A dissimilar metal welding method, a welding system and a copper base material

Abstract

The present invention relates to a dissimilar metal welding method, a welding system and a copper substrate, belonging to the field of laser welding. It includes the following steps: S1: Clean the mating surface of the copper component and the mating surface of the aluminum component; S2: Abut the mating surface of the copper component against the mating surface of the aluminum component so that the copper component and the aluminum component are stacked; S3: Use a composite laser and an infrared pulsed laser coaxially arranged therewith to irradiate the surface of the aluminum component facing away from the copper component and scan along the cladding track to melt the aluminum component; The infrared pulsed laser inputs energy in a periodic pulse form, slowing down the cooling rate of the molten pool, which is beneficial to the escape of bubbles in the molten pool and the generation of photoinduced plasma induced by the infrared pulsed laser. When the plasma expands, a shock wave is formed, which has a high-frequency impact on the molten pool. The impact effect significantly enhances the radial divergent movement generated at the gas-liquid interface in the center of the molten pool, thereby increasing the steady-state convection inside the center of the molten pool.

Description

Technical Field

[0001] The present invention belongs to the field of laser welding, and particularly relates to a method for welding dissimilar metals, a welding system and a copper substrate. Background Art

[0002] Copper components have been widely used in the fields of electric vehicles, electronic engineering and solar energy due to their excellent electrical and thermal conductivity. However, with the increasing demand for copper resources in modern manufacturing, finding alternative materials for copper has become an urgent issue. Aluminum and its alloys have become the focus of research due to their light weight, cost-effectiveness, good electrical and thermal conductivity, and excellent corrosion resistance. Although the electrical conductivity of aluminum is only 61% of that of copper, its weight is only 30% of that of copper, which makes aluminum a potential candidate for replacing copper. Therefore, the reliable connection technology between aluminum and copper dissimilar metals has become the key in the research of aluminum-copper composite structures.

[0003] In the research of aluminum-copper dissimilar metal connection technology, scientists have explored various welding methods, including friction stir welding, ultrasonic welding, brazing and explosion welding, etc. However, due to problems such as welding site limitations, fume pollution and equipment loss, these methods have not been widely used in aluminum-copper connections. In contrast, laser welding technology has gradually gained favor in the manufacturing process of aluminum-copper dissimilar metal welding due to its high precision, high degree of automation and environmental protection characteristics. However, the laser welding cooling rate is high, and the weld microstructure is prone to form coarse columnar crystals, which affects the mechanical properties of the weld. Therefore, how to overcome these challenges and improve the performance of aluminum-copper dissimilar metal welded joints remains an important research direction at present. Summary of the Invention

[0004] In view of the above problems, the embodiments of the present application provide a method for welding dissimilar metals, a welding system and a copper substrate, which can reduce the size of columnar crystals in the weld microstructure, thereby improving the mechanical properties of the weld.

[0005] In a first aspect, the embodiments of the present application provide a method for welding dissimilar metals, which includes the following steps: S1: Clean the mating surface of the copper component and the mating surface of the aluminum component; S2: Abut the mating surface of the copper component against the mating surface of the aluminum component so that the copper component and the aluminum component are stacked; S3: Use a composite laser and an infrared pulsed laser coaxially arranged with it to irradiate the surface of the aluminum component facing away from the copper component and scan along the cladding track to melt the aluminum component and make the aluminum component cladded on the mating surface of the copper component.

[0006] In the above technical solution, infrared pulsed laser is used to input energy in the form of periodic pulses, which slows down the cooling rate of the molten pool and is beneficial to the escape of bubbles in the molten pool. At the same time, the infrared pulsed laser is used to induce the generation of photoinduced plasma. When the plasma expands, a shock wave is formed, which can produce a high-frequency impact on the molten pool. On the one hand, this impact effect significantly enhances the radial divergent motion generated at the gas-liquid interface in the center of the molten pool, thereby increasing the steady-state convection inside the center of the molten pool, promoting the escape of bubbles in the molten pool, and further reducing the formation of pore defects. On the other hand, this impact effect is beneficial to breaking the dendrite arms in the molten pool, thereby providing nucleation sites, helping to refine the grain structure in the weld area, and improving the strength and plasticity of the welded joint.

[0007] In some embodiments, in step S3, the laser cladding parameters include: the power of the infrared pulsed laser is 100W - 150W, the frequency of the infrared pulsed laser is 40Hz - 100Hz, the wavelength of the infrared pulsed laser is 980nm - 1180nm, and the scanning speed of the composite laser and the infrared pulsed laser is 40mm / s - 80mm / s.

[0008] In some embodiments, in step S3, the composite laser is an infrared-blue coaxial composite laser formed by coaxially setting an infrared continuous laser and a blue laser.

[0009] In the above technical solution, highly reflective metals (such as copper, aluminum, and gold) have a much higher absorption rate of blue light than infrared laser. At the same time, the absorption rate of blue laser changes little during metal melting, avoiding the welding instability problem caused by the sudden change in absorption rate of infrared laser from solid state to liquid state. The infrared continuous laser stabilizes the welding keyhole, thereby further improving the utilization rate of laser energy by the welding small hole. At the same time, the longer wavelength of the infrared continuous laser can reduce the shielding effect of plasma on laser energy, so as to reduce the shielding of laser energy by the photoinduced plasma induced by the infrared pulsed laser and ensure the stability of the weld. Therefore, a blue-light-infrared coaxial composite laser is used as the composite laser, with a large blue-light outer spot for preheating and slow cooling and a small infrared inner spot for deep penetration welding, so as to balance the absorption rate and energy density.

[0010] In some embodiments, in step S3, the laser cladding parameters include: the power of the infrared continuous laser is 700W - 1200W, the wavelength of the infrared continuous laser is 864nm - 1064nm, and / or the power of the blue laser is 100W - 300W, and the wavelength of the blue laser is 450nm - 495nm.

[0011] In some embodiments, in step S3, during the laser cladding process, the defocusing cladding method is used to scan along a fixed cladding trajectory to melt the aluminum component and make the aluminum component cladded on the mating surface of the copper component.

[0012] In some embodiments, in step S3, during the laser cladding process, the molten pool generated by melting the aluminum component is protected by an inert medium.

[0013] In the above technical solution, the molten pool is protected by an inert medium, which reduces the risk of aluminum parts and copper parts coming into contact with air, thereby reducing the risk of hydrogen pores and pinhole-type pores being easily formed during the welding process.

[0014] In some embodiments, step S1 includes: S11: polishing the surface to be bonded of the copper component with sandpaper, and polishing the surface to be bonded of the aluminum component with sandpaper; S12: scrubbing the surface to be bonded of the copper component with acetone, and scrubbing the surface to be bonded of the aluminum component with acetone; S13: cleaning the surface to be bonded of the copper component with ultrasonic cleaning, and cleaning the surface to be bonded of the aluminum component with acoustic cleaning.

[0015] In a second aspect, an embodiment of the present application provides a dissimilar metal welding system for welding copper components to aluminum components, comprising a positioning mechanism, a laser processing head, a compound laser mechanism, a first semi-transparent semi-reflective beam combining mirror and a first laser; the positioning mechanism is used to fix the stacked copper components and the aluminum components; the laser processing head is located on one side of the positioning mechanism in the stacking direction; the compound laser mechanism is used to provide a compound laser; the first semi-transparent semi-reflective beam combining mirror is located between the compound laser mechanism and the laser processing head, and the compound laser passes through the first semi-transparent semi-reflective beam combining mirror to enter the laser processing head; the first laser is used to provide an infrared pulse laser to the first semi-transparent semi-reflective beam combining mirror, and the infrared pulse laser is reflected by the first semi-transparent semi-reflective beam combining mirror to enter the laser processing head coaxially with the compound laser.

[0016] In the above technical solution, an infrared pulse laser is provided by a first laser, and energy is input in the form of periodic pulses using the infrared pulse laser, which slows down the cooling rate of the molten pool and is beneficial to the escape of bubbles in the molten pool; at the same time, an infrared pulse laser is used to induce the generation of photo-induced plasma, and shock waves are formed when the plasma expands, which can produce a high-frequency impact on the molten pool. On the one hand, this impact effect significantly enhances the radial divergent motion generated at the gas-liquid interface in the center of the molten pool, thereby increasing the steady-state convection inside the center of the molten pool, thereby promoting the escape of bubbles in the molten pool, and then reducing the formation of porosity defects; on the other hand, this impact effect is beneficial to breaking up the dendrite arms in the molten pool, thereby providing nucleation sites, helping to refine the grain structure in the weld area, and thus improving the strength and plasticity of the welded joint.

[0017] In some embodiments, the composite laser mechanism includes a second laser, a second semi-transmissive and semi-reflective beam combiner, and a third laser. The second laser is configured to provide blue laser light. The second semi-transmissive and semi-reflective beam combiner is located between the second laser and the first semi-transmissive and semi-reflective beam combiner. The blue laser light passes through the second semi-transmissive and semi-reflective beam combiner and the first semi-transmissive and semi-reflective beam combiner to enter the laser processing head. The third laser is configured to provide continuous infrared laser light to the second semi-transmissive and semi-reflective beam combiner. The continuous infrared laser light is reflected by the second semi-transmissive and semi-reflective beam combiner to form the composite laser coaxial with the blue laser light.

[0018] In a third aspect, embodiments of the present application provide a copper substrate. The surface of the copper substrate includes a wear-resistant coating, and the wear-resistant coating is made by cladding an aluminum component using coaxial composite laser and infrared pulsed laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a schematic flowchart of a dissimilar metal welding method provided by some embodiments of the present invention;

[0021] Figure 2 It is a schematic flowchart of a cleaning step provided by some embodiments of the present invention;

[0022] Figure 3 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 1 of the present invention;

[0023] Figure 4 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 2 of the present invention;

[0024] Figure 5 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 3 of the present invention;

[0025] Figure 6 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 4 of the present invention;

[0026] Figure 7 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 5 of the present invention;

[0027] Figure 8 It is a cross-sectional morphology diagram of a cladding layer prepared in Embodiment 6 of the present invention;

[0028] Figure 9It is the cross-sectional morphology diagram of the cladding layer prepared in Embodiment 7 of the present invention;

[0029] Figure 10 It is the structural schematic diagram of a dissimilar metal welding system provided by an embodiment of the present invention. Detailed implementation manners

[0030] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0031] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0032] The terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "plural" is two or more.

[0033] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0034] Due to their excellent electrical and thermal conductivity, copper components have been widely used in the fields of electric vehicles, electronic engineering, and solar energy. However, with the increasing demand for copper resources in modern manufacturing, finding alternative materials for copper has become an urgent issue. Aluminum and its alloys have become the focus of research due to their light weight, cost-effectiveness, good electrical and thermal conductivity, and excellent corrosion resistance. Although the conductivity of aluminum is only 61% of that of copper, its weight is only 30% of that of copper, which makes aluminum a potential candidate material to replace copper. Therefore, the reliable connection technology between aluminum and copper dissimilar metals has become the key in the research of aluminum-copper composite structures.

[0035] In the research of aluminum-copper dissimilar metal joining technologies, scientists have explored various welding methods, including friction stir welding, ultrasonic welding, brazing, and explosive welding. However, these methods have not been widely used in aluminum-copper joining due to limitations in welding space, smoke pollution, and equipment wear and tear. In contrast, laser welding technology, with its high precision, high degree of automation, and environmentally friendly characteristics, has gradually gained favor in the aluminum-copper dissimilar metal welding process. However, the high reflectivity of aluminum and copper to infrared lasers (1080 nm) limits the effective application of laser energy in the weld zone. To address this, hybrid blue-light and infrared laser technology has been proposed to improve the laser absorption rate of aluminum-copper components, thereby achieving precise control of weld penetration and reducing weld spatter. However, the active chemical properties of aluminum and copper make them highly susceptible to oxidation, which easily forms hydrogen pores and pinhole-type pores during welding, affecting the strength and toughness of the weld joint. Furthermore, the high cooling rate of laser welding easily leads to the formation of coarse columnar crystals in the weld microstructure, which affects the mechanical properties of the weld. Therefore, overcoming these challenges and improving the performance of aluminum-copper dissimilar metal welds remains an important research direction.

[0036] In order to solve the above technical problems, refer to Figure 1 - Figure 2 , an embodiment of the present application provides a dissimilar metal welding method, which includes the following steps: S1: cleaning the surface to be joined of the copper component and the surface to be joined of the aluminum component; S2: abutting the surface to be joined of the copper component with the surface to be joined of the aluminum component so that the copper component and the aluminum component are stacked; S3: using a composite laser and an infrared pulse laser coaxially arranged therewith to irradiate the surface of the aluminum component facing away from the copper component, and scanning along the cladding trajectory to melt the aluminum component, and make the aluminum component clad on the surface to be joined of the copper component.

[0037] In this technical solution, laser induces the generation of photo-induced plasma, and shock waves are formed when the plasma expands, which can produce high-frequency impact on the molten pool. On the one hand, this impact effect significantly enhances the radial divergent motion generated at the gas-liquid interface in the center of the molten pool, thereby increasing the steady-state convection inside the center of the molten pool, thereby promoting the escape of bubbles in the molten pool and reducing the formation of porosity defects; on the other hand, this impact effect is conducive to breaking up the dendrite arms in the molten pool, thereby providing nucleation sites, helping to refine the grain structure of the weld area, and thus improving the strength and plasticity of the weld joint.

[0038] According to some embodiments of the present application, in step S3, the laser cladding parameters include: the power of the infrared pulse laser is 100W-150W, the frequency of the infrared pulse laser is 40Hz-100Hz, the wavelength of the infrared pulse laser is 980nm-1180nm, and the scanning speed of the composite laser and the infrared pulse laser is 40 mm / s-80 mm / s.

[0039] According to some embodiments of the present application, in step S3, the composite laser is an infrared-blue coaxial composite laser composed of an infrared continuous laser and a blue laser coaxially arranged.

[0040] In the above technical solution, the absorption rate of blue light by highly reflective metals (such as copper, aluminum, and gold) far exceeds that of infrared lasers. Furthermore, the absorption rate of blue lasers changes less when the metal melts, thus avoiding the welding instability caused by the sudden change in absorption rate from solid to liquid phase caused by infrared lasers. The infrared continuous laser stabilizes the weld keyhole, further improving the utilization of laser energy from the weld keyhole. The longer wavelength of the infrared continuous laser reduces the shielding effect of plasma on the laser energy, thereby reducing the shielding of laser energy by the photo-induced plasma generated by the infrared pulse laser, ensuring weld stability. Therefore, a blue-infrared coaxial composite laser is used as the composite laser. The large blue light spot on the outer circle is preheated and slowly cooled, while the small infrared spot on the inner circle is used for deep penetration welding, thus achieving a balanced absorption rate and energy density.

[0041] According to some embodiments of the present application, in step S3, the laser cladding parameters include: the power of the infrared continuous laser is 700 W-1200 W, the wavelength of the infrared continuous laser is 864 nm-1064 nm, and / or, the power of the blue laser is 100 W-300 W, and the wavelength of the blue laser is 450 nm-495 nm.

[0042] According to some embodiments of the present application, in step S3, during the laser cladding process, a defocused cladding method is used to scan along a fixed cladding trajectory to melt the aluminum component and clad the aluminum component on the surface to be bonded with the component.

[0043] According to some embodiments of the present application, in step S3, during the laser cladding process, the molten pool generated by the melting of the aluminum component is protected by an inert medium.

[0044] In some embodiments, the inert medium may be argon.

[0045] In the above technical solution, the molten pool is protected by an inert medium, which reduces the risk of aluminum parts and copper parts coming into contact with air, thereby reducing the risk of hydrogen pores and pinhole-type pores being easily formed during the welding process.

[0046] According to some embodiments of the present application, step S1 includes: S11: using sandpaper to polish the surface to be bonded of the copper component, and using sandpaper to polish the surface to be bonded of the aluminum component; S12: using acetone to scrub the surface to be bonded of the copper component, and using acetone to scrub the surface to be bonded of the aluminum component; S13: using an ultrasonic cleaning method to clean the surface to be bonded of the copper component, and using an acoustic cleaning method to clean the surface to be bonded of the aluminum component.

[0047] The technical solution of the present invention will be further described in detail below with reference to specific examples and comparative examples:

[0048] Example 1

[0049] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the dissimilar aluminum-copper metals with a welding fixture. Among them, the aluminum component is above the copper component; Combine blue laser, infrared continuous laser and infrared pulsed laser through a beam combination system, so that the focal points of the three lasers converge on the upper surface position of the welding area, and the defocus amount is 0; Set the power of the blue laser to 200 W, the power of the infrared continuous laser to 800 W, the power of the infrared pulsed laser to 100 W, the frequency of the infrared pulsed laser to 50 Hz, and the welding speed to 50 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. The connection of dissimilar aluminum-copper metals with high reflectivity is realized by the above process parameters. The porosity in the aluminum-copper weld obtained in this example is low, and the grain structure is fine (as Figure 3 shown), the maximum shear strength is 100 MPa, and the elongation is about 12%.

[0050] Example 2

[0051] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the aluminum and copper components with a fixture. Among them, the copper component is above the aluminum metal; Combine blue laser, infrared continuous laser and infrared pulsed laser through a beam combination system, so that the focal points of the three lasers converge on the upper surface position of the welding area, and the defocus amount is 0.2 mm; Set the power of the blue laser to 300 W, the power of the infrared continuous laser to 1200 W, the power of the infrared pulsed laser to 150 W, the frequency of the infrared pulsed laser to 50 Hz, and the welding speed to 70 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. The connection of high reflectivity aluminum and copper components is realized by the above process parameters. The porosity in the aluminum-copper weld obtained in this example is low, and the grain structure is fine (as Figure 4 shown), the maximum shear strength is 110 MPa, and the elongation is about 6%.

[0052] Example 3

[0053] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the aluminum and copper components with a welding fixture. Among them, the aluminum component is above the copper component. Combine blue light laser, infrared continuous laser, and infrared pulsed laser through a beam combination system so that the foci of the three lasers converge to the upper surface position of the welding area, and the defocus amount is 0 mm. Set the power of the blue light laser to 100 W, the power of the infrared continuous laser to 1000 W, the power of the infrared pulsed laser to 150 W, the frequency of the infrared pulsed laser to 100 Hz, and the welding speed to 80 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. Connect the high-reflectivity aluminum and copper components using the above process parameters. The obtained aluminum-copper weld in this embodiment has a low porosity and a fine grain structure (as Figure 5 shown), the maximum shear strength is 110 MPa, and the elongation is about 15%.

[0054] Example 4

[0055] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the dissimilar aluminum and copper metals with a welding fixture. Among them, the aluminum component is above the copper component. Combine blue light laser, infrared continuous laser, and infrared pulsed laser through a beam combination system so that the foci of the three lasers converge to the upper surface position of the welding area, and the defocus amount is 0. Set the power of the blue light laser to 200 W, the power of the infrared continuous laser to 1000 W, the power of the infrared pulsed laser to 200 W, the frequency of the infrared pulsed laser to 80 Hz, and the welding speed to 50 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. Connect the high-reflectivity dissimilar aluminum and copper metals using the above process parameters. The obtained aluminum-copper weld in this embodiment has a low porosity and a fine grain structure (as Figure 6 shown), the maximum shear strength is 110 MPa, and the elongation is about 12%.

[0056] Example 5

[0057] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the dissimilar aluminum-copper metals with a welding fixture. Among them, the aluminum component is above the copper component. Combine blue laser, infrared continuous laser, and infrared pulsed laser through a beam combining system so that the foci of the three lasers converge to the upper surface position of the welding area, and the defocus amount is 0. Set the power of the blue laser to 200 W, the power of the infrared continuous laser to 1000 W, the power of the infrared pulsed laser to 150 W, the frequency of the infrared pulsed laser to 150 Hz, and the welding speed to 70 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. High-reflectivity dissimilar aluminum-copper metals are joined using the above process parameters. In this embodiment, the porosity in the aluminum-copper weld is low, and the grain structure is fine (as Figure 7 shown), the maximum shear strength is 105 MPa, and the elongation is about 15%.

[0058] Example 6

[0059] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the dissimilar aluminum-copper metals with a welding fixture. Among them, the aluminum component is above the copper component. Converge the focus of the blue laser to the upper surface position of the welding area, and the defocus amount is 0. Set the power of the blue laser to 800 W and the welding speed to 50 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. High-reflectivity dissimilar aluminum-copper metals are joined using the above process parameters. In this embodiment, the porosity in the aluminum-copper weld is low, and the grain structure is fine (as Figure 8 shown), the maximum shear strength is 90 MPa, and the elongation is about 6%.

[0060] Example 7

[0061] Select aluminum and copper components with a thickness of 1 mm respectively as welding materials. Sand the aluminum and copper components to be welded, scrub them with acetone, clean and dry them by ultrasonic cleaning, and fix the dissimilar aluminum-copper metals with a welding fixture. Among them, the aluminum component is above the copper component. Converge the infrared continuous laser to the upper surface position of the welding area, and the defocus amount is 0. Set the power of the infrared continuous laser to 1000 W and the welding speed to 50 mm / s. At the same time, use argon protection during the welding process to prevent oxidation. High-reflectivity dissimilar aluminum-copper metals are joined using the above process parameters. In this embodiment, the porosity in the aluminum-copper weld is low, and the grain structure is fine (as Figure 9 shown), the maximum shear strength is 50 MPa, and the elongation is about 4%.

[0062] Refer to Figure 10, an embodiment of the present application provides a dissimilar metal welding system for welding copper components and aluminum components, including a positioning mechanism (not shown in the figure), a laser processing head 4, a composite laser mechanism, a first semi-transmissive semi-reflective beam combiner 23, and a first laser 3; the positioning mechanism is used to fix the stacked copper components and aluminum components; the laser processing head 4 is located on one side of the positioning mechanism in the stacking direction; the composite laser mechanism is used to provide composite laser; the first semi-transmissive semi-reflective beam combiner 23 is located between the composite laser mechanism and the laser processing head 4, and the composite laser passes through the first semi-transmissive semi-reflective beam combiner 23 to enter the laser processing head 4; the first laser 3 is used to provide infrared pulsed laser to the first semi-transmissive semi-reflective beam combiner 23, and the infrared pulsed laser is reflected by the first semi-transmissive semi-reflective beam combiner 23 and enters the laser processing head 4 coaxially with the composite laser.

[0063] Exemplarily, the positioning mechanism can be a fixture, and the first laser 3 can be an infrared pulsed laser.

[0064] The semi-transmissive semi-reflective beam combiner is an optical lens with both transmission and reflection characteristics. Exemplarily, the semi-transmissive semi-reflective beam combiner can transmit laser with wavelengths below 964 nm and reflect laser with wavelengths above 964 nm. And it is used to recombine light beams with different paths into a single optical path, maintaining phase and direction consistency.

[0065] In some embodiments, a first collimating mirror 13 is provided between the laser emitting end of the first laser emitter and the first semi-transmissive semi-reflective beam combiner 23.

[0066] The collimating mirror can be a lens group or a mirror 21 system, which is used to convert a divergent Gaussian beam into a parallel beam, significantly improving the beam transmission distance and energy density. For example, a Kepler-type collimating mirror compresses the light spot through a small focal length lens and then expands the divergence angle through a large focal length lens to achieve efficient collimation.

[0067] In the above technical solution, infrared pulsed laser is provided by the first laser 3, and the energy is input in the form of periodic pulses by using the infrared pulsed laser, slowing down the cooling rate of the molten pool, which is beneficial to the escape of bubbles in the molten pool; at the same time, the infrared pulsed laser is used to induce the generation of photo-induced plasma, and when the plasma expands, a shock wave is formed, which can have a high-frequency impact on the molten pool. On the one hand, this impact effect significantly enhances the radial divergent movement generated at the gas-liquid interface in the center of the molten pool, thereby increasing the steady-state convection inside the center of the molten pool, promoting the escape of bubbles in the molten pool, and further reducing the formation of pore defects; on the other hand, this impact effect is conducive to breaking the dendrite arms in the molten pool, thereby providing nucleation sites, helping to refine the grain structure in the weld area, and thus improving the strength and plasticity of the welded joint.

[0068] In some embodiments, the composite laser mechanism includes a second laser 1, a second semi-transmissive and semi-reflective beam combiner 22, and a third laser 2. The second laser 1 is used to provide blue laser light; the second semi-transmissive and semi-reflective beam combiner 22 is located between the second laser 1 and the first semi-transmissive and semi-reflective beam combiner 23, and the blue laser light passes through the second semi-transmissive and semi-reflective beam combiner 22 and the first semi-transmissive and semi-reflective beam combiner 23 to enter the laser processing head 4; the third laser 2 is used to provide continuous infrared laser light to the second semi-transmissive and semi-reflective beam combiner 22, and the continuous infrared laser light is reflected by the second semi-transmissive and semi-reflective beam combiner 22 to form a composite laser light coaxial with the blue laser light.

[0069] In some embodiments, a second collimating mirror 11 is provided between the laser emission end of the second laser emitter and the second semi-transmissive and semi-reflective beam combiner 22. A third collimating mirror 12 is provided between the laser emission end of the third laser emitter and the second semi-transmissive and semi-reflective beam combiner 22, and a reflecting mirror 21 is provided between the second semi-transmissive and semi-reflective beam combiner 22 and the third collimating mirror 12. The reflecting mirror 21 is used to reflect the continuous infrared laser light to the second semi-transmissive and semi-reflective beam combiner 22.

[0070] Exemplarily, the second laser 1 can be a blue laser, and the third laser 2 can be a continuous infrared laser.

[0071] An embodiment of the present application provides a copper substrate, the surface of the copper substrate includes a wear-resistant coating, and the wear-resistant coating is made by cladding an aluminum component with a composite laser and an infrared pulsed laser arranged coaxially.

[0072] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0073] The above embodiments are only used to illustrate the technical solutions of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A method for welding dissimilar metals for welding a copper component to an aluminum component, characterized in that: The dissimilar metal welding method includes the following steps: S1: Cleaning the surface of the copper component to be bonded, and cleaning the surface of the aluminum component to be bonded; S2: placing the surface of the copper component to be joined in contact with the surface of the aluminum component to be joined, so that the copper component and the aluminum component are stacked; S3: using a composite laser and an infrared pulse laser coaxially arranged therewith to irradiate the surface of the aluminum component facing away from the copper component, and scanning along the cladding track to melt the aluminum component and clad the aluminum component on the surface to be bonded with the copper component; In step S3, the composite laser is an infrared-blue coaxial composite laser composed of an infrared continuous laser and a blue laser coaxially arranged.

2. The method for welding dissimilar metals according to claim 1, wherein: In step S3, the laser cladding parameters include: The power of the infrared pulse laser is 100W-150W, the frequency of the infrared pulse laser is 40Hz-100Hz, the wavelength of the infrared pulse laser is 980nm-1180nm, and the scanning speed of the composite laser and the infrared pulse laser is 40mm / s-80 mm / s.

3. The method for welding dissimilar metals according to claim 1, wherein: In step S3, the laser cladding parameters include: The power of the infrared continuous laser is 700 W-1200 W, and the wavelength of the infrared continuous laser is 864 nm-1064 nm, and / or the power of the blue laser is 100 W-300 W, and the wavelength of the blue laser is 450 nm-495 nm.

4. The method for welding dissimilar metals according to claim 1, wherein: In step S3, during the laser cladding process, a defocused cladding method is adopted to scan along a fixed cladding trajectory to melt the aluminum component and clad the aluminum component on the surface to be bonded with the component.

5. The method for welding dissimilar metals according to claim 1, wherein: In step S3, during the laser cladding process, an inert medium is used to protect the molten pool generated by melting the aluminum component.

6. The method for welding dissimilar metals according to claim 1, characterized in that: Step S1 includes: S11: polishing the surface of the copper component to be bonded with sandpaper, and polishing the surface of the aluminum component to be bonded with sandpaper; S12: scrubbing the surface of the copper component to be bonded with acetone, and scrubbing the surface of the aluminum component to be bonded with acetone; S13: Cleaning the surface of the copper component to be bonded by ultrasonic cleaning, and cleaning the surface of the aluminum component to be bonded by sonic cleaning.

7. A dissimilar metal welding system for welding copper parts to aluminum parts, characterized in that: include: A positioning mechanism for fixing the copper component and the aluminum component that are stacked; a laser processing head, located on one side of the positioning mechanism in the stacking direction; A compound laser mechanism, used for providing compound laser; a first semi-transparent and semi-reflective beam combining mirror, located between the composite laser mechanism and the laser processing head, wherein the composite laser passes through the first semi-transparent and semi-reflective beam combining mirror to enter the laser processing head; The first laser is used to provide an infrared pulse laser to the first semi-transparent and semi-reflective beam combining mirror. The infrared pulse laser is reflected by the first semi-transparent and semi-reflective beam combining mirror to enter the laser processing head coaxially with the composite laser. The composite laser is an infrared-blue light coaxial composite laser composed of an infrared continuous laser and a blue light laser coaxially arranged.

8. The dissimilar metal welding system according to claim 7, characterized in that: The composite laser mechanism comprises: a second laser for providing blue laser light; A second semi-transparent and semi-reflective beam combining mirror is located between the second laser and the first semi-transparent and semi-reflective beam combining mirror, and the blue laser passes through the second semi-transparent and semi-reflective beam combining mirror and the first semi-transparent and semi-reflective beam combining mirror to enter the laser processing head; The third laser is used to provide infrared continuous laser light to the second semi-transparent semi-reflective beam combiner, and the infrared continuous laser light is reflected by the second semi-transparent semi-reflective beam combiner to form the composite laser light coaxially with the blue laser light.

9. A copper substrate, characterized in that The surface of the copper substrate includes a wear-resistant coating, which is made by melting aluminum components with a coaxially arranged composite laser and an infrared pulse laser. The composite laser is an infrared-blue coaxial composite laser composed of a coaxially arranged infrared continuous laser and a blue laser.

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