Preparation process of high-strength aluminum alloy for electric vehicle pedal

Abstract

The invention discloses a preparation process of a high-strength aluminum alloy for an electric vehicle pedal, and relates to the technical field of aluminum alloy preparation, and the high-strength aluminum alloy comprises the following components in parts by weight: 85.0 to 92.5 parts of Al, 3.5 to 5.8 parts of Cu, 0.8 to 1.6 parts of Si, 1.2 to 2.4 parts of Mg, 0.5 to 1.2 parts of Zn, 0.3 to 0.9 part of Mn, 0.15 to 0.45 part of Cr, 0.08 to 0.25 part of Ti, 0.05 to 0.18 part of Zr and 0.03 to 0.12 part of rare earth elements. Through addition of rare earth elements and a complete preparation process including gradient temperature control smelting, electromagnetic stirring refining, composite modification treatment, solid solution and aging treatment and the like, the bending strength and the fatigue resistance of the aluminum alloy are enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy preparation, and in particular to a process for preparing a high-strength aluminum alloy for an electric vehicle pedal. Background Art

[0002] Traditional electric vehicle pedals are often made of ordinary aluminum alloy materials, which are obviously insufficient in strength and toughness. In daily use, the pedals frequently bear the pedaling force of the rider and the impact load under various complex road conditions. Ordinary aluminum alloy pedals are prone to deformation, wear and even breakage.

[0003] In addition, ordinary aluminum alloy pedals have poor corrosion resistance. During the use of electric vehicles, they are often exposed to erosion by rain, muddy water and humid environments, which makes the pedal surface very prone to corrosion. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a process for preparing a high-strength aluminum alloy for an electric vehicle pedal, and the preparation method can solve the above-mentioned problems.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a high-strength aluminum alloy for an electric vehicle pedal, wherein the aluminum alloy components are, by weight: 85.0-92.5 parts of Al, 3.5-5.8 parts of Cu, 0.8-1.6 parts of Si, 1.2-2.4 parts of Mg, 0.5-1.2 parts of Zn, 0.3-0.9 parts of Mn, 0.15-0.45 parts of Cr, 0.08-0.25 parts of Ti, 0.05-0.18 parts of Zr, and 0.03-0.12 parts of rare earth elements.

[0006] Preferably, the rare earth elements are lanthanum and cerium in a mass ratio of 1:1-1:3.

[0007] Preferably, the high-strength aluminum alloy for the electric vehicle pedal has a bending strength of ≥600MPa and a corrosion rate of ≤8mg / (m 2 ·h) After 2 million fatigue cycles, the residual deformation is ≤0.12mm.

[0008] A process for preparing a high-strength aluminum alloy for an electric vehicle pedal comprises the following steps: S1, gradient temperature controlled melting: in the first stage, the temperature is raised to 680℃-710℃ to melt the Al matrix, in the second stage, the temperature is raised to 720℃-750℃ to add Cu, Si, and Mg, in the third stage, the temperature is raised to 760℃-780℃ to add Zn, Mn, and Cr, and in the fourth stage, the temperature is raised to 790℃-810℃ to add Ti, Zr, and rare earth elements; S2. Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 20 Hz - 40 Hz at 780 °C - 800 °C, and stir for 15 - 30 minutes; S3. Composite modification treatment: Add 0.05% - 0.12% Al - 5Ti - B master alloy and 0.03% - 0.08% Al - 10Sr master alloy; S4. Step - by - step cooling: Cool at 5 °C / min - 8 °C / min to 680 °C - 700 °C and hold for 1 - 2 hours, then cool to room temperature at 10 °C / min - 15 °C / min to obtain the preliminary product.

[0009] Preferably, the heating rate in each stage of S1 is 3 °C / min - 5 °C / min, and argon is introduced for protection for 5 - 8 minutes at intervals of each stage.

[0010] Preferably, the magnetic field strength in step S2 is 0.8 - 1.5 T, and ultrasonic treatment is applied synchronously during the stirring process, with a frequency of 28 - 35 kHz.

[0011] Preferably, the preliminary product is further processed as follows: Solution treatment: Hold at 520 - 550 °C for 4 - 6 hours, and water quench to below 50 °C; Aging treatment: The first stage is to hold at 160 - 180 °C for 8 - 12 hours, and the second stage is to hold at 120 - 140 °C for 16 - 20 hours to obtain the intermediate product.

[0012] Preferably, the surface of the intermediate product is treated by micro - arc oxidation. The electrolyte contains 12 - 18 g / L of sodium silicate, 6 - 10 g / L of potassium dihydrogen phosphate, 3 - 5 g / L of sodium hydroxide, the voltage is 400 - 500 V, and the treatment time is 15 - 25 minutes to obtain the high - strength aluminum alloy.

[0013] Compared with the prior art, the present invention provides a preparation process of high - strength aluminum alloy for electric vehicle pedals, having the following beneficial effects: The addition of rare - earth elements and the complete preparation process, including gradient - controlled temperature melting, electromagnetic stirring refining, composite modification treatment, solution and aging treatments, etc., enhance the bending strength and fatigue resistance of the aluminum alloy; The gradient - controlled temperature melting and the two - stage aging treatment process cooperate with each other, can play a synergistic promotion role, greatly optimize the corrosion resistance of the aluminum alloy, provide a more reliable material guarantee for electric vehicle pedals, effectively extend its service life in complex environments, reduce maintenance costs, and improve the overall quality and performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a line graph of the corrosion resistance test for the comparative examples and examples of the present invention; Figure 2Column chart for the flexural strength test of the comparative examples and examples of the present invention. Detailed implementation manners

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0016] Flexural strength test: In accordance with GB / T228.1-2021 "Tensile testing of metallic materials - Part 1: Method of test at room temperature" and relevant industry standards for the testing of aluminum alloy materials. These standards stipulate the general requirements for the tensile testing of metallic materials, including aspects such as specimen preparation, testing equipment, testing conditions, and result calculation, providing a standardized guidance for accurately measuring the flexural strength of aluminum alloys.

[0017] Test steps: Specimen preparation: Rectangular specimens with standard dimensions are intercepted from the aluminum alloy material for electric vehicle pedals. The specimen length is 200mm, the width is 20mm, and the thickness is the same as the actual pedal thickness (within the range of 3mm - 5mm). The surface of the specimen needs to be finely polished to ensure smoothness and flatness, without obvious scratches, cracks and other defects to avoid stress concentration affecting the test results; Equipment installation: Install the prepared specimen on the bending fixture of a universal material testing machine (model: WDW-100E). The span of the specimen is set to 160mm, ensuring that the loading point is located at the center of the span; Loading test: Apply a bending load to the specimen at a slow and uniform rate, and the loading rate is controlled at 0.5mm / min. During the loading process, continuously record the load borne by the specimen and the corresponding deflection changes. As the load increases, the specimen gradually undergoes bending deformation until the specified failure condition (such as obvious cracks or fractures) occurs, and at this time, record the maximum load value; Test instrument: The universal material testing machine (WDW-100E) used is produced by a well-known testing machine manufacturing enterprise in Jinan. The equipment has a high-precision load measurement system and displacement measurement system. The load measurement accuracy can reach ±0.5%, and the displacement measurement accuracy can reach ±0.01mm, which can meet the high-precision requirements for the flexural strength test of aluminum alloys.

[0018] Fatigue resistance test: Follow GB / T37616-2019 "Axial force controlled fatigue test method for aluminum alloy extruded profiles". This standard specifies in detail the method of fatigue testing of aluminum alloy extruded profiles under axial force control, including test equipment, specimens, test procedures, evaluation of test results, etc., providing a reliable basis for evaluating the performance of aluminum alloys under cyclic loads.

[0019] Test steps: Sample preparation: Select aluminum alloy samples with the same size and processing technology as the bending strength test. Paste strain gauges on the surface of the sample to monitor the strain changes during fatigue. The strain gauges must be firmly pasted and accurately positioned to avoid affecting the test results.

[0020] Equipment debugging: Install the sample on the fatigue testing machine (model: MTS810) and adjust the test parameters. Set the maximum and minimum values ​​of the cycle load. The maximum load is determined based on 1.5 times the maximum force that the pedal may withstand in actual use, and the minimum load is 0. The cycle frequency is set to 10Hz to simulate the loading frequency during actual riding.

[0021] Fatigue test: Start the fatigue tester and start cyclic loading of the specimen. During the test, monitor the strain, number of cycles and other data of the specimen in real time. Stop the test when cracks or breaks appear on the specimen, or when the predetermined number of cycles reaches 2 million. Record the number of cycles and the residual deformation of the specimen at this time. The residual deformation is measured by a high-precision displacement sensor with a measurement accuracy of ±0.001mm.

[0022] Test equipment: MTS810 fatigue testing machine is a product of MTS Systems, Inc., USA. This equipment has advanced closed-loop control technology, which can accurately control the size and frequency of the loading force to ensure the stability and accuracy of the test process. Its maximum loading capacity can reach 100kN, which meets the needs of fatigue resistance testing of aluminum alloy for electric vehicle pedals.

[0023] The relevant national standard for salt spray test corrosion rate test is GB / T10125-2012 "Artificial atmosphere corrosion test salt spray test".

[0024] The following are the detailed test steps: Prepare samples: Select suitable metal materials or coated metal material samples, and perform pretreatment such as cleaning and polishing as needed to remove surface oil, impurities, etc. to ensure surface cleanliness.

[0025] Install the specimen: Hang or place the specimen in the salt spray test chamber, paying attention to the position and angle of the specimen. Generally, it is required that the main surface of the specimen is inclined at an angle of 15 to 30 degrees with the plumb line and parallel to the main flow direction of the spray. At the same time, it is necessary to ensure that the specimens do not contact each other, nor contact metallic conductors or other substances that may affect the test results, so as to ensure that the specimens can fully and evenly contact the salt spray.

[0026] Prepare the salt spray solution: According to the standard regulations, use analytical pure sodium chloride and distilled water to prepare the salt spray solution. For example, in the neutral salt spray test, the solution concentration is (50 ± 10) g / L. At 25°C, use pH test paper to measure the pH value of the solution, which should be 6.5 - 7.5. When it exceeds the range, analytical pure hydrochloric acid or sodium hydroxide solution can be added for adjustment. The prepared solution needs to be filtered before use.

[0027] Start the test: Start the salt spray test chamber, spray the salt spray solution on the specimen, and at the same time keep the parameters such as the salt spray concentration, temperature, and humidity in the test chamber stable. For example, in the neutral salt spray test, the laboratory temperature needs to be controlled at 35°C ± 1°C, and the pressure barrel temperature is 47°C ± 1°C, and a certain spray pressure and spray volume need to be maintained. Generally, the spray volume is 1 - 2 mL / 80 cm 2 ·h.

[0028] Exposure time: Set an appropriate exposure time according to the test requirements, which can range from several hours to several days. For example, in the neutral salt spray test, it can be continuously sprayed for 96 hours, etc. The specific time is determined according to the relevant standards or actual needs of the product or material.

[0029] Observation and recording: During the exposure period, regularly observe and record the corrosion situation of the specimen, including the appearance characteristics of corrosion, the starting time of corrosion, the development process of corrosion, etc. It is also necessary to record the parameters such as the temperature, humidity, and salt spray deposition rate in the test chamber, as well as the pH value of the solution, etc. For the evaluation of the corrosion rate, it can be measured and calculated by methods such as the weighing method and electrochemical method. For example, the specimen can be weighed before and after the test, and the corrosion rate can be evaluated by calculating the mass loss of the specimen.

[0030] End the test: After the exposure time ends, turn off the salt spray test chamber, carefully take out the specimen to avoid damaging the surface of the specimen. Then carry out subsequent treatment and analysis on the specimen, such as cleaning the specimen with clean water below 38°C to remove the salt particles attached to the surface, then using a brush or sponge to remove the corrosion products outside the corrosion points, and finally, if necessary, perform operations such as drying and weighing on the specimen to further analyze the corrosion situation and calculate the corrosion rate.

[0031] The main relevant instrument used in the test is the salt spray test chamber.

[0032] It should be noted that the test methods, relevant standards, and test equipment adopted in this application are not restrictive. Those skilled in the art can achieve the objectives of the present invention by other means.

[0033] Table 1 contains the following parameters: Material: It indicates that the material corresponding to the table data is 7075 aluminum alloy. 7075 aluminum alloy is a high-strength aluminum alloy, commonly used in fields such as aerospace and mold manufacturing because it has a high strength-to-weight ratio.

[0034] Density ρ / (kg·m -3 ) : The value is 2810, indicating that the mass of 7075 aluminum alloy per cubic meter is 2810 kilograms. Density is a basic physical property of the material, used to calculate the weight of the material, etc.

[0035] Elastic modulus E / GPa: The value is 71. The elastic modulus, also known as Young's modulus, is an index to measure the ability of a material to resist elastic deformation. The larger the value, the less likely the material is to undergo elastic deformation. The elastic modulus of 7075 aluminum alloy is 71 GPa (gigapascals).

[0036] Poisson's ratio ν: The value is 0.33. Poisson's ratio is the ratio of the lateral strain to the longitudinal strain of the material, reflecting the relationship between the lateral and longitudinal deformations of the material when it is stressed.

[0037] σ_HEL / GPa: The value is 1.1. Here, σ_HEL refers to a certain specific stress of the material (such as Hugoniot elastic limit), and the unit is GPa, which represents the stress value that the material can withstand under specific conditions.

[0038] Example 1 A preparation process for high-strength aluminum alloy for an electric vehicle pedal. The aluminum alloy composition (in parts by weight) is: 85.0 parts of Al, 3.5 parts of Cu, 0.8 part of Si, 1.2 parts of Mg, 0.5 part of Zn, 0.3 part of Mn, 0.15 part of Cr, 0.08 part of Ti, 0.05 part of Zr, and 0.03 part of rare earth elements (mass ratio of lanthanum to cerium is 1:1).

[0039] Preparation process: Gradient temperature-controlled melting: In the first stage, it is heated to 680 °C at a rate of 3 °C / min to melt the Al matrix, and argon is introduced for protection for 5 minutes; in the second stage, it is heated to 720 °C at a rate of 3 °C / min to add Cu, Si, and Mg, and argon is introduced for protection for 5 minutes; in the third stage, it is heated to 760 °C at a rate of 3 °C / min to add Zn, Mn, and Cr, and argon is introduced for protection for 5 minutes; in the fourth stage, it is heated to 790 °C at a rate of 3 °C / min to add Ti, Zr, and rare earth elements.

[0040] Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 20 Hz and an intensity of 0.8 T at 780 °C, and synchronously apply ultrasonic treatment at 28 kHz during the stirring process for 15 minutes.

[0041] Composite modification treatment: Add 0.05% Al-5Ti-B master alloy and 0.03% Al-10Sr master alloy.

[0042] Stepwise cooling: Cool at 5 °C / min to 680 °C and hold for 1 hour, then cool to room temperature at 10 °C / min.

[0043] Subsequent treatment: Solution treatment at 520 °C for 4 hours, water quench to below 50 °C; Aging treatment, the first stage at 160 °C for 8 hours, the second stage at 120 °C for 16 hours.

[0044] Surface treatment: Micro-arc oxidation treatment, the electrolyte contains 12 g / L sodium silicate, 6 g / L potassium dihydrogen phosphate, 3 g / L sodium hydroxide, voltage 400 V, treatment for 15 minutes.

[0045] Example 2 A preparation process for high-strength aluminum alloy used in electric vehicle pedals, the aluminum alloy composition (in weight parts) is: 87.5 parts of Al, 4.0 parts of Cu, 1.0 parts of Si, 1.5 parts of Mg, 0.7 parts of Zn, 0.5 parts of Mn, 0.25 parts of Cr, 0.12 parts of Ti, 0.08 parts of Zr, 0.05 parts of rare earth elements (mass ratio of lanthanum to cerium is 1:1.5).

[0046] Preparation process: Gradient temperature-controlled melting: In the first stage, heat up to 690 °C at 4 °C / min to melt the Al matrix, introduce argon for protection for 6 minutes; in the second stage, heat up to 730 °C at 4 °C / min and add Cu, Si, Mg, introduce argon for protection for 6 minutes; in the third stage, heat up to 770 °C at 4 °C / min and add Zn, Mn, Cr, introduce argon for protection for 6 minutes; in the fourth stage, heat up to 800 °C at 4 °C / min and add Ti, Zr, rare earth elements.

[0047] Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 30 Hz and an intensity of 1.1 T at 790 °C, and synchronously apply ultrasonic treatment at 32 kHz during the stirring process for 20 minutes.

[0048] Composite modification treatment: Add 0.07% Al-5Ti-B master alloy and 0.05% Al-10Sr master alloy.

[0049] Stepwise cooling: Cool at 6 °C / min to 690 °C and hold for 1.5 hours, then cool to room temperature at 12 °C / min.

[0050] Subsequent treatment: Solution treatment at 530°C for 5 hours, water quenched to below 50°C; Aging treatment, the first stage at 170°C for 10 hours, the second stage at 130°C for 18 hours.

[0051] Surface treatment: Micro-arc oxidation treatment, the electrolyte contains 15 g / L sodium silicate, 8 g / L potassium dihydrogen phosphate, 4 g / L sodium hydroxide, voltage 450 V, treatment for 20 minutes.

[0052] Example 3 A preparation process of high-strength aluminum alloy for electric vehicle pedals, the aluminum alloy composition (by weight) is: 90.0 parts of Al, 4.8 parts of Cu, 1.2 parts of Si, 1.8 parts of Mg, 0.9 parts of Zn, 0.6 parts of Mn, 0.3 parts of Cr, 0.18 parts of Ti, 0.12 parts of Zr, 0.08 parts of rare earth elements (mass ratio of lanthanum and cerium is 1:2).

[0053] Preparation process: Gradient temperature-controlled melting: In the first stage, heat up to 700°C at a rate of 4°C / min to melt the Al matrix, introduce argon for protection for 7 minutes; in the second stage, heat up to 740°C at a rate of 4°C / min and add Cu, Si, Mg, introduce argon for protection for 7 minutes; in the third stage, heat up to 775°C at a rate of 4°C / min and add Zn, Mn, Cr, introduce argon for protection for 7 minutes; in the fourth stage, heat up to 805°C at a rate of 4°C / min and add Ti, Zr, rare earth elements.

[0054] Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 35 Hz and an intensity of 1.3 T at 795°C, and apply 33 kHz ultrasonic treatment synchronously during the stirring process, stir for 25 minutes.

[0055] Composite modification treatment: Add 0.1% Al-5Ti-B master alloy and 0.06% Al-10Sr master alloy.

[0056] Step-by-step cooling: Cool at a rate of 7°C / min to 695°C and hold for 1.7 hours, then cool to room temperature at a rate of 13°C / min.

[0057] Subsequent treatment: Solution treatment at 540°C for 5.5 hours, water quenched to below 50°C; Aging treatment, the first stage at 175°C for 11 hours, the second stage at 135°C for 19 hours.

[0058] Surface treatment: Micro-arc oxidation treatment, the electrolyte contains 16 g / L sodium silicate, 9 g / L potassium dihydrogen phosphate, 4.5 g / L sodium hydroxide, voltage 470 V, treatment for 22 minutes.

[0059] Example 4 A preparation process of high-strength aluminum alloy for an electric vehicle pedal, the aluminum alloy composition (by weight) being: 92.0 parts of Al, 5.2 parts of Cu, 1.4 parts of Si, 2.0 parts of Mg, 1.0 parts of Zn, 0.8 parts of Mn, 0.4 parts of Cr, 0.22 parts of Ti, 0.15 parts of Zr, and 0.1 part of rare earth elements (mass ratio of lanthanum to cerium is 1:2.5).

[0060] Preparation process: Gradient temperature-controlled melting: In the first stage, heat up to 705°C at a rate of 5°C / min to melt the Al matrix, and introduce argon for protection for 7 minutes; in the second stage, heat up to 745°C at a rate of 5°C / min and add Cu, Si, and Mg, and introduce argon for protection for 7 minutes; in the third stage, heat up to 780°C at a rate of 5°C / min and add Zn, Mn, and Cr, and introduce argon for protection for 7 minutes; in the fourth stage, heat up to 810°C at a rate of 5°C / min and add Ti, Zr, and rare earth elements.

[0061] Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 40 Hz and an intensity of 1.5 T at 800°C, and synchronously apply ultrasonic treatment at 35 kHz during the stirring process for 30 minutes.

[0062] Composite modification treatment: Add 0.12% Al-5Ti-B master alloy and 0.08% Al-10Sr master alloy.

[0063] Step-by-step cooling: Cool at a rate of 8°C / min to 700°C and hold for 2 hours, then cool to room temperature at a rate of 15°C / min.

[0064] Subsequent treatment: Solution treatment at 550°C for 6 hours, water quench to below 50°C; aging treatment, the first stage at 180°C for 12 hours, the second stage at 140°C for 20 hours.

[0065] Surface treatment: Micro-arc oxidation treatment, the electrolyte contains 18 g / L of sodium silicate, 10 g / L of potassium dihydrogen phosphate, 5 g / L of sodium hydroxide, the voltage is 500 V, and the treatment time is 25 minutes.

[0066] Example Five A preparation process of high-strength aluminum alloy for an electric vehicle pedal, the aluminum alloy composition (by weight) being: 92.5 parts of Al, 5.8 parts of Cu, 1.6 parts of Si, 2.4 parts of Mg, 1.2 parts of Zn, 0.9 parts of Mn, 0.45 parts of Cr, 0.25 parts of Ti, 0.18 parts of Zr, and 0.12 parts of rare earth elements (mass ratio of lanthanum to cerium is 1:3).

[0067] Preparation process: Gradient temperature-controlled melting: In the first stage, the temperature is raised to 710 °C at a rate of 5 °C / min to melt the Al matrix, and argon is introduced for 8 minutes of protection; in the second stage, the temperature is raised to 750 °C at a rate of 5 °C / min, and Cu, Si, and Mg are added, and argon is introduced for 8 minutes of protection; in the third stage, the temperature is raised to 780 °C at a rate of 5 °C / min, and Zn, Mn, and Cr are added, and argon is introduced for 8 minutes of protection; in the fourth stage, the temperature is raised to 810 °C at a rate of 5 °C / min, and Ti, Zr, and rare earth elements are added.

[0068] Electromagnetic stirring refining: At 800 °C, a rotating magnetic field with a frequency of 40 Hz and an intensity of 1.5 T is applied, and ultrasonic treatment at 35 kHz is applied synchronously during the stirring process for 30 minutes.

[0069] Composite modification treatment: Add 0.12% Al-5Ti-B master alloy and 0.08% Al-10Sr master alloy.

[0070] Stepwise cooling: Cool at a rate of 8 °C / min to 700 °C and hold for 2 hours, then cool to room temperature at a rate of 15 °C / min.

[0071] Subsequent treatment: Solution treatment at 550 °C for 6 hours, water quenched to below 50 °C; aging treatment, the first stage at 180 °C for 12 hours, the second stage at 140 °C for 20 hours.

[0072] Surface treatment: Micro-arc oxidation treatment, the electrolyte contains 18 g / L of sodium silicate, 10 g / L of potassium dihydrogen phosphate, 5 g / L of sodium hydroxide, the voltage is 500 V, and the treatment is carried out for 25 minutes.

[0073] Comparative Example 1 The composition of the aluminum alloy (in parts by weight) is: 85.0 parts of Al, 3.5 parts of Cu, 0.8 part of Si, 1.2 parts of Mg, 0.5 part of Zn, 0.3 part of Mn, 0.15 part of Cr, 0.08 part of Ti, 0.05 part of Zr.

[0074] Preparation process: The same as that of Example 1.

[0075] Comparative Example 2 The composition of the aluminum alloy: The same as that of Example 3.

[0076] Preparation process: Do not carry out the electromagnetic stirring refining step, and the rest is the same as that of Example 3.

[0077] Comparative Example 3 The composition of the aluminum alloy: The same as that of Example 3.

[0078] Preparation process: Do not carry out the composite modification treatment, and the rest is the same as that of Example 3.

[0079] Comparative Example 4 The composition of the aluminum alloy: The same as that of Example 3.

[0080] Preparation process: No solution treatment and aging treatment are carried out, and the rest is the same as that of Example 3.

[0081] Comparative Example 5 Aluminum alloy composition: The same as that of Example 3.

[0082] Preparation process: No surface micro-arc oxidation treatment is carried out, and the rest is the same as that of Example 3.

[0083] Comparative Example 6 Purchase 7075 aluminum alloy sold on the market.

[0084] Table 1 Performance parameters of 7075 aluminum alloy materials Group the aluminum alloys obtained in Examples 1, 2, 3, 4, 5 and Comparative Examples 1, 2, 3, 4, 5, 6, and conduct sequential experimental numbers on each group. The numbers are GQDLVJ-2501, GQDLVJ-2502, GQDLVJ-2503, GQDLVJ-2504, GQDLVJ-2505, GQDLVJ-2506, GQDLVJ-2507, GQDLVJ-2508, GQDLVJ-2509, GQDLVJ-25010, GQDLVJ-25011 in sequence. Test the corrosion resistance, flexural strength and residual deformation amount after fatigue cycling of the products of the examples and comparative examples. The lower the corrosion rate value in the salt spray test, the better the corrosion resistance. On the contrary, the worse it is. The larger the value of the flexural strength test, the better the flexural strength. On the contrary, the worse it is. The smaller the value of the residual deformation amount test after fatigue cycling, the better. On the contrary, the worse it is. The specific test results are shown in Table 2.

[0085] Table 2 Test results of various performances of comparative examples and examples The addition of rare earth elements and the complete preparation process, including gradient temperature-controlled melting, electromagnetic stirring refining, composite modification treatment, solution treatment and aging treatment, etc., enhance the flexural strength of the aluminum alloy. The optimization of the aluminum alloy composition and the improvement of the microstructure by each preparation process step enable the aluminum alloy to have better fatigue resistance.

[0086] GQDLVJ-2506 lacks rare earth elements, and its various performances are lower than those of the examples. It can be seen that rare earth elements play a key role in improving the comprehensive performance; GQDLVJ-2507 does not carry out electromagnetic stirring refining, resulting in poor uniformity of alloy composition, and then reducing the strength and fatigue resistance. This shows that this step is of great significance for promoting the uniform distribution of alloy composition and optimizing the microstructure; GQDLVJ-2508 was not subjected to composite modification treatment, resulting in insufficient grain refinement and improvement of casting properties of the alloy, which affected the final strength and fatigue resistance, highlighting the important value of Al-5Ti-B and Al-10Sr master alloys in enhancing the alloy properties; GQDLVJ-2509 was not subjected to solution and aging treatments, and the alloy could not fully precipitate strengthening phases, and the strength and fatigue resistance did not reach the optimal state, indicating that these two subsequent treatment steps are crucial for enhancing the alloy strength and hardness.

[0087] GQDLVJ-2510 was not subjected to micro-arc oxidation treatment, and its corrosion resistance was much worse than that of the example, proving that this surface treatment process can form an effective protective layer on the aluminum alloy surface and greatly improve the corrosion resistance; After GQDLVJ-2501 to GQDLVJ-2505 simultaneously adopted the gradient controlled-temperature melting and two-stage aging treatment processes, the corrosion rate of their salt spray tests was relatively low, indicating good corrosion resistance. Since GQDLVJ-2506 did not add rare earth elements, even though the gradient controlled-temperature melting process was adopted, its corrosion rate was significantly higher than that of GQDLVJ-2501, indicating that rare earth elements have a certain contribution to the corrosion resistance under the gradient melting process. In Comparative Example 4, without solution and aging treatments, despite the gradient controlled-temperature melting, its corrosion rate was much higher than that of GQDLVJ-2503, indicating that the two-stage aging treatment significantly improved the corrosion resistance. Through comprehensive comparison of the examples and comparative examples, only the examples that simultaneously adopted the gradient controlled-temperature melting and two-stage aging treatment processes had the best corrosion resistance, proving that there is a synergistic promotion effect on the corrosion resistance between these two processes.

[0088] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent replacements or modifications made based on the present invention to solve basically the same technical problems and achieve basically the same technical effects are all covered by the protection scope of the present invention.

Claims

1. A high-strength aluminum alloy for an electric vehicle pedal, characterized in that: By weight, the aluminum alloy components are: 85.0 - 92.5 parts of Al, 3.5 - 5.8 parts of Cu, 0.8 - 1.6 parts of Si, 1.2 - 2.4 parts of Mg, 0.5 - 1.2 parts of Zn, 0.3 - 0.9 parts of Mn, 0.15 - 0.45 parts of Cr, 0.08 - 0.25 parts of Ti, 0.05 - 0.18 parts of Zr, and 0.03 - 0.12 parts of rare earth elements.

2. The high-strength aluminum alloy for an electric vehicle pedal according to claim 1, wherein: The rare earth elements are lanthanum and cerium, and the mass ratio is 1:1 - 1:

3.

3. The preparation process of the high-strength aluminum alloy for the electric vehicle pedal according to any one of claims 1-2, characterized in that, It includes the following steps: S1. Gradient temperature-controlled melting: In the first stage, heat up to 680°C - 710°C to melt the Al matrix. In the second stage, heat up to 720°C - 750°C and add Cu, Si, and Mg. In the third stage, heat up to 760°C - 780°C and add Zn, Mn, and Cr. In the fourth stage, heat up to 790°C - 810°C and add Ti, Zr, and rare earth elements. S2. Electromagnetic stirring refining: Apply a rotating magnetic field with a frequency of 20 Hz - 40 Hz at 780°C - 800°C, and the stirring time is 15 - 30 minutes. S3. Composite modification treatment: Add 0.05% - 0.12% of Al-5Ti-B master alloy and 0.03% - 0.08% of Al-10Sr master alloy. S4. Stepwise cooling: Cool at 5°C / min - 8°C / min to 680°C - 700°C and hold for 1 - 2 hours, then cool at 10°C / min - 15°C / min to room temperature to obtain the preliminary product.

4. The preparation process according to claim 3, characterized in that: In S1, the heating rate for each stage is 3°C / min - 5°C / min, and argon is introduced for protection at intervals of 5 - 8 minutes for each stage.

5. The preparation process according to claim 3, characterized in that: In S2, the magnetic field strength is 0.8 - 1.5 T, and ultrasonic treatment is applied synchronously during the stirring process, with a frequency of 28 - 35 kHz.

6. The preparation process according to claim 3, characterized in that: The preliminary product is further processed as follows: Solution treatment: Hold at 520 - 550°C for 4 - 6 hours and water quench to below 50°C. Aging treatment: In the first stage, hold at 160 - 180°C for 8 - 12 hours, and in the second stage, hold at 120 - 140°C for 16 - 20 hours to obtain the intermediate product.

7. The preparation process according to claim 6, characterized in that: The surface of the intermediate product is subjected to micro-arc oxidation treatment. The electrolyte contains 12 - 18 g / L of sodium silicate, 6 - 10 g / L of potassium dihydrogen phosphate, 3 - 5 g / L of sodium hydroxide, the voltage is 400 - 500 V, and the treatment time is 15 - 25 minutes to obtain the high-strength aluminum alloy.

8. An electric vehicle pedal, characterized in that, It is made of the aluminum alloy described in any one of claims 1 - 2.

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