Thermomechanical treatment method for improving comprehensive performance of 6xxx aluminum alloy coiled material containing Cu element and aluminum alloy coiled material

Abstract

The invention discloses a thermomechanical treatment method for improving the comprehensive performance of a 6xxx aluminum alloy coiled material containing the Cu element and the aluminum alloy coiled material, and belongs to the technical field of aluminum alloy manufacturing, the method comprises the following procedures of fusion casting, homogenization heat treatment, gradient cooling rolling, solid solution quenching, low-temperature rolling and aging treatment, the production process is optimized, and the overall performance of the 6xxx aluminum alloy coiled material containing the Cu element is improved. According to the method, the distribution and the size of precipitated phases are regulated, the microstructure and the mechanical property of the aluminum alloy are improved, the excellent mechanical property is maintained while high-content copper is added, the mechanical strength and the ductility of a product are improved, the anisotropy of the material is reduced, meanwhile, the process steps are shortened, annealing and secondary cold rolling are not needed, energy consumption is reduced, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy manufacturing, and in particular to a thermomechanical treatment method for improving the comprehensive performance of 6xxx aluminum alloy coils containing Cu element and an aluminum alloy coil. Background Art

[0002] The lightweight of the battery pack can improve the energy density, and it is also an effective method for new energy vehicles to increase the cruising range. The battery pack bottom plate requires the material to have high strength and good stamping formability, adapt to processing technologies such as bending and SPR, have good corrosion resistance, and meet the design requirements of automotive safety and durability. The development and application of new high-strength aluminum alloy products play an important role in promoting the development of new energy vehicles.

[0003] 6xxx aluminum alloy has become the preferred material for the battery pack bottom plate due to its excellent extrusion performance. The copper content of 6xxx aluminum alloy is generally below 0.3%. On the basis of maintaining the good weldability, corrosion resistance and formability of 6xxx aluminum alloy, the strength and hardness of the alloy are significantly improved by adding copper element, which is suitable for application scenarios with higher performance requirements. However, the 6xxx aluminum alloy containing copper element in the traditional process has certain limitations: in order to ensure the mechanical strength, certain corrosion resistance, electrical and thermal conductivity, the process flow is often complex, the production cycle is long, the efficiency is low, and the energy consumption is high. A preparation method of a homogenized and heat-separated 6xxx aluminum alloy coil with the application number of CN202210878837.0 cannot meet the preparation of 6xxx high-strength aluminum alloy with a higher copper content, and requires two cold rolling processes and intermediate annealing, with a long process cycle and high energy consumption. This method mainly considers the optimization of mechanical properties before baking, and there are limitations in the application under high-strength state after baking.

[0004] Based on this, it is expected to explore a thermomechanical treatment method for improving the comprehensive performance of 6xxx aluminum alloy coils containing Cu element, which can improve the microstructure and mechanical properties, maintain excellent mechanical properties while adding a higher content of copper element, reduce material anisotropy, and at the same time reduce energy consumption and improve production efficiency. Summary of the Invention

[0005] Aiming at the above deficiencies, the present invention provides a thermomechanical treatment method for improving the comprehensive performance of 6xxx aluminum alloy coils containing Cu element and an aluminum alloy coil, which can achieve excellent mechanical properties. The obtained product has a tensile strength ≥ 400 MPa, a yield strength ≥ 350 MPa, an elongation ≥ 12%, and the 90° bending of the 1.5T bending radius in the transverse and longitudinal directions does not crack. At the same time, it reduces energy consumption and improves production efficiency. The specific technical solutions are as follows: A thermomechanical treatment method for improving the comprehensive performance of 6xxx aluminum alloy coils containing Cu element, comprising the following steps: S1. Casting: The aluminum alloy raw materials are cast to obtain ingots. S2. Homogenization heat treatment: The ingots obtained in step S1 are cut at both ends, milled on the surface, and then subjected to homogenization heat treatment to obtain homogenized heat-treated ingots. S3. Gradient cooling rolling: The homogenized heat-treated ingots obtained in step S2 are directly subjected to gradient cooling rolling, controlling the cooling rate after each pass of rolling to be 20 - 50 °C / min, the final rolling temperature < 200 °C, the total rolling reduction rate > 90%, and the number of rolling passes < 20 to obtain gradient cooling rolled coils. S4. Solution quenching: The gradient cooling rolled coils obtained in step S3 are subjected to solution quenching to obtain solution quenched coils. S5. Cold rolling: The solution quenched coils obtained in step S4 are subjected to cold rolling to obtain cold rolled coils. S6. Aging treatment: The cold rolled coils obtained in step S5 are subjected to aging treatment to obtain finished aluminum alloy coils. The mass percentages of the chemical components of the aluminum alloy are as follows: Si = 0.6 - 1.5%, Fe ≤ 0.3%, Cu = 0.4 - 1.2%, Mn = 0.4 - 0.8%, Mg = 0.6 - 1.5%, Cr ≤ 0.25%, Zn ≤ 0.3%, Ti ≤ 0.1%, and the balance is Al and unavoidable impurity elements.

[0006] Preferably, the holding temperature of the homogenization heat treatment is 530 - 560 °C, and the holding time is 6 - 12 h.

[0007] Preferably, the holding temperature of the solution quenching is 540 - 570 °C, and the holding time is 0.2 - 1 h.

[0008] Preferably, the cold rolling temperature is 0 - 20 °C, the pass reduction rate is 2 - 20%, and the number of rolling passes > 2.

[0009] Preferably, the aging treatment temperature is 190 - 230 °C, and the holding time is 3 - 10 h.

[0010] Preferably, in the solution quenching step, the cooling rate > 50 °C / s.

[0011] The present invention also provides a 6xxx aluminum alloy coil containing Cu element prepared by the above method.

[0012] The properties of the 6xxx aluminum alloy coil containing Cu element of the present invention meet: Tensile strength ≥ 400 MPa, yield strength ≥ 350 MPa, elongation ≥ 12%, and no cracking occurs during 90° bending with a bending radius of 1.5T in both transverse and longitudinal directions.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element provided by the present invention includes the following processes: melting and casting, homogenization heat treatment, gradient cooling rolling, solution quenching, cold rolling at low temperature, and aging treatment. The production process is optimized, and the average size of dispersed phases such as Al2Cu2Mn3 is controlled to be <1 μm, and the average size of precipitation phases such as β (Mg2Si), S (Al2CuMg), Q (Al5Cu2Mg8Si6), and θ (Al2Cu) is <500 nm. The second phases are uniformly distributed in the crystal grains and grain boundaries. It improves the microstructure and mechanical properties of the aluminum alloy, maintains excellent mechanical properties while adding a relatively high content of copper element, improves the mechanical strength and elongation of the product, reduces the anisotropy of the material, and at the same time shortens the process steps, without annealing and without secondary cold rolling, reducing energy consumption and improving production efficiency.

[0014] 2. Through the combination of homogenization treatment and gradient cooling rolling in the present invention, the low-melting-point elements in the primary phase are effectively redissolved, the atomic solid solubility is controlled, and the growth of dispersed phases is avoided. The gradient cooling rolling process effectively breaks the second phases and promotes redissolution, making the distribution of precipitation phases more uniform during the subsequent solution quenching and aging processes. After gradient cooling rolling, it enters the solution quenching step without annealing. After solution quenching, cold rolling at low temperature is carried out, effectively increasing the matrix energy storage and increasing lattice defects such as dislocations, which is beneficial to uniformly and rapidly nucleate during the low-temperature and short-time aging process and grow to obtain a certain number and size of precipitation phases.

[0015] 3. Through the implementation of this solution, the obtained product has a tensile strength ≥ 400 MPa, a yield strength ≥ 350 MPa, an elongation ≥ 12%, and does not crack during 90° bending with a bending radius of 1.5T in the transverse and longitudinal directions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 is the process flow schematic diagram of the present invention; Figure 2 is the schematic diagram of the microstructure of the finished aluminum alloy coil of Example 1 of the present invention; Figure 3 is the schematic diagram of the tensile fracture of the finished aluminum alloy coil of Example 1 of the present invention; among them, there is dimple fracture in cleavage fracture. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The specific embodiments of the present invention will be described in detail below, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments. Unless otherwise defined, all the technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0019] Referring to Figure 1 , the process flow of the embodiment of the present invention includes: subjecting the ingot formed by melting and casting aluminum alloy raw materials to homogenization heat treatment at 530 - 560 °C for 6 - 12 h, then directly performing gradient cooling rolling, then heating to 540 - 570 °C for solution quenching for 0.2 - 1 h, cooling after solution quenching is completed, performing cold rolling, and heating after cold rolling is completed for aging treatment at 190 - 230 °C for 3 - 10 h.

[0020] Example 1 The mass percentages of the chemical components of the aluminum alloy in this example are: Si = 1.4%, Fe = 0.2%, Cu = 1.2%, Mn = 0.6%, Mg = 0.9%, Cr = 0.20%, Zn = 0.2%, Ti = 0.05%, and the balance is Al and inevitable impurity elements.

[0021] A thermomechanical treatment method for improving the comprehensive performance of 6xxx aluminum alloy coils containing Cu element in this example includes the following steps: S1. Melting and casting: Melting and casting aluminum alloy raw materials to obtain an ingot; S2. Homogenization heat treatment: Cutting the head and tail and milling the surface of the ingot obtained in step S1, and then performing homogenization heat treatment. The holding temperature of the homogenization heat treatment is 545 °C, and the holding time is 9 h to obtain the ingot after homogenization heat treatment; S3. Gradient cooling rolling: Directly performing gradient cooling rolling on the ingot after homogenization heat treatment obtained in step S2, controlling the cooling rate after each rolling pass to be 20 - 25 °C / min, the final rolling temperature to be 130 °C, the total rolling reduction to be 93%, and the number of rolling passes to be 19 to obtain gradient cooling rolled coils; S4. Solution quenching: Performing solution quenching on the gradient cooling rolled coils obtained in step S3, with the holding temperature of 550 °C and the holding time of 0.6 h to obtain solution quenched coils; S5. Cold rolling: Performing cold rolling on the solution quenched coils obtained in step S4, with the rolling temperature of 0 - 10 °C, the pass reduction of 10%, and the number of rolling passes of 3 to obtain cold rolled coils; S6. Aging treatment: The cold-rolled coil obtained in step S5 is subjected to aging treatment at a temperature of 210°C for 6 hours, and then cooled to obtain the finished aluminum alloy coil.

[0022] Figure 2 is a schematic diagram of the microstructure of the finished aluminum alloy coil obtained through Example 1 of the present invention. It can be seen that there are a large number of dislocation tangles and dislocation cells inside the grains, mostly near the dispersed phases with larger sizes, and new dispersed phases precipitate near the dislocations. All these characteristics indicate that the mechanical properties of the coil have been strengthened; Figure 3 is a schematic diagram of the tensile fracture surface of the finished aluminum alloy coil obtained through Example 1 of the present invention. It can be seen that the fracture mode is mainly cleavage fracture, and there are dimples of different sizes. Cleavage fracture indicates that there is brittle fracture during the tensile process of the material, while dimple fracture indicates that there is ductile fracture during the tensile process of the material. The simultaneous occurrence of these two fractures indicates that the material exhibits dual characteristics of brittleness and ductility during the fracture process, and the bending ability is improved.

[0023] Example 2 The mass percentages of the chemical components of the aluminum alloy in this example are: Si = 0.8%, Fe = 0.2%, Cu = 0.5%, Mn = 0.5%, Mg = 0.7%, Cr = 0.23%, Zn = 0.2%, Ti = 0.06%, and the balance is Al and inevitable impurity elements.

[0024] A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element in this example includes the following steps: S1. Melting and casting: The aluminum alloy raw materials are melted and cast to obtain an ingot; S2. Homogenization heat treatment: The ingot obtained in step S1 is cut at both ends, milled on the surface, and then subjected to homogenization heat treatment at a holding temperature of 530°C for 12 hours to obtain the homogenized heat-treated ingot; S3. Gradient cooling rolling: The homogenized heat-treated ingot obtained in step S2 is directly subjected to gradient cooling rolling, controlling the cooling rate after each rolling pass to be 30 - 45°C / min, the final rolling temperature to be 100°C, the total rolling reduction to be 91%, and the number of rolling passes to be 14 to obtain the gradient cooling rolled coil; S4. Solution quenching: The gradient cooling rolled coil obtained in step S3 is subjected to solution quenching at a holding temperature of 540°C for 1 hour to obtain the solution quenched coil; S5. Cold rolling: The solution quenched coil obtained in step S4 is subjected to cold rolling at a rolling temperature of 0 - 10°C, with a per-pass reduction of 20% and the number of rolling passes of 4 to obtain the cold rolled coil; S6. Aging treatment: The cold-rolled coil obtained in step S5 is subjected to aging treatment at a temperature of 190°C for 10 hours, and then cooled to obtain the finished aluminum alloy coil.

[0025] Example 3 The mass percentages of the chemical components of the aluminum alloy in this example are: Si = 1.2%, Fe = 0.3%, Cu = 1.0%, Mn = 0.8%, Mg = 1.5%, Cr = 0.10%, Zn = 0.1%, Ti = 0.09%, and the balance is Al and unavoidable impurity elements.

[0026] A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element in this example includes the following steps: S1. Melting and casting: The aluminum alloy raw materials are melted and cast to obtain an ingot. S2. Homogenization heat treatment: The ingot obtained in step S1 is cut at both ends, milled on the surface, and then subjected to homogenization heat treatment at a holding temperature of 560°C for 6 hours to obtain the homogenized ingot. S3. Gradient cooling rolling: The homogenized ingot obtained in step S2 is directly subjected to gradient cooling rolling, controlling the cooling rate after each rolling pass to be 25 - 45°C / min, the final rolling temperature to be 150°C, the total rolling reduction to be 95%, and the number of rolling passes to be 15 to obtain the gradient cooling rolled coil. S4. Solution quenching: The gradient cooling rolled coil obtained in step S3 is subjected to solution quenching at a holding temperature of 570°C for 0.2 hours to obtain the solution quenched coil. S5. Cold rolling: The solution quenched coil obtained in step S4 is subjected to cold rolling at a rolling temperature of 5 - 15°C, with a pass reduction of 20% and the number of rolling passes being 3 to obtain the cold rolled coil. S6. Aging treatment: The cold rolled coil obtained in step S5 is subjected to aging treatment at a temperature of 230°C for 3 hours, and then cooled to obtain the finished aluminum alloy coil.

[0027] Comparative Example 1 The final hot rolling temperature in this comparative example is 250°C. The other processes are the same as those in Example 1.

[0028] Comparative Example 2 The mass percentages of the chemical components of the aluminum alloy in this comparative example are: Si = 1.4%, Fe = 0.2%, Cu = 1.2%, Mn = 0.6%, Mg = 0.9%, Cr = 0.20%, Zn = 0.2%, Ti = 0.05%.

[0029] A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element in this comparative example includes the following steps: S1. Melting and casting: Melting and casting aluminum alloy raw materials to obtain an ingot; S2. Homogenization heat treatment: Cutting the head and tail and milling the surface of the ingot obtained in step S1, and then performing homogenization heat treatment. The holding temperature for homogenization heat treatment is 540 °C, and the holding time is 3 h to obtain an ingot after homogenization heat treatment; S3. Gradient cooling rolling: Directly performing gradient cooling rolling on the ingot after homogenization heat treatment obtained in step S2. The final rolling temperature is 250 °C, and the total rolling reduction is 70% to obtain gradient cooling rolled coils; S4. First cold rolling: Performing room-temperature first cold rolling on the gradient cooling rolled coils obtained in step S3. The pass reduction is 10% to obtain first cold rolled coils; S5. Annealing: Annealing the first cold rolled coils obtained in step S4. The holding temperature is 450 °C, and the holding time is 0.2 - 1 h to obtain annealed coils; S6. Second cold rolling: Performing room-temperature second cold rolling on the annealed coils obtained in step S5. The pass reduction is 10% to obtain second cold rolled coils; S7. Solution quenching: Performing solution quenching on the second cold rolled coils obtained in step S6. The holding temperature is 550 °C, and the holding time is 0.6 h to obtain solution quenched coils; S8. Aging treatment: Performing aging treatment on the solution quenched coils obtained in step S7. The aging treatment temperature is 210 °C, and the holding time is 6 h, and then cooling to obtain the finished aluminum alloy coils.

[0030] The remaining processes are the same as those in Example 1.

[0031] Comparative Example 3 The mass percentages of the chemical components of the aluminum alloy in this comparative example are: Si = 1.5%, Fe = 0.2%, Cu = 0.8%, Mn = 0.5%, Mg = 0.9%, Cr = 0.18%, Zn = 0.1%, Ti = 0.05%.

[0032] The preparation method of the aluminum alloy in this comparative example includes the following steps: S1. Melting and casting: Melting and casting aluminum alloy raw materials to obtain an ingot; S2. Homogenization heat treatment: Cutting the head and tail and milling the surface of the ingot obtained in step S1, and then performing homogenization heat treatment. The holding temperature for homogenization heat treatment is 560 °C, and the holding time is 10 h to obtain an ingot after homogenization heat treatment; S3. Hot rolling: Directly performing hot rolling on the ingot after homogenization heat treatment obtained in step S2. The final rolling temperature is 310 °C, and the total rolling reduction is 70% to obtain hot rolled coils; S4. Cold rolling: Cold roll the hot-rolled coil obtained in step S3 with a total rolling reduction rate of 60% to obtain a cold-rolled coil; S5. Solution quenching: Perform solution quenching on the annealed coil obtained in step S4 at a holding temperature of 560 °C for a holding time of 0.6 h to obtain a solution-quenched coil; S8. Aging treatment: Perform aging treatment on the solution-quenched coil obtained in step S7 at an aging treatment temperature of 220 °C for a holding time of 3 h, and cool to obtain the finished aluminum alloy product.

[0033] Perform microstructure tests and performance tests on the finished aluminum alloy coil products of the examples and comparative examples.

[0034] The samples were electrochemically polished using an HNO3 + CH3OH solution, and the microstructure was observed using a Tecnai G2 F20 transmission electron microscope. The room-temperature tensile properties of the samples were tested, and the room-temperature tensile test was carried out in accordance with the requirements of GB / T 228.1-2021. The bending test was carried out using the three-point bending method.

[0035] The results are shown in Table 1 below.

[0036] Table 1 Performance test results of the finished aluminum alloy coil products of the examples and comparative examples In summary, a thermomechanical treatment method and aluminum alloy coil for improving the comprehensive properties of 6xxx aluminum alloy coil containing Cu element provided by the present invention include the following processes: melting and casting, homogenization heat treatment, gradient cooling rolling, solution quenching, cold rolling at low temperature, and aging treatment. The production process is optimized, and the average size of dispersed phases such as Al2Cu2Mn3 is controlled to be <1 μm, and the average size of precipitation phases such as β (Mg2Si), S (Al2CuMg), Q (Al5Cu2Mg8Si6), and θ (Al2Cu) is <500 nm. The second phase is evenly distributed in the grains and grain boundaries. The microstructure and mechanical properties of the aluminum alloy are improved, excellent mechanical properties are maintained, the mechanical strength and elongation of the product are increased, the anisotropy of the material is reduced, and at the same time, the process steps are shortened, annealing is not required, and secondary cold rolling is not required, reducing energy consumption and improving production efficiency. By combining homogenization treatment and gradient cooling rolling, the low-melting-point elements in the primary phase are effectively redissolved, the atomic solid solubility is controlled, and the growth of dispersed phases is avoided. The gradient cooling rolling process effectively breaks the second phase and promotes redissolution, making the precipitation phase distribution more uniform during the subsequent solution quenching and aging processes. After gradient cooling rolling, the solution quenching step is carried out without annealing. After solution quenching, cold rolling at low temperature is implemented to effectively increase the matrix energy storage and increase lattice defects such as dislocations, which is beneficial to uniform and rapid nucleation during the low-temperature and short-time aging process and grow to obtain a certain number and size of precipitation phases. Through the implementation of this solution, the obtained tensile strength is ≥400 MPa, the yield strength is ≥350 MPa, the elongation is ≥12%, and the 90° bending of the 1.5T bending radius in the transverse and longitudinal directions does not crack.

[0037] The foregoing description of the specific exemplary embodiments of the present invention is for the purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize the various different exemplary embodiments of the present invention, as well as various different selections and changes. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element, characterized in that, It includes the following steps: S1. Melting and casting: Melting and casting aluminum alloy raw materials to obtain ingots; S2. Homogenization heat treatment: Cutting the heads and tails and milling the surfaces of the ingots obtained in step S1, and then performing homogenization heat treatment to obtain homogenized heat-treated ingots; S3. Gradient cooling rolling: Directly performing gradient cooling rolling on the homogenized heat-treated ingots obtained in step S2, controlling the cooling rate after each rolling pass to be 20 - 50 °C / min, the final rolling temperature < 200 °C, the total rolling reduction rate > 90%, and the number of rolling passes < 20 to obtain gradient cooling rolled coils; S4. Solution quenching: Performing solution quenching on the gradient cooling rolled coils obtained in step S3 to obtain solution quenched coils; S5. Low-temperature rolling: Performing low-temperature rolling on the solution quenched coils obtained in step S4 to obtain low-temperature rolled coils; S6. Aging treatment: Performing aging treatment on the low-temperature rolled coils obtained in step S5 to obtain finished aluminum alloy coils; The mass percentages of the chemical components of the aluminum alloy are as follows: Si = 0.6 - 1.5%, Fe ≤ 0.3%, Cu = 0.4 - 1.2%, Mn = 0.4 - 0.8%, Mg = 0.6 - 1.5%, Cr ≤ 0.25%, Zn ≤ 0.3%, Ti ≤ 0.1%, and the balance is Al and inevitable impurity elements.

2. The thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element according to claim 1, wherein, The holding temperature of the homogenization heat treatment is 530 - 560 °C, and the holding time is 6 - 12 h.

3. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element according to claim 1, characterized in that, The holding temperature of the solution quenching is 540 - 570 °C, and the holding time is 0.2 - 1 h.

4. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element according to claim 1, characterized in that, The low-temperature rolling temperature is 0 - 20 °C, the pass reduction rate is 2 - 20%, and the number of rolling passes > 2.

5. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element according to claim 1, characterized in that, The aging treatment temperature is 190 - 230 °C, and the holding time is 3 - 10 h.

6. A thermomechanical treatment method for improving the comprehensive properties of 6xxx aluminum alloy coils containing Cu element according to claim 3, characterized in that, In the solution quenching step, the cooling rate > 50 °C / s.

7. A 6xxx aluminum alloy coil containing Cu element prepared by the method according to any one of claims 1 - 6.

8. The 6xxx aluminum alloy coil containing Cu element according to claim 7, characterized in that, Its properties meet the following: Tensile strength ≥ 400 MPa, yield strength ≥ 350 MPa, elongation ≥ 12%, and no cracking occurs during 90° bending with a 1.5T bending radius in both transverse and longitudinal directions.

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