Production process of high-quality 6101 aluminum alloy coiled strip for new energy vehicle power supply

Abstract

This invention relates to a production process for high-quality 6101 aluminum alloy coils and strips for power supply in new energy vehicles, comprising: S1, preparing raw materials according to the chemical composition of 6101 aluminum alloy, smelting, refining, filtering, and horizontal continuous casting to obtain a coiled rod billet; S2, using a drawing and peeling method to remove casting defects on the surface of the aluminum alloy coiled rod billet, with a peeling depth of 0.2-0.5mm; S3, low-temperature direct cooling continuous extrusion: the extrusion wheel groove temperature is 280-350℃, and cooling water is led to the exit end of the extrusion die to directly cool the die and the extruded product; S4, tension traction and coiling; S5, holding the coiled product at 200-280℃ for 8-16 hours. The 6101 aluminum alloy coils and strips prepared by this invention have the characteristics of good uniformity and consistency of performance, high dimensional accuracy, smooth and clean surface, and high coil weight. The comprehensive mechanical (tensile strength, yield strength, elongation) and electrical conductivity of the high-strength and high-conductivity products and the medium-strength and high-conductivity products are better than the standard values ​​of the corresponding states, and can replace copper as conductive strips for power supply of new energy vehicles.

Description

Technical Field

[0001] This invention belongs to the field of metal plastic processing technology, specifically relating to a production process for high-quality 6101 aluminum alloy coils and strips for power supply in new energy vehicles. Background Technology

[0002] With the rapid development of new energy vehicles, lightweighting and reducing manufacturing costs have become common goals for new energy vehicle manufacturers, which also brings new opportunities for supporting vehicle cables. Battery range issues have become a technological barrier hindering the development of electric vehicles. However, using aluminum alloy core cables can significantly reduce vehicle weight and help improve range. Aluminum alloy core cables for new energy vehicles are suitable for electrical system connections in various vehicles, and are particularly suitable for high-voltage connections of batteries and motors within automobiles.

[0003] Copper conductors are 3.3 times denser than aluminum conductors. However, aluminum's conductivity is only 61% that of copper. This means that to carry the same current, the cross-sectional area of ​​an aluminum conductor must be approximately 66% larger than that of a copper conductor. Therefore, in terms of conductor weight, to achieve the same current carrying capacity, the copper conductor would need to weigh about twice as much as the aluminum conductor. Furthermore, the unit price of copper is 3.5 times that of aluminum. Thus, the equivalent cost of a copper conductor is seven times that of an aluminum conductor. This demonstrates that lightweight aluminum alloy conductors are extremely effective in utilizing energy, reducing both the weight and cost of new energy vehicles—an advantage that is foreseeable in the new energy vehicle sector.

[0004] 6101 aluminum-magnesium-silicon alloys possess moderate strength and excellent bending and electrical conductivity, making them widely used as high-performance aluminum alloy conductor materials. For example, 6101 aluminum alloy extruded conductive busbars for electrical engineering are widely used in power supply equipment (such as distribution cabinets) to replace copper busbars. However, the performance requirements for aluminum alloy conductors vary significantly across different application areas. See Table 1 for the commonly used states and corresponding performance requirements of 6101 aluminum alloy extruded busbars (B / T32184-2015 High Conductivity Aluminum Alloy Extruded Flat Bars and Plates).

[0005] Table 1 Performance Standards for 6101 Aluminum Alloy Extruded Flat Bars and Sheets

[0006]

[0007] Currently, 6101 aluminum alloy conductive busbars are produced using a semi-continuous casting-hot extrusion process (see...). Figure 2The main process flow of this method is as follows: semi-continuous casting → homogenization treatment → heating → hot extrusion → air cooling (i.e., online or offline solution treatment) → automatic traction → sawing → stretching and straightening → heat treatment (aging treatment). The biggest technical problem with this process is the limited length (usually 6 meters) and the differences in product structure and properties along the length direction. (The length or weight of the products produced by this process is limited by the weight of the extrusion ingot and the extrusion ratio, making it difficult to produce single pieces longer than 50 meters. In addition, conventional extrusion causes severe uneven deformation due to the large friction between the extrusion ingot and the extrusion cylinder. As the extrusion process progresses, the friction length decreases, causing the extrusion pressure to gradually decrease. The heat generated by friction and deformation causes the subsequent extrusion temperature to rise continuously. All of these factors contribute to the unevenness of product structure and properties along the length direction.) This will seriously affect the strength of the final conductive busbar and the uniformity of its conductivity along the length direction. In addition, due to cooling during the ingot production process, the ingot grain structure becomes coarse and has greater internal and external differences (such as solidification segregation), and more obvious casting defects such as inclusions, shrinkage porosity, and gas pores. These phenomena reduce the strength and electrical conductivity of the extruded material to a certain extent. Figure 2 The existing process shown requires sawing to remove the edge material, which is not conducive to improving the yield.

[0008] Unlike the 610L aluminum alloy extruded busbars used in power supply equipment, modern automotive parts manufacturing is increasingly moving towards large-scale, highly intelligent, and standardized assembly line production. As a conductor material for power supply in new energy vehicles, in addition to higher requirements for mechanical and electrical properties, it also demands higher dimensional accuracy and surface quality to meet the requirements of sheathing and impregnation insulation materials. Therefore, the new energy vehicle sector urgently needs to develop and produce high-quality aluminum alloy conductor materials and manufacturing processes for power supply with large roll weights (single roll weight not less than 300 kg) to reduce vehicle weight and alleviate the problem of poor driving range. On the other hand, this can partially solve the over-reliance on copper resources in traditional electrical materials, reducing vehicle manufacturing costs. Summary of the Invention

[0009] (a) Technical problems to be solved

[0010] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a production process for high-quality 6101 aluminum alloy coils and strips for power supply of new energy vehicles. This process can produce products with synergistically improved and uniform mechanical and electrical properties. These products can be used as conductor materials for new energy vehicles to reduce vehicle weight, alleviate the problem of poor vehicle range, and partially solve the problem of excessive reliance on copper resources in traditional electrical materials, thereby reducing vehicle manufacturing costs.

[0011] (II) Technical Solution

[0012] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0013] In a first aspect, the present invention provides a production process for high-quality 6101 aluminum alloy coils and strips for power supply in new energy vehicles, comprising the following steps:

[0014] S1. Horizontal continuous casting yields aluminum alloy disc-shaped rod billets:

[0015] According to the chemical composition of 6101 aluminum alloy, the raw materials are batched, smelted, refined, filtered, and horizontally continuously cast to obtain aluminum alloy disc rod billets;

[0016] S2, pulling and peeling:

[0017] The casting defects on the surface of the aluminum alloy disc rod blank are removed by a pulling and peeling method, with a peeling depth of 0.2-0.5mm.

[0018] S3, Low-temperature direct cooling continuous extrusion:

[0019] Control the temperature of the extrusion roller groove at 280-350℃, and lead the cooling water to the outlet end face of the extrusion die to directly cool the die and the extruded product;

[0020] S4, tension traction, winding and coiling;

[0021] S5, Low-temperature, long-time annealing:

[0022] The initial product, which is rolled up, is annealed and held at 200-280℃ for 8-16 hours.

[0023] According to a preferred embodiment of the present invention, in S1, the diameter of the aluminum alloy disc rod blank is 16.2mm-16.7mm, preferably 16.5mm.

[0024] According to a preferred embodiment of the present invention, in S1, the casting temperature of the horizontal continuous casting is 690-700°C, and the horizontal continuous casting speed is 600-700 mm / min. If the temperature and speed are too high, the casting will not form properly; if the temperature is too low or the speed is too high, fracture is likely to occur.

[0025] Preferably, the cooling rate of the horizontal continuous casting is 280-350℃ / s, more preferably 300-350℃ / s.

[0026] According to a preferred embodiment of the present invention, in S3, the temperature of the extrusion wheel groove is controlled at 300-320°C.

[0027] This invention employs medium-temperature extrusion. If the extrusion temperature is too high, dynamic recrystallization will occur, reducing product strength and surface quality; conversely, if the extrusion temperature is too low, continuous extrusion will be difficult, and the product may not be extruded. According to a preferred embodiment of the invention, in S4, the product subjected to low-temperature direct cooling continuous extrusion is wound into a coil by a double winding and winding machine on the extrusion production line. Tension traction is used during winding to ensure neat winding and stable product dimensions.

[0028] According to a preferred embodiment of the present invention, in S5, the conditions for low-temperature long-term annealing are: annealing and holding at 220-260°C for 10-16 hours.

[0029] (III) Beneficial Effects

[0030] The process of this invention mainly involves obtaining fine-grained aluminum alloy disc rods with extremely high solid solubility through horizontal continuous casting. Then, casting defects on the surface of the rod blank are removed by drawing and peeling, reducing their adverse effects on the electrical conductivity of the extruded alloy product. Low-temperature direct cooling continuous extrusion is used to form an extruded microstructure with a high dislocation density and a recovered fibrous substructure. Simultaneously, low-temperature long-term annealing enhances the alloy's age hardening, subgrain hardening, and extrusion effect strengthening (texture) effects, ensuring synergistic and uniform improvement in mechanical and electrical properties. Furthermore, low-temperature direct cooling continuous extrusion helps ensure dimensional accuracy and improve the surface quality of the extruded product. This invention is particularly suitable for producing high-quality aluminum alloy conductor materials for power supply with a single roll weight of not less than 300 kg.

[0031] According to the performance verification of the tested and produced products, the high-quality 6101 aluminum alloy coils and strips prepared by this invention have the characteristics of good uniformity and consistency of performance, high dimensional accuracy, clean and smooth surface, and heavy coil weight (single coil weight not less than 300Kg); high-strength and high-conductivity state (or corresponding T65 state) products: tensile strength greater than 200MPa, yield strength greater than 180MPa, elongation A 50 Products with conductivity greater than 20% and conductivity higher than 58.5% IACS (or corresponding T64 condition) have tensile strength greater than 155MPa, yield strength greater than 130MPa, and elongation A... 50 Greater than 21% and conductivity higher than 60% IACS. The product's overall mechanical and electrical properties are superior to the standard values ​​for the corresponding conditions.

[0032] The 6101 aluminum alloy coil strip of this invention has excellent uniformity and consistency in performance, achieving a uniform and synergistic improvement in the product's mechanical and electrical properties. It is a high-quality 6101 aluminum alloy coil strip that can replace copper for power supply in new energy vehicles. Attached Figure Description

[0033] Figure 1 This is a production process flow diagram of the high-quality 6101 aluminum alloy coil strip for power supply of new energy vehicles according to the present invention.

[0034] Figure 2 This is a process flow diagram of the existing semi-continuous casting-hot extrusion method. Detailed Implementation

[0035] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] like Figure 1 The diagram illustrates a production process for high-quality 6101 aluminum alloy coils and strips for power supply in new energy vehicles, comprising: horizontal continuous casting of aluminum alloy disc billets → drawing and peeling → low-temperature direct cooling continuous extrusion → tension traction → coiling → low-temperature long-term annealing. The horizontal continuous casting of aluminum alloy disc billets further includes steps such as batching according to the alloy's chemical composition, smelting, refining, filtering, and horizontal continuous casting.

[0038] In an embodiment of the present invention, specifically, based on the standard chemical composition of the alloy, 99.7 aluminum ingots, magnesium ingots, and Al-30Si master alloy are used to prepare the aluminum alloy according to the designed weight ratio and feeding rules. The alloy is then smelted in a dual 500Kg capacity gas-fired melting furnace. After degassing and slag removal refining treatment, the melt is sampled using a direct reading spectral method for chemical composition analysis. The measured composition is shown in Table 2.

[0039] Table 2. Main chemical composition (weight percentage, %) of the 6101 aluminum alloy of this invention

[0040] alloy Si Fe Cu Mn Mg Cr Zn B Ingredient Standards 0.30-0.70 ≤0.50 ≤0.10 ≤0.03 0.35-0.80 ≤0.03 ≤0.10 ≤0.06 Actual measurement 0.362 0.116 0.021 0.004 0.487 0.005 0.074 0.019

[0041] After heat preservation and filtration, the round wire rod billet with a diameter of Ф16.5mm is cast using a horizontal continuous casting process with a crystallizer. The casting temperature is 690-700℃ and the horizontal continuous casting speed is 650mm / min.

[0042] Then, the Ф16.5mm diameter round wire rod blank was drawn and peeled to Ф16mm (average peeling depth 0.25mm). It was then extruded into coils of four specifications: 2.5×22mm, 3.0×20mm, 4.0×40mm, and 5.3×35mm, using a low-temperature direct cooling method on an LJ300 continuous aluminum extrusion press. The measured extrusion roller groove temperature was 310℃. The thickness (accuracy ±0.08mm) and width (accuracy ±0.10mm) of the extruded products met the requirements of ±0.08mm and ±0.10mm respectively (significantly higher than the B / T32184-2015 high conductivity aluminum alloy extruded flat bars and plates). The single coil weights were 336Kg, 324Kg, 341Kg, and 319Kg respectively (customer requirement 300-350Kg). During continuous extrusion, cooling water is directed to the exit end face of the extrusion die to directly cool the die and the extruded product.

[0043] After tension traction and coiling, the strip was subjected to two low-temperature long-term annealing treatments in a 110KW box-type thermal circulation resistance furnace: heating to 220℃ and holding for 16 hours, and heating to 260℃ and holding for 10 hours (eight trial production products were obtained according to different processing techniques). Three samples each from the head and tail of the annealed strip were taken (a total of six samples were tested) for performance testing. The average mechanical and electrical properties of the 6101 aluminum alloy strip are shown in Table 3.

[0044] Table 3 Performance test results of the 6101 aluminum alloy coil and strip product of this invention

[0045]

[0046] Table 1 shows the common conditions and corresponding performance requirements of 610l aluminum alloy extruded busbars (B / T 32184-2015 High conductivity aluminum alloy extruded flat bars and plates).

[0047] A comparison of Tables 1 and 3 shows that the mechanical properties of the 6101 aluminum alloy coil strip of this invention, after annealing at 220℃ for 16 hours, including tensile strength, yield strength, elongation, and conductivity, are all higher than those of existing extruded 6101-T65 aluminum alloy conductive bars. Furthermore, after annealing at 260℃ for 10 hours, the mechanical properties of the 6101 aluminum alloy coil strip of this invention, including tensile strength, yield strength, elongation, and conductivity, are all higher than those of existing extruded 6101-T64 aluminum alloy conductive bars. In addition, random sampling tests conducted by users at three layers per roll show that the average performance of the entire roll falls within the range of the minimum and maximum measured values ​​in Table 3. This indicates that the 6101 aluminum alloy coil strip of this invention exhibits excellent uniformity in performance (ensuring stable and consistent performance in new energy vehicles), achieving a uniform and synergistic improvement in the product's mechanical and electrical properties. Moreover, the performance test values ​​at the head and tail of a single roll are very close, indicating uniform product performance.

[0048] Example 2-3

[0049] Example 2 is based on Example 1, with the annealing temperature of 2.5×22mm coil strip determined to be 200℃ and held for 16 hours. Other conditions are the same as in Example 1.

[0050] Example 3 is based on Example 1, with the annealing temperature of the 2.5×22mm coil strip set at 280℃ and held for 8 hours. Other conditions are the same as in Example 1.

[0051] Three samples each from the head and tail of the annealed strip were taken for performance testing. The average mechanical and electrical properties of the aluminum alloy strip were measured as follows:

[0052]

[0053] In summary, the products treated with low-temperature long-term annealing at 220-260℃ for 10-16 hours exhibit superior mechanical properties such as tensile strength, yield strength, and elongation, as well as electrical conductivity.

[0054] Examples 4-5

[0055] Example 4 is based on Example 1, but the extrusion roller groove temperature is increased to 350°C when extruding 2.5×22mm coil strip. Other conditions are the same as in Example 1, and the artificial aging is carried out at 220°C for 16 hours (accuracy ±0.08mm).

[0056] Example 5 is based on Example 1, but the extrusion roller groove temperature is increased to 280°C when extruding 2.5×22mm coil strip. Other conditions are the same as in Example 1, and the artificial aging is carried out at 220°C for 16 hours (accuracy ±0.08mm).

[0057] Three samples each from the head and tail of the annealed strip were taken for performance testing. The average mechanical and electrical properties of the aluminum alloy strip were measured as follows:

[0058]

[0059] In summary, under the process conditions of low-temperature direct cooling continuous extrusion, with an extrusion roller groove temperature of 280-350℃ and a subsequent annealing temperature of 200-280℃ for 8-16 hours, products with superior performance can be obtained. Furthermore, when the extrusion roller groove temperature is 300-320℃, and more preferably 310℃, the manufactured products exhibit even better comprehensive performance in terms of tensile strength, yield strength, elongation, and electrical conductivity.

[0060] Compare with Example 1

[0061] When directly cooling and continuously extruding to form 2.5×22mm coils and strips, the temperature of the extrusion roller groove is increased to 400°C. Other conditions are the same as in Example 1.

[0062] Three samples each from the head and tail of the annealed strip of Comparative Example 1 were taken for performance testing. The average mechanical and electrical properties of the aluminum alloy strip were measured as follows:

[0063]

[0064] It is evident that when the temperature of the extrusion wheel groove is too high, even if the subsequent annealing conditions are the same, the conductivity of the resulting product decreases, and the tensile strength and yield strength decrease particularly significantly.

[0065] Compare with Example 2

[0066] When continuously extruding 2.5×22mm coils of material under direct cooling, lowering the temperature of the extrusion roller groove to 260℃ caused excessive extrusion load, resulting in a stall and preventing normal production.

[0067] Furthermore, during product trial production, if the annealing temperature of Example 3 was increased to 300℃ and held for 8 hours, the mechanical strength of the aluminum alloy coil / strip decreased significantly; if the annealing temperature of Example 2 was reduced to 180℃ and held for 16 hours, the elongation and conductivity of the aluminum alloy coil / strip decreased significantly. Therefore, the low-temperature long-term annealing conditions of the present invention should be controlled at 200-280℃ for 8-16 hours, thereby achieving a product with superior mechanical properties such as tensile strength, yield strength, and elongation, as well as excellent conductivity.

[0068] Therefore, it can be seen that the product produced by the present invention has better performance than the product produced by the traditional semi-continuous casting-hot homogenization extrusion method; and in the experimental test, according to the sampling test results of the beginning and end, the difference between the sampling test results of the beginning and end is very small, which indicates that the conductive tape prepared by the present invention has better structure and conductivity uniformity along the length direction.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A production process of high-quality 6101 aluminum alloy coiled strip for power supply of new energy vehicles, characterized in that, Includes the following steps: S1. Horizontal continuous casting yields aluminum alloy disc-shaped rod billets: According to the chemical composition of 6101 aluminum alloy, the raw materials are batched, smelted, refined, filtered, and horizontally continuously cast to obtain aluminum alloy disc rod billets; S2, pulling and peeling: The casting defects on the surface of the aluminum alloy disc rod blank are removed by a pulling and peeling method, with a peeling depth of 0.2-0.5mm. S3, Low-temperature direct cooling continuous extrusion: Control the temperature of the extrusion roller groove at 280-350℃, and lead the cooling water to the outlet end face of the extrusion die to directly cool the die and the extruded product; S4, tension traction, winding and coiling; S5, Low-temperature, long-time annealing: The initial product, which is rolled up, is annealed and held at 200-260℃ for 10-16 hours.

2. The production process according to claim 1, characterized in that, In S1, the diameter of the aluminum alloy disc rod blank is 16.2-16.7 mm.

3. The production process according to claim 1, characterized in that, In S1, the casting temperature for horizontal continuous casting is 690-700℃, and the horizontal continuous casting speed is 600-700mm / min.

4. The production process according to claim 1, characterized in that, In S3, the temperature of the extrusion wheel groove is controlled at 300-320℃.

5. The production process according to claim 1, characterized in that, In S4, the product that has undergone continuous low-temperature direct cooling extrusion is rolled into a coil by a double take-up and winding machine on the extrusion production line.

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