High-temperature-resistant aluminum alloy for new energy vehicle electric drive shell and preparation method thereof

Abstract

The application discloses a high-temperature-resistant new energy automobile electric drive shell aluminum alloy and a preparation method thereof; the application is different from the existing ADC12 aluminum alloy, and the tensile strength and the yield strength are not poor, and the application is suitable for high-pressure casting production of parts with high requirements for strength and toughness; after forming, the tensile strength of the aluminum alloy component is 330-360 MPa, the yield strength is 230-250 MPa, and the elongation after breaking is 3.0%-5.0%, which is higher than the performance of a conventional aluminum alloy forming component.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy manufacturing technology, specifically to a high-temperature resistant aluminum alloy for the electric drive housing of new energy vehicles and its preparation method. Background Technology

[0002] High-strength and tough materials are widely needed in the automotive body industry (transmission, clutch, motor and electronic control housings). From a technological development perspective, research in the field of aluminum alloy materials is accelerating due to increasingly higher requirements for material strength, corrosion resistance, and stability under high-temperature environments. For example, higher-standard aluminum alloy body materials can increase tensile strength and yield strength by more than 30% compared to traditional automotive body materials. Therefore, higher requirements for yield strength and toughness allow for weight reduction in parts, achieving lightweighting goals. Automobiles are used in outdoor environments where the air contains corrosive factors such as oxygen, moisture, and acidic substances. Combined with changes in environmental conditions such as temperature and humidity, corrosion easily occurs, leading to functional or performance degradation or failure. Therefore, corrosion resistance is a crucial aspect of material development and verification, and a necessary requirement for automotive body materials.

[0003] The shortcomings of existing technology:

[0004] Currently, the commonly used aluminum alloy for automotive bodies is the traditional cast aluminum alloy ADC12. This type of alloy belongs to eutectic die-cast aluminum alloy, and the overall product has low hardness and strength. The tensile strength is (260-280) MPa, the yield strength is (130-160) MPa, the elongation after fracture is (1.5-2.5)%, and the corrosion rate is relatively high after 720 hours of cyclic salt spray. It cannot meet the new technical requirements of high strength, toughness and high corrosion resistance, which to some extent limits the improvement of automotive body performance. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature resistant aluminum alloy for the electric drive housing of new energy vehicles and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-temperature resistant aluminum alloy for the electric drive housing of new energy vehicles, wherein the elemental composition of the aluminum alloy includes: Cu 0.5%-0.8%, Si 8.5%-10.5%, Zn 2.5%-3.5%, Mn 0.3%-0.65%, Mg 1.0%-1.5%, Fe 0.25%-0.55%, Sr 0.010%-0.035%, Ti 0.05%-0.25%, Zr 0.05%-0.095%, Re 0.03%-0.08%, Ga 0.01%-0.045%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0007] Preferably, the mass relationship between Cu and Mg is as follows:

[0008] 7.7≤Cu+6.8Mg≤10.5;

[0009] The mass relationship between Zn and Mg is as follows:

[0010] 1.8 < Zn / Mg < 2.5;

[0011] The mass relationship between Re and Zr is as follows:

[0012] 0.6 < Re / Zr < 1.3.

[0013] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically comprising:

[0014] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0015] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0016] S3. The alloy melt is processed into aluminum alloy components using equipment.

[0017] Preferably, step S1 specifically includes:

[0018] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0019] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0020] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and master alloys of AlZr, AlTi, and AlGa and stir evenly to obtain the alloy melt. Set the melting furnace temperature to 730-800℃, the stirring time to 5-15min, and the stirring speed to 40-43rpm.

[0021] Preferably, step S2 specifically comprises:

[0022] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 minutes, wherein the amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt.

[0023] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is set to 750-800 mm, the width is set to 400-450 mm, the length is set to 500-550 mm, the temperature is set to 700-710℃, the working frequency is set to 40-50 Hz, the current is set to 20-25 A, the voltage is set to 220 V, the electrode length is set to 900-950 mm, and the electrode depth into the alloy melt is set to 650-700 mm. The alloy melt has a slag content of ≤0.1 mm² / kg and a hydrogen content of <0.15 cc / 100gAl.

[0024] Preferably, in step a3, the relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0025] t=TS 18;

[0026] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0027] Preferably, the protective gas in step b1 is nitrogen or argon, and the protective gas flow rate is set to 0.15-6 L / min.

[0028] Preferably, the forming equipment in step S3 is a high-pressure casting machine, and the aluminum alloy component is obtained through high-pressure casting.

[0029] Preferably, the aluminum alloy component after high-pressure casting has a strength > 330 MPa, a yield strength > 230 MPa, and an elongation after fracture > 3.0%; and under the working condition of high temperature holding at 200℃ for 30 minutes, the mechanical properties of the part reach a tensile strength ≥ 300 MPa, a yield strength ≥ 210 MPa, and an elongation after fracture ≥ 5.0%.

[0030] Preferably, the aluminum alloy is used for automotive electric drive housings or gearbox housings.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] This invention relates to a high-temperature resistant aluminum alloy for electric drive housings in new energy vehicles and its preparation method. The alloy composition is designed with Cu+6.8Mg and a Zn / Mg range, while simultaneously controlling the design range of Re / Zr and Ga mass fraction ratios. This eliminates the root cause of "poisoning" and achieves the dual effects of fine-grain strengthening and interface coherent synergistic strengthening. Strontium modification refines the eutectic silicon, and combined with solid solution strengthening from Cu, Mg, and Zn elements and the synergistic effect of Re and Zr elements, the alloy is endowed with excellent high-temperature mechanical properties. Employing a near-eutectic Al-Si-Cu-Mg-Zn aluminum alloy system, unlike existing ADC12 aluminum alloys, it does not suffer from poor tensile strength and yield strength. It is suitable for high-pressure casting production of components requiring high strength and toughness. After forming, the aluminum alloy component exhibits a tensile strength of 330-360 MPa, a yield strength of 230-250 MPa, and an elongation after fracture of 3.0%-5.0%, exceeding the performance of conventional aluminum alloy formed components. Attached Figure Description

[0033] Fig. 1 This is a representative microstructure of the aluminum alloy after high-pressure casting according to the present invention;

[0034] Fig. 2 A schematic diagram of the representative metallographic structure of the present invention observed under an electron microscope;

[0035] Fig. 3 This is a microscopic image of the representative cross-sectional microstructure of the present invention observed under an electron microscope. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0038] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integrated connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0040] Example 1

[0041] Please see Figs. 1-3 As shown, the present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.6%, Si 8.8%, Zn 2.8%, Mn 0.35%, Mg 1.2%, Fe 0.35%, Sr 0.025%, Ti 0.055%, Zr 0.06%, Re 0.05%, Ga 0.015%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the mass ratio of Cu to Mg is Cu + 6.8Mg = 8.76; the mass ratio of Zn to Mg is Zn / Mg = 2.33; the mass ratio of Re to Zr is Re / Zr = 0.83.

[0042] This invention controls the ranges of Cu+6.8Mg and Zn / Mg while simultaneously controlling the design range of Re. Re, as a slow-diffusing element, and the presence of rhenium in the aluminum matrix may increase the diffusion activation energy of other atoms, thus slowing down the overall diffusion rate of various elements at high temperatures. Diffusion is the basis of phase transformation, recrystallization, and creep; slowing down diffusion is equivalent to delaying the performance degradation of materials at high temperatures. Combining the solid solution strengthening provided by Cu, Mg, and Zn, and the synergistic effect of rhenium and zirconium: zirconium can form a very fine and stable dispersed phase in aluminum. Zr ( (Rhenium structure) is an important heat-strengthening phase. Studies have found that the addition of rhenium can promote... The Zr phase precipitates more uniformly and finely, further improving its thermal stability and delaying its coarsening at high temperatures, thus endowing the alloy with excellent high-temperature mechanical properties.

[0043] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0044] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0045] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0046] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0047] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and master alloys of AlZr, AlTi, and AlGa and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0048] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0049] t=TS 18;

[0050] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0051] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0052] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0053] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0054] S3. The alloy melt is processed into aluminum alloy components through equipment. After high-pressure casting, the tensile strength of the aluminum alloy components is 345MPa, the yield strength is 235MPa, and the elongation after fracture is 3.8%.

[0055] Example 2

[0056] Please see Figs. 1-3 As shown, the present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.7%, Si 9.5%, Zn 2.9%, Mn 0.45%, Mg 1.4%, Fe 0.45%, Sr 0.026%, Ti 0.075%, Zr 0.07%, Re 0.06%, Ga 0.018%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the mass ratio of Cu to Mg is Cu + 6.8Mg = 10.22; the mass ratio of Zn to Mg is Zn / Mg = 2.07; the mass ratio of Re to Zr is Re / Zr = 0.85.

[0057] This invention controls the ranges of Cu+6.8Mg and Zn / Mg while simultaneously controlling the design range of Re. Re, as a slow-diffusing element, and the presence of rhenium in the aluminum matrix may increase the diffusion activation energy of other atoms, thus slowing down the overall diffusion rate of various elements at high temperatures. Diffusion is the basis of phase transformation, recrystallization, and creep; slowing down diffusion is equivalent to delaying the performance degradation of materials at high temperatures. Combining the solid solution strengthening provided by Cu, Mg, and Zn, and the synergistic effect of rhenium and zirconium: zirconium can form a very fine and stable dispersed phase in aluminum. Zr ( (Rhenium structure) is an important heat-strengthening phase. Studies have found that the addition of rhenium can promote... The Zr phase precipitates more uniformly and finely, further improving its thermal stability and delaying its coarsening at high temperatures, thus endowing the alloy with excellent high-temperature mechanical properties.

[0058] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0059] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0060] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0061] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0062] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and master alloys of AlZr, AlTi, and AlGa and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0063] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0064] t=TS 18;

[0065] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0066] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0067] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0068] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0069] S3. The alloy melt is processed into aluminum alloy components through equipment. After high-pressure casting, the tensile strength of the aluminum alloy components is 352 MPa, the yield strength is 245 MPa, and the elongation after fracture is 3.3%.

[0070] Example 3

[0071] Please see Figs. 1-3As shown, the present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.65%, Si 9.3%, Zn 2.8%, Mn 0.55%, Mg 1.3%, Fe 0.35%, Sr 0.016%, Ti 0.085%, Zr 0.08%, Re 0.065%, Ga 0.025%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%; the mass ratio of Cu to Mg is Cu + 6.8Mg = 9.49; the mass ratio of Zn to Mg is Zn / Mg = 2.15; the mass ratio of Re to Zr is Re / Zr = 0.81.

[0072] This invention controls the ranges of Cu+6.8Mg and Zn / Mg while simultaneously controlling the design range of Re. Re, as a slow-diffusing element, and the presence of rhenium in the aluminum matrix may increase the diffusion activation energy of other atoms, thus slowing down the overall diffusion rate of various elements at high temperatures. Diffusion is the basis of phase transformation, recrystallization, and creep; slowing down diffusion is equivalent to delaying the performance degradation of materials at high temperatures. Combining the solid solution strengthening provided by Cu, Mg, and Zn, and the synergistic effect of rhenium and zirconium: zirconium can form a very fine and stable dispersed phase in aluminum. Zr ( (Rhenium structure) is an important heat-strengthening phase. Studies have found that the addition of rhenium can promote... The Zr phase precipitates more uniformly and finely, further improving its thermal stability and delaying its coarsening at high temperatures, thus endowing the alloy with excellent high-temperature mechanical properties.

[0073] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0074] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0075] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0076] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0077] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and master alloys of AlZr, AlTi, and AlGa and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0078] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0079] t=TS 18;

[0080] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0081] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0082] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0083] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0084] S3. The alloy melt is processed into aluminum alloy components through equipment. After high pressure casting, the tensile strength of the aluminum alloy components is 342MPa, the yield strength is 248MPa, and the elongation after fracture is 4.3%.

[0085] Furthermore, representative metallographic structures of the samples prepared in Examples 1, 2, and 3 were observed under an electron microscope, such as... Fig. 2 With largely similar distribution, the introduction of AlRe and AlZr master alloys further disperses the intermetallic compounds, effectively limiting the size of the dispersed particles, weakening the grain boundary segmentation effect, and significantly enhancing the pinning effect. In addition, considering the Cu+6.8Mg ratio, Zn / Mg mass fraction ratio, and Re / Zr mass fraction ratio in the design elements significantly improves the grain size, precipitate size, and concentration gradient, fully leveraging the combined effect of fine grain strengthening on strength and toughness.

[0086] The microstructure of representative cross-sections of samples prepared in Examples 1, 2, and 3 were observed under an electron microscope. Fig. 3 The dimples at the cross-section are evenly distributed, with moderate density and relatively uniform size. Combined with the measurement data, it can be determined that the present invention can meet the mechanical performance requirements of the next generation of automotive electric drive housing materials.

[0087] Example 4

[0088] The present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.65%, Si 8.8%, Zn 2.6%, Mn 0.45%, Mg 1.3%, Fe 0.35%, Sr 0.025%, Zr 0.15%, Re 0.078%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0089] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0090] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0091] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0092] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0093] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and AlZr master alloys and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0094] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0095] t=TS 18;

[0096] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0097] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0098] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0099] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0100] S3. The alloy melt is processed into aluminum alloy components through equipment. After high pressure casting, the tensile strength of the aluminum alloy components is 348MPa, the yield strength is 245MPa, and the elongation after fracture is 4.5%.

[0101] Example 5

[0102] The present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.65%, Si 8.7%, Zn 2.75%, Mn 0.35%, Mg 1.25%, Fe 0.3%, Sr 0.021%, Zr 0.12%, Re 0.075%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0103] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0104] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0105] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0106] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0107] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and AlZr master alloys and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0108] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0109] t=TS 18;

[0110] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0111] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0112] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0113] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0114] S3. The alloy melt is processed into aluminum alloy components through equipment. After high pressure casting, the tensile strength of the aluminum alloy components is 345MPa, the yield strength is 245MPa, and the elongation after fracture is 3.5%.

[0115] Example 6

[0116] The present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.75%, Si 8.9%, Zn 2.75%, Mn 0.45%, Mg 1.15%, Fe 0.25%, Sr 0.019%, Zr 0.12%, Re 0.085%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0117] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0118] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0119] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0120] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0121] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and AlZr master alloys and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0122] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0123] t=TS 18;

[0124] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0125] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0126] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0127] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0128] S3. The alloy melt is processed into aluminum alloy components through equipment. After high-pressure casting, the tensile strength of the aluminum alloy components is 335MPa, the yield strength is 235MPa, and the elongation after fracture is 3.6%.

[0129] Example 7

[0130] The present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.55%, Si 9.5%, Zn 3.2%, Mn 0.38%, Mg 1.28%, Fe 0.3%, Sr 0.025%, Zr 0.06%, Re 0.12%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0131] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0132] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0133] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0134] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0135] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and AlZr master alloys and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0136] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0137] t=TS 18;

[0138] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0139] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0140] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0141] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0142] S3. The alloy melt is processed into aluminum alloy components through equipment. After high pressure casting, the tensile strength of the aluminum alloy components is 342MPa, the yield strength is 248MPa, and the elongation after fracture is 3.5%.

[0143] Example 8

[0144] The present invention provides a high-temperature resistant aluminum alloy housing for electric drive systems in new energy vehicles: the aluminum alloy elemental composition includes: Cu 0.67%, Si 8.8%, Zn 3.1%, Mn 0.55%, Mg 1.35%, Fe 0.41%, Sr 0.024%, Zr 0.05%, Re 0.098%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%.

[0145] This invention also provides a method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, the method specifically including:

[0146] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0147] a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material.

[0148] a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence.

[0149] a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and AlZr master alloys and stir evenly to obtain the alloy melt. The melting furnace temperature is set to 730-800℃, the stirring time is set to 5-15min, and the stirring speed is set to 40-43rpm.

[0150] The relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula:

[0151] t=TS 18;

[0152] Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

[0153] S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal;

[0154] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0155] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0156] S3. The alloy melt is processed into aluminum alloy components through equipment. After high-pressure casting, the tensile strength of the aluminum alloy components is 349 MPa, the yield strength is 245 MPa, and the elongation after fracture is 3.3%.

[0157] Comparative Example 1

[0158] Another aluminum alloy technical solution is provided: the elemental composition of the aluminum alloy includes: Cu 1.8%, Si 10.5%, Zn 0.85%, Mn 0.15%, Mg 0.25%, Fe 0.78%, Sr 0.0015%, Zr 0.0015%, Re 0.0012%, with the balance being Al and impurities.

[0159] Another method for preparing an aluminum alloy is provided, the specific preparation method including:

[0160] S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt;

[0161] b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 min. The amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. The protective gas is nitrogen or argon, and the protective gas inlet rate is set to 0.15-6 L / min.

[0162] b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is 750-800 mm, the width is 400-450 mm, the length is 500-550 mm, the temperature is 700-710℃, the operating frequency is 40-50 Hz, the current is 20-25 A, the voltage is 220 V, the electrode length is 900-950 mm, and the electrode penetrates 650-700 mm into the alloy melt. The alloy melt has a slag content ≤ 0.1 mm² / kg and a hydrogen content < 0.15 cc / 100gAl.

[0163] S3. The alloy melt is processed into aluminum alloy components through equipment. After high-pressure casting, the tensile strength of the aluminum alloy components is 280MPa, the yield strength is 155MPa, and the elongation after fracture is 1.5%.

[0164]

[0165] Table 1. Comparison of main chemical components and mechanical properties between Comparative Example 1 and Example 4

[0166] As shown in Table 1, under the same conditions, the aluminum alloy material of this invention exhibits superior mechanical properties after high-pressure casting, with tensile strength and yield strength significantly better than the material in Comparative Example 1.

[0167]

[0168] Table 2 Comparison of main chemical components and mechanical properties of Examples 5, 6, 7, and 8

[0169] As shown in Table 2, the aluminum alloy materials obtained according to Examples 5, 6, 7 and 8 all have tensile strength greater than 330 MPa, yield strength greater than 230 MPa, and elongation after fracture greater than 3.0%. They fully meet the requirements of the automotive electric drive housing field for lightweight, high strength and moderate toughness, and can be used in the manufacture of automotive chassis parts, providing excellent materials for reducing the weight of parts and improving performance.

[0170] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle, characterized in that: The aluminum alloy composition includes: Cu 0.5%-0.8%, Si 8.5%-10.5%, Zn 2.5%-3.5%, Mn 0.3%-0.65%, Mg 1.0%-1.5%, Fe 0.25%-0.55%, Sr 0.010%-0.035%, Ti 0.05%-0.25%, Zr 0.05%-0.095%, Re 0.03%-0.08%, Ga 0.01%-0.045%, with the balance being Al and impurities, wherein the total impurity content is not greater than 0.15%. The mass relationship between Cu and Mg is as follows: 7.7≤Cu+6.8Mg≤10.5; The mass relationship between Zn and Mg is as follows: 1.8 < Zn / Mg < 2.5; The mass relationship between Re and Zr is as follows: 0.6 < Re / Zr < 1.

3.

2. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to any one of claims 1, characterized in that: The preparation method specifically includes: S1. Prepare aluminum alloy raw materials, dry and preheat them, melt them, and stir them evenly to obtain an alloy melt; S2. Refine the alloy melt to complete degassing and electromagnetic impurity removal; S3. The alloy melt is processed into aluminum alloy components using equipment.

3. The method for preparing a high-temperature resistant electric drive housing for new energy vehicles according to claim 2, characterized in that: Step S1 specifically includes: a1. Prepare aluminum alloy raw materials according to the aluminum alloy formula, and take the corresponding percentage of each raw material. a2. Dry and preheat the aluminum alloy raw materials. Set the drying and preheating temperature to 100-450℃ and add the aluminum alloy raw materials to the melting furnace in sequence. a3. Add the Al-Si alloy ingot to the melting furnace and melt it. After it is completely melted, add pure metals or master alloys of Cu, Mg, and Zn elements. After it is completely melted, add Al-Re, Al-Sr, and master alloys of AlZr, AlTi, and AlGa and stir evenly to obtain the alloy melt. Set the melting furnace temperature to 730-800℃, the stirring time to 5-15min, and the stirring speed to 40-43rpm.

4. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 2, characterized in that: Step S2 specifically involves: b1. Introduce a protective gas into the alloy melt and add RJ-01 refining agent. Set the refining time to 15-30 minutes, wherein the amount of refining agent added is 0.2%-0.5% of the mass of the alloy melt. b2. The alloy melt is passed through a filter box and further purified by a preheated ceramic filter plate. The ceramic filter plate has a pore size of 50 ppi, the degassing box depth is set to 750-800 mm, the width is set to 400-450 mm, the length is set to 500-550 mm, the temperature is set to 700-710℃, the working frequency is set to 40-50 Hz, the current is set to 20-25 A, the voltage is set to 220 V, the electrode length is set to 900-950 mm, and the electrode depth into the alloy melt is set to 650-700 mm. The alloy melt has a slag content of ≤0.1 mm² / kg and a hydrogen content of <0.15 cc / 100gAl.

5. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 3, characterized in that: In step a3, the relationship between stirring time, aluminum melt temperature, and stirring speed is expressed by the following formula: t=T-S 18; Where t is the stirring time in min; T is the alloy melt temperature in °C; and S is the rotation speed in rpm.

6. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 4, characterized in that: In step b1, the protective gas is nitrogen or argon, and the protective gas flow rate is set to 0.15-6 L / min.

7. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 2, characterized in that: The forming equipment in step S3 is high-pressure casting, and aluminum alloy components are obtained through high-pressure casting.

8. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 7, characterized in that: After high-pressure casting, the aluminum alloy components have a strength >330MPa, a yield strength >230MPa, and an elongation after fracture >3.0%. Furthermore, under the working condition of holding at 200℃ for 30 minutes, the mechanical properties of the parts reach a tensile strength ≥300MPa, a yield strength ≥210MPa, and an elongation after fracture ≥5.0%.

9. The method for preparing a high-temperature resistant aluminum alloy for the electric drive housing of a new energy vehicle according to claim 2, characterized in that: The aluminum alloy is used for automotive electric drive housings or gearbox housings.

Images