Preparation method of high-performance 1060-o-state aluminum alloy connecting sheet

Abstract

The present application belongs to the technical field of aluminum-based materials, and specifically relates to a preparation method of a high-performance 1060-O-state aluminum alloy connecting sheet. The preparation method comprises the following steps: step one, preparing a hot-rolled coil; step two, preheating treatment; step three, preparing a cold-rolled coil; step four, air cushion type continuous annealing; step five, box furnace finished product annealing; and step six, finished product slitting. The present application solves the problems of low production efficiency, poor comprehensive performance and high energy consumption in the preparation of the O-state aluminum alloy connecting sheet by using a single box furnace annealing process, realizes high-efficiency, high-consistency and low-energy-consumption production, and the prepared connecting sheet has stable low strength and high elongation, and can meet the application requirements of new energy vehicles and energy storage battery modules.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based materials technology, specifically relating to a method for preparing a high-performance 1060-O state aluminum alloy connecting piece. Background Technology

[0002] With the rapid development of new energy vehicles, energy storage systems, and consumer electronics, the performance requirements for battery connectors, a key component of power batteries and a core energy carrier, are increasingly stringent. Connectors in battery modules perform multiple functions, including conductivity, structural support, and thermal management, requiring excellent conductivity, high flexibility, stable mechanical properties, and good formability. 1060 aluminum alloy, due to its high aluminum content (≥99.6%), excellent conductivity, and corrosion resistance, has become one of the ideal materials for manufacturing connectors. Especially in its O-state (fully soft state), it should theoretically possess excellent plasticity and low strength, facilitating stamping and maintaining connection reliability under vibration. However, the limitations of existing manufacturing processes severely restrict the optimization of product performance and industrialization efficiency.

[0003] Currently, the mainstream process for preparing O-state aluminum alloy strip in the industry still relies on the conventional route of "hot rolling - cold rolling - box furnace annealing". In this route, the cold-rolled strip is directly fed into a box furnace for batch annealing, and recrystallization and softening are achieved by controlling the temperature and time. However, this traditional method has several inherent drawbacks:

[0004] First, production efficiency is low. Box furnace annealing is an intermittent operation, with heating, holding, and cooling cycles lasting tens of hours, resulting in a slow production pace that cannot meet the high-efficiency requirements of modern continuous rolling, thus creating a capacity bottleneck.

[0005] Second, product performance consistency is poor. The temperature field distribution inside the box furnace is uneven. Especially when processing wide or heavy strip materials, the temperature difference at different locations inside the furnace can easily lead to differences in the degree of annealing, resulting in significant fluctuations in the mechanical properties of the finished product (such as yield strength and elongation). It is also difficult to control the shape of the strip, which directly affects the reliability and safety of the connecting piece in the battery pack.

[0006] Third, the precision of the process control is insufficient. Relying solely on box furnace annealing to simultaneously achieve recrystallization and stress relief results in a narrow process window. If the annealing temperature is too high or the time is too long, it can easily lead to grain coarsening, resulting in low strength. If the temperature is insufficient or the time is too short, work hardening cannot be completely eliminated, leaving residual internal stress. As a result, the yield strength is too high and the elongation is insufficient. Both of these situations are difficult to meet the stringent requirements of O-state materials for low yield strength (target 20~40MPa) and high elongation (target 35~48%).

[0007] Fourth, it consumes a lot of energy. The long-term high-temperature insulation process leads to energy waste and increases production costs, which contradicts the concept of green manufacturing.

[0008] To address these issues, the industry has explored improved solutions, such as replacing box furnaces with continuous annealing furnaces (e.g., air cushion furnaces). While continuous annealing can improve efficiency, for the O-state treatment of pure aluminum like 1060, a single continuous annealing process, lacking subsequent stabilization treatment, often makes it difficult to accurately balance the degree of recrystallization and the effect of internal stress relief. Especially in practical applications, single annealing can easily lead to insufficient yield strength stability (e.g., fluctuations exceeding 60 MPa) or elongation not reaching the optimal value. Therefore, how to simultaneously achieve high efficiency, high consistency, and low energy consumption in the production of 1060-O-state aluminum alloy connecting pieces while ensuring high performance (low strength, high plasticity) has become a critical technical bottleneck that urgently needs to be overcome in this field. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing high-performance 1060-O state aluminum alloy connecting pieces.

[0010] The objective of this invention is achieved through the following technical solution:

[0011] A method for preparing a high-performance 1060-O state aluminum alloy connecting piece includes the following steps:

[0012] Step 1: Preparation of hot-rolled coils: Heat 1060 alloy flat ingots and then hot-roll them, controlling the final rolling temperature at 320~340℃ to obtain hot-rolled coils with a thickness of 6.0~7.0mm;

[0013] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 120~160℃ at a rate of 30-50℃ / hour, and keep it at 120~160℃ for 5~8 hours, then air cool to room temperature;

[0014] Step 3: Preparation of cold-rolled coils: The preheated hot-rolled coils are cold-rolled to obtain cold-rolled coils with a thickness of 1.0~2.0mm;

[0015] Step 4, Air-cushion continuous annealing: After the cold-rolled coil is cooled to ≤50°C, it is dynamically unfolded in an air-cushion furnace to form a strip. The strip is then cleaned, continuously annealed and straightened. The treated strip is then rewound to obtain a pre-annealed coil.

[0016] Step 5, Box furnace annealing: The pre-annealed coil obtained in step 4 is subjected to box furnace annealing to obtain the O-state finished product;

[0017] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece.

[0018] Furthermore, in step one, the heating conditions are: heating to 490~540℃ and holding at that temperature for 2 hours.

[0019] Furthermore, in step one, the hot rolling is carried out in multiple passes using one roughing mill and three finishing mills, with the roughing process consisting of 16 to 18 passes.

[0020] Furthermore, in step three, the cold rolling is carried out using a double-stand rolling mill with a total of two passes. The surface roughness Ra of the rolls used is 0.37~0.43μm, and the roll body crown is 0.3~0.35%.

[0021] Furthermore, in step four, the process parameters for continuous annealing are: annealing temperature 350~420℃, and the speed of the strip passing through the heating zone 15~28m / min.

[0022] Furthermore, in step four, within the heating zone of the air cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within the range of 20~40℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area.

[0023] Furthermore, in step five, the process for annealing the finished product in the box furnace is as follows: heating to 240~280℃ at a heating rate of ≤50℃ / h; holding at 240~280℃ for 4~8 hours; and then cooling with the furnace to below 150℃ before being removed from the furnace.

[0024] Furthermore, the temperature T2 for the box furnace annealing of the finished product in step five and the temperature T1 for the preheating treatment in step two satisfy the following condition: 120 ≤ (T2 - T1) ≤ 160. This temperature difference range helps to more effectively eliminate the microstructure features introduced by the preheating treatment during the finished product annealing stage, and promotes more complete and uniform recrystallization and stress relief, thereby obtaining more stable and superior O-state comprehensive properties.

[0025] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0026] 1. The method for preparing high-performance 1060-O state aluminum alloy connecting pieces provided by the present invention optimizes and integrates the entire process of "hot rolling - preheating treatment - cold rolling - air cushion continuous annealing - box furnace finished product annealing", and innovatively adopts a two-stage annealing system of "air cushion furnace + box furnace", which has achieved remarkable results.

[0027] 2. The product of this invention possesses excellent and stable mechanical properties, the key to which lies in the introduction of preheating treatment after hot rolling: by holding at 120~160℃, the trace amounts of Fe and Si elements dissolved in the hot-rolled material are further diffused and segregated towards defects such as dislocations and subgrain boundaries, and the existing fine AlFeSi phase particles in the matrix are more evenly distributed. These evenly distributed solute segregation regions or fine second-phase particles have a dual function: on the one hand, they can serve as uniform nucleation cores, ensuring that subsequent recrystallization yields a fine equiaxed crystal structure; on the other hand, by maintaining a specific temperature difference between the preheating temperature and the finished product annealing temperature, a smooth transition and stabilization of the microstructure is achieved during the final heat treatment, which can both assist in pinning grain boundaries and stabilizing the microstructure, and avoid over-strengthening.

[0028] Air-cushion continuous annealing, as an intermediate annealing process, can quickly and uniformly eliminate cold rolling work hardening and complete recrystallization, laying the foundation for the high plasticity of the product. The subsequent box furnace finishing annealing uses low-temperature time heat treatment to completely eliminate internal stress and stabilize the microstructure, thereby ensuring that the product obtains low and stable yield strength.

[0029] The three processes mentioned above work together to optimize and match the tensile strength, yield strength and elongation of the product, fully meeting the stringent performance requirements of the power battery connector.

[0030] 3. This invention offers high production efficiency and excellent product consistency. Compared to traditional single-box furnace annealing, this invention moves the recrystallization process to a continuously operating air cushion furnace, significantly shortening the overall production cycle and dramatically improving efficiency. Simultaneously, preheating optimizes the initial microstructure, and the dynamic, uniform heating of the air cushion furnace combined with the overall stabilization treatment of the box furnace effectively solves the problems of uneven product performance and poor plate shape associated with traditional processes, resulting in superior consistency and quality stability.

[0031] 4. The process parameters of this invention have been precisely optimized, resulting in high reproducibility. The ranges of key parameters such as preheating temperature and time, air cushion furnace annealing temperature, and box furnace annealing temperature determined in this invention, as well as their interrelationships (temperature difference control between T2 and T1), ensure the acquisition of an ideal O-state microstructure. Practice has proven that deviations from these ranges will directly lead to performance failures, thus ensuring the industrial feasibility and excellent reproducibility of this method.

[0032] In summary, this invention not only ensures high product performance but also boasts outstanding advantages such as high efficiency, high consistency, and high reliability. Attached Figure Description

[0033] Figure 1 This is a metallographic diagram of the high-performance 1060-O state aluminum alloy connecting piece obtained in Example 1 of the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Fabrication of 1.5mm thick 1060-O state aluminum alloy connecting pieces

[0037] Step 1: Preparation of hot-rolled coil: Heat 1060 alloy flat ingots to 500℃ and hold for 2 hours, then hot roll; hot rolling is carried out by one roughing mill and three finishing mills in multiple passes, and the final rolling temperature is controlled at 330℃ to obtain a hot-rolled coil with a thickness of 6.5mm.

[0038] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 140°C at a rate of 40°C / hour, and hold it at 140°C for 6.5 hours, then air cool to room temperature;

[0039] Step 3: Preparation of cold-rolled coil: The preheated hot-rolled coil is cold-rolled; the cold rolling is carried out using a two-stand rolling mill with a total of 2 passes; a cold-rolled coil with a thickness of 1.5 mm is obtained.

[0040] Step 4, Air-cushion continuous annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unfolded into a strip in an air-cushion furnace. The strip is then cleaned, continuously annealed, and straightened. The process parameters for continuous annealing are: annealing temperature 380℃, strip speed through the heating zone 22m / min; within the heating zone of the air-cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within 25℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area; then the treated strip is rewound to obtain a pre-annealed coil.

[0041] Step 5, Box furnace annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing. The process is as follows: heating to 260℃ at a heating rate of 45℃ / h; holding at 260℃ for 6 hours; then cooling in the furnace to below 150℃ to obtain the O-state finished product; wherein the difference between the finished annealing temperature T2 (260℃) and the preheating temperature T1 (140℃) (T2-T1) is 120℃, which meets the requirement of 120≤(T2-T1)≤160.

[0042] Metallographic analysis of the obtained O-state product was performed, and the results are as follows: Figure 1 As shown. From Figure 1As can be seen, a uniform and fine equiaxed recrystallized grain structure has formed inside the material, with clear and complete grain boundaries. This microstructure indicates that, through the preparation method of this invention, the work-hardened structure after cold rolling has been fully and uniformly transformed into a fully recrystallized softened structure, while the internal stress is effectively eliminated, thus laying a solid microstructural foundation for the product to obtain excellent mechanical properties (see Table 1).

[0043] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece with a thickness of 1.5mm.

[0044] Example 2

[0045] Fabrication of 1.2 mm thick 1060-O state aluminum alloy connecting pieces

[0046] Step 1: Preparation of hot-rolled coil: Heat 1060 alloy flat ingots to 495℃ and hold for 2 hours, then hot roll. Control the final rolling temperature at 325℃ to obtain a hot-rolled coil with a thickness of 6.0 mm;

[0047] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 130°C at a rate of 35°C / hour, and hold it at 130°C for 7 hours, then air cool to room temperature;

[0048] Step 3: Preparation of cold-rolled coil: The preheated hot-rolled coil is cold-rolled; the cold rolling is carried out using a two-stand rolling mill with a total of 2 passes; a cold-rolled coil with a thickness of 1.2 mm is obtained;

[0049] Step 4, Air-cushion continuous annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unfolded into a strip in an air-cushion furnace. The strip is then cleaned, continuously annealed, and straightened. The process parameters for continuous annealing are: annealing temperature 360℃, strip speed through the heating zone 18m / min; within the heating zone of the air-cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within 30℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area; then the treated strip is rewound to obtain a pre-annealed coil.

[0050] Step 5, Box furnace annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing; the process is as follows: heating to 250°C at a heating rate of 40°C / h; holding at 250°C for 5 hours; then cooling in the furnace to below 150°C and exiting the furnace to obtain the O-state finished product; wherein the difference between T2 (250°C) and T1 (130°C) is 120°C;

[0051] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece with a thickness of 1.2mm.

[0052] Example 3

[0053] Fabrication of 2.0 mm thick 1060-O state aluminum alloy connecting pieces

[0054] Step 1: Preparation of hot-rolled coil: Heat 1060 alloy flat ingots to 510℃ and hold for 2 hours, then hot roll. Control the final rolling temperature at 335℃ to obtain a hot-rolled coil with a thickness of 7.0 mm;

[0055] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 150°C at a rate of 45°C / hour, and hold it at 150°C for 5.5 hours, then air cool to room temperature;

[0056] Step 3: Preparation of cold-rolled coil: The preheated hot-rolled coil is cold-rolled. Cold rolling is performed using a two-stand mill with two passes; a cold-rolled coil with a thickness of 2.0 mm is obtained.

[0057] Step 4, Air-cushion continuous annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unfolded into a strip in an air-cushion furnace. The strip is then cleaned, continuously annealed, and straightened. The process parameters for continuous annealing are: annealing temperature 400℃, strip speed through the heating zone 25m / min; within the heating zone of the air-cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within 20℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area; then the treated strip is rewound to obtain a pre-annealed coil.

[0058] Step 5, Box Furnace Annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing. The process is as follows: heating to 270℃ at a heating rate of 50℃ / h; holding at 270℃ for 7 hours; then cooling in the furnace to below 150℃ to obtain the O-state finished product. The difference between T2 (270℃) and T1 (150℃) is 120℃.

[0059] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece with a thickness of 2.0mm.

[0060] Example 4

[0061] Fabrication of 1.8 mm thick 1060-O state aluminum alloy connecting pieces

[0062] Step 1: Preparation of hot-rolled coil: Heat 1060 alloy flat ingot to 520℃ and hold for 2 hours, then hot roll; control the final rolling temperature at 340℃ to obtain a hot-rolled coil with a thickness of 6.8mm;

[0063] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 120°C at a rate of 50°C / hour, and hold it at 120°C for 5 hours, then air cool to room temperature;

[0064] Step 3: Preparation of cold-rolled coil: The preheated hot-rolled coil is cold-rolled; the cold rolling is carried out using a two-stand rolling mill with a total of 2 passes; a cold-rolled coil with a thickness of 1.8 mm is obtained.

[0065] Step 4, Air-cushion continuous annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unfolded into a strip in an air-cushion furnace. The strip is then cleaned, continuously annealed, and straightened. The process parameters for continuous annealing are: annealing temperature 370℃, strip speed through the heating zone 20m / min; within the heating zone of the air-cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within 35℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area; then the treated strip is rewound to obtain a pre-annealed coil.

[0066] Step 5, Box furnace annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing; the process is as follows: heating to 280℃ at a heating rate of 42℃ / h; holding at 280℃ for 4.5 hours; then cooling in the furnace to below 150℃ to obtain the O-state finished product; wherein the difference between T2 (280℃) and T1 (120℃) is 160℃, which satisfies the requirement of 120≤(T2-T1)≤160;

[0067] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece with a thickness of 1.8mm.

[0068] Example 5

[0069] Fabrication of 1.0 mm thick 1060-O state aluminum alloy connecting pieces

[0070] Step 1: Preparation of hot-rolled coil: Heat 1060 alloy flat ingots to 490℃ and hold for 2 hours, then hot roll. Control the final rolling temperature at 320℃ to obtain a hot-rolled coil with a thickness of 6.2 mm;

[0071] Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 125°C at a rate of 30°C / hour, and hold it at 125°C for 8 hours, then air cool to room temperature;

[0072] Step 3: Preparation of cold-rolled coil: The preheated hot-rolled coil is cold-rolled; the cold rolling is carried out using a two-stand rolling mill with a total of 2 passes; a cold-rolled coil with a thickness of 1.0 mm is obtained;

[0073] Step 4, Air-cushion Continuous Annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unrolled into a strip in an air-cushion furnace. The strip is then cleaned, continuously annealed, and straightened. The continuous annealing process parameters are: annealing temperature 390℃, strip speed through the heating zone 16m / min; within the air-cushion furnace heating zone, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within 40℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area; the treated strip is then rewound to obtain a pre-annealed coil.

[0074] Step 5, Box furnace annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing; the process is as follows: heating to 265℃ at a heating rate of 48℃ / h; holding at 265℃ for 8 hours; then cooling in the furnace to below 150℃ to obtain the O-state finished product; wherein the difference between T2 (265℃) and T1 (125℃) is 140℃, which meets the requirement of 120≤(T2-T1)≤160;

[0075] Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece with a thickness of 1.0mm.

[0076] To illustrate the technical effects of this invention, the inventors set up comparative examples and conducted performance tests as follows:

[0077] Comparative Example 1:

[0078] The steps of Comparative Example 1 are basically the same as those of Example 1, except that the preheating treatment and air cushion furnace annealing are missing. Specifically:

[0079] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1;

[0080] Step 2, Preheating: This step is omitted; the hot-rolled coil is directly air-cooled to room temperature;

[0081] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0082] Step 4, Air Cushion Continuous Annealing: This step is omitted;

[0083] Step 5, box furnace annealing of finished products: exactly the same as in Example 1 (heating to 260°C at 45°C / h and holding for 6 hours).

[0084] Step 6: Finished product cutting: exactly the same as in Example 1.

[0085] Comparative Example 2

[0086] The steps of Comparative Example 2 are basically the same as those of Example 1, except that the box furnace annealing of the finished product is missing. Specifically:

[0087] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1;

[0088] Step 2, Preheating treatment: exactly the same as in Example 1;

[0089] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0090] Step 4, Air-cushion continuous annealing: exactly the same as in Example 1 (annealing temperature 380°C);

[0091] Step 5, Box furnace annealing: This step is omitted; products rolled up after air cushion furnace annealing are directly used as finished products.

[0092] Step 6: Finished product cutting: exactly the same as in Example 1.

[0093] Comparative Example 3

[0094] The steps of Comparative Example 3 are basically the same as those of Example 1, except that the annealing temperature of the air cushion furnace is too high. Specifically:

[0095] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1;

[0096] Step 2, Preheating treatment: exactly the same as in Example 1;

[0097] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0098] Step 4, Air-cushion continuous annealing: Increase the annealing temperature to 430℃ (exceeding the range of 350-420℃), and other parameters are the same as in Example 1;

[0099] Step 5, Annealing of finished products in a box furnace: exactly the same as in Example 1;

[0100] Step 6: Finished product cutting: exactly the same as in Example 1.

[0101] Comparative Example 4

[0102] The steps in Comparative Example 4 are basically the same as those in Example 1, except that the annealing temperature in the box furnace is too low. Specifically:

[0103] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1;

[0104] Step 2, Preheating treatment: exactly the same as in Example 1;

[0105] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0106] Step 4, Air-cushion continuous annealing: exactly the same as in Example 1;

[0107] Step 5, box furnace annealing of finished products: reduce the annealing temperature to 230℃ (below the range of 240-280℃) and extend the holding time to 10 hours. At this time, the difference between T2 (230℃) and T1 (140℃) is 90℃, which does not meet the requirement of 120≤(T2-T1)≤160.

[0108] Step 6: Finished product cutting: exactly the same as in Example 1.

[0109] Comparative Example 5

[0110] Comparative Example 5 uses a traditional full-process box furnace annealing process. Details are as follows:

[0111] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1;

[0112] Step 2, Preheating: This step is omitted.

[0113] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0114] Step 4: Continuous annealing without air cushion; cold-rolled coils are directly loaded into a box furnace.

[0115] Step 5, Box furnace annealing of finished products: The traditional O-state annealing process is adopted: heating to 380℃ at a heating rate of ≤50℃ / h, holding for 17 hours, and then cooling with the furnace;

[0116] Step 6: Finished product cutting: exactly the same as in Example 1.

[0117] Comparative Example 6

[0118] The steps of Comparative Example 6 are basically the same as those of Example 1, except that the difference between the preheating temperature and the finished product annealing temperature is too large. Specifically:

[0119] Step 1: Preparation of hot-rolled coils: exactly the same as in Example 1.

[0120] Step 2, Preheating treatment: Set the preheating temperature to 110℃, and the holding time is the same as in Example 1, then air cool to room temperature;

[0121] Step 3: Preparation of cold-rolled coils: exactly the same as in Example 1;

[0122] Step 4, Air-cushion continuous annealing: exactly the same as in Example 1;

[0123] Step 5, box furnace annealing of finished products: The annealing temperature of the finished products is set to 290℃, and the holding time is the same as in Example 1. At this time, the difference between T2 (290℃) and T1 (110℃) is 180℃.

[0124] Step 6: Finished product cutting: exactly the same as in Example 1.

[0125] Experimental Example

[0126] Performance testing

[0127] Tensile strength, yield strength, and elongation were tested according to GB / T228.1-2021 standard. Detailed performance test results for each embodiment and comparative example are shown in Table 1.

[0128] Table 1 Comparison of Performance Test Results

[0129]

[0130] Note: The required performance range is: tensile strength 70~90MPa, yield strength 20~40MPa, elongation 35~48%.

[0131] Results Analysis

[0132] As can be clearly seen from the data in Table 1, the mechanical properties of Examples 1 to 5, which strictly follow the process route of this invention, all fall within the target range, exhibiting stable low strength and high elongation, and fully meeting the performance requirements of the 1060-O state connecting piece.

[0133] Comparative analysis revealed that the product performance of Comparative Example 1 (lacking preheating and air-cushion continuous annealing) and Comparative Example 2 (lacking box furnace annealing) deviated significantly from the requirements. The former exhibited excessively high strength and severely insufficient plasticity, while the latter had excessively high yield strength and poor plasticity. This directly demonstrates that preheating, air-cushion annealing, and box furnace annealing play different but indispensable roles in the process, working synergistically and none can be omitted. Preheating optimizes the microstructure after hot rolling; air-cushion annealing is mainly responsible for rapid recrystallization to eliminate work hardening; while box furnace annealing focuses on thoroughly eliminating internal stress and stabilizing the microstructure at a suitable temperature (maintaining a specific temperature difference from the preheating temperature), collectively ensuring that the final product achieves excellent O-state properties.

[0134] Furthermore, the results of Comparative Examples 3, 4, and 6 reveal the importance of the range of key process parameters and their interrelationships. When the annealing temperature in the air cushion furnace is too high (430℃), excessive grain coarsening occurs, resulting in low strength and elongation below the standard requirements, leading to substandard performance. When the annealing temperature in the box furnace is too low (230℃) or the difference between the annealing temperature and the preheating temperature (T2-T1) does not meet the requirements (90℃ in Comparative Example 4, and 180℃ in Comparative Example 6), an ideal performance combination cannot be obtained, manifesting as either excessively high yield strength and insufficient elongation, or uncoordinated overall performance. The results of Comparative Example 6 show that when the difference between (T2-T1) is too large (180℃), the yield strength of the finished product exceeds the upper limit, while the elongation is severely insufficient, resulting in substandard overall performance. This demonstrates that controlling (T2-T1) within the range of 120~160℃ is crucial for obtaining the synergistic effect of low yield strength and high elongation.

[0135] Finally, Comparative Example 5 uses traditional single box furnace annealing. Although its product performance meets the standards, as mentioned above, this process has inherent disadvantages such as low production efficiency and poor consistency. (The strip in Comparative Example 5 involves multiple stages, including slow heating to 380°C at a rate of ≤50°C / h, long-term holding for 17 hours, slow cooling to a safe temperature in the furnace, and unloading from the furnace. A complete annealing cycle takes about 40 hours, while Example 1 only requires heating to 240~280°C and holding for 6 hours, which greatly reduces the required heat energy. The heating and cooling time in the furnace is only about 18 hours, and the equipment occupancy time is less. This overcomes the bottleneck of low production efficiency caused by the limited volume and loading capacity of the box furnace, which makes it difficult to match the high-speed rolling rhythm.) This highlights the significant advantages of the "preheating treatment + air cushion furnace + box furnace" combination scheme adopted in this invention, which ensures high performance while also having high efficiency and high consistency.

[0136] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A method for preparing a high-performance 1060-O state aluminum alloy connecting piece, characterized in that, Includes the following steps: Step 1: Preparation of hot-rolled coils: Heat 1060 alloy flat ingots and then hot-roll them, controlling the final rolling temperature at 320~340℃ to obtain hot-rolled coils with a thickness of 6.0~7.0mm; Step 2, Preheating treatment: Cool the hot-rolled coil obtained in Step 1 to 120~160℃ at a rate of 30-50℃ / hour, and keep it at 120~160℃ for 5~8 hours, then air cool to room temperature; Step 3: Preparation of cold-rolled coils: The preheated hot-rolled coils are cold-rolled to obtain cold-rolled coils with a thickness of 1.0~2.0mm; Step 4, Air-cushion continuous annealing: After cooling the cold-rolled coil to ≤50℃, it is dynamically unrolled in an air-cushion furnace to form a strip. The strip is then cleaned, continuously annealed, and straightened. The treated strip is then re-wound to obtain a pre-annealed coil. The process parameters for continuous annealing are: annealing temperature 350~420℃, strip speed through the heating zone 15~28m / min; within the heating zone of the air-cushion furnace, the overall average temperature difference between the upper and lower surface areas of the strip is controlled within the range of 20~40℃, and the average temperature of the upper surface area is not lower than the average temperature of the lower surface area. Step 5, Box Furnace Annealing: The pre-annealed coil obtained in Step 4 is subjected to box furnace annealing to obtain an O-state finished product. The process of box furnace annealing is as follows: heating to 240~280℃ at a heating rate of ≤50℃ / h, holding at 240~280℃ for 4~8 hours; then cooling in the furnace to below 150℃ before being removed from the furnace. The temperature T2 of box furnace annealing and the temperature T1 of preheating treatment in Step 2 satisfy: 120≤(T2-T1)≤160. Step 6: Finished product slitting: The O-state finished product is slitting to obtain the high-performance 1060-O-state aluminum alloy connecting piece.

2. The method according to claim 1, characterized in that, In step one, the heating conditions are: heating to 490~540℃ and holding at that temperature for 2 hours.

3. The method according to claim 1, characterized in that, In step one, the hot rolling process is carried out using one roughing mill and three finishing mills in multiple passes, with the roughing process consisting of 16 to 18 passes.

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