A method for producing an aluminum strip

Abstract

The present application relates to a kind of aluminum bar preparation method, belong to non-ferrous metal plastic processing technical field.The present application cancels offline solid solution, pickling, intermediate annealing process throughout, sequentially complete alloy smelting bar, Conclad tangential continuous extrusion, online water mist rapid cooling, no external cold and hot medium room temperature continuous cold rolling, single-stage artificial aging, finishing detection six major processes;Rely on extrusion deformation heat original site to reach solid solution temperature, complete retention supersaturated solid solution with online ultra-fast quenching;Cold rolling uses room temperature to open rolling, relies on deformation heat self-heating to maintain safe rolling interval, realizes large deformation continuous rolling without intermediate annealing;While supporting grain, dislocation, quantitative organization control model of precipitation strengthening, can accurately match whole-process technology reversely.The present application greatly shortens production process, reduces energy consumption and wastewater discharge, and the product conductivity, strength, plasticity are simultaneously improved, and batch and width performance uniformity are significantly improved.

Description

Technical Field

[0001] This invention relates to a method for preparing aluminum busbars, belonging to the field of non-ferrous metal plastic processing technology. Background Technology

[0002] Aluminum busbars are core conductive profiles used in the power battery convergence of new energy vehicles, high and low voltage power distribution, and power grid transmission, with a global annual demand exceeding 6 million tons. Current mainstream industrial production routes for aluminum busbars fall into two categories: hot rolling-cold rolling and conventional continuous extrusion combined with drawing and cold rolling. Both methods suffer from drawbacks such as lengthy processes, high energy consumption, large fluctuations in product performance, and significant environmental pressure.

[0003] Conclad tangential continuous extrusion technology is gradually replacing traditional hot extrusion processes due to its material utilization rate of over 98% and dynamic grain refinement advantages during the extrusion process. However, existing Conclad-supporting rolling processes still have four major drawbacks:

[0004] (1) Uncontrolled thermal process: continuous spray cooling throughout the rolling process will greatly increase the deformation resistance and rolling load of aluminum billet; direct rolling at high temperature will cause dynamic precipitation of Mg2Si phase, consume the supersaturated solid solution atoms of the matrix, and greatly weaken the potential for subsequent aging strengthening.

[0005] (2) Mandatory intermediate annealing process: It is generally recognized in the industry that intermediate annealing must be set up when the total deformation of cold rolling exceeds 30%. Each additional annealing process will simultaneously increase the working time and fuel consumption of the entire process of heating, heat preservation, cooling and transfer, resulting in a significant increase in production costs.

[0006] (3) Lack of quantitative control basis for organizational evolution: The existing process has not established a quantitative model for the evolution of grains, dislocations and precipitates under the thermal process of room temperature rolling and deformation heat self-heating. The process parameters rely on experience to adjust, and the mechanical and electrical properties of the product can fluctuate by ±10%, which cannot meet the stringent consistency requirements of new energy busbars.

[0007] (4) The offline solution treatment process cannot be omitted: the air cooling rate after conventional extrusion is insufficient, solute atoms precipitate out in advance, and a large offline solution treatment furnace must be added for heat preservation and quenching. The equipment investment is large and the energy consumption per ton is high. At the same time, the acid washing process to remove oxide scale is also required, resulting in a large amount of wastewater discharge and high environmental protection costs.

[0008] In view of the above-mentioned shortcomings, the designer has actively researched and innovated in order to create a method for preparing aluminum busbars that has greater industrial application value. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a method for preparing aluminum busbars.

[0010] This invention discloses a method for preparing aluminum busbars, used to prepare 6101A aluminum busbars for power batteries in new energy vehicles. The method includes alloy melting and casting, tangential continuous extrusion of conclad rods, cooling, cold rolling, aging, and finishing processes, eliminating offline solution treatment, pickling, and intermediate annealing processes throughout the entire process. The method comprises the following steps: S1. Alloy smelting and rod preparation: Smelt pure aluminum ingots, Mg ingots, and Al-Si master alloy according to the proportions at 740–760℃, refine with argon for 15–20 min, allow to stand and remove slag, then semi-continuously cast Φ100–Φ150mm round rods at a casting temperature of 710–730℃ and a casting speed of 80–120 mm / min; strictly control the Mg / Si atomic ratio to 1.73, and impurities Fe ≤ 0.10wt%, Cu ≤ 0.02wt%, Zn ≤ 0.03wt%. S2, Conclad tangential continuous extrusion billet: The cast bar is fed directly into the extruder without preheating, and the temperature is raised to 510-530℃ by frictional shear deformation. The extrusion ratio is 20:1-30:1, the extrusion wheel speed is 6-10 rpm, the billet exit temperature is stable at 510-530℃, and it enters the cooling unit within 0.5s after exiting the mold. S3. Online rapid water mist cooling: adopts a double-layer annular array water mist nozzle, water pressure 0.6~1.0MPa, water mist particle size 50~100μm, total cooling time ≤3s, cooling rate ≥150℃ / s, final cooling temperature ≤40℃, billet cross-section temperature difference ≤5℃, online rapid quenching to form supersaturated solid solution; S4. Room temperature continuous cold rolling without cooling: The quenched billet is directly fed into the four-roll cold rolling mill. The initial rolling temperature is ≤40℃. No external cooling or heating is applied during the entire rolling process. The single-pass reduction rate is 15%~20%, the total reduction rate is 50%~70%, and the number of rolling passes is 4~7. The rolling range is stably controlled at 50~80℃ by relying on the self-heating of deformation heat. No intermediate annealing is performed during the entire process. S5. Artificial aging treatment: After rolling, the aluminum busbar is directly put into the furnace for single-stage aging at an aging temperature of 170-180℃ and held for 5-7 hours. After exiting the furnace, it is air-cooled. The furnace temperature uniformity is ±3℃ and the temperature difference of the same batch of material is ≤2℃. S6. Finishing and Finished Product Inspection: After roller straightening, fixed-length sawing, surface and performance testing, the performance fluctuation of the finished product is controlled within ±1.5%.

[0011] Furthermore, after the online water mist rapid cooling in step S3, the solid solubility is increased by more than 20% compared with the traditional air cooling, the pickling process is eliminated, and wastewater discharge is reduced by more than 95%.

[0012] Furthermore, in step S4, the total reduction rate of cold rolling reaches up to 70%, and the rolling temperature of 50-80℃ is lower than the dynamic precipitation temperature of Mg2Si; the self-heating of the rolling deformation heat reduces the deformation resistance by 10%-15%.

[0013] Furthermore, step S4 cold rolling includes thin-gauge extreme rolling conditions: extruded billet thickness 16.7mm, total reduction rate of 70% in 7 rolling passes, finished aluminum busbar thickness 5mm, thickness tolerance ±0.03mm.

[0014] Furthermore, step S2 extrusion can produce a rectangular irregular blank with rounded corners, and step S4 uses die rolling to prepare a rounded corner busbar with a finished corner size tolerance of ±0.2mm.

[0015] Furthermore, step S3 adapts to wide aluminum strip cooling: adopts a contoured wide array nozzle, and the transverse temperature difference of the wide billet is ≤4℃; step S4 wide rolling process transverse temperature difference is ≤3℃, and the mechanical property difference between the left and right sides of the finished product is ≤0.8%.

[0016] Furthermore, the method is accompanied by a quantitative regulatory model for tissues, including: Dislocation density model ρ = ρ0 + 9 × 10¹ 4 ×ε_total, ρ0 is the initial dislocation density after rapid cooling, and ε_total is the total true strain during rolling; Grain size model d = d0 / (1 + k ε_total), d0 is the initial grain size after rapid quenching, and k=0.35 is the grain refinement factor; The quantitative strength model σ = σ0 + σ_grain boundary + σ_dislocation + σ_precipitation is calculated based on Hall-Petch, Taylor, and Orowan strengthening mechanisms, respectively. The model fit correlation coefficient R² > 0.95, realizing accurate performance prediction and reverse process control.

[0017] By means of the above-described solution, the present invention has at least the following advantages: (1) This invention takes Conclad tangential continuous extrusion, online rapid solution treatment, room temperature self-heating cold rolling without external cooling, and short aging as the main line, completely eliminating the three core high-energy-consuming processes of offline solution treatment, pickling, and intermediate annealing required by traditional processes; it relies on the extrusion deformation heat to achieve in-situ solution treatment and the rolling relies on the deformation heat to self-heat, eliminating the need for additional billet heating and rolling temperature control cooling energy consumption, greatly reducing the overall production cycle, and reducing fuel, electricity, and equipment maintenance costs simultaneously; at the same time, Conclad continuous extrusion has no material head loss, greatly improving material utilization and further reducing the manufacturing cost per ton.

[0018] By replacing the offline solution furnace with online water mist rapid cooling, the pickling process for removing oxide scale in traditional processes is eliminated. The production process only generates recyclable cooling water, significantly reducing the discharge of heavy metals and acid / alkali wastewater. The scale of supporting wastewater treatment equipment and environmental protection operation and maintenance costs are greatly reduced, which meets the requirements of green and low-carbon production of non-ferrous metals.

[0019] This invention utilizes online ultra-fast cooling to completely preserve the supersaturated solid solution under high extrusion temperatures, avoiding premature solute precipitation and loss caused by conventional air cooling. During the cold rolling stage, deformation heat is used to stably maintain the billet within a safe low-temperature range, preventing the dynamic precipitation of the Mg2Si phase throughout the process, ensuring sufficient solid solution atoms in the matrix for aging strengthening. The subsequent aging process precipitates a uniformly dispersed nano-strengthening phase, achieving synergistic optimization of the conductivity and mechanical strength of aluminum busbars, while also meeting the requirements of high conductivity, high load-bearing capacity, and high bending plasticity for power battery busbars.

[0020] (2) The present invention establishes a quantitative control model for the whole process of grains, dislocations and precipitates, and accurately matches the temperature and deformation of each process. It eliminates the batch-to-batch and plate transverse structure differences caused by multi-stage annealing and offline solid solution in traditional processes. The fluctuation range of mechanical and electrical properties of finished products is greatly narrowed. Wide, irregular and thin products have good transverse performance uniformity, no edge performance deterioration, size unevenness and plate cracking defects, and the dimensional accuracy meets the national standard requirements for high-precision profiles.

[0021] Relying on a unique rolling mechanism that combines room temperature open rolling with deformation heat self-heating, it can achieve continuous rolling with high total reduction rate without the need for segmented intermediate annealing; the process is adaptable to various cross-section products such as conventional thick plates, ultra-thin specifications, wide flat plates, and irregularly shaped busbars with rounded corners. One main process line can cover the production of conductive aluminum busbars for different models of power batteries in new energy vehicles. The equipment has strong versatility and is easy to adjust when changing production.

[0022] It is equipped with quantitative models for dislocation density, grain size, and multi-mechanism superposition strength, which can reverse-engineer the process parameters of the entire process of melting, extrusion, cooling, rolling, and aging based on the target performance, without the need for a lot of trial and error debugging; the calculated values ​​of microstructure evolution have small deviations from actual production, which facilitates stable mass production in industrialization and reduces the development cycle of new products and trial production losses.

[0023] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Detailed Implementation

[0024] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0025] This process centers on Conclad tangential continuous extrusion, online rapid solution treatment, room temperature open rolling without cooling, and short aging. Through precise control of the entire thermal process, it achieves complete preservation of the supersaturated solid solution and large deformation rolling without intermediate annealing. Offline solution treatment, pickling, and intermediate annealing processes are completely eliminated, resulting in a short-process, low-energy-consumption, and highly consistent aluminum busbar preparation solution. The entire process consists of six core steps, and the parameter control and technical functions of each step are as follows: 1. Alloy smelting and rod preparation Preparing 6101A aluminum alloy billets with precise composition and controllable impurities lays the compositional foundation for subsequent microstructure and property regulation.

[0026] Operating procedures: Pure aluminum ingots, Mg ingots, Al-Si master alloy and other trace elements are added according to the composition ratio and smelted at 740-760℃. Argon gas is introduced into the furnace for refining, degassing and slag removal. The refining time is 15-20 minutes. After standing for 10 minutes, the slag is removed. Aluminum alloy round casting rods with diameters of 100-150 mm were prepared by a semi-continuous casting method at a casting temperature of 710-730℃ and a casting speed of 80-120 mm / min.

[0027] During the process, the Mg / Si atomic ratio must be strictly controlled to be 1.73, and the impurity elements Fe≤0.10wt%, Cu≤0.02wt%, and Zn≤0.03wt% must be kept to maximize the effective content of solid solution atoms and balance conductivity and strength.

[0028] Precise composition control avoids the loss of conductivity due to the precipitation of impurity phases, while ensuring the uniformity of the precipitated phases during subsequent aging processes.

[0029] 2. Conclad tangential continuous extrusion for preform production The large shear deformation of continuous extrusion is used to break up the as-cast structure, while the extrusion heat is used to achieve dynamic recovery of the material, providing a temperature basis for subsequent online solution treatment.

[0030] Operating procedures: Aluminum cast bars do not require preheating and are directly fed into the feed chamber of the Conclad continuous extruder. The billet is bitten into the deformation zone by the friction between the extrusion rollers and the trough wall. The billet undergoes severe plastic deformation under the tangential shearing action of the extrusion rollers. The frictional heat and deformation heat together raise the material temperature to 510-530℃, reaching the solution temperature range. The material is extruded through a die into aluminum billet with a specified cross-sectional size. The extrusion ratio is controlled at 20:1-30:1, and the extrusion roller speed is 6-10 rpm.

[0031] The extrusion outlet temperature is kept stable at 510-530℃, and the billet enters the cooling unit within 0.5s after exiting the mold to avoid premature precipitation of the precipitated phase during the cooling process.

[0032] Conclad tangential continuous extrusion enables continuous production without a blank, achieving a material utilization rate of over 98.5%. Simultaneously, it utilizes deformation heat to directly heat the material to the solution temperature, eliminating the billet heating process required in traditional processes.

[0033] 3. Online rapid water mist cooling Ultra-rapid cooling retains all solute atoms in the high-temperature extruded billet within the aluminum matrix, forming a supersaturated solid solution that completely replaces the traditional offline solution treatment process.

[0034] Operating procedures: A ring-shaped array water mist cooling device is installed at the extrusion outlet, with nozzles arranged in a double layer along the circumference and axial direction of the billet to cover the entire cross section of the billet. High-pressure pure water atomization cooling is adopted, with water pressure of 0.6-1.0MPa and water mist particle size controlled at 50-100μm; The billet passes through the cooling section at a constant speed, with a total cooling time of ≤3s, a cooling rate of ≥150℃ / s, and a final cooling temperature of ≤40℃.

[0035] The entire cooling process is free of temperature dead zones, the temperature difference between the billet sections is ≤5℃, and the final cooling temperature is strictly controlled below 40℃ to ensure that no dynamic precipitation occurs.

[0036] Ultra-fast quenching fully preserves the supersaturated solid solution, increasing the solid solubility by more than 20% compared to traditional air cooling; the online layout eliminates the need for offline solution furnaces and pickling processes, reducing wastewater discharge by more than 95%.

[0037] 4. Room temperature rolling Rolling is started at room temperature, and the billet is heated by the cumulative deformation heat of multiple deformation passes. The rolling temperature is stably controlled in the range of 50-80℃, achieving large deformation rolling without intermediate annealing.

[0038] Operating procedures: After rapid cooling, the aluminum billet is directly fed into the four-roll cold rolling mill. The initial rolling temperature is ≤40℃, and there are no external cooling or heating devices throughout the process. Multi-pass continuous rolling is adopted, with the single-pass reduction rate controlled at 15%-20%, the average single-pass reduction rate at about 20%, and the total reduction rate reaching up to 70%; By matching and controlling the rolling speed and the single-pass reduction rate, the rate of heat accumulation in deformation and the rate of natural heat dissipation are balanced, and the rolling temperature throughout the process is stabilized in the range of 50-80℃, with the maximum temperature not exceeding 80℃.

[0039] in: Rolling temperature: ≤40℃; The rolling temperature range is 50-80℃. Total reduction rate: 50%-70%; Number of passes: 4-6 passes (20%-30% less than traditional processes); The temperature range of 50-80℃ reduces the deformation resistance by 10%-15% by increasing the temperature, and is far below the dynamic precipitation temperature of the Mg2Si phase, completely avoiding the precipitation loss of solute atoms during the rolling process. The deformation heat self-heating process requires no external heating energy consumption, saving more than 60% energy compared to the traditional hot rolling process; It exhibits no dynamic precipitation and a uniform deformed structure, achieving a total reduction rate of 70% without intermediate annealing, thus shortening the production cycle by more than 70%.

[0040] 5. Artificial aging treatment By aging at low temperature, nanoscale Mg2Si reinforcing phase is uniformly precipitated in the supersaturated solid solution, thereby achieving a simultaneous improvement in strength and conductivity.

[0041] Operating procedures: The rolled aluminum busbars are directly fed into the aging furnace without any pretreatment; The process employs a single-stage aging process with an aging temperature of 170-180℃ and an aging time of 5-7 hours, which shortens the aging time by 20%-30% compared to the traditional T6 process. After the aging period is over, remove from the oven and air-cool to room temperature.

[0042] Among them: furnace temperature uniformity ±3℃, and temperature difference of materials in the same batch ≤2℃.

[0043] Because there is no dynamic precipitation loss during the rolling process, the matrix has high supersaturation, and the nuclei of aging precipitates are numerous and evenly distributed, resulting in a significant improvement in aging efficiency while ensuring the synergistic optimization of strength and conductivity.

[0044] 6. Finishing and Finished Product Inspection The finished products undergo dimensional straightening and performance testing to ensure dimensional accuracy and performance consistency.

[0045] Operation process: roller straightening, fixed-length sawing, surface quality inspection, and performance sampling test.

[0046] Among them, the product performance fluctuation is controlled within ±1.5%, and the dimensional tolerance meets the requirements of GB / T6892 standard.

[0047] Example The following examples all use 6101A aluminum alloy as raw material, and the composition is strictly controlled as follows: Mg 0.45-0.50wt%, Si 0.26-0.29wt% (Mg / Si atomic ratio ≈ 1.73), Fe ≤ 0.10wt%, Cu ≤ 0.02wt%, Zn ≤ 0.03wt%, with the balance being Al.

[0048] Example 1: Preparation of 10mm thick aluminum busbar with medium pressure reduction 1. Process parameters: Raw material: Φ120mm 6101A cast rod Conclad continuous extrusion: extrusion roller speed 8 rpm, extrusion ratio 25:1, extrusion outlet temperature 520℃, extruded billet size 25mm (thickness) × 100mm (width). Online water mist quenching: cooling water pressure 0.8MPa, cooling time 2.8s, cooling rate ≈165℃ / s, final cooling temperature 36℃; Continuous rolling without cooling: The initial rolling temperature is 36℃, with a total of 5 passes. The reduction rates for each pass are 18%, 19%, 20%, 19%, and 17%, respectively, for a total reduction rate of 60%. The finished product thickness is 10mm. The highest temperature during the rolling process is 72℃, and the temperature remains stable within the range of 50-80℃ throughout the process. Aging process: Artificial aging at 175℃ for 6 hours, air cooling; 2. Performance and Organization Test Results Mechanical properties: tensile strength 221 MPa, specified plastic elongation Rp0.2 is 198 MPa, elongation after fracture 26.5%; Electrical conductivity: 60.9% IACS; Performance consistency: Performance fluctuation of 100 samples from the same batch is ±1.2%; Microstructure characterization: Average grain size 1.2 μm, measured dislocation density 8.7 × 10¹ 4 m - ², and the formula ρ=ρ0+9×10 14 ×ε_total calculated value (8.5×10¹) 4 m - ²) Deviation <3%; Production efficiency: The production cycle per ton of product is shortened by 72% compared to traditional processes, and the material utilization rate is 98.7%; Example 2: Preparation of 8mm thick aluminum busbar with high reduction ratio 1. Process parameters Raw material: Φ120mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 9 rpm, extrusion ratio 28:1, extrusion outlet temperature 525℃, extruded billet size 26.7mm (thickness) × 100mm (width); Online water mist quenching: cooling water pressure 0.9MPa, cooling time 2.7s, cooling rate ≈175℃ / s, final cooling temperature 34℃; Continuous rolling without cooling: The initial rolling temperature is 34℃, and a total of 6 rolling passes are made. The single-pass reduction rates are 17%, 18%, 20%, 20%, 19%, and 18% respectively, with a total reduction rate of 70% and a finished product thickness of 8mm. The highest temperature during the rolling process is 78℃, and the temperature remains stable in the range of 50-80℃ throughout the process, without intermediate annealing. Aging process: Artificial aging at 175℃ for 5.5 hours, air-cooled; 2. Performance and Organization Test Results Mechanical properties: tensile strength 228 MPa, specified plastic elongation Rp0.2 is 205 MPa, elongation after fracture 25.2%; Electrical conductivity: 60.6% IACS; Performance consistency: Performance fluctuation of ±1.4% among 100 samples from the same batch; Microstructure characterization: Average grain size 1.0 μm, measured dislocation density 1.12 × 10¹ 5 m - ², compared with the calculated value (1.08 × 10¹) 5 m - ²) Deviation <4%; Production efficiency: The production cycle per ton of product is shortened by 76% compared to traditional processes, and the material utilization rate is 98.6%; Example 3: Preparation of 12mm thick aluminum busbar with low pressure reduction ratio 1. Process parameters Raw material: Φ120mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 7 rpm, extrusion ratio 22:1, extrusion outlet temperature 515℃, extruded billet size 24mm (thickness) × 100mm (width). Online water mist quenching: cooling water pressure 0.7MPa, cooling time 2.9s, cooling rate ≈155℃ / s, final cooling temperature 38℃; Continuous rolling without cooling: The initial rolling temperature is 38℃, and a total of 4 rolling passes are made. The single-pass reduction rates are 16%, 18%, 19%, and 17% respectively, with a total reduction rate of 50% and a finished product thickness of 12mm. The maximum temperature during the rolling process is 65℃, and the temperature remains stable in the range of 50-80℃ throughout the process. Aging process: Artificial aging at 175℃ for 6.5 hours, air-cooled; 2. Performance and Organization Test Results Mechanical properties: tensile strength 218 MPa, specified plastic elongation Rp0.2 is 192 MPa, elongation after fracture 27.3%; Electrical conductivity: 61.2% IACS; Performance consistency: Performance fluctuation of 100 samples from the same batch is ±1.1%; Microstructure characterization: Average grain size 1.4 μm, measured dislocation density 6.9 × 10¹ 4 m - ², compared with the calculated value (6.7 × 10¹) 4 m - ²) Deviation <3%; Production efficiency: The production cycle per ton of product is shortened by 68% compared to traditional processes, and the material utilization rate is 98.8%; Example 4: Validation under the lower limit of rolling temperature (50–55℃ range) Verification objective: To verify the feasibility of the lower limit of the process temperature range and confirm that rolling without intermediate annealing can still be achieved in the low-temperature range while maintaining performance standards.

[0049] 1. Process parameters Raw material: Φ100mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 6 rpm, extrusion ratio 20:1, extrusion outlet temperature 510℃, extruded billet size 20mm (thickness) × 80mm (width); Online water mist quenching: cooling water pressure 0.6MPa, cooling time 3.0s, cooling rate ≈150℃ / s, final cooling temperature 39℃; Continuous rolling without cooling: The initial rolling temperature is 39℃, and a total of 4 passes are rolled. The single-pass reduction rates are 15%, 16%, 17%, and 15% respectively, with a total reduction rate of 50% and a finished product thickness of 10mm. Low-speed rolling is used to control the accumulation of deformation heat, and the temperature is kept stable at 51–54℃ throughout the rolling process. Aging process: Artificial aging at 170℃ for 7 hours, air-cooled; 2. Performance and Organization Test Results Mechanical properties: tensile strength 216 MPa, specified plastic elongation Rp0.2 = 190 MPa, elongation after fracture 27.8%; Electrical conductivity: 61.3% IACS; Performance consistency: Performance fluctuation of 100 samples from the same batch is ±1.0%; Microstructure characterization: Average grain size 1.5 μm, measured dislocation density 6.5 × 10¹ 4 m - ², the deviation from the calculated value of the theoretical formula is <3%; Additional notes: The rolling deformation resistance increases slightly in the low-temperature range, but intermediate annealing is still not required. The product has better plasticity and conductivity, making it suitable for busbar scenarios with higher requirements for bending plasticity.

[0050] Example 5: Verification of the upper limit of rolling temperature (75–80℃ range) Verification objective: To verify the safety of the upper limit of the process temperature range, confirm that there is no dynamic precipitation below 80℃, and that the strength index reaches the optimal level.

[0051] 1. Process parameters Raw material: Φ150mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 10 rpm, extrusion ratio 30:1, extrusion outlet temperature 530℃, extruded billet size 33.3mm (thickness) × 120mm (width); Online water mist quenching: cooling water pressure 1.0MPa, cooling time 2.5s, cooling rate ≈185℃ / s, final cooling temperature 32℃; Continuous rolling without cooling: The initial rolling temperature is 32℃, and a total of 6 rolling passes are made. The single-pass reduction rates are 19%, 20%, 20%, 20%, 19%, and 18% respectively, with a total reduction rate of 70% and a finished product thickness of 10mm. By increasing the rolling speed, the heat accumulation of deformation is increased, and the highest temperature during the entire rolling process is 79℃, which is stable in the range of 72–79℃. Aging process: Artificial aging at 180℃ for 5 hours, air cooling; 2. Performance and Organization Test Results Mechanical properties: tensile strength 230 MPa, specified plastic elongation Rp0.2 = 208 MPa, elongation after fracture 25.0%; Electrical conductivity: 60.5% IACS; Performance consistency: Performance fluctuation of ±1.4% among 100 samples from the same batch; Microstructure characterization: Average grain size 0.95 μm, measured dislocation density 1.15 × 10¹ 5 m - ², the deviation from the theoretical calculation value is <4%; transmission electron microscopy did not detect premature precipitation of Mg2Si phase during rolling. Additional explanation: The reduction in deformation resistance is most significant when the temperature is close to the upper limit of 80°C. There is no risk of cracking during rolling with a large reduction rate. The strength reaches its peak and the conductivity still meets the standard, which verifies the scientific nature of the upper temperature limit setting.

[0052] Example 6: Preparation of ultra-thin aluminum busbars (5mm thick) with high reduction ratio Verification objective: To verify the feasibility of large deformation rolling of thin-gauge products, adapting to the demand for lightweight busbars in new energy vehicles.

[0053] 1. Process parameters Raw material: Φ120mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 8 rpm, extrusion ratio 25:1, extrusion outlet temperature 520℃, extruded billet size 16.7mm (thickness) × 100mm (width); Online water mist quenching: cooling water pressure 0.85MPa, cooling time 2.7s, cooling rate ≈170℃ / s, final cooling temperature 35℃; Continuous rolling without cooling: the initial rolling temperature is 35℃, a total of 7 passes are rolled, the single pass reduction rate is 15%–19%, the average single pass reduction rate is 17%, the total reduction rate is 70%, and the finished product thickness is 5mm; the rolling temperature is kept stable in the range of 58–75℃ throughout the rolling process, without intermediate annealing. Aging process: Artificial aging at 175℃ for 6 hours, air cooling; 2. Performance and Organization Test Results Mechanical properties: tensile strength 225 MPa, specified plastic elongation Rp0.2 = 202 MPa, elongation after fracture 25.8%; Electrical conductivity: 60.7% IACS; Dimensional accuracy: thickness tolerance ±0.03mm, flatness ≤1mm / m, no edge cracks or poor plate shape; Performance consistency: Performance fluctuation within the same batch of samples is ±1.3%; Additional explanation: It maintains good sheet shape and plasticity even under thin-gauge, high-reduction conditions, eliminating the need for the multi-pass intermediate annealing process of traditional thin strip rolling.

[0054] Example 7: Preparation of wide aluminum busbar (150mm wide) Verification objective: To verify the ability of wide-width products to achieve uniform cooling and rolling across the entire cross-section, thereby addressing the industry pain point of uneven lateral performance in wide-width aluminum bars.

[0055] 1. Process parameters Raw material: Φ150mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 7 rpm, extrusion ratio 26:1, extrusion outlet temperature 518℃, extruded billet size 20mm (thickness) × 150mm (width). Online water mist rapid cooling: adopts wide array-type contour nozzles, cooling water pressure 0.75MPa, cooling time 2.9s, cooling rate ≈160℃ / s, final cooling temperature 37℃, and transverse temperature difference ≤4℃. Continuous rolling without cooling: The initial rolling temperature is 37℃, with a total of 5 rolling passes, a single pass reduction rate of 16%–19%, a total reduction rate of 60%, and a finished product thickness of 8mm; the rolling temperature is kept stable in the range of 55–70℃ throughout the rolling process, and the transverse temperature difference across the width is ≤3℃. Aging process: Artificial aging at 175℃ for 6.5 hours, air-cooled; 2. Performance and Organization Test Results Mechanical properties: tensile strength 219 MPa, specified plastic elongation Rp0.2 = 195 MPa, elongation after fracture 26.2%; Electrical conductivity: 61.0% IACS; Lateral uniformity: The performance difference between the left and right sides of the web is ≤0.8%, with no edge performance degradation; Performance consistency: Performance fluctuation within the same batch of samples is ±1.2%; Additional explanation: Wide cross-section products can still achieve uniform temperature control throughout the entire process, avoiding the problem of significant differences in microstructure and properties between the edges and center of wide-section products compared to traditional processes. Example 8: Validation of optimized operating conditions with low impurity content Verification objective: To verify the effect of precise control of impurity elements on improving the balance between conductivity and strength, and to support the creativity of composition-limited design.

[0056] 1. Process parameters Raw material: 6101A aluminum alloy, with strictly controlled Fe=0.08wt%, Cu=0.015wt%, Zn=0.02wt%, Mg / Si atomic ratio 1.73; Φ120mm cast ingot; Conclad continuous extrusion: extrusion roller speed 8 rpm, extrusion ratio 25:1, extrusion outlet temperature 520℃, extruded billet 25mm×100mm; Online water mist quenching: cooling water pressure 0.8MPa, cooling rate 165℃ / s, final cooling temperature 36℃. Continuous rolling without cooling: 5 passes, total reduction rate 60%, finished thickness 10mm, rolling temperature 55–70℃; Aging process: Artificial aging at 175℃ for 6 hours, air cooling; 2. Performance and Organization Test Results Mechanical properties: tensile strength 224 MPa, specified plastic elongation Rp0.2 = 201 MPa, elongation after fracture 26.8%; Electrical conductivity: 61.1% IACS; Performance fluctuation: Performance fluctuation within the same batch of samples is ±1.1%; Additional explanation: After controlling impurity elements to the lower limit, the balance between conductivity and strength was further optimized, verifying the technical value of precise composition control. Example 9: Preparation of a special irregular cross-section for rounded corner busbars Verification objective: To verify the ability of this process to adapt to the commonly used rounded corner busbar cross-section in new energy vehicles, and to confirm that there is no stress cracking at the rounded corners under the roll pass.

[0057] 1. Process parameters Raw material: Φ120mm 6101A cast rod; Conclad continuous extrusion: extrusion roller speed 8 rpm, extrusion ratio 24:1, extrusion outlet temperature 522℃, extruded rectangular billet with rounded corners, cross section 22mm (thickness) × 80mm (width), corner radius R3mm; Online water mist rapid cooling: It adopts a contoured water mist nozzle, with a cooling water pressure of 0.8MPa, a cooling time of 2.8s, a cooling rate of 160℃ / s, a final cooling temperature of 36℃, and no cooling dead corners at the rounded corners; Continuous rolling without cooling: a total of 4 passes of rolling with a total reduction of 54.5%, a finished product thickness of 10 mm, and finished product fillet radius of R2.5–R3 mm; the rolling temperature is kept stable in the range of 53–68℃ throughout the rolling process. Aging process: Artificial aging at 175℃ for 6 hours, air cooling; 2. Performance and Organization Test Results Mechanical properties: tensile strength 220MPa, specified plastic elongation Rp0.2=197MPa, elongation after fracture 26.3%; Electrical conductivity: 60.8% IACS; Corner accuracy: Corner size tolerance ±0.2mm, metallographic inspection shows no deformation cracks or abnormal grain growth at the corners; Performance consistency: Performance fluctuation within the same batch is ±1.2%; Additional explanation: The irregular cross-section undergoes uniform deformation during rolling, with no stress concentration or performance degradation in the rounded corner areas, making it directly compatible with the finished cross-section requirements of new energy vehicle busbars.

[0058] The core metrics of all implementation examples are summarized in the table below:

[0059] All embodiments consistently achieved comprehensive performance indicators of tensile strength ≥215MPa, elongation ≥25%, and conductivity ≥60.5% IACS, with performance fluctuations controlled within ±1.5%, fully verifying the reliability of the process parameter range and the universality of the technical effect.

[0060] Comparative Example Comparative Example 1: Traditional hot-rolling-cold-rolling alternating process 1. Process parameters The same composition 6101A cast rod is heated to 500℃ and then hot rolled in 3 passes to a thickness of 15mm. The rolling process is continuously water-cooled and temperature controlled. Intermediate annealing at 350℃ for 2 hours, followed by cold rolling to a thickness of 10 mm, with a total reduction of 33% during the cold rolling stage; Offline solution treatment at 540℃ for 2 hours, followed by water quenching and artificial aging at 175℃ for 8 hours.

[0061] 2. Test Results Mechanical properties: tensile strength 205 MPa, elongation 22%; Electrical conductivity: 59.8% IACS; Performance consistency: Performance fluctuation within the same batch is ±8.7%; Production cycle: 75% longer than Example 1, material utilization rate 92.1%, includes pickling wastewater discharge process; Comparative Example 2: Conventional extrusion air-cooling combined with cold rolling process 1. Process parameters The same composition cast rod is conventionally hot extruded and air-cooled to room temperature at the outlet, with a cooling rate of about 10℃ / s; When the material is cold-rolled to a thickness of 10 mm, with a total reduction of 60% and a deformation of 30%, it undergoes intermediate annealing at 320℃ for 1.5 hours. Offline solid solution treatment followed by 8-hour aging process.

[0062] 2. Test Results Mechanical properties: tensile strength 210 MPa, elongation 23%; Electrical conductivity: 59.5% IACS; Performance consistency: Performance fluctuation within the same batch is ±7.2%; Production cycle: 82% longer than Example 1; The following table compares the core metrics of the examples and the comparative examples:

[0063] III. Validation of the Organization-Performance Quantitative Relationship Based on 200 sets of industrial production data from the above embodiments, the accuracy of the quantification model proposed in this scheme is verified: 1. Dislocation density evolution model: ρ = ρ0 + 9 × 10¹ 4 ×ε_total Where ρ0 is the initial dislocation density after rapid cooling (approximately 1.2 × 10¹). 4 m - ²), where ε_total is the total true strain; The average deviation between the measured and calculated values ​​in Examples 1-3 was <4%, with a correlation coefficient R² = 0.962. 2. Grain size evolution model: d = d0 / (1 + k·ε_total) Where d0 is the initial grain size after rapid cooling (approximately 2.8 μm), and k is the grain refinement factor (value 0.35). The average deviation between the measured and calculated values ​​is <5%, and the correlation coefficient R² = 0.957. 3. Performance-tissue quantitative relationship: Tensile strength σ = σ0 + σ_grain boundary + σ_dislocation + σ_precipitation; Grain boundary strengthening conforms to the Hall-Petch relationship, dislocation strengthening conforms to the Taylor relationship, and precipitation strengthening is calculated according to the Orowan mechanism. The overall fitting correlation coefficient R²>0.95, which can realize accurate prediction and reverse control of the performance of the entire process.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing aluminum busbars, comprising alloy melting and casting, Conclad tangential continuous extrusion, cooling, cold rolling, aging, and finishing processes, characterized in that, The entire process eliminates offline solution treatment, pickling, and intermediate annealing steps; it includes the following steps: S1. Alloy smelting and rod preparation: Smelt pure aluminum ingots, Mg ingots, and Al-Si master alloy according to the proportions at 740–760℃, refine with argon for 15–20 min, allow to stand and remove slag, then semi-continuously cast Φ100–Φ150mm round rods at a casting temperature of 710–730℃ and a casting speed of 80–120 mm / min; strictly control the Mg / Si atomic ratio to 1.73, and impurities Fe ≤ 0.10wt%, Cu ≤ 0.02wt%, Zn ≤ 0.03wt%. S2, Conclad tangential continuous extrusion billet: The cast bar is fed directly into the extruder without preheating, and the temperature is raised to 510-530℃ by frictional shear deformation. The extrusion ratio is 20:1-30:1, the extrusion wheel speed is 6-10 rpm, the billet exit temperature is stable at 510-530℃, and it enters the cooling unit within 0.5s after exiting the mold. S3. Online rapid water mist cooling: adopts a double-layer annular array water mist nozzle, water pressure 0.6~1.0MPa, water mist particle size 50~100μm, total cooling time ≤3s, cooling rate ≥150℃ / s, final cooling temperature ≤40℃, billet cross-section temperature difference ≤5℃, online rapid quenching to form supersaturated solid solution; S4. Room temperature continuous cold rolling without cooling: The quenched billet is directly fed into the four-roll cold rolling mill. The initial rolling temperature is ≤40℃. No external cooling or heating is applied during the entire rolling process. The single-pass reduction rate is 15%~20%, the total reduction rate is 50%~70%, and the number of rolling passes is 4~7. The rolling range is stably controlled at 50~80℃ by relying on the self-heating of deformation heat. No intermediate annealing is performed during the entire process. S5. Artificial aging treatment: After rolling, the aluminum busbar is directly put into the furnace for single-stage aging at an aging temperature of 170-180℃ and held for 5-7 hours. After exiting the furnace, it is air-cooled. The furnace temperature uniformity is ±3℃ and the temperature difference of the same batch of material is ≤2℃. S6. Finishing and Finished Product Inspection: After roller straightening, fixed-length sawing, surface and performance testing, the performance fluctuation of the finished product is controlled within ±1.5%.

2. The method for preparing aluminum busbars according to claim 1, characterized in that, After rapid online water mist cooling in step S3, the solid solubility is increased by more than 20% compared with traditional air cooling, eliminating the pickling process and reducing wastewater discharge by more than 95%.

3. The method for preparing aluminum busbars according to claim 1, characterized in that, In step S4, the total reduction rate of cold rolling reaches up to 70%, and the rolling temperature is 50-80℃, which is lower than the dynamic precipitation temperature of Mg2Si. The self-heating of the rolling deformation heat reduces the deformation resistance by 10%-15%.

4. The method for preparing aluminum busbars according to claim 1, characterized in that, Step S4 cold rolling includes thin-gauge extreme rolling conditions: extruded billet thickness 16.7mm, total reduction rate of 70% in 7 rolling passes, finished aluminum busbar thickness 5mm, thickness tolerance ±0.03mm.

5. The method for preparing aluminum busbars according to claim 1, characterized in that, Step S2 extrusion can produce a rectangular irregular blank with rounded corners. Step S4 uses die rolling to prepare a rounded corner busbar. The finished product's rounded corner size tolerance is ±0.2mm.

6. The method for preparing aluminum busbars according to claim 1, characterized in that, Step S3: Adapting to wide aluminum busbar cooling: Using contoured wide array nozzles, the transverse temperature difference of the wide billet is ≤4℃; Step S4: During the wide rolling process, the transverse temperature difference of the width is ≤3℃, and the difference in mechanical properties between the left and right sides of the finished width is ≤0.8%.

7. The method for preparing aluminum busbars according to claim 1, characterized in that, The method is accompanied by a quantitative tissue regulation model, including: Dislocation density model ρ = ρ0 + 9 × 10¹ 4 ×ε_total, ρ0 is the initial dislocation density after rapid cooling, and ε_total is the total true strain during rolling; Grain size model d = d0 / (1 + k ε_total), d0 is the initial grain size after rapid quenching, and k=0.35 is the grain refinement factor; The quantitative strength model σ = σ0 + σ_grain boundary + σ_dislocation + σ_precipitation is calculated based on Hall-Petch, Taylor, and Orowan strengthening mechanisms, respectively. The model fit correlation coefficient R² > 0.95, realizing accurate performance prediction and reverse process control.

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