Method for manufacturing copper-iron alloy strip for electrical connection terminals and electrical connection terminal

Abstract

The application relates to the technical field of copper alloy, in particular to a preparation method of a copper-iron alloy strip for an electrical connection terminal and the electrical connection terminal, which comprises the following steps: S1, heating: heating a semi-continuous cast copper-iron alloy; S2, hot rolling forming: repeatedly rolling, quenching and cooling after hot rolling, and coiling to form a hot-rolled blank; S3, rough rolling: rolling the hot-rolled blank to the thickness of a semi-finished product strip; S4, twice annealing: sequentially annealing the semi-finished product strip after rough rolling twice to eliminate work hardening and promote second phase precipitation; S5, finish rolling: cleaning the strip after the twice annealing, and then finish rolling; S6, stretch bending and straightening: cleaning the strip after the finish rolling, and then stretch bending and straightening to control the plate shape of a finished product. The application improves the surface quality of the strip, the internal organization is uniform and dense, and the comprehensive optimization of the copper-iron alloy strip in strength, electrical conductivity and corrosion resistance is realized through fine control of the processing procedures of hot rolling, rough rolling and finish rolling.

Description

Technical Field

[0001] This application relates to the field of copper alloy technology, and in particular to a method for preparing copper-iron alloy strip for electrical connection terminals and an electrical connection terminal. Background Technology

[0002] Currently, copper alloy strip is commonly used as the base material for electrical component connection terminals. Its application fields include information electronics, new energy vehicles, aerospace, and high-end equipment. Due to its unique structure, the connection terminal includes male and female terminals, which need to be plugged in to complete the transmission of electrical signals. Therefore, the fit between the male and female terminals must be reliable and facilitate maintenance, which requires that the insertion force between them not be too large or too small.

[0003] Existing processing technologies typically use ordinary copper or brass to produce electrical connection terminals through stamping. However, copper is relatively soft, has poor processing performance, insufficient insertion force during use, and inadequate corrosion resistance. While brass has better processing performance and corrosion resistance, its poor conductivity significantly impacts the transmission speed of electrical signals. Therefore, there is an urgent need for a manufacturing method that enables the production of copper-iron alloy strips for electrical connection terminals to meet the performance requirements of stable and suitable insertion force between the male and female terminals of connectors, good corrosion resistance, and high conductivity. Summary of the Invention

[0004] In order to enable the copper-iron alloy strip for electrical connection terminals to meet the performance requirements of stable and suitable insertion force between the male and female terminals of the connector, good corrosion resistance, and high conductivity, this application provides a method for preparing copper-iron alloy strip for electrical connection terminals and an electrical connection terminal.

[0005] The above-mentioned technical objective of this application is achieved through the following technical solution:

[0006] A method for preparing a copper-iron alloy strip for electrical connection terminals, using copper-iron alloy as raw material, includes the following steps:

[0007] S1. Heating: Heating the semi-continuously cast copper-iron alloy;

[0008] S2, Hot rolling: The copper-iron alloy heated by S1 is repeatedly rolled, and after hot rolling, it is quenched, cooled, and rolled to form a hot-rolled billet.

[0009] S3, Rough rolling: Rolling the hot-rolled billet of S2 to the thickness of the semi-finished strip;

[0010] S4. Two-stage annealing: The semi-finished strip after rough rolling is annealed twice in sequence to eliminate work hardening and promote the precipitation of the second phase;

[0011] S5. Finish rolling: After cleaning the strip that has undergone two annealing processes, it is finished rolled, and the finished product processing rate is controlled at 30%-50%.

[0012] S6. Stretch straightening: After cleaning the strip that has been precision rolled by S5, stretch straightening is performed to control the shape of the finished strip.

[0013] The specific processing steps using the above scheme are as follows: First, copper-iron alloy is used as raw material and obtained through a semi-continuous casting process. In step S1, the semi-continuously cast copper-iron alloy ingot is heated to homogenize the internal structure of the alloy and reduce the deformation resistance of the material, preparing it for subsequent hot working. In step S2, the heated copper-iron alloy is repeatedly rolled to achieve hot rolling. In step S3, the hot-rolled billet is rough-rolled to further reduce its thickness to the specifications of the semi-finished strip. In step S4, the rough-rolled semi-finished strip undergoes two annealing treatments. In step S5, the strip after two annealings is cleaned to remove surface oxides and stains, and then fine-rolled. In step S6, the fine-rolled strip is cleaned and then straightened by tension bending. By precisely controlling the hot rolling, rough rolling, and fine rolling processes, and optimizing the microstructure through two annealing processes, the prepared copper-iron alloy strip exhibits excellent electrical conductivity, achieving comprehensive optimization of the copper-iron alloy strip in terms of strength, electrical conductivity, and corrosion resistance. Compared to brass, which has poor conductivity, the copper-iron alloy strip of this application can ensure high-speed and efficient transmission of electrical signals, meeting the stringent conductivity requirements of modern electrical connection terminals.

[0014] Furthermore, in step S1, the semi-continuously cast copper-iron alloy is heated in a walking beam furnace, with the heating temperature controlled at 920℃-950℃ and the holding time controlled at 2.5h-3.5h.

[0015] Furthermore, in step S2, the copper-iron alloy heated in S1 is repeatedly rolled, with the final rolling temperature controlled at 580℃-600℃, and the thickness rolled to 15mm-18mm.

[0016] Furthermore, in step S3: rough rolling, the following steps are included:

[0017] S31. Milling: After the hot-rolled billet is cooled to ambient temperature, the oxide layer on the upper and lower surfaces and the left and right sides of the hot-rolled billet is removed. The total milling amount on the upper and lower surfaces is controlled between 1.2mm and 1.5mm.

[0018] S32, Rough rolling: The hot-rolled billet after milling in S31 is rolled by a rough rolling mill, with a processing rate of 90%-93%.

[0019] Furthermore, in step S4, the two annealing processes include the following steps:

[0020] S41. First annealing: The strip after rough rolling in S32 is placed in a bell-type annealing furnace for the first annealing, and the holding time is 6h-6.5h.

[0021] S42. Pickling: The strip after the first annealing in S41 is pickled in the cleaning line to remove the emulsion on the surface of the strip.

[0022] S43, Cold rolling: The strip after S42 pickling is processed to the required thickness using a cold rolling mill;

[0023] S44. Second annealing: After the S43 cold-rolled strip is re-wound and loosened by the cleaning line, it is placed in a bell-type annealing furnace for a second annealing, and the holding time is 6h-6.5h.

[0024] Furthermore, in the first annealing, the annealing temperature is 480℃-500℃;

[0025] In the second annealing, the annealing temperature is 460℃-480℃.

[0026] Furthermore, in step S5, after cleaning the strip that has undergone the second annealing in S44, it is rolled by a finishing mill, and the finished product processing rate is controlled at 35%-45%.

[0027] Furthermore, in step S6: tension bending and straightening, after the strip is cleaned after precision rolling in step S5, it is tension bending and straightened by a 23-roll strip straightener to control the final shape of the finished product.

[0028] Among them, the uncoiling tension of the tension straightening is 800 to 1000 times the thickness of the strip, in kg;

[0029] The winding tension for bending straightening is 1000 to 1200 times the thickness of the strip, in kg.

[0030] The elongation range of tension straightening is 0.2%–0.4%.

[0031] Furthermore, after step S6, the following is also included:

[0032] S7. Finished Product Inspection: Test the performance of the finished product after S6 treatment, and after keeping it at 460℃-480℃ for 3-5 minutes, test the Vickers hardness of the softened material.

[0033] Furthermore, an electrical connection terminal is provided with a copper-iron alloy strip prepared by the above-described method for preparing copper-iron alloy strips for electrical connection terminals;

[0034] The copper-iron alloy strip is C19210.

[0035] In summary, this application has the following technical effects:

[0036] 1. By precisely controlling the hot rolling, rough rolling, and finish rolling processes, and optimizing the microstructure through two annealing processes, the prepared copper-iron alloy strip exhibits excellent electrical conductivity, achieving comprehensive optimization in terms of strength, conductivity, and corrosion resistance. Compared to brass, which has poor conductivity, the copper-iron alloy strip of this application can ensure high-speed and efficient transmission of electrical signals, meeting the stringent conductivity requirements of modern electrical connection terminals.

[0037] 2. By introducing pickling and cold rolling as intermediate treatments between two annealing processes, work hardening can be eliminated more effectively, the uniform precipitation of the second phase can be promoted, and the surface quality of the strip can be significantly improved. Pickling ensures the smooth progress of the cold rolling process and the surface finish of the final product, while cold rolling provides additional deformation energy for the second annealing, making the recrystallization and precipitation process more complete and uniform. This refined processing flow results in copper-iron alloy strips with superior comprehensive mechanical and electrical properties, while significantly improving surface quality.

[0038] 3. By precisely controlling the unwinding tension, winding tension, and appropriate elongation, residual stress inside the strip can be effectively eliminated, and various shape defects can be corrected, thereby obtaining a copper-iron alloy strip with high flatness, low internal stress, and good dimensional stability. This ensures the reliability and durability of the electrical connection terminals during subsequent processing and use, avoiding performance degradation or premature failure caused by poor shape or excessive residual stress. Attached Figure Description

[0039] Figure 1 This is a flowchart of the method for preparing copper-iron alloy strip for electrical connection terminals according to this application;

[0040] Figure 2 This is a general flow chart of the method for preparing copper-iron alloy strip for electrical connection terminals according to this application;

[0041] Figure 3 This is a flowchart of the first embodiment of the method for preparing copper-iron alloy strip for electrical connection terminals of this application;

[0042] Figure 4 This is a flowchart of a second embodiment of the method for preparing copper-iron alloy strip for electrical connection terminals according to this application. Detailed Implementation

[0043] The present application will be further described in detail below with reference to the accompanying drawings.

[0044] In the description of this specific embodiment, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this specific embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] In the description of this specific embodiment, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0046] In the manufacturing process of electrical connection terminals, copper alloy strips, as the base material, often fail to simultaneously meet requirements for mating stability, corrosion resistance, and electrical conductivity. Specifically, while pure copper possesses high electrical conductivity, its insufficient mechanical strength leads to inadequate mating force, easily causing poor contact. Brass, on the other hand, while offering good machinability and corrosion resistance, suffers from low electrical conductivity, impacting signal transmission efficiency. This issue directly results in decreased connector reliability and compromised signal integrity during use, ultimately affecting the stable operation of the overall system.

[0047] For example, in the connector application of the power battery management system of new energy vehicles, the connection terminals need to withstand frequent insertion and removal operations in high temperature and high humidity environments. Due to the limitations of existing materials, the contact pressure between the male and female terminals decreases after repeated insertion and removal. At the same time, corrosion is accelerated in high salt spray environments, leading to increased contact resistance, which in turn causes signal transmission interruption or false triggering, seriously affecting the functional realization of the vehicle control system.

[0048] Reference Figure 1 - Figure 4 To address the aforementioned problems, this application provides a method for preparing copper-iron alloy strip for electrical connection terminals, using copper-iron alloy as raw material, comprising the following steps:

[0049] S1. Heating: Heating the semi-continuously cast copper-iron alloy;

[0050] S2, Hot rolling: The copper-iron alloy heated by S1 is repeatedly rolled, and after hot rolling, it is quenched, cooled, and rolled to form a hot-rolled billet.

[0051] S3, Rough rolling: Rolling the hot-rolled billet of S2 to the thickness of the semi-finished strip;

[0052] S4. Two-stage annealing: The semi-finished strip after rough rolling is annealed twice to eliminate work hardening and promote the precipitation of the second phase.

[0053] S5. Finish rolling: After cleaning the strip that has undergone two annealing processes, it is then finished rolled, with the finished product processing rate controlled at 30%-50%.

[0054] S6. Stretch straightening: After cleaning the strip that has been precision rolled by S5, stretch straightening is performed to control the shape of the finished strip.

[0055] The specific processing steps are as follows: First, copper-iron alloy is used as raw material and obtained through a semi-continuous casting process. In step S1, the semi-continuously cast copper-iron alloy ingot is heated to homogenize the internal structure of the alloy and reduce the material's deformation resistance, preparing it for subsequent hot working. In step S2, the heated copper-iron alloy is repeatedly rolled to achieve hot rolling. In step S3, the hot-rolled billet is rough rolled to further reduce its thickness to the specifications of the semi-finished strip. In step S4, the rough-rolled semi-finished strip undergoes two annealing treatments. In step S5, the strip after two annealings is cleaned to remove surface oxides and stains, and then precision rolled. In step S6, the precision-rolled strip is cleaned and then subjected to tension bending and straightening.

[0056] By precisely controlling the hot rolling, rough rolling, and finish rolling processes, and optimizing the microstructure through two annealing processes, the prepared copper-iron alloy strip exhibits excellent electrical conductivity, achieving comprehensive optimization in terms of strength, conductivity, and corrosion resistance. Compared to brass, which has poor conductivity, the copper-iron alloy strip of this application can ensure high-speed and efficient transmission of electrical signals, meeting the stringent conductivity requirements of modern electrical connection terminals.

[0057] During the preparation process, the rational selection of copper-iron alloys and the optimization of heat treatment processes enable the final product to possess excellent corrosion resistance. For example, in the above example, after precision rolling and tension straightening, the surface quality of the strip is improved, and the internal structure is uniform and dense. This helps to enhance the material's oxidation and corrosion resistance, thereby extending the service life of electrical connection terminals, which is superior to the insufficient corrosion resistance of copper in the prior art.

[0058] To facilitate understanding of the technical solution of this application, further explanation is provided:

[0059] In this embodiment, a copper-iron alloy is used as the raw material. A copper-iron alloy is an alloy formed by adding iron to a copper base. By precisely controlling the content and distribution of iron, the alloy's strength, hardness, and wear resistance can be significantly improved, while maintaining good electrical conductivity.

[0060] In this embodiment, the copper-iron alloy is obtained through semi-continuous casting, an advanced casting technology used to produce long ingots or billets. This method, through continuous pouring and cooling, can produce castings with uniform microstructure and fewer defects, providing high-quality starting material for subsequent rolling processes.

[0061] In this embodiment, the copper-iron alloy strip is C19210. C19210 is a specific copper-iron alloy grade, generally referring to an alloy with a high copper content and a small amount of iron. Its characteristics include good electrical conductivity, high strength, and excellent heat resistance. This alloy strip can be processed into shapes such as contact pieces, leads, or springs according to the specific design requirements of the terminals.

[0062] Specifically, for step S1: heating, the aim is to raise the semi-continuously cast copper-iron alloy to a specific temperature range to reduce its deformation resistance, improve its plasticity, and create favorable conditions for subsequent hot rolling.

[0063] In this embodiment, in step S1, the semi-continuously cast copper-iron alloy is heated in a walking beam furnace, with the heating temperature controlled at 920℃-950℃ and the holding time controlled at 2.5h-3.5h.

[0064] A walking beam furnace is an industrial heating device characterized by the periodic forward movement of materials within the furnace via a walking mechanism, achieving uniform heating. This furnace type ensures controllable residence time of materials within the furnace and reduces friction between the material and the furnace bottom, thus helping to maintain the surface quality of the material. It can be implemented through a hydraulically or mechanically driven walking beam system, or by using a roller hearth walking conveyor.

[0065] In this embodiment, heating temperature is a key parameter affecting the internal microstructure and plastic deformation capacity of the copper-iron alloy. Controlling the heating temperature within a specific range aims to ensure the alloy reaches a suitable plastic state before hot rolling, while avoiding overheating or excessive grain growth. The selection of this temperature range is based on the alloy's phase transformation point, recrystallization temperature, and subsequent processing requirements.

[0066] In this embodiment, sufficient holding time helps to homogenize the internal temperature of the alloy, promotes element diffusion, eliminates casting defects, and provides a uniform initial microstructure for subsequent hot rolling. Too short a holding time may result in insufficient heating, while too long a holding time may lead to coarse grains or increased energy consumption. The holding time can be precisely adjusted by combining the furnace temperature control system with the material's residence time in the furnace, for example, by adjusting the stepper speed or furnace length.

[0067] By precisely controlling the temperature and time of the copper-iron alloy in a walking beam furnace, a uniform and suitable internal microstructure can be ensured before hot rolling, effectively avoiding microstructure inhomogeneity and performance fluctuations caused by improper heating. This significantly improves the material's plastic deformation capacity and the stability of subsequent processing, laying a solid foundation for the preparation of copper-iron alloy strips for electrical connection terminals with excellent performance, thus effectively solving the limitation of difficult material performance control under traditional heating methods.

[0068] Furthermore, hot rolling refers to the repeated rolling of copper-iron alloys at high temperatures to significantly reduce their thickness and improve their internal structure. The hot rolling process can refine the grains, break down and uniformly distribute the second phase, thereby improving the overall mechanical properties of the material.

[0069] In this embodiment, in step S2, when the copper-iron alloy heated in S1 is repeatedly rolled, the final rolling temperature is controlled to 580℃-600℃, and the thickness is rolled to 15mm-18mm. Specifically, the C19210 after S1 is repeatedly rolled on a reversible hot rolling mill, the final rolling temperature is controlled to 580℃-600℃, and the thickness is rolled to 15mm-18mm. After hot rolling, it is quenched, cooled, and rolled to form a hot-rolled billet.

[0070] The final rolling temperature refers to the temperature of the material when it leaves the last rolling mill during hot rolling. It is a key parameter affecting the material's microstructure and mechanical properties. Precise control of the final rolling temperature helps achieve ideal dynamic and static recrystallization during hot rolling, resulting in a fine and uniform grain structure and effectively eliminating work hardening. If the final rolling temperature is too high, it may lead to excessive grain growth, reducing the material's strength and toughness; if the final rolling temperature is too low, it may result in incomplete recrystallization, leading to high residual stress within the material and affecting subsequent processing. The final rolling temperature can be controlled through various methods, including adjusting the rolling speed, roll gap, cooling intensity between rolling passes, and initial heating temperature. For example, an infrared thermometer can be used to monitor the strip temperature in real time, and rolling parameters can be adjusted based on the feedback signal.

[0071] In this embodiment, the rolling thickness refers to the final thickness of the strip after hot rolling. Rolling the thickness to 15mm-18mm provides a qualified semi-finished billet for the subsequent rough rolling process. Precisely controlling the thickness after hot rolling ensures that the billet has consistent geometric dimensions and uniform deformation, which is crucial for the subsequent cold working process. Uneven thickness will lead to inconsistent processing rates in different parts during subsequent rolling, potentially causing localized stress concentration, uneven deformation, and even defects such as cracks.

[0072] In this embodiment, the quenching method is water-cooled quenching. Quenching is a heat treatment process that obtains specific microstructures and properties by rapidly cooling metallic materials. Water-cooled quenching refers to rapidly immersing heated metallic materials in water or cooling them through water spraying. Water, as a quenching medium, has a high thermal conductivity and specific heat capacity, providing a very fast cooling rate. This rapid cooling can effectively suppress the precipitation and growth of alloying elements during the cooling process, thereby obtaining fine grain structures or supersaturated solid solutions, laying the foundation for subsequent processing and the performance of the final product. One implementation method is to install a spray device at the hot rolling mill exit, directly spraying high-pressure water onto the surface of the hot-rolled flat ingot for rapid cooling. Another implementation method is to install a water tank at the hot rolling mill exit, directly immersing the hot-rolled flat ingot in the water tank for cooling.

[0073] By employing water-cooled quenching as the quenching method, an extremely high cooling rate can be ensured for the hot-rolled flat ingot. This rapid cooling effectively suppresses the precipitation and growth of the iron phase in the copper-iron alloy, preventing the formation of coarse iron phase particles, thereby maintaining the solid solution strengthening state of the alloy or forming fine, dispersed precipitate precursors. This is crucial for subsequent cold rolling, as fine grains and a uniform microstructure significantly improve the material's plasticity and reduce its work hardening tendency. This allows the material to withstand greater deformation without cracking during subsequent rough rolling, cold rolling, and finish rolling, ensuring a high processing rate and ultimately obtaining copper-iron alloy strips for electrical connection terminals with excellent mechanical and electrical properties.

[0074] Furthermore, rough rolling is a further rolling process performed on hot-rolled billets, aiming to reduce the material thickness to the specifications of semi-finished strip. The rough rolling process can be carried out on cold rolling mills or hot rolling mills, achieving a significant reduction in thickness through multiple rolling passes.

[0075] In this embodiment, specifically, step S3: rough rolling includes the following steps:

[0076] S31. Milling: After the hot-rolled billet is cooled to ambient temperature, the oxide layer on the upper and lower surfaces and the left and right sides of the hot-rolled billet is removed. The total milling amount on the upper and lower surfaces is controlled between 1.2mm and 1.5mm.

[0077] S32, Rough rolling: The hot-rolled billet after milling in S31 is rolled by a rough rolling mill, with a processing rate of 90%-93%.

[0078] Milling refers to removing the defective layer from the surface of a material through mechanical cutting. In the preparation of copper-iron alloy strip, hot-rolled billets are exposed to air at high temperatures, easily forming an oxide layer. This oxide layer not only affects the surface quality of the strip but may also be pressed into the material during subsequent rolling, creating defects. Milling the hot-rolled billet after it has cooled to ambient temperature avoids excessive plastic deformation of the material at high temperatures, ensuring milling accuracy. Removing the oxide layer is a crucial step in ensuring the quality of subsequent processing and can be done using a milling machine, or through grinding, planing, or other methods.

[0079] In this embodiment, the control of milling amount aims to effectively remove the oxide layer without losing too much usable material, ensuring the uniformity of strip thickness.

[0080] In this embodiment, rough rolling is a crucial step in strip processing, aiming to significantly reduce strip thickness and improve the internal microstructure of the material. Rough rolling on a milled hot-rolled billet avoids the introduction of surface defects. Rough rolling mills typically employ multi-roll mills, such as four-roll or six-roll mills, where the strip undergoes plastic deformation through adjustments to the roll gap and the application of rolling force.

[0081] In this embodiment, the processing rate refers to the percentage reduction in material thickness. A high processing rate helps to refine the grains and improve the strength and toughness of the material.

[0082] In the preparation of copper-iron alloy strip for electrical connection terminals, the semi-continuously cast copper-iron alloy is first heated to 920℃-950℃ in a walking beam furnace and held for 2.5h-3.5h. Subsequently, the heated copper-iron alloy is repeatedly rolled, with the final rolling temperature controlled at 580℃-600℃, rolling the thickness to 15mm-18mm. Immediately after hot rolling, it is cooled by water quenching and then rolled into a hot-rolled billet. After the hot-rolled billet cools to ambient temperature, it is fed into a milling machine for surface milling. By adjusting the milling cutter depth, the oxide layer on the upper and lower surfaces and the left and right sides is precisely removed, ensuring that the total milling amount on the upper and lower surfaces is controlled at 1.2mm-1.5mm. The surface of the milled billet is smooth and free of oxide residue. Next, the milled billet is fed into a roughing mill for rolling. Through multiple rolling passes, the thickness of the billet is significantly reduced, achieving a processing rate of 90%-93%, thus obtaining a semi-finished strip.

[0083] Furthermore, in step S4, the two annealing processes include:

[0084] S41. First annealing: The strip after rough rolling in S32 is placed in a bell-type annealing furnace for the first annealing, and the holding time is 6h-6.5h.

[0085] S42. Pickling: The strip after the first annealing in S41 is pickled in the cleaning line to remove the emulsion on the surface of the strip.

[0086] S43, Cold rolling: The strip after S42 pickling is processed to the required thickness using a cold rolling mill;

[0087] S44. Second annealing: After the S43 cold-rolled strip is re-wound and loosened by the cleaning line, it is placed in a bell-type annealing furnace for a second annealing, and the holding time is 6h-6.5h.

[0088] Specifically, the first annealing aims to eliminate work hardening generated during rough rolling and provide a good plastic foundation for subsequent cold rolling, while simultaneously promoting the precipitation of the second phase in the alloy. Annealing the strip in a bell-type annealing furnace ensures uniform heating under a controlled atmosphere, preventing oxidation and maintaining a longer holding time to guarantee a thorough annealing process. Besides bell-type annealing furnaces, continuous annealing furnaces can also be used, achieving annealing through precise control of furnace temperature and strip throughput speed, or vacuum annealing furnaces can be used to anneal in a vacuum environment to obtain a purer surface.

[0089] In this embodiment, the purpose of pickling is to remove the oxide layer that may form on the surface of the strip after the first annealing, as well as contaminants such as rolling emulsion remaining from the rough rolling and first annealing processes. Pickling via a cleaning line enables continuous and efficient surface cleaning, providing a clean surface for subsequent cold rolling and preventing surface defects from being pressed into the strip during the cold rolling process. The pickling solution can be dilute sulfuric acid, dilute hydrochloric acid, or a mixture thereof, applied by spraying or immersion. Electrolytic pickling or mechanical brushing can also be used to assist in removing surface contaminants.

[0090] In this embodiment, cold rolling is a key plastic deformation step introduced between two annealing processes. It uses a cold rolling mill to process the pickled strip to a predetermined thickness, further refining the grains and introducing new work hardening and deformation energy. This deformation energy acts as the driving force for the second annealing, promoting more uniform and complete recrystallization and second-phase precipitation. The cold rolling mill can be a four-high, six-high, or twenty-high mill, selected according to the strip width and thickness requirements. Dry rolling or wet rolling can be used during the cold rolling process.

[0091] In this embodiment, the second annealing aims to eliminate work hardening introduced by cold rolling, further promote the uniform precipitation of the second phase and grain growth, and ultimately enable the strip to achieve the desired mechanical properties and microstructure. Before the second annealing, the strip is rewinded and loosened through a cleaning line, which helps the strip to be heated uniformly in the bell-type annealing furnace, avoiding local overheating or uneven heating, and ensuring the consistency of the annealing effect. Similarly, in addition to the bell-type annealing furnace, a continuous annealing furnace or a vacuum annealing furnace can also be used. Rewinding and loosening can be achieved by setting tension control devices and winding devices on the cleaning line to ensure that the strip is in a relaxed state before annealing.

[0092] By cleverly introducing pickling and cold rolling intermediate processing steps between the two annealing processes following rough rolling, the first annealing eliminates most of the internal stress introduced by rough rolling, providing the strip with good plasticity to withstand subsequent cold rolling deformation. Subsequently, the pickling step effectively removes the oxide layer and residues from the strip surface, ensuring a smooth cold rolling process and providing excellent surface quality for the final product. The following cold rolling step not only further thins the strip but, more importantly, introduces new plastic deformation and strain energy, providing a strong driving force for the second annealing, thereby promoting finer, more uniform grain recrystallization and second-phase precipitation. Finally, the second annealing completely eliminates the work hardening introduced by cold rolling and stabilizes the microstructure and macroscopic properties of the material. This multi-stage, refined processing flow synergistically optimizes the microstructure and mechanical properties of the copper-iron alloy strip, resulting in a high-strength, highly conductive material with excellent surface quality for electrical connection terminals.

[0093] In this embodiment, the annealing temperature is 480℃-500℃ in the first annealing and 460℃-480℃ in the second annealing.

[0094] Specifically, annealing temperature is a key parameter affecting the microstructure and properties of metallic materials. For copper-iron alloys, the main purpose of the first annealing is to eliminate work hardening after rough rolling and create conditions for subsequent second-phase precipitation. Controlling the annealing temperature within the range of 480℃–500℃ ensures that the material can fully recover and recrystallize after undergoing rough rolling with large deformation, effectively reducing internal stress, restoring plasticity, and preventing excessive grain growth. This lays a good microstructure foundation for subsequent cold rolling and the second annealing. For example, if the annealing temperature is too low, it may lead to incomplete recrystallization and high residual stress; if the annealing temperature is too high, it may cause grain coarsening, affecting the overall properties of the material.

[0095] In this embodiment, the second annealing is performed after cold rolling. Its main function is to further eliminate the work hardening introduced by cold rolling and promote the full precipitation and uniform distribution of the second phase, thereby optimizing the strength and conductivity of the material. Controlling the annealing temperature within the range of 460℃–480℃ allows for precise regulation of the precipitation kinetics of the second phase, enabling it to form a fine, dispersed reinforcing phase in the matrix. This significantly improves the material's strength while maintaining good conductivity. For example, if the annealing temperature deviates from this range, it may result in insufficient precipitation of the second phase, an insignificant strengthening effect, or excessively large precipitated phases, which could reduce the material's plasticity and toughness.

[0096] In this embodiment, the second annealing temperature range is lower than the first annealing temperature range, aiming to finely control the precipitation behavior of the second phase. Cold rolling introduces new work hardening and provides more grain boundaries and dislocations for the nucleation of the second phase. Performing the second annealing at a lower but precisely controlled temperature promotes the uniform precipitation of the second phase in a fine, dispersed manner, thereby significantly improving the strength and hardness of the material without significantly sacrificing conductivity. This staged, differentiated temperature control strategy ensures that the microstructure evolution of the material remains under control throughout the entire preparation process, guaranteeing that the final copper-iron alloy strip possesses excellent comprehensive performance, meeting the requirements of electrical connection terminals for high-strength, high-conductivity materials.

[0097] Furthermore, finish rolling is the final rolling process performed on the annealed strip, aiming to roll the strip to the precise thickness required for the final product. In step S5, the strip that has undergone the second annealing in S44 is cleaned and then rolled through a finish rolling mill, with the finished product yield controlled at 35%–45%.

[0098] In step S5, the strip after the second annealing in S44 is cleaned and then rolled through a finishing mill. During this process, by precisely controlling the finished product processing rate within the range of 35%–45%, it is ensured that the strip achieves appropriate plastic deformation during the finishing rolling stage. This precise processing rate control allows the copper-iron alloy strip to further refine its grains and form a uniform microstructure after undergoing two annealing processes to eliminate work hardening and promote the precipitation of the second phase. Compared to a wider processing rate range, limiting the processing rate to a narrower range of 35%–45% more effectively avoids problems such as insufficient grain refinement or uneven microstructure caused by too low a processing rate, as well as the risk of excessive material hardening, reduced plasticity, or even microcracks caused by too high a processing rate.

[0099] In this way, the finishing rolling process not only imparts the required final thickness to the strip, but more importantly, it optimizes the material's microstructure at the micro level, giving it excellent strength, hardness, and good plasticity, thereby meeting the stringent material performance requirements of electrical connection terminals. This precisely controlled finishing rolling step works closely with the preceding heating, hot rolling, rough rolling, and double annealing steps to create a complete process flow capable of stably producing high-performance copper-iron alloy strips.

[0100] Furthermore, in step S6, the strip after finishing rolling in S5 is cleaned and then subjected to tension straightening to control the shape of the finished product. Tension straightening is a processing technique used to improve the shape of the strip and eliminate internal stress. By applying tensile and bending stress to the strip, the straightness of the strip can be effectively corrected, and defects such as wavy edges can be eliminated, thereby obtaining a flat and stable finished product shape.

[0101] Specifically, in step S6, after the strip finished in step S5 is cleaned, it is straightened by a 23-roll strip straightener to control the final shape of the finished product. The 23-roll strip straightener is a high-precision strip straightening device that applies a combination of bending and stretching forces to the strip through a precise configuration of multiple sets of work rolls, intermediate rolls, and support rolls. This equipment enables fine adjustment of the strip shape, effectively eliminating residual stress within the strip, thereby significantly improving the straightness and surface quality of the strip.

[0102] In this embodiment, the unwinding tension of the tension straightening is 800 to 1000 times the strip thickness, in kg. The winding tension of the tension straightening is 1000 to 1200 times the strip thickness, in kg. The elongation range of the tension straightening is 0.2% to 0.4%.

[0103] Uncoiling tension refers to the tensile force exerted on the strip as it exits the uncoiler during the bending and straightening process. Precise control of uncoiling tension helps ensure that the strip enters the straightening area smoothly and without vibration, preventing the strip from becoming loose or deformed before straightening, and providing stable input conditions for the subsequent straightening process.

[0104] Winding tension refers to the tensile force exerted on the strip during winding on a winding machine after it has been straightened by bending. Appropriate winding tension ensures that the strip is wound tightly and neatly, preventing loose winding, collapse, or edge damage, and also helps maintain a good sheet shape after straightening.

[0105] Elongation is a key parameter in the stretch straightening process, representing the degree of plastic deformation experienced by the strip during straightening. By precisely controlling the elongation, the fiber length inside the strip can be made to change uniformly, thereby effectively eliminating residual stress generated by processes such as rolling and annealing, and improving strip shape defects such as wavy edges and warping.

[0106] In this embodiment, the elongation range is designed for the characteristics of copper-iron alloy strips, ensuring effective plastic deformation while avoiding excessive stretching that could degrade material properties. The method of setting the elongation determines the control strategy for the straightening process. Specifically, either a tension mode or a constant elongation mode can be used. In tension mode, the elongation of the strip is indirectly controlled by precisely controlling the difference between the unwinding and winding tensions, combined with the internal roller configuration of the straightener. This mode is suitable for materials sensitive to tension response. In constant elongation mode, a constant elongation is directly set and maintained by precisely controlling the speed difference between the inlet and outlet rollers of the straightener, ensuring uniform plastic deformation of the strip throughout the straightening process. This mode allows for more direct control of the deformation amount and is suitable for applications requiring strict control of the elongation.

[0107] Through the above technical solutions, the strip shape accuracy and internal quality of the copper-iron alloy strip for electrical connection terminals can be significantly improved during the manufacturing process. Precise control of uncoiling tension, winding tension, and appropriate elongation, combined with the efficient straightening capability of a 23-roll strip straightener, effectively eliminates residual stress within the strip and corrects various shape defects, resulting in a copper-iron alloy strip with high flatness, low internal stress, and good dimensional stability. This not only improves the product's appearance quality but, more importantly, ensures the reliability and durability of the electrical connection terminals during subsequent processing and use, avoiding performance degradation or premature failure caused by poor shape or excessive residual stress.

[0108] In this embodiment, after the S6 bending and straightening process, to ensure the performance of the final product, especially its stability under high-temperature environments, an S7: finished product inspection step is also included. Finished product inspection is a crucial part of the production process, aiming to ensure that the final product meets predetermined quality standards and performance requirements. Its role is to promptly identify and reject unqualified products, preventing defective products from entering the market, thereby ensuring product quality, improving customer satisfaction, and maintaining the company's reputation. Finished product inspection can include comprehensive testing of multiple aspects such as the product's appearance, dimensions, surface quality, mechanical properties, and electrical properties. For example, various methods can be used, such as visual inspection, dimensional measurement, tensile testing, and resistivity testing.

[0109] The testing of the finished product performance after S6 treatment specifically refers to the various physical and mechanical properties that the copper-iron alloy strip should possess after bending and straightening. Testing these properties verifies whether the entire manufacturing process has successfully imparted the required final use characteristics to the strip, such as strength, hardness, conductivity, and ductility. Performance testing can cover a variety of indicators; for example, tensile strength, yield strength, and elongation can be tested using a universal testing machine; Rockwell or Brinell hardness can be tested using a hardness tester; and electrical conductivity can be measured using a conductivity meter.

[0110] In this embodiment, finished product inspection involves testing the performance of the finished product after S6 treatment and then testing its Vickers hardness after softening at 460℃-480℃ for 3-5 minutes. The 3-5 minute holding at 460℃-480℃ simulates the high-temperature environment that electrical connection terminals may encounter during actual operation or service, and assesses the material's stability after short-term exposure to high temperatures. By performing heat treatment at specific temperatures and times, changes in the internal structure of the material can be accelerated, allowing for a faster assessment of its softening resistance. This is crucial for the long-term reliability of electrical connection terminals at high temperatures.

[0111] In this embodiment, Vickers hardness is a commonly used material hardness testing method. It calculates the hardness value by measuring the diagonal length of the indentation and is applicable to materials of various hardnesses. Here, the Vickers hardness is tested after high-temperature insulation to quantitatively assess the degree of softening of the material after heat exposure. The material's resistance to softening is a key indicator for maintaining the mechanical properties and connection stability of electrical connection terminals in high-temperature environments. Vickers hardness testing is typically performed using a Vickers hardness tester, where a diamond indenter is pressed into the material surface with a specified test force, and then the diagonal length of the indentation is measured. The test can be performed at multiple points, and the average value is taken to improve accuracy.

[0112] By adding the S7 finished product inspection step after the S6 bending and straightening process, and specifically introducing a step to test the Vickers hardness of the material after heat treatment at a specific high temperature environment, the softening resistance of the copper-iron alloy strip can be effectively evaluated. This solves the problem of the difficulty in comprehensively and accurately evaluating the performance stability of materials under high-temperature service conditions in traditional preparation methods. By quantitatively testing the hardness of the material after simulated high-temperature softening, it can be ensured that the prepared copper-iron alloy strip can maintain its key mechanical properties even in high-temperature environments when used as an electrical connection terminal, thereby significantly improving the long-term reliability and stability of the electrical connection terminal and avoiding connection failures caused by material softening.

[0113] After the copper-iron alloy strip is produced and processed through the above steps, the grains are made fine and uniform by controlling the final rolling temperature and cooling rate in the hot rolling process, and the solid solution is fully precipitated, which lays a good foundation for the performance of the finished product. After two cold rollings and two annealings, the second phase is further precipitated, which improves the conductivity while ensuring the precipitation of the strengthening phase. Finally, after work hardening, the material properties required for connector terminals are met.

[0114] As a first embodiment, the following process is used for production:

[0115] S1. The C19210 flat ingots after semi-continuous casting are heated in a walking beam furnace. The heating temperature is controlled at 920℃ and the holding time is controlled at 3.5h.

[0116] S2. The C19210 flat ingot heated by S1 is repeatedly rolled on a reversible hot rolling mill to roll the thickness to 17.5mm, and the final rolling temperature is controlled to 580℃. After quenching and rolling, it forms a hot-rolled billet.

[0117] S31. After the hot-rolled billet is cooled to ambient temperature, it is subjected to a double-sided milling machine to remove the oxide layer on the upper and lower surfaces and the left and right sides of the hot-rolled billet. The total milling amount on the upper and lower surfaces is 1.2mm.

[0118] S32. The billet milled in S31 is rolled to the semi-finished thickness using a four-roll reversible primary rolling mill, with a processing rate of 92.6%.

[0119] S41. The strip that has been rough rolled by S32 is placed into a bell-type annealing furnace for the first annealing. The heating temperature for the first annealing is 500℃ and the holding time is 6h.

[0120] S42. After the first annealing in S41, the strip is pickled through the cleaning line to fully remove the emulsion on the surface of the strip.

[0121] S43. Transfer the strip pickled in S42 to a six-roll cold rolling mill and roll it to the required thickness.

[0122] S44. After the strip processed in S43 is rewound and loosened in the cleaning line, it is annealed for the second time in a rotating bell furnace. The heating temperature range for the second annealing is 480℃, and the holding time is 6h.

[0123] S5. After cleaning the strip after the second annealing of S44, it is transferred to a six-roll reversible finishing mill for finishing rolling, with a finished product rate of 45%.

[0124] S6. The strip processed in S5 is cleaned, and then transferred to a 23-roll strip straightener for tension bending and straightening to control the final shape of the finished product. Constant tension straightening is performed, with the tension set at 200 kg for the 23-roll strip straightener and the single-bend single-straightening device, and the uncoiling tension set at 300 kg. The elongation rate of the 23-roll strip straightener and the single-bend single-straightening device is set at 0.2%.

[0125] S7. Test the performance of the finished product after S6 treatment, and keep it in a heating furnace at 470℃ for 3 minutes to test the Vickers hardness of the softened material, as shown in Table 1.

[0126] Rm / MPa A11.3 HV Conductivity / %IACS HV after softening experiment 430 6.5% 125 95.4 105

[0127] Table 1

[0128] In this embodiment, for clear comparison, the copper-iron alloy strips that only underwent the first annealing were tested under the same conditions, as shown in Table 2.

[0129] Rm / MPa A11.3 HV Conductivity / %IACS HV after softening experiment 415 5% 118 85.2 92

[0130] Table 2

[0131] In this embodiment, for clear comparison, under the condition that other conditions are the same, the test results are shown in Table 3 when the first annealing and the second annealing are isothermal.

[0132] Rm / MPa A11.3 HV Conductivity / %IACS HV after softening experiment 425 6% 122 88.6 98

[0133] Table 3

[0134] As a second embodiment, the following process is used for production:

[0135] S1. The C19210 flat ingot after semi-continuous casting is heated in a walking beam furnace. The heating temperature is controlled at 950℃ and the holding time is controlled at 2.5h.

[0136] S2. The C19210 flat ingot heated by S1 is repeatedly rolled on a reversible hot rolling mill to roll the thickness to 17.5mm, and the final rolling temperature is controlled to 600℃. After water cooling and coiling, it forms a hot-rolled billet.

[0137] S31. After the hot-rolled billet is cooled to ambient temperature, it is subjected to a double-sided milling machine to remove the oxide layer on the upper and lower surfaces and the left and right sides of the hot-rolled billet. The total milling amount on the upper and lower surfaces is controlled at 1.5mm.

[0138] S32. The billet milled in S31 is rolled to the semi-finished thickness using a four-roll reversible roughing mill, with the processing rate controlled at 91%.

[0139] S41. The strip that has been rough rolled by S32 is placed into a bell-type annealing furnace for the first annealing. The heating temperature for the first annealing is 480℃ and the holding time is 6h.

[0140] S42. After the strip annealed in S41 is passed through the cleaning line, it is pickled to fully remove the emulsion on the surface of the strip.

[0141] S43. Transfer the strip pickled in S42 to a six-roll cold rolling mill and roll it to the required thickness.

[0142] S44. After the strip processed in S43 is rewound and loosened in the cleaning line, it is annealed for the second time in a rotating bell furnace. The heating temperature for the second annealing is 480℃ and the holding time is 6h.

[0143] S5. After cleaning the strip after the second annealing of S44, it is transferred to a six-roll reversible finishing mill for finishing rolling, with a finished product rate of 35%.

[0144] S6. Clean the strip material processed in S5, and then transfer it to a 23-roll strip straightener for tension bending and straightening to control the final shape of the finished product. The tension straightening is performed in a constant elongation mode. The elongation rate of the 23-roll strip straightener is set to 0.4%, the elongation rate of the single bend and single straightening is set to 0.4%, the uncoiling tension is set to 500 kg, the tension of the 23-roll strip straightener is set to 1353 kg, and the tension of the single bend and single straightening device is set to 902 kg.

[0145] S7. Test the performance of the finished product after S6 treatment, and keep it in a heating furnace at 470℃ for 3 minutes to test the Vickers hardness of the softened material, as shown in Table 4.

[0146] Rm / MPa A11.3 HV Conductivity / %IACS HV after softening experiment 435 6.5% 130 89.4 110

[0147] Table 4

[0148] In this application, a two-stage annealing process with a temperature gradient is employed, which significantly outperforms single-stage annealing. The first, higher-temperature annealing provides sufficient diffusion activation energy, allowing Fe atoms dissolved in the copper matrix after hot rolling to fully diffuse and form Fe2P nuclei. The second, slightly lower-temperature annealing promotes uniform growth of the precipitates based on the existing nuclei, avoiding excessive coarsening of the precipitates caused by a single high-temperature, long-duration annealing process.

[0149] In this embodiment, the Fe precipitation rate after two annealing processes reaches over 85%, higher than the approximately 65% ​​achieved with a single annealing process. Solid-solution Fe atoms are the primary source of scattering for conductive electrons in the copper matrix; the more complete the precipitation, the higher the conductivity. Example 1 achieved a conductivity of 95.4% IACS, approaching the level of pure copper, while maintaining a strength of 430 MPa, thus achieving the goal of high strength and high conductivity.

[0150] In this embodiment, the first annealing completes recrystallization and establishes the initial grain size of 12-15 μm. The temperature of the second annealing is reduced by 20°C, which effectively suppresses the secondary growth of grains and keeps the finished grains in the fine grain range of 12-18 μm, which is beneficial to the balance between strength and plasticity.

[0151] In this embodiment, an electrical connection terminal is also provided, which is fitted with a copper-iron alloy strip prepared by the above method. The electrical connection terminal is a connecting component used to realize the transmission of electrical signals or electrical energy. It comes in various forms, including but not limited to plugs, sockets, terminals, or connectors, and is typically composed of conductive and insulating components. The prepared copper-iron alloy strip is fixed to the conductive portion of the terminal, allowing it to serve as a key conductive or elastic component of the terminal, thus exhibiting its excellent conductivity, strength, and fatigue resistance.

[0152] The present application integrates a C19210 copper-iron alloy strip, optimized through a specific preparation method, into an electrical connection terminal to form a fully functional electrical connection assembly. The aforementioned preparation method allows for precise control of the microstructure of the C19210 alloy. For example, through steps such as hot rolling, annealing, and precision rolling, its grain size, second-phase precipitation morphology, and distribution are optimized, thereby endowing the C19210 copper-iron alloy strip with excellent comprehensive properties, including high conductivity, high strength, good fatigue resistance, and outstanding heat resistance.

[0153] Applying the optimized C19210 copper-iron alloy strip to electrical connection terminals can significantly improve the overall performance of the terminals. For example, the excellent conductivity of the C19210 alloy strip ensures low contact resistance and efficient power transmission; its high strength and good fatigue resistance guarantee the contact stability of the terminals under repeated insertion and removal and long-term vibration environments; at the same time, its excellent heat resistance effectively inhibits the softening and stress relaxation of the terminals under high-temperature operating conditions, thereby greatly improving the long-term reliability and service life of electrical connection terminals.

[0154] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has disclosed the preferred embodiment as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-mentioned technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. The implementation schemes in the above embodiments can also be further combined or replaced. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the content of the technical solution of this application shall still fall within the scope of this application.

Claims

1. A method for preparing a copper-iron alloy strip for electrical connection terminals, characterized in that: Using copper-iron alloy as raw material, the process includes the following steps: S1. Heating: Heating the semi-continuously cast copper-iron alloy; S2, Hot rolling: The copper-iron alloy heated by S1 is repeatedly rolled, and after hot rolling, it is quenched, cooled, and rolled to form a hot-rolled billet. S3, Rough rolling: Rolling the hot-rolled billet of S2 to the thickness of the semi-finished strip; S4. Two-stage annealing: The semi-finished strip after rough rolling is annealed twice in sequence to eliminate work hardening and promote the precipitation of the second phase; S5. Finish rolling: After cleaning the strip that has undergone two annealing processes, it is finished rolled, and the finished product processing rate is controlled at 30%-50%. S6. Stretch straightening: After cleaning the strip that has been precision rolled by S5, stretch straightening is performed to control the shape of the finished strip.

2. The method for preparing copper-iron alloy strip for electrical connection terminals according to claim 1, characterized in that: In step S1, the semi-continuously cast copper-iron alloy is heated in a walking beam furnace, with the heating temperature controlled at 920℃-950℃ and the holding time controlled at 2.5h-3.5h.

3. The method for preparing copper-iron alloy strip for electrical connection terminals according to claim 2, characterized in that: In step S2, the copper-iron alloy heated in S1 is repeatedly rolled, with the final rolling temperature controlled at 580℃-600℃, and the thickness rolled to 15mm-18mm.

4. The method for preparing copper-iron alloy strip for electrical connection terminals according to any one of claims 1-3, characterized in that: In step S3: rough rolling, the following steps are included: S31. Milling: After the hot-rolled billet is cooled to ambient temperature, the oxide layer on the upper and lower surfaces and the left and right sides of the hot-rolled billet is removed. The total milling amount on the upper and lower surfaces is controlled between 1.2mm and 1.5mm. S32, Rough rolling: The hot-rolled billet after milling in S31 is rolled by a rough rolling mill, with a processing rate of 90%-93%.

5. The method for preparing copper-iron alloy strip for electrical connection terminals according to claim 4, characterized in that: Step S4, the two annealing processes, includes the following steps: S41. First annealing: The strip after rough rolling in S32 is placed in a bell-type annealing furnace for the first annealing, and the holding time is 6h-6.5h. S42. Pickling: The strip after the first annealing in S41 is pickled in the cleaning line to remove the emulsion on the surface of the strip. S43, Cold rolling: The strip after S42 pickling is processed to the required thickness using a cold rolling mill; S44. Second annealing: After the S43 cold-rolled strip is re-wound and loosened by the cleaning line, it is placed in a bell-type annealing furnace for a second annealing, and the holding time is 6h-6.5h.

6. The method for preparing copper-iron alloy strip for electrical connection terminals according to claim 5, characterized in that: In the first annealing, the annealing temperature is 480℃-500℃; In the second annealing, the annealing temperature is 460℃-480℃.

7. The method for preparing copper-iron alloy strip for electrical connection terminals according to claim 5, characterized in that: In step S5, the strip that has undergone the second annealing in S44 is cleaned and then rolled by a finishing mill, with the finished product processing rate controlled at 35%-45%.

8. The method for preparing copper-iron alloy strip for electrical connection terminals according to any one of claims 1-3, characterized in that: In step S6: tension bending and straightening, the strip after precision rolling in step S5 is cleaned and then tension bending and straightened by a 23-roll strip straightener to control the final shape of the finished product. Among them, the uncoiling tension of the tension straightening is 800 to 1000 times the thickness of the strip, in kg; The winding tension for tension straightening is 1000 to 1200 times the thickness of the strip, in kg. The elongation range of tension straightening is 0.2%–0.4%.

9. The method for preparing copper-iron alloy strip for electrical connection terminals according to any one of claims 1-3, characterized in that: The process after step S6 also includes: S7. Finished Product Inspection: Test the performance of the finished product after S6 treatment, and after keeping it at 460℃-480℃ for 3-5 minutes, test the Vickers hardness of the softened material.

10. An electrical connection terminal, characterized in that: The device is equipped with a copper-iron alloy strip prepared by the method for preparing copper-iron alloy strip for electrical connection terminals as described in any of claims 1-9; The copper-iron alloy strip is C19210.

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