Dissimilar metal welding method, welding system and copper base material

Abstract

The invention relates to a dissimilar metal welding method, a dissimilar metal welding system and a copper base material, and belongs to the field of laser welding. Comprising the following steps that S1, the to-be-combined face of a copper part is cleaned, and the to-be-combined face of an aluminum part is cleaned; s2, the to-be-combined face of the copper component abuts against the to-be-combined face of the aluminum component, so that the copper component and the aluminum component are arranged in a stacked mode; s3, composite laser and infrared pulse laser coaxial with the composite laser are adopted for irradiating the surface, deviating from the copper part, of the aluminum part, and scanning is conducted along the cladding track so as to melt the aluminum part; energy is input in a periodic pulse mode through infrared pulse laser, the cooling speed of a molten pool is reduced, bubbles in the molten pool can escape easily, light-induced plasmas are generated through induction of the infrared pulse laser, shock waves are formed when the plasmas expand, and the high-frequency impact effect is generated on the molten pool; the impact effect remarkably enhances radial divergent motion generated at a gas-liquid interface of the center of the molten pool, so that steady-state convection in the center of the molten pool is increased.

Description

Technical Field

[0001] The invention belongs to the field of laser welding, and in particular relates to a dissimilar metal welding method, a welding system and a copper substrate. Background Art

[0002] Copper components have been widely used in electric vehicles, electronic engineering and solar energy due to their excellent electrical and thermal conductivity. However, with the growing demand for copper resources in modern manufacturing, the scarcity of copper resources in my country has become a bottleneck restricting industrial development. Therefore, finding alternative materials to copper has become an urgent issue. Aluminum and its alloys have become the focus of research due to their light weight, high 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, 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 joining technology, scientists have explored a variety of welding methods, including stir friction welding, ultrasonic welding, brazing and explosion welding. However, these methods have not been widely used in aluminum-copper joining due to the limitations of welding sites, smoke pollution and equipment loss. In contrast, laser welding technology has gradually gained favor in the aluminum-copper dissimilar metal welding manufacturing process due to its high precision, high degree of automation and environmental protection characteristics. However, laser welding has a high cooling rate, and the weld structure is very likely 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 is still an important direction of current research. Summary of the invention

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

[0005] In a first aspect, an embodiment of the present application provides a method for welding dissimilar metals, which comprises the following steps: S1: cleaning the surface to be joined of the copper component, and cleaning 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 away from the copper component, and scanning along the cladding trajectory to melt the aluminum component, and cladding the aluminum component on the surface to be joined of the copper component.

[0006] In the above technical scheme, an infrared pulse 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, an infrared pulse laser is used to induce the generation of photo-induced 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, 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 beneficial to breaking the dendrite arms in the molten pool, thereby providing nucleation sites, which helps to refine the grain structure in the weld area, thereby 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 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-80mm / s.

[0008] In some embodiments, in step S3, the composite laser is an infrared-blue light coaxial composite laser composed of an infrared continuous laser and a blue light laser coaxially arranged.

[0009] In the above technical scheme, the absorption rate of blue light by highly reflective metals (such as copper, aluminum, and gold) far exceeds that of infrared lasers. At the same time, the absorption rate of blue lasers changes little when the metal melts, which avoids the welding instability problem caused by the sudden change of the absorption rate of infrared lasers from solid to liquid. The infrared continuous laser stabilizes the welding keyhole, thereby further improving the utilization rate of laser energy by the welding keyhole. At the same time, the longer wavelength of the infrared continuous laser can reduce the shielding effect of plasma on laser energy, thereby reducing the shielding of laser energy by photo-induced plasma induced by infrared pulse lasers, and ensuring the stability of the weld. Therefore, a blue-infrared coaxial composite laser is used as the composite laser, the outer circle blue light large spot is preheated and slowly cooled, and the inner circle infrared small spot is deep-melted for welding, so as to take into account both 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 light laser is 100W-300W, and the wavelength of the blue light laser is 450nm-495nm.

[0011] In some embodiments, 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 allow the aluminum component to be clad on the surface to be bonded with 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 to reduce 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 welding.

[0014] In some embodiments, 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 ultrasonic cleaning method to clean the surface to be bonded of the copper component, and using acoustic cleaning method to clean the surface to be bonded of the aluminum component.

[0015] In the 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 and semi-reflective beam combining mirror and a first laser; the positioning mechanism is used to fix the copper components and the aluminum components that are stacked; 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 and 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 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, and 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 compound laser.

[0016] In the above technical scheme, an infrared pulse laser is provided by a first laser, and energy is input in the form of periodic pulses using an 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 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 the dendrite arms in the molten pool, thereby providing nucleation sites, which helps to refine the grain structure in the weld area, thereby improving the strength and plasticity of the welded joint.

[0017] In some embodiments, the composite laser mechanism includes a second laser, a second semi-transparent and semi-reflective beam combining mirror, and a third laser, the second laser is used to provide a blue light laser; the 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, the blue light 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 an infrared continuous laser to the second semi-transparent and semi-reflective beam combining mirror, the infrared continuous laser is reflected by the second semi-transparent and semi-reflective beam combining mirror to form the composite laser coaxially with the blue light laser.

[0018] In a third aspect, an embodiment of the present application provides a copper substrate, wherein the surface of the copper substrate includes a wear-resistant coating, and the wear-resistant coating is produced by cladding an aluminum component using a coaxially arranged composite laser and an infrared pulse laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of a process for welding dissimilar metals provided in some embodiments of the present invention; Figure 2 A schematic diagram of a cleaning process according to some embodiments of the present invention; Figure 3 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 1 of the present invention; Figure 4 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 2 of the present invention; Figure 5 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 3 of the present invention; Figure 6 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 4 of the present invention; Figure 7 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 5 of the present invention; Figure 8 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 6 of the present invention; Fig. 9 This is a cross-sectional morphology diagram of the cladding layer prepared in Example 7 of the present invention; Fig.10 A schematic structural diagram of a dissimilar metal welding system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0022] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0023] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0024] In the description of this 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 can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0025] Copper components have been widely used in electric vehicles, electronic engineering and solar energy due to their excellent electrical and thermal conductivity. However, with the growing demand for copper resources in modern manufacturing, the scarcity of copper resources in my country has become a bottleneck restricting industrial development. Therefore, finding alternative materials to copper has become an urgent issue. Aluminum and its alloys have become the focus of research due to their light weight, high 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, reliable connection technology between aluminum and copper dissimilar metals has become the key in the research of aluminum-copper composite structures.

[0026] In the research of aluminum-copper dissimilar metal joining technology, scientists have explored a variety of welding methods, including stir friction welding, ultrasonic welding, brazing and explosion welding. However, these methods have not been widely used in aluminum-copper joining due to problems such as welding site limitations, smoke pollution and equipment loss. In contrast, laser welding technology has gradually gained favor in the aluminum-copper dissimilar metal welding manufacturing process with its high precision, high degree of automation and environmental protection characteristics. Nevertheless, the high reflectivity of aluminum and copper to infrared laser (1080 nm) limits the effective effect of laser energy in the weld area. For this reason, blue light and infrared laser composite technology has been proposed to improve the laser absorption rate of aluminum-copper parts, thereby achieving precise control of the penetration depth and reducing welding spatter. However, the active chemical properties of aluminum and copper make them extremely easy to oxidize, and hydrogen pores and small pores are easily formed during the welding process, which affects the strength and toughness of the weld joint; in addition, the cooling rate of laser welding is high, and the weld structure is very easy 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 welding joints is still an important direction of current research.

[0027] In order to solve the above technical problems, refer to Figure 1-Figure 2 The 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 away from the copper component, and scanning along the cladding trajectory to melt the aluminum component, and clad the aluminum component on the surface to be joined of the copper component.

[0028] In the present technical solution, laser-induced photo-plasma is generated. When the plasma expands, shock waves are formed, 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 in the weld area, and thus improving the strength and plasticity of the welded joint.

[0029] 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.

[0030] According to some embodiments of the present application, in step S3, the composite laser is an infrared-blue light coaxial composite laser constituted by a coaxial arrangement of an infrared continuous laser and a blue light laser.

[0031] In the above technical scheme, the absorption rate of blue light by highly reflective metals (such as copper, aluminum, and gold) far exceeds that of infrared lasers. At the same time, the absorption rate of blue lasers changes little when the metal melts, which avoids the welding instability problem caused by the sudden change of the absorption rate of infrared lasers from solid to liquid. The infrared continuous laser stabilizes the welding keyhole, thereby further improving the utilization rate of laser energy by the welding keyhole. At the same time, the longer wavelength of the infrared continuous laser can reduce the shielding effect of plasma on laser energy, thereby reducing the shielding of laser energy by photo-induced plasma induced by infrared pulse lasers, and ensuring the stability of the weld. Therefore, a blue-infrared coaxial composite laser is used as the composite laser, the outer circle blue light large spot is preheated and slowly cooled, and the inner circle infrared small spot is deep-melted for welding, so as to take into account both the absorption rate and energy density.

[0032] 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 864nm-1064nm, and / or, the power of the blue light laser is 100W-300W, and the wavelength of the blue light laser is 450nm-495nm.

[0033] 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.

[0034] According to some embodiments of the present application, in step S3, during the laser cladding process, an inert medium is used to protect the molten pool generated by the melting of the aluminum component.

[0035] In some embodiments, the inert medium may be argon.

[0036] In the above technical solution, the molten pool is protected by an inert medium to reduce 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 welding.

[0037] 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 ultrasonic cleaning method to clean the surface to be bonded of the copper component, and using acoustic cleaning method to clean the surface to be bonded of the aluminum component.

[0038] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and comparative examples: Example 1 Select aluminum parts and copper parts with a thickness of 1 mm respectively as welding materials, grind the aluminum parts and copper parts to be welded with sandpaper, scrub with acetone, clean and dry with ultrasonic cleaning, and fix the aluminum and copper dissimilar metals with a welding fixture, wherein the aluminum part is above the copper part; combine the blue light laser, infrared continuous laser and infrared pulse laser through a beam combining system so that the focal points of the three laser beams converge to the upper surface position of the area to be welded, and the defocus amount is 0; set the blue light laser power to 200 W, the infrared continuous laser power to 800 W, the infrared pulse laser power to 100 W, the infrared pulse laser frequency to 50 Hz, the welding speed to 50 mm / s, and use argon protection to prevent oxidation during the welding process. The above-mentioned process parameters are used to achieve high-reflectivity aluminum-copper dissimilar metal connection. The aluminum-copper weld obtained in this embodiment has low porosity and fine grain structure (such as Figure 3 As shown), the maximum shear strength is 100 MPa and the elongation is about 12%.

[0039] Example 2 Aluminum parts and copper parts with a thickness of 1 mm are selected as welding materials. The aluminum parts and copper parts to be welded are polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum parts and copper parts are fixed with a clamp, wherein the copper part is above the aluminum metal; the blue light laser, infrared continuous laser and infrared pulse laser are combined through a beam combining system so that the focus of the three laser beams converges to the upper surface position of the area to be welded, and the defocus amount is 0.2 mm; the blue light laser power is set to 300 W, the infrared continuous laser power is set to 1200 W, the infrared pulse laser power is set to 150 W, the infrared pulse laser frequency is set to 50 Hz, the welding speed is set to 70 mm / s, and argon protection is used during the welding process to prevent oxidation. The above process parameters are used to achieve the connection of high-reflectivity aluminum parts and copper parts. The aluminum-copper weld obtained in this embodiment has low porosity and fine grain structure (such as Figure 4 As shown), the maximum shear strength is 110MPa and the elongation is about 6%.

[0040] Example 3 Aluminum parts and copper parts with a thickness of 1 mm respectively are selected as welding materials. The aluminum parts and copper parts to be welded are polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum parts and copper parts are fixed with a welding fixture, wherein the aluminum parts are above the copper parts. The blue light laser, infrared continuous laser and infrared pulse laser are combined through a beam combining system so that the focal points of the three laser beams converge to the upper surface position of the area to be welded, and the defocus amount is 0 mm. The blue light laser power is set to 100 W, the infrared continuous laser power is set to 1000 W, the infrared pulse laser power is set to 150 W, the infrared pulse laser frequency is set to 100 Hz, the welding speed is set to 80 mm / s, and argon gas protection is used during the welding process to prevent oxidation. The above process parameters are used to achieve the connection of high-reflectivity aluminum parts and copper parts. The aluminum-copper weld obtained in this embodiment has low porosity and fine grain structure (such as Figure 5 As shown), the maximum shear strength is 110 MPa and the elongation is about 15%.

[0041] Example 4 Aluminum parts and copper parts with a thickness of 1 mm respectively are selected as welding materials. The aluminum parts and copper parts to be welded are polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum and copper dissimilar metals are fixed with a welding fixture, wherein the aluminum parts are above the copper parts. The blue light laser, infrared continuous laser and infrared pulse laser are combined through a beam combining system so that the focal points of the three laser beams converge to the upper surface position of the area to be welded, and the defocus amount is 0. The blue light laser power is set to 200 W, the infrared continuous laser power is set to 1000 W, the infrared pulse laser power is set to 200 W, the infrared pulse laser frequency is set to 80 Hz, the welding speed is set to 50 mm / s, and argon protection is used during the welding process to prevent oxidation. The above process parameters are used to achieve high reflectivity aluminum-copper dissimilar metal connection. The aluminum-copper weld obtained in this embodiment has low porosity and fine grain structure (such as Figure 6 As shown), the maximum shear strength is 110 MPa and the elongation is about 12%.

[0042] Example 5 Aluminum parts and copper parts with a thickness of 1 mm respectively are selected as welding materials. The aluminum parts and copper parts to be welded are polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum and copper dissimilar metals are fixed with a welding fixture, wherein the aluminum parts are above the copper parts. The blue light laser, infrared continuous laser and infrared pulse laser are combined through a beam combining system so that the focal points of the three laser beams converge to the upper surface position of the area to be welded, and the defocus amount is 0. The blue light laser power is set to 200 W, the infrared continuous laser power is set to 1000 W, the infrared pulse laser power is set to 150 W, the infrared pulse laser frequency is set to 150 Hz, the welding speed is set to 70 mm / s, and argon protection is used during the welding process to prevent oxidation. The above process parameters are used to achieve high-reflectivity aluminum-copper dissimilar metal connection. The aluminum-copper weld obtained in this embodiment has low porosity and fine grain structure (such as Figure 7 As shown), the maximum shear strength is 105 MPa and the elongation is about 15%.

[0043] Example 6 Aluminum and copper parts with a thickness of 1 mm were selected as welding materials. The aluminum and copper parts to be welded were polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum and copper dissimilar metals were fixed with a welding fixture, wherein the aluminum part was above the copper part. The focus of the blue laser was focused to the upper surface of the area to be welded, and the defocus amount was 0. The blue laser power was set to 800 W, the welding speed was 50 mm / s, and argon gas was used to prevent oxidation during the welding process. The above process parameters were used to achieve high reflectivity aluminum-copper dissimilar metal connection. The aluminum-copper weld obtained in this embodiment had low porosity and fine grain structure (such as Figure 8 As shown), the maximum shear strength is 90 MPa and the elongation is about 6%.

[0044] Example 7 Aluminum and copper parts with a thickness of 1 mm were selected as welding materials. The aluminum and copper parts to be welded were polished with sandpaper, scrubbed with acetone, and ultrasonically cleaned and dried. The aluminum and copper dissimilar metals were fixed with a welding fixture, wherein the aluminum part was above the copper part. The infrared continuous laser was focused to the upper surface of the area to be welded, and the defocus amount was 0. The infrared continuous laser power was set to 1000 W, and the welding speed was 50 mm / s. At the same time, argon protection was used during the welding process to prevent oxidation. The above process parameters were used to achieve high reflectivity aluminum-copper dissimilar metal connection. The aluminum-copper weld obtained in this embodiment had low porosity and fine grain structure (such as Fig. 9 As shown), the maximum shear strength is 50 MPa and the elongation is about 4%.

[0045] Reference Fig.10, an embodiment of the present application provides a dissimilar metal welding system for welding copper components to aluminum components, including a positioning mechanism (not shown in the figure), a laser processing head 4, a composite laser mechanism, a first semi-transparent and semi-reflective beam combining mirror 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-transparent and semi-reflective beam combining mirror 23 is located between the composite laser mechanism and the laser processing head 4, and the composite laser passes through the first semi-transparent and semi-reflective beam combining mirror 23 to enter the laser processing head 4; the first laser 3 is used to provide infrared pulse laser to the first semi-transparent and semi-reflective beam combining mirror 23, and the infrared pulse laser is reflected by the first semi-transparent and semi-reflective beam combining mirror 23 to enter the laser processing head 4 coaxially with the composite laser.

[0046] Exemplarily, the positioning mechanism may be a fixture, and the first laser 3 may be an infrared pulse laser.

[0047] A semi-transparent and semi-reflective beam combiner is an optical lens with both transmission and reflection properties. For example, a semi-transparent and semi-reflective beam combiner can transmit wavelengths below 964nm and reflect lasers with wavelengths above 964nm. It is used to reintegrate light beams from different paths into a single optical path to maintain phase and direction consistency.

[0048] In some embodiments, a first collimator 13 is disposed between the laser emission end of the first laser emitter and the first semi-transparent and semi-reflective beam combining mirror 23 .

[0049] The collimator can be a lens group or a reflector 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 collimator 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.

[0050] In the above technical solution, an infrared pulse laser is provided by the first laser 3, 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, the 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 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 the dendrite arms in the molten pool, thereby providing nucleation sites, which helps to refine the grain structure in the weld area, thereby improving the strength and plasticity of the welded joint.

[0051] In some embodiments, the composite laser mechanism includes a second laser 1, a second semi-transparent and semi-reflective beam combining mirror 22 and a third laser 2, wherein the second laser 1 is used to provide a blue light laser; the second semi-transparent and semi-reflective beam combining mirror 22 is located between the second laser 1 and the first semi-transparent and semi-reflective beam combining mirror 23, and the blue light laser passes through the second semi-transparent and semi-reflective beam combining mirror 22 and the first semi-transparent and semi-reflective beam combining mirror 23 to enter the laser processing head 4; the third laser 2 is used to provide an infrared continuous laser to the second semi-transparent and semi-reflective beam combining mirror 22, and the infrared continuous laser is reflected by the second semi-transparent and semi-reflective beam combining mirror 22 to form a composite laser coaxially with the blue light laser.

[0052] In some embodiments, a second collimator 11 is disposed between the laser emission end of the second laser emitter and the second semi-transparent and semi-reflective beam combining mirror 22. A third collimator 12 is disposed between the laser emission end of the third laser emitter and the second semi-transparent and semi-reflective beam combining mirror 22, and a reflector 21 is disposed between the second semi-transparent and semi-reflective beam combining mirror 22 and the third collimator 12, and the reflector 21 is used to reflect the infrared continuous laser to the second semi-transparent and semi-reflective beam combining mirror 22.

[0053] Exemplarily, the second laser 1 may be a blue laser, and the third laser 2 may be an infrared continuous laser.

[0054] 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 produced by cladding an aluminum component using a coaxially arranged composite laser and an infrared pulse laser.

[0055] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0056] The above embodiments are only used to illustrate the technical solution of the present application and are not used to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in 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: bringing the surface of the copper component to be bonded into contact with the surface of the aluminum component to be bonded, 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 make the aluminum component clad on the surface to be bonded with the copper component.

2. A dissimilar metal welding method according to claim 1, characterized in that: 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. A dissimilar metal welding method according to claim 1 or 2, characterized in that: In step S3, the composite laser is an infrared-blue light coaxial composite laser composed of an infrared continuous laser and a blue light laser coaxially arranged.

4. A dissimilar metal welding method according to claim 3, characterized in that: 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, the wavelength of the blue laser is 450 nm-495 nm.

5. The method for welding dissimilar metals according to claim 1, characterized in that: 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 allow the aluminum component to be clad on the surface to be bonded with the component.

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

7. The method for welding dissimilar metals according to claim 1, characterized in that: Step S1 includes: S11: grinding the surface of the copper component to be bonded with using sandpaper, and grinding the surface of the aluminum component to be bonded with using 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 of the copper component to be bonded by ultrasonic cleaning, and cleaning the surface of the aluminum component to be bonded by sonic cleaning.

8. A dissimilar metal welding system for welding a copper component to an aluminum component, characterized in that: include: A positioning mechanism, used for fixing the copper component and the aluminum component which are stacked; A laser processing head is 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 is located between the composite laser mechanism and the laser processing head, and 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 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.

9. A dissimilar metal welding system according to claim 8, 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 and semi-reflective beam combining mirror. The infrared continuous laser light is reflected by the second semi-transparent and semi-reflective beam combining mirror to form the composite laser light coaxially with the blue laser light.

10. A copper substrate, characterized in that: The surface of the copper substrate comprises a wear-resistant coating, and the wear-resistant coating is produced by melting and cladding an aluminum component with a coaxially arranged composite laser and an infrared pulse laser.

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