Welding forming process for aluminum alloy copper bar and terminal

Abstract

The invention relates to the technical field of metal connection, and discloses a welding forming process of an aluminum alloy copper bar and a terminal, which comprises the following steps: sequentially carrying out mechanical cleaning, chemical oil removal and chemical activation pretreatment on the surfaces to be welded of an aluminum alloy base material and a brass terminal; the aluminum-based brazing filler metal foil and the potassium fluoroaluminate scaling powder are sequentially arranged between the aluminum alloy base material and the brass terminal, and an assembly to be welded is assembled; and finally, placing the assembly in hot pressing equipment under vacuum or inert atmosphere protection, carrying out constant-temperature and constant-pressure treatment at the temperature of 600-630 DEG C and under the pressure of 5-15 MPa, cooling, relieving the pressure, and molding. According to the method, a metallurgical bonding transition layer which is compact in structure and free of welding defects is formed at an aluminum-copper dissimilar metal interface under the combined action of liquid-phase filling and solid-phase diffusion, and a prepared welding joint has mechanical shear strength superior to that of an aluminum alloy base material and extremely low interface contact resistance; and reliable connection with high strength and high conductivity is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of metal connection, and in particular to a welding forming process for a copper busbar and a terminal made of an aluminum alloy. Background Art

[0002] In sectors such as new energy vehicles, power electronics, and rail transit, the demand for lightweight and high electrical conductivity is growing. Aluminum alloys are often used as conductors, for example as a replacement for copper busbars, due to their low density, high specific strength, and excellent electrical conductivity. Connection points in devices or systems, such as electrical terminals, typically require copper or brass due to their superior conductivity, wear resistance, and creep resistance. Therefore, achieving high-quality, reliable connections between aluminum alloy busbars and copper terminals has become a critical engineering challenge.

[0003] Existing technologies face fundamental challenges in attempting to solve the problem of aluminum-copper heterogeneous metal connections, stemming from the significant differences in the physical and chemical properties of the materials. Using traditional fusion welding methods, such as arc welding or laser welding, extremely high local temperature inputs are unavoidable. This causes violent metallurgical reactions between aluminum and copper. A series of thick and brittle intermetallic compound (IMC) layers form at the interface. This compound layer is a natural weak link in the mechanical properties of the joint and can easily become a source of cracks, leading to failure of the connection during service due to vibration or thermal stress. In addition, the huge difference in the thermal expansion coefficients of the two materials introduces huge residual stresses during the rapid heating and cooling cycles of fusion welding, which in itself can directly lead to microcracks in the welded joint, reducing the long-term reliability of the connection.

[0004] Even seemingly gentler joining processes, such as traditional brazing, have inherent technical bottlenecks. Aluminum alloys have a highly melting, chemically stable aluminum oxide passivation film on their surface. This oxide layer is a significant barrier to achieving a good metallurgical bond, severely hindering the effective wetting and spreading of the liquid brazing filler metal onto the substrate. While flux is used to remove this oxide film during brazing, the flux's activity, coating uniformity, and post-weld residue removal are difficult to precisely control in existing processes. This can lead to defects such as incomplete penetration and slag inclusions at the interface, significantly impacting bond strength and significantly increasing interfacial resistance, degrading electrical performance. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a welding forming process for copper busbars and terminals made of aluminum alloy, which solves the problem that it is difficult to synergistically suppress the formation of brittle intermetallic compounds and effectively remove the interface oxide film during the welding of aluminum and copper dissimilar metals, thereby failing to obtain a reliable joint with both high mechanical strength and excellent electrical properties.

[0006] A welding process for forming an aluminum alloy copper busbar and a terminal comprises the following steps:

[0007] Step S1: providing an aluminum alloy substrate, a copper or brass piece, and a sheet-shaped or powdered aluminum-based brazing filler metal. The aluminum-based brazing filler metal is disposed between the aluminum alloy substrate and the surface to be welded of the copper or brass piece.

[0008] Step S2: Laminating and assembling the aluminum alloy substrate, the aluminum-based brazing filler metal, and the copper or brass member to form a component to be welded.

[0009] Step S3: The assembly is placed in a hot press and hot-pressed under preset temperature and pressure conditions. During this process, the aluminum-based brazing filler metal first melts to form a liquid phase, which fills the interfacial gap between the aluminum alloy substrate and the copper or brass component. Simultaneously, under the combined effects of temperature and pressure, solid-phase atomic interdiffusion occurs at the interface between the copper or brass component and the aluminum alloy substrate, ultimately forming a metallurgical bond that combines the characteristics of liquid-phase bonding and solid-phase diffusion.

[0010] In one specific embodiment, the hot pressing process is performed at a preset temperature of 600°C to 630°C. This temperature range is selected based on the following principles: its lower limit is above the solidus temperature of the selected aluminum-based brazing filler metal, ensuring complete melting of the filler metal for effective wetting and filling of the interface; its upper limit is below the solidus temperature of the 6061 aluminum alloy substrate, ensuring that the substrate remains solid throughout the process, thereby fundamentally avoiding macroscopic deformation and the formation of brittle intermetallic compounds caused by substrate melting. Furthermore, this temperature range provides sufficient thermodynamic activation energy for interfacial atomic diffusion.

[0011] Atomic diffusion provides sufficient thermodynamic activation energy. The atomic diffusion flux (J) is related to the diffusion coefficient (D), which follows the Arrhenius relation:

[0012]

[0013] Where D is the diffusion coefficient, D0 is the diffusion constant, Q is the diffusion activation energy, R is the ideal gas constant, and T is the thermodynamic temperature. Within the temperature range of 600°C to 630°C, a diffusion coefficient sufficient to form an effective diffusion layer within a limited time can be achieved.

[0014] In a specific embodiment, during the stacking assembly process of step S2, a flux is further applied on the aluminum-based solder or at the interface between the copper or brass part and the aluminum alloy substrate, and the flux is potassium fluoroaluminate (KAIF 4) Its mechanism of action is that, at the preset temperature, potassium fluoroaluminate reacts with aluminum oxide (Al2O 3)A chemical reaction occurs to form a low-melting-point compound, effectively removing the oxide film that hinders alloy bonding. The simplified chemical reaction formula can be expressed as:

[0015] 4KAlF4+Al2O3→2K2AlF5O+2AlF3;

[0016] The reaction product is liquid at the process temperature and can be displaced by the molten aluminum-based solder, thereby exposing a clean, fresh metal surface with high chemical activity, greatly improving the wettability of the liquid solder to the substrate.

[0017] In a specific embodiment, the aluminum alloy substrate is 6061 aluminum alloy in T6 heat treatment state, and the copper or brass piece is an H62 brass piece or a red copper piece.

[0018] In a specific embodiment, the pressure is a constant unidirectional pressure continuously applied during the hot pressing process, and the pressure value is 5 MPa to 15 MPa. The technical principle of applying this pressure is that the pressure value (σ) exceeds the yield strength (σ) of the 6061 aluminum alloy substrate at the process temperature. y (T)), that is, σ>σ y This causes the softer aluminum alloy substrate to undergo microscopic plastic deformation at the interface, crushing the extremely thin brittle oxide remaining on the interface after chemical pretreatment. This forces close physical contact at the atomic level, eliminates microscopic gaps between interfaces, and creates the necessary physical prerequisites for subsequent solid-phase atomic diffusion.

[0019] In a specific embodiment, the stacking assembly further includes a step of performing surface pretreatment on the surfaces to be welded of the aluminum alloy substrate and the copper or brass part, wherein the pretreatment is intended to obtain a clean and chemically active surface to be welded that is free of macroscopic physical defects, oil stains and particles, and original oxide film.

[0020] In one embodiment, the hot pressing treatment is performed in a vacuum or argon atmosphere. This is to prevent the highly active surface to be welded, which has undergone surface pretreatment, from reacting with active gases such as oxygen in the environment during the heating and pressure holding process, leading to secondary oxidation, thereby ensuring the purity of the metallurgical reaction at the interface.

[0021] The surface pretreatment step may specifically include:

[0022] The surface to be welded is mechanically cleaned by sandpaper grinding to remove rough oxide layers, scratches and macroscopic physical defects on the surface.

[0023] The mechanically cleaned surface to be welded is placed in an acetone solution for ultrasonic cleaning, and the cavitation effect of the ultrasonic wave is used to remove oil stains and particles adhering to the surface that may be introduced during the grinding process.

[0024] The chemically cleaned surface to be welded is immersed in an alkaline solution or an acid solution for chemical activation treatment, and the dense microscopic oxide film with a thickness of nanometer level that is rapidly formed in the air is removed by chemical corrosion to expose a fresh metal matrix.

[0025] A second aspect of the present invention provides a welded assembly prepared by any of the aforementioned processes, comprising an aluminum alloy substrate, a copper or brass member, and an interfacial transition layer formed therebetween. The interfacial transition layer is composed of a solidified phase of the aluminum-based brazing filler metal and a solid-phase atomic diffusion zone formed between the aluminum alloy substrate and the copper or brass member.

[0026] The present invention provides a welding process for aluminum alloy copper busbars and terminals. It has the following beneficial effects:

[0027] 1. The present invention precisely controls the hot-pressing temperature within the range of 600°C to 630°C, which is lower than the solidus temperature of the 6061 aluminum alloy substrate. This kinetically inhibits the excessive growth of brittle intermetallic compounds (such as CuAl2 and Cu9Al4) at the copper-aluminum interface. This ensures that the thickness of the resulting interface transition layer is controllable and the structure is uniform, directly improving the mechanical toughness and structural reliability of the welded joint and avoiding the problem of premature joint failure caused by the formation of large amounts of brittle phases in traditional fusion welding processes.

[0028] 2. This invention combines two joining mechanisms: liquid-phase solder filling and solid-phase atomic diffusion. The molten aluminum-based solder completely wets and fills the microscopic gaps between the surfaces to be welded, ensuring gap-free physical contact and laying the foundation for a low-resistance electrical path. Under pressures of 5 to 15 MPa, microscopic plastic deformation occurs at the interface, which not only destroys the residual oxide film but also greatly promotes solid-phase atomic diffusion, forming a deep metallurgical bond. The synergistic effect of these two mechanisms achieves the dual optimization of high bond strength and low interfacial resistance.

[0029] 3. This invention integrates a comprehensive set of control steps, including multi-step surface pretreatment: mechanical cleaning, chemical cleaning, chemical activation, the use of a specialized flux, potassium fluoroaluminate, and autoclaving in an inert atmosphere. This ensures highly consistent initial conditions for each soldering operation. This precise control of key process parameters throughout the entire process eliminates process fluctuations caused by random factors such as surface variations and secondary oxidation, thereby ensuring highly stable and consistent final product performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a process flow chart of the present invention;

[0031] Figure 2 This is a schematic diagram of the assembly structure of the components to be welded according to the present invention. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the present specification. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] Refer to the attached Figure 1 , Figure 1 The figure is a schematic flow chart of a welding process for an aluminum alloy copper busbar and terminal according to one embodiment of the present invention. The present invention provides a welding process for an aluminum alloy copper busbar and terminal. In a specific embodiment, the process may include surface pretreatment, component assembly, and hot-pressing.

[0034] In this embodiment, the raw materials used include: a 6061 aluminum alloy substrate in a T6 heat-treated state, a terminal made of H62 brass, a sheet or foil-shaped Al-Si aluminum-based solder, and a powdered potassium fluoroaluminate (KAlF4) flux.

[0035] The core technical principle of this process is to form a low-defect, high-bonding-strength metallurgical bonding interface between the aluminum alloy and the copper or brass parts by utilizing the filling effect of liquid solder and the diffusion effect of solid atoms under precisely controlled temperature and pressure conditions.

[0036] The process begins with a multi-step pretreatment of the aluminum alloy substrate and brass terminal surfaces to be welded, ensuring a clean, chemically active surface free of macroscopic physical defects, oil, particulates, and an original oxide film. Subsequently, an aluminum-based brazing filler metal is placed on the aluminum alloy substrate surface to be welded, and potassium fluoroaluminate flux is evenly applied to the interface. The brass terminal is then stacked on top to form the welded assembly.

[0037] After the stack is assembled, the components are placed in a hot press, where they are subjected to a preset temperature and pressure under vacuum or an inert gas atmosphere. The hot press temperature is set between 600°C and 630°C. This temperature range ensures that the aluminum-based brazing filler metal completely melts, forming a liquid phase, while also providing the necessary thermodynamic activation energy for the interdiffusion of solid-phase atoms at the interface.

[0038] Atomic diffusion provides sufficient thermodynamic activation energy. The atomic diffusion flux (J) is related to the diffusion coefficient (D), which follows the Arrhenius relation:

[0039]

[0040] Where D is the diffusion coefficient, D0 is the diffusion constant, Q is the diffusion activation energy, R is the ideal gas constant, and T is the thermodynamic temperature. At the set process temperature, the diffusion coefficients of copper and aluminum atoms are sufficient to form a diffusion layer of a specific thickness within a limited dwell time.

[0041] During this process, the potassium fluoroaluminate flux applied to the interface reacts chemically with aluminum oxide (Al2O3) on the aluminum alloy surface at the process temperature to form a low-melting-point compound, thereby removing the oxide film that hinders metallurgical bonding. This chemical reaction can be expressed as:

[0042] 4KAlF4+Al2O3→2K2AlF5O+2AlF3;

[0043] The reaction products work together with the molten liquid solder to expose a clean metal surface and improve the wetting and spreading behavior of the liquid solder on the substrate.

[0044] At the same time, during the hot pressing process, a constant unidirectional pressure of 5 to 15 MPa is continuously applied to the component. This pressure causes the softer aluminum alloy substrate to undergo microscopic plastic deformation at the interface. This deformation crushes and destroys the extremely thin brittle oxide remaining on the interface after chemical pretreatment, and forces close physical contact at the atomic level, eliminating microscopic gaps between the interfaces and creating the physical prerequisites for subsequent solid-phase atomic diffusion.

[0045] Finally, under the coordinated control of temperature, pressure, time and atmosphere, liquid phase filling and solid phase diffusion are completed together to form a composite interface transition layer composed of the solidified phase of aluminum-based solder and the aluminum-copper atomic diffusion zone, thereby achieving high-quality connection between the aluminum alloy substrate and the brass terminal.

[0046] Refer to the attached Figure 1 The first step in the process is to pre-treat the surfaces of the aluminum alloy substrate and brass terminals to be welded. This step aims to remove oxide layers, oil stains, adsorbed matter, and other impurities from the surfaces, resulting in a clean and chemically active metal surface that is essential for the subsequent formation of a high-quality metallurgical bond. This step can include mechanical cleaning, chemical degreasing, and chemical activation.

[0047] First, the surfaces to be welded, both the aluminum alloy substrate and the brass terminal, were mechanically cleaned. In this example, 400-grit silicon carbide sandpaper was used to polish the surfaces in one direction until they exhibited a uniform metallic luster. This step removes thick oxide layers, surface scratches, and other macroscopic physical defects that may have formed during storage and transportation.

[0048] After mechanical cleaning, the workpieces undergo a chemical degreasing step. In this example, the polished aluminum alloy substrates and brass terminals were placed in an ultrasonic cleaning tank filled with acetone solution and ultrasonically cleaned at room temperature for 10 minutes. The cavitation effect of ultrasound can strip and remove grease, dust, and other fine particles adhering to the workpiece surface that were introduced during the polishing process.

[0049] After chemical degreasing, the workpiece undergoes chemical activation to remove the dense microscopic oxide film that rapidly forms in air. For 6061 aluminum alloy substrates, they are immersed in a 5% (by mass) sodium hydroxide aqueous solution at 50°C for 30 to 60 seconds. This alkaline cleaning step chemically dissolves the aluminum oxide film on the surface, exposing the fresh aluminum alloy substrate.

[0050] After alkali cleaning, the aluminum alloy is immediately rinsed with plenty of deionized water and then immersed in a 30% nitric acid aqueous solution at room temperature for 30 seconds to remove ash. This step is used to remove black deposits remaining on the aluminum alloy surface due to the alkali cleaning reaction. These deposits are mainly insoluble alloying elements in the aluminum alloy (such as silicon and copper).

[0051] Brass terminals are similarly treated with a chemical activation solution suitable for copper alloys (e.g., dilute sulfuric acid or hydrochloric acid solution) to achieve a clean surface. After the final chemical activation treatment, all parts are thoroughly rinsed with deionized water and immediately dried with high-purity nitrogen or argon. The treated parts should be immediately used for the next assembly step or stored in a vacuum-dried environment to minimize re-oxidation of the surface.

[0052] Refer to the attached Figure 2 , Figure 2 Figure 1 is a schematic diagram of the assembly structure of components to be welded according to one embodiment of the present invention. After completing the surface pretreatment step, the process flow enters the component assembly phase. This step aims to precisely assemble the cleaned materials into a laminated structure to be welded.

[0053] First, an Al-Si aluminum-based brazing filler metal foil that has been pre-cut and whose size matches the area to be welded is placed on the surface to be welded of the pre-treated aluminum alloy substrate.

[0054] To facilitate subsequent uniform application, powdered potassium fluoroaluminate flux and anhydrous ethanol are mechanically mixed in a predetermined ratio to form a uniform paste. Using a coating tool, such as a scraper or brush, the paste is evenly applied to the upper surface of the aluminum-based solder foil to form a flux layer. This ensures that the flux evenly covers the entire soldering interface during the subsequent hot pressing process, completely removing the oxide film.

[0055] Subsequently, the brass terminal, which has also undergone surface pretreatment, is aligned and stacked on the aluminum-based solder foil coated with flux from the side of its surface to be welded. During the stacking process, it is ensured that the areas to be welded of the aluminum alloy substrate, aluminum-based solder, and brass terminal are completely overlapped and aligned to form a welded assembly.

[0056] To prevent relative displacement of components during transfer to the hot press, high-temperature-resistant fixtures, such as graphite fixtures, can be used to apply initial positioning pressure to the assembled components. The entire assembly process is performed quickly after surface pretreatment is completed to shorten the time the clean metal surface is exposed to the environment, thereby reducing the degree of re-oxidation.

[0057] After the components are assembled, the process enters the core hot pressing connection stage, which is performed in a vacuum hot pressing furnace.

[0058] First, place the components to be welded, which have been initially fixed by the clamp, between the graphite pressing heads of the vacuum hot pressing furnace, ensuring that they are centered and stable. After closing the furnace door, start the vacuum system and pump the vacuum degree in the furnace to 5×10 -3 Pa or lower to remove residual air and water vapor in the furnace.

[0059] After reaching the preset vacuum level, the furnace is backfilled with 99.999% high-purity argon until the pressure inside the furnace returns to 0.05 MPa. The purpose of establishing this inert gas protective atmosphere is to prevent secondary oxidation of the cleaned metal surface during the entire high-temperature process.

[0060] Then, the heating program was started to uniformly heat the assembly to a target soldering temperature of 615° C. at a heating rate of 10° C. / min. The target temperature was within the process temperature range of 600° C. to 630° C. preset in the present invention.

[0061] During the heating process, or after the furnace temperature reaches the target temperature of 615°C, the equipment's hydraulic system applies unidirectional pressure to the components, precisely controlling and maintaining the pressure at 10 MPa. This pressure falls within the predetermined process pressure range of 5 MPa to 15 MPa.

[0062] The temperature and pressure are maintained at 615°C and 10 MPa for 15 minutes. During this stage, the aluminum-based solder completely melts and wets the filler interface, the flux reacts with the residual oxide, and, driven by the high temperature and high pressure, the aluminum and copper atoms undergo significant solid-phase interdiffusion at the interface.

[0063] After the heat and pressure holding phase, heating is stopped and the components are allowed to cool naturally in the furnace. To prevent excessive internal stress during cooling due to differences in thermal expansion coefficients among materials, which could lead to weld defects, the applied 10 MPa pressure is completely removed once the component temperature cools below 300°C. Once the furnace temperature has returned to room temperature, the furnace door is opened and the welded components are removed.

[0064] To verify the performance of the welded assembly prepared by the above process, a post-weld inspection and performance characterization were performed. The main physical and mechanical properties of the base material used in this embodiment are shown in Table 1.

[0065] Table 1 Physical and mechanical properties of matrix materials

[0066]

[0067] First, the interface microstructure analysis is performed. Metallographic specimens are cut vertically from the bonding area of ​​the welded assembly. After standard mounting, grinding, and polishing procedures, the micromorphology of the interface area is observed using a scanning electron microscope (SEM). This analysis allows the bonding quality of the interface to be evaluated. A successfully prepared joint should have a tightly bonded interface between the aluminum alloy substrate and the brass terminal, without any welding defects such as cracks or holes. This morphological feature confirms that the molten aluminum-based brazing filler metal has completely filled the interface under pressure.

[0068] Based on the SEM observations, line scan analysis of the interface was performed using an energy dispersive X-ray spectrometer (EDS) coupled to the SEM. The results revealed the presence of an atomic diffusion zone with a smooth composition transition, approximately several microns thick, within the interface transition region. The concentrations of key elements, such as aluminum, copper, and zinc, were distributed in a gradient, confirming effective solid-phase atomic interdiffusion during the hot pressing process, forming a true metallurgical bond, rather than a simple physical fit.

[0069] Secondly, the mechanical properties of the joints were tested. The welded components were processed into shear specimens according to the standards and subjected to tensile shear tests on a universal material testing machine. The test results showed that the average shear strength of the joints reached a specific value (e.g., above 80 MPa), and the fracture position was located on the side of the aluminum alloy substrate, not at the bonding interface. This result quantitatively proves that the bonding strength of the welding interface obtained by this process exceeds the strength of the aluminum alloy substrate itself.

[0070] Finally, the electrical performance of the joint was tested. The interface resistance of the welded joint area was measured using the four-probe method. The measurement results showed that the contact resistivity of the interface was at an extremely low level (e.g. 10 -8 Ω·cm 2 The results of the above tests and characterization confirm that the process provided by this invention can stably produce aluminum-copper heterogeneous material welded assemblies with excellent overall performance.

[0071] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A welding forming process for aluminum alloy copper busbars and terminals, characterized in that: The following steps are involved: Providing an aluminum alloy substrate, a copper or brass piece, and an aluminum-based brazing filler metal disposed between the aluminum alloy substrate and the copper or brass piece; Laminating and assembling the aluminum alloy substrate, the aluminum-based brazing filler metal, and the copper or brass member to form an assembly; The assembly is hot-pressed under preset temperature and pressure conditions to melt the aluminum-based brazing filler metal. Simultaneously, under the pressure, atomic diffusion occurs at the interface between the copper or brass component and the aluminum alloy substrate, thereby forming a metallurgical bond.

2. The welding forming process of the aluminum alloy copper busbar and terminal according to claim 1 is characterized in that: The preset temperature of the hot pressing treatment is 600° C. to 630° C., which is higher than the melting point of the aluminum-based brazing material to ensure its full melting and provide activation energy for solid-phase atomic diffusion between the copper or brass part and the aluminum alloy substrate.

3. The welding forming process of the aluminum alloy copper busbar and terminal according to claim 1, characterized in that: A flux is also applied on the aluminum-based brazing filler metal or at the interface between the copper or brass part and the aluminum alloy substrate. The flux is potassium fluoroaluminate, which can remove the oxide film on the surface of the aluminum alloy substrate and the copper or brass part at the preset temperature and improve the wettability of the molten aluminum-based brazing filler metal to the substrate and the copper or brass part.

4. The welding forming process of the aluminum alloy copper busbar and terminal according to claim 1, characterized in that: The aluminum alloy substrate is 6061 aluminum alloy in T6 heat treatment state, and the copper or brass part is an H62 brass part or a red copper part.

5. The welding forming process of the aluminum alloy copper busbar and terminal according to claim 1, characterized in that: The pressure is a constant unidirectional pressure continuously applied during the hot pressing process, and the pressure value is 5 MPa to 15 MPa. The pressure is sufficient to cause local plastic deformation at the interface between the copper or brass part and the aluminum alloy substrate, thereby destroying the residual brittle oxide at the interface and ensuring physical contact without voids, thereby creating conditions for atomic diffusion.

6. The welding forming process of the aluminum alloy copper busbar and terminal according to claim 1, characterized in that: Before the stacking assembly, the step of performing surface pretreatment on the surfaces to be welded of the aluminum alloy substrate and the copper or brass piece is also included. The surface pretreatment is used to obtain clean and chemically active surfaces to be welded.

7. The welding forming process of aluminum alloy copper busbar and terminal according to claim 6, characterized in that: The hot pressing treatment is carried out in a vacuum or argon protective atmosphere to prevent the surface to be welded that has undergone surface pretreatment from being oxidized again during the heating and hot pressing treatment process.

8. The welding forming process of aluminum alloy copper busbar and terminal according to claim 7, characterized in that: The surface pretreatment step includes: mechanically cleaning the surface to be welded by sandpaper polishing to remove the rough oxide layer and macroscopic physical defects on the surface.

9. The welding forming process of aluminum alloy copper busbar and terminal according to claim 7, characterized in that: The surface pretreatment step includes placing the surface to be welded in an acetone solution and performing ultrasonic cleaning to remove oil stains and particles adhering to the surface.

10. The welding forming process of aluminum alloy copper busbar and terminal according to claim 7, characterized in that: The surface pretreatment step includes: immersing the surface to be welded in an alkaline solution or an acid solution for chemical activation treatment to remove the dense microscopic oxide film formed in the air and expose a fresh metal matrix.

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