it was found that when the internal defect size was 0.2mm~1.0mm and the porosity was 0.02%~0.50%, the aluminum alloy material finally prepared could exhibit higher mechanical properties and electrical conductivity.

[0035] The second aspect of the present invention provides an aluminum alloy material, which is prepared by the above-mentioned aluminum alloy material preparation method. The obtained aluminum alloy material has excellent comprehensive performance, taking into account mechanical properties, electrical conductivity and high-temperature service life, and meets the use requirements of various fields, especially the new energy vehicle field.

[0036] In several preferred embodiments, the aluminum alloy material has a tensile strength of 110 MPa to 130 MPa, a yield strength of 65 MPa to 80 MPa, an elongation of 18% to 24%, and an electrical conductivity of 31.5 MS / m to 35.0 MS / m.

[0037] The third aspect of the present invention provides an application of the above-mentioned aluminum alloy material as a rotor material in the motor system of a new energy vehicle; preferably, the aluminum alloy material is processed into a profile and used as a rotor; more preferably, the working environment of the rotor is: temperature -40°C to 320°C, humidity 25RH% to 95RH%. Because the above-mentioned aluminum alloy material obtained by the present invention has excellent mechanical properties, that is, higher strength and elongation, and also exhibits extremely high electrical conductivity, it can show an extremely good state when used as a rotor material in the motor system of a new energy vehicle, especially when the humidity is ≥50RH%. Compared with other aluminum alloys for rotors in the field, the aluminum alloy material provided by the present invention has higher comprehensive properties such as corrosion resistance, electrical conductivity and mechanical properties due to the optimized design of alloy composition and microstructure.

[0038] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0039] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0040] Example 1

[0041] A method for preparing an aluminum alloy material:

[0042] (1) Raw material preparation: The aluminum alloy material comprises, by weight percentage, 1.0% Si, 0.05% Mg (i.e., Si / Mg=20, Si+Mg=1.05%), 0.014% impurity elements, and the balance is Al. The impurity elements include Mn, Cr, and V. Raw materials are prepared according to the above composition. The contents of each raw material are shown in Table 1.

[0043] (2) Before smelting, the smelting furnace is cleaned with aluminum ingots, that is, the aluminum ingots are placed in the smelting furnace and heated until melted, and the furnace washing melt is poured out after uniform stirring. The total amount of Mn+Cr+V elements in the furnace washing melt S1 is 0.014wt%;

[0044] (3) According to the above alloy composition, pure Si and pure Al are first added into a melting furnace at the same time, and heated until completely melted to obtain an initial melt. When the temperature of the initial melt is adjusted to 725° C., pure Mg is added, and the mixture is heated again until completely melted and stirred to obtain a first melt.

[0045] (4) The first melt was degassed and refined at 725°C to obtain a density of 2.68 g / cm 3 The second melt;

[0046] (5) feeding the second melt into a centrifugal casting machine, casting at a casting speed of 300 rpm, a heating temperature of 735° C., and a mold temperature of 175° C., and cooling within 1.0 min after the casting is completed to obtain a casting having an internal defect size of 0.2 mm and a porosity of 0.05%;

[0047] (6) The obtained casting is subjected to T5 aging treatment at a temperature of 275°C and a time of 2.0 h to obtain an aluminum alloy material.

[0048] The metallographic structure of the aluminum alloy material is shown in Figure 1 .

[0049] Example 2

[0050] A method for preparing an aluminum alloy material:

[0051] (1) Raw material preparation: The aluminum alloy material comprises, by weight percentage, 1.125% Si, 0.075% Mg (i.e., Si / Mg=15, Si+Mg=1.2%), 0.016% impurity elements, and the balance is Al. The impurity elements include Mn, Cr, and V. Raw materials are prepared according to the above composition. The contents of each raw material are shown in Table 1.

[0052] (2) Before smelting, the smelting furnace is cleaned with aluminum ingots, that is, the aluminum ingots are placed in the smelting furnace and heated until melted, and the furnace washing melt is poured out after uniform stirring. The total amount of Mn+Cr+V elements in the furnace washing melt S1 is 0.016wt%;

[0053] (3) According to the above alloy composition, pure Si and pure Al are first added into a melting furnace at the same time, and heated until completely melted to obtain an initial melt. When the temperature of the initial melt is adjusted to 730° C., pure Mg is added, and the mixture is heated again until completely melted and stirred to obtain a first melt.

[0054] (4) The first melt was degassed and refined at 730°C to obtain a density of 2.65 g / cm 3 The second melt;

[0055] (5) feeding the second melt into a centrifugal casting machine, casting at a casting speed of 200 rpm, a heating temperature of 740° C., and a mold temperature of 200° C., and cooling within 2.0 min after the casting is completed to obtain a casting having an internal defect size of 0.3 mm and a porosity of 0.25%;

[0056] (6) The obtained casting was subjected to T5 aging treatment at a temperature of 300°C for a time of 1.5 h to obtain an aluminum alloy material.

[0057] Example 3

[0058] A method for preparing an aluminum alloy material:

[0059] (1) Raw material preparation: The aluminum alloy material comprises, by weight percentage, 0.8% Si, 0.027% Mg (i.e., Si / Mg=29.6, Si+Mg=0.827%), 0.01% impurity elements, and the remainder is Al. The impurity elements include Mn, Cr, and V. Raw materials are prepared according to the above composition. The contents of each raw material are shown in Table 1.

[0060] (2) Before smelting, the smelting furnace is cleaned with aluminum ingots, that is, the aluminum ingots are placed in the smelting furnace and heated until melted, and the furnace washing melt is poured out after uniform stirring. The total amount of Mn+Cr+V elements in the furnace washing melt S1 is 0.01wt%;

[0061] (3) According to the above alloy composition, pure Si and pure Al are first added into a melting furnace at the same time, and heated until completely melted to obtain an initial melt. When the temperature of the initial melt is adjusted to 720° C., pure Mg is added, and the mixture is heated again until completely melted and stirred to obtain a first melt.

[0062] (4) The first melt was degassed and refined at 720°C to obtain a density of 2.69 g / cm 3 The second melt;

[0063] (5) feeding the second melt into a centrifugal casting machine, casting at a casting speed of 400 rpm, a heating temperature of 730° C., and a mold temperature of 150° C., and cooling within 0.5 min after the casting is completed to obtain a casting having an internal defect size of 0.2 mm and a porosity of 0.02%;

[0064] (6) The obtained casting is subjected to T5 aging treatment at a temperature of 250°C for a time of 2.5 h to obtain an aluminum alloy material.

[0065] Example 4

[0066] A method for preparing an aluminum alloy material:

[0067] Step (1) to step (2) are the same as in Example 1.

[0068] (3) According to the above alloy composition, pure Si and pure Al are first added into a smelting furnace at the same time, and heated until completely melted to obtain an initial melt. When the temperature of the initial melt is adjusted to 700°C, pure Mg is added, and then heated until completely melted and stirred evenly to obtain a first melt.

[0069] Steps (4) to (6) are also the same as in Example 1.

[0070] Example 5

[0071] A method for preparing an aluminum alloy material:

[0072] Step (1) to step (2) are the same as in Example 1.

[0073] (3) According to the above alloy composition, pure Si and pure Al are first added into a smelting furnace at the same time, and heated until completely melted to obtain an initial melt. When the temperature of the initial melt is adjusted to 750°C, pure Mg is added, and then heated until completely melted and stirred evenly to obtain a first melt.

[0074] Steps (4) to (6) are also the same as in Example 1.

[0075] Example 6

[0076] A method for preparing an aluminum alloy material:

[0077] Steps (1) to (3) are the same as those in Example 1.

[0078] (4) The first melt was degassed and refined at 700°C to obtain a density of 2.62 g / cm 3 of the second melt.

[0079] Steps (5) to (6) are also the same as in Example 1.

[0080] Example 7

[0081] A method for preparing an aluminum alloy material:

[0082] Steps (1) to (3) are the same as those in Example 1.

[0083] (4) The first melt was degassed and refined at 750°C to obtain a density of 2.6 g / cm 3 of the second melt.

[0084] Steps (5) to (6) are also the same as in Example 1.

[0085] Example 8

[0086] A method for preparing an aluminum alloy material:

[0087] Steps (1) to (4) are the same as those in Example 1.

[0088] (5) The second melt is fed into a centrifugal casting machine, cast at a casting speed of 150 rpm, a heating temperature of 735° C., and a mold temperature of 175° C., and cooled within 1.0 min after the casting is completed to obtain a casting; the internal defect size of the casting is 0.5 mm, and the porosity is 0.42%.

[0089] Step (6) is also the same as in Example 1.

[0090] Example 9

[0091] A method for preparing an aluminum alloy material:

[0092] Steps (1) to (4) are the same as those in Example 1.

[0093] (5) The second melt is fed into a centrifugal casting machine, cast at a casting speed of 450 rpm, a heating temperature of 735° C., and a mold temperature of 175° C., and cooled within 1.0 min after the casting is completed to obtain a casting; the internal defect size of the casting is 0.6 mm, and the porosity is 0.48%.

[0094] Step (6) is also the same as in Example 1.

[0095] Example 10

[0096] A method for preparing an aluminum alloy material:

[0097] Steps (1) to (4) are the same as those in Example 1.

[0098] (5) The second melt is fed into a centrifugal casting machine, and is cast at a casting speed of 300 rpm, a heating temperature of 720° C., and a mold temperature of 120° C., and is cooled within 1.0 min after the casting is completed to obtain a casting; the internal defect size of the casting is 0.8 mm, and the porosity is 0.50%.

[0099] Step (6) is also the same as in Example 1.

[0100] Embodiment 11

[0101] A method for preparing an aluminum alloy material:

[0102] Steps (1) to (4) are the same as those in Example 1.

[0103] (5) The second melt is fed into a centrifugal casting machine, cast at a casting speed of 300 rpm, a heating temperature of 750° C., and a mold temperature of 220° C., and cooled within 1.0 min after the casting is completed to obtain a casting; the internal defect size of the casting is 1.0 mm, and the porosity is 0.44%.

[0104] Step (6) is also the same as in Example 1.

[0105] The difference between Comparative Example 1 and Comparative Example 2 and Example 1 is only the different element contents in the alloys, see Table 1 for details.

[0106] Comparative Example 3

[0107] A method for preparing an aluminum alloy material:

[0108] The only difference between this comparative example and Example 1 is that no furnace cleaning treatment is performed before smelting. The contents of each element in the obtained aluminum alloy material are shown in Table 1.

[0109] Comparative Example 4

[0110] A method for preparing an aluminum alloy material:

[0111] Steps (1) to (5) are the same as those in Example 1.

[0112] (6) The obtained casting was subjected to T5 aging treatment at a temperature of 230°C for a time of 3.0 h to obtain an aluminum alloy material.

[0113] Comparative Example 5

[0114] A method for preparing an aluminum alloy material:

[0115] Steps (1) to (5) are the same as those in Example 1.

[0116] (6) The obtained casting was subjected to T5 aging treatment at a temperature of 320°C for a time of 1.0 h to obtain an aluminum alloy material.

[0117] Comparative Example 6

[0118] A method for preparing an aluminum alloy material:

[0119] Steps (1) to (4) are the same as those in Example 1.

[0120] (5) The second melt was fed into a centrifugal casting machine, and was cast at a casting speed of 300 rpm, a heating temperature of 735° C., and a mold temperature of 175° C., and was cooled within 5.0 min after the casting was completed to obtain a casting; the internal defect size of the casting was 1.5 mm, and the porosity was 0.47%.

[0121] Step (6) is also the same as in Example 1.

[0122] Table 1

[0123] Si / % Mg / % Si+Mg / % Si / Mg Impurities / % Al Example 1 1.000 0.050 1.050 20.0 0.014 margin Example 2 1.125 0.075 1.200 15.0 0.016 margin Example 3 0.800 0.027 0.827 29.6 0.010 margin Comparative Example 1 1.800 0.180 1.980 10.0 0.018 margin Comparative Example 2 0.800 0.020 0.820 40.0 0.010 margin Comparative Example 3 1.000 0.050 1.050 20.0 0.042 margin

[0124] The examples and comparative examples not listed in Table 1 all have the same element types and contents as those in Example 1.

[0125] Test Method

[0126] Internal defect size and porosity: tested using a computed tomography (CT) scanner.

[0127] Tensile strength, yield strength and elongation: tested according to GB / T 228.1-2021.

[0128] Conductivity: Tested according to GB / T 12966-2008 standard.

[0129] The above performance tests were performed on the castings obtained by casting in each embodiment and comparative example and the aluminum alloy material finally obtained. The results are shown in Table 2.

[0130] Table 2

[0131]

[0132] From the above description, it can be seen that the above embodiments of the present invention achieve the preparation of aluminum alloy materials that take into account mechanical properties, electrical conductivity and high-temperature service life. The obtained aluminum alloy material not only exhibits high strength, elongation, and high-temperature fatigue performance, but also has excellent electrical conductivity.

[0133] Specifically, compared with Examples 1 to 3, Example 4 has a lower temperature when Mg is added and a poor melting rate, so the performance is slightly reduced; Example 5 has a higher temperature when Mg is added, which causes Mg burning and air absorption, resulting in an increase in porosity and a slight reduction in performance; Examples 6 and 7 show that the refining temperature of 720°C to 730°C can optimize the purity and microstructure of the aluminum alloy and make the resulting aluminum alloy exhibit higher electrical conductivity; Examples 8 to 11 have changes in the casting speed or cooling rate during the casting process, resulting in internal component segregation and microstructural degradation, resulting in a reduction in performance, but are still better than the prior art represented by Comparative Examples 1 to 6.

[0134] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those described herein, for example.

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an aluminum alloy material, characterized in that: The preparation method of the aluminum alloy material comprises: Prepare raw materials: In terms of weight percentage, the composition of the aluminum alloy material includes 0.8% to 1.2% of Si element, 0.02% to 0.1% of Mg element, 0% to 0.02% of impurity elements, and the balance is Al, and the weight ratio of the Si element to the Mg element is (15 to 30): 1, and the impurity elements include Mn element, Cr element and V element; prepare raw materials according to the composition of the aluminum alloy material; Furnace washing: adding aluminum ingots into a smelting furnace and heating them to melt the aluminum ingots, and then pouring out the melted aluminum ingots to obtain furnace washing melts; Smelting: adding the raw materials into the smelting furnace and obtaining a first melt after smelting; Refining: refining the first melt to obtain a second melt; Casting: Casting the second melt to obtain a casting; the casting includes casting and cooling in sequence, and the cooling is performed within 0.5 min to 2.0 min after the casting is completed; Aging: The casting is subjected to aging treatment at a temperature of 250° C. to 300° C. for a time of 1.5 h to 2.5 h to obtain the aluminum alloy material.

2. The method for preparing the aluminum alloy material according to claim 1, characterized in that: The weight sum of the Si element and the Mg element is 0.8% to 1.2%; Preferably, when the aluminum ingot is used for the furnace cleaning, the furnace cleaning step is terminated after the total weight of the Mn element, the Cr element and the V element in the furnace cleaning melt is 0% to 0.02%.

3. The method for preparing the aluminum alloy material according to claim 1 or 2, characterized in that: The smelting process includes firstly adding the Al element and the Si element into the smelting furnace, performing a first smelting to obtain an initial melt, and then adding the Mg element into the initial melt, performing a second smelting to obtain the first melt; Preferably, when the Mg element is added, the temperature of the initial melt is 720°C to 730°C.

4. The method for preparing an aluminum alloy material according to any one of claims 1 to 3, characterized in that: The refining temperature is 720°C to 730°C, and the density of the second melt is 2.65 g / cm 3 ~2.70g / cm 3 .

5. The method for preparing an aluminum alloy material according to any one of claims 1 to 4, characterized in that: In the casting, the heating temperature of the casting is 730°C to 740°C, and the mold temperature is 150°C to 200°C.

6. The method for preparing an aluminum alloy material according to any one of claims 1 to 5, characterized in that: The casting is centrifugal casting or gravity casting; Preferably, the casting is centrifugal casting, and the casting speed of the centrifugal casting is 200 rpm to 400 rpm.

7. The method for preparing an aluminum alloy material according to any one of claims 1 to 6, characterized in that: The internal defect size of the casting is 0.2mm-1.0mm, and the porosity is 0.02%-0.50%.

8. An aluminum alloy material, characterized in that: The aluminum alloy material is prepared by the method for preparing the aluminum alloy material according to any one of claims 1 to 7.

9. The aluminum alloy material according to claim 8, characterized in that: The aluminum alloy material has a tensile strength of 110 MPa to 130 MPa, a yield strength of 65 MPa to 80 MPa, an elongation of 18% to 24%, and an electrical conductivity of 31.5 MS / m to 35.0 MS / m.

10. Use of the aluminum alloy material according to claim 8 or 9 as a rotor material in a motor system of a new energy vehicle; Preferably, the aluminum alloy material is processed into a profile and used as the rotor; More preferably, the working environment of the rotor is: temperature -40°C to 320°C, humidity 25RH% to 95RH%.

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