Aluminum-copper dissimilar metal composite laser welding method and aluminum-copper welded joint

Abstract

The embodiment of the present application provides an aluminum-copper dissimilar metal composite laser welding method and an aluminum-copper welding joint, which relates to the field of laser welding technology. The aluminum-copper dissimilar metal composite laser welding method of the embodiment of the present application includes the following steps: S1, stacking and relatively fixing aluminum metal plates and copper metal plates to obtain parts to be welded; S2, combining blue laser, point infrared laser and ring infrared laser, and focusing them to the welding position on the surface of the parts to be welded to form a composite laser beam; S3, welding the parts to be welded in an oscillating manner by keeping the composite laser beam. The aluminum-copper dissimilar metal composite laser welding method and the aluminum-copper welding joint of the embodiment of the present application can reduce the porosity in the weld and improve the mechanical properties and ductility of the weld.

Description

Technical Field

[0001] The present application relates to the field of laser welding technology, and in particular to a method for laser welding dissimilar metal composites of aluminum and copper and an aluminum-copper welded joint. Background Art

[0002] The tabs in soft-pack batteries for new energy vehicles are typically made of highly conductive copper and connected to the busbar in parallel or series, consuming significant amounts of copper resources during the battery manufacturing process. Aluminum and its alloys are lightweight, inexpensive, and offer excellent electrical and thermal conductivity and corrosion resistance, prompting a growing number of industries to explore the feasibility of replacing copper with aluminum.

[0003] After extensive research, aluminum-copper welds have become a focus of attention in the automotive power battery industry. However, aluminum and copper are dissimilar metals with vastly different chemical and physical properties, such as thermal conductivity, thermal expansion coefficient, and melting point. Furthermore, their limited mutual solubility leads to the formation of a large amount of highly brittle intermetallic compound phases in the weld, which reduces the strength and ductility of the weld. Furthermore, aluminum and copper have strong thermal conductivity and high reflectivity to infrared lasers. In conventional infrared laser welding, the laser energy applied to the weld area is very limited, necessitating an increase in the minimum laser welding power, and the porosity in the weld also increases significantly.

[0004] Therefore, it is necessary to develop a laser welding method for aluminum-copper dissimilar metals that can reduce the porosity in the weld and improve the mechanical properties and ductility of the weld to meet the urgent demand for high-quality aluminum-copper welded joints. Summary of the Invention

[0005] The purpose of the embodiments of the present application is to provide an aluminum-copper dissimilar metal composite laser welding method and an aluminum-copper welding joint, which can reduce the porosity in the weld and improve the mechanical properties and ductility of the weld.

[0006] In a first aspect, an embodiment of the present application provides an aluminum-copper dissimilar metal composite laser welding method, which includes the following steps:

[0007] S1. stacking and relatively fixing the aluminum metal sheet and the copper metal sheet to obtain a part to be welded;

[0008] S2, combining a blue laser, a point infrared laser, and a ring infrared laser, and focusing the laser beams onto a welding position on the surface of the workpiece to be welded to form a composite laser beam;

[0009] S3, welding the parts to be welded by keeping the composite laser beam in an oscillating manner.

[0010] In the above technical solution, a blue laser is used to preheat the surface of aluminum or copper metal, utilizing the effect of blue light to increase the laser absorption rate of highly reflective metals. The high energy density characteristics of a point infrared laser (central infrared beam) are utilized to maintain a deep penetration welding (also called keyhole welding) mode during the welding process of highly reflective metals. The combination of a ring infrared laser (annular infrared beam) reduces the temperature gradient on the material surface during single central infrared beam welding, stabilizes the welding keyhole, and further improves the utilization rate of the laser energy in the welding keyhole. The oscillation of the composite laser beam can provide stirring force to the molten pool, which is conducive to the floating of bubbles, thereby achieving the purpose of reducing porosity. It also facilitates the mixing of dissimilar metal base materials and refines the grain size of the weld zone, effectively eliminating the welding difficulties caused by the poor performance differences of dissimilar metals, thereby reducing the porosity in the weld and improving the mechanical properties and ductility of the weld.

[0011] In a possible implementation, the aluminum metal includes aluminum or an aluminum alloy, and the copper metal includes copper or a copper alloy.

[0012] In a possible implementation, in step S1, the aluminum metal plate and the copper metal plate are polished, cleaned, dried, and then stacked and fixed with a welding fixture;

[0013] And / or, the aluminum metal plate and the copper metal plate are stacked up and down or stacked up and down.

[0014] In the above technical solution, a welding fixture is used to clamp and fix the stacked aluminum and copper metals to prevent thermal deformation during welding.

[0015] In a possible implementation, in step S2, a blue laser and an infrared tunable mode laser are used to emit a blue laser, a point infrared laser, and a ring infrared laser, which are then beam-combined through a welding head;

[0016] And / or, the distance between the focus of each laser beam and the welding site is adjusted so that the beam waist of each laser beam is located at the welding site to form the composite laser beam.

[0017] In a possible implementation, in the composite laser beam, the radius of the blue laser is 0.8-1 mm, the diameter of the point infrared laser is 0.01-0.05 mm, the diameter of the ring infrared laser is 0.1-0.3 mm, and the central energy density is greater than 10 6 W / mm 2 .

[0018] In the above technical solution, the central energy density is greater than 10 6 W / mm 2 The keyhole welding mode is reached.

[0019] In a possible implementation, the oscillation mode of the composite laser beam includes at least one of an ∞ type, an 8 type, and an o type.

[0020] In the above technical solution, the composite laser beam in oscillating mode has a strong stirring effect on the welding molten pool, which can significantly refine the grains and suppress weld porosity, and is a feasible way to achieve high-quality welding.

[0021] In one possible implementation, the welding process parameters are: the power of the blue laser is 100-300 W, the power of the point infrared laser is 500-1000 W, and the power of the ring infrared laser is 500-1000 W; the amplitude of the oscillation is 0.5-2 mm, and the frequency is 50-200 Hz; the welding speed is 10-100 mm / s, and the defocus is 0-0.5 mm.

[0022] In a possible implementation, in step S3, an inert medium is used to protect the welding area during the welding process; optionally, the flow rate of the inert medium is 5-15 L / min.

[0023] In the second aspect, an embodiment of the present application provides an aluminum-copper welded joint, which is manufactured using the aluminum-copper dissimilar metal composite laser welding method provided by the first aspect. The aluminum-copper welded joint includes aluminum metal plates and copper metal plates stacked and welded together. The porosity in the weld is <0.5 vol.%, the shear strength is 80-110 MPa, and the elongation is 6%-8%.

[0024] In the above technical solution, compared with the existing laser welding technology, the weld is well formed, without welding defects such as cracks, pores, and lack of fusion, and the welding process performance is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic diagram of a laser welding method for aluminum-copper dissimilar metal composites provided in an embodiment of the present application;

[0027] Figure 2 This is a macroscopic morphology of the weld of the aluminum-copper welded joint of Example 1;

[0028] Figure 3 Graph showing the shear performance of the weld of the aluminum-copper welded joint of Example 1;

[0029] Figure 4 This is a macroscopic morphology of the weld of the aluminum-copper welded joint of Example 2;

[0030] Figure 5 Graph showing the shear performance of the weld of the aluminum-copper welded joint of Example 2;

[0031] Figure 6 This is a macroscopic morphology of the weld of the aluminum-copper welded joint of Example 3;

[0032] Figure 7 This is a shear performance diagram of the weld of the aluminum-copper welded joint of Example 3. DETAILED DESCRIPTION

[0033] Aluminum-copper welds have become a focus of attention in the automotive power battery industry. However, aluminum and copper have significantly different chemical and physical properties, such as thermal conductivity, thermal expansion coefficient, and melting point. Furthermore, their limited mutual solubility leads to the formation of a large amount of highly brittle intermetallic compound phases in the weld, thereby reducing the strength and ductility of the weld.

[0034] Aluminum and copper have strong thermal conductivity and high reflectivity to infrared lasers (1064 nm). This results in very limited laser energy in the weld area during laser welding, raising the minimum power for laser welding of highly reflective dissimilar metals and significantly increasing the porosity in the weld. The hybrid technology of blue light and infrared lasers can enhance the laser absorptivity of highly reflective aluminum and copper, making penetration easier to control and improving weld joint strength. However, due to the active nature of aluminum and copper and their high oxidizability, hydrogen pores and cavitation caused by the collapse of some keyholes are easily formed in the weld, reducing the performance of the weld joint.

[0035] Currently, the main method for reducing porosity in laser welding is to increase the stirring effect of the molten pool. After analyzing the existing technology, it can be found that there is a prior art that discloses a method of introducing ultrasonic vibration and pulse stirring in ultrasonic-assisted pulse laser-MIG composite heat source welding to increase the fluidity of the aluminum alloy molten pool. This effectively solves the problem of a large number of pores easily forming in the aluminum alloy laser-MIG composite heat source welded joint. However, the introduction of an external auxiliary energy field device in the lap laser welding of aluminum-copper thin plates is not conducive to high-efficiency mass production. There is also prior art that uses dual-focus laser-TIG composite welding technology, which uses two laser beams and an arc to act on the welding area. It can effectively eliminate welding porosity defects, but its welding speed is relatively slow. In addition, there is prior art that introduces an oscillating scanning laser beam in laser-arc composite welding, which has a stronger weld porosity suppression ability and improves weld strength. However, this oscillating laser beam achieves synergistic strengthening in a local micro-area around the arc action point, and the welding effect needs to be improved.

[0036] After extensive research, the applicant discovered that developing a blue light-spot ring infrared composite laser oscillating welding method for aluminum-copper dissimilar metals can achieve in-situ preheating of the molten pool to stabilize it, while also suppressing spatter, reducing porosity, preventing cracks, and improving the mechanical properties of the weld, thereby overcoming the shortcomings of the existing technology and meeting the urgent demand for high-quality Al / Cu welds.

[0037] To make the purpose, technical solutions and advantages of the examples of the present application clearer, the technical solutions in the examples of the present application will be described clearly and completely below. Where specific conditions are not specified in the examples, conventional conditions or conditions recommended by the manufacturer are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0038] The following is a detailed description of the aluminum-copper dissimilar metal composite laser welding method and the aluminum-copper welding joint according to the embodiment of the present application.

[0039] Please see Figure 1 The present invention provides a method for laser welding of aluminum-copper dissimilar metal composites, which includes the following steps:

[0040] S1. Stacking and relatively fixing aluminum metal plates and copper metal plates to obtain parts to be welded.

[0041] In some embodiments of the present application, the aluminum metal includes pure aluminum (such as 1050, 1060, etc.) or aluminum alloy (such as 5052, 6061, etc.), and the aluminum metal plate is selected from the above-mentioned aluminum metal material plate, the surface should be clean and free of oxide layer, the thickness of the aluminum metal plate is 0.1-1 mm, and the thickness tolerance is controlled within ±0.05 mm; the copper metal includes pure copper (such as T2) or copper alloy (such as brass H70, tin bronze QSn6.5-0.1), the surface should be clean and free of oil, and the copper metal plate is selected from the above-mentioned copper metal material plate, the thickness of the copper metal plate is 0.1-1 mm, and the thickness tolerance is controlled within ±0.05 mm.

[0042] In some embodiments of the present application, in step S1, the plates to be welded: aluminum metal plates and copper metal plates are polished, cleaned (using acetone scrubbing and ultrasonic cleaning), dried, and then stacked and fixed with a welding fixture. Sandpaper can be used for polishing, and acetone scrubbing and ultrasonic cleaning can be used for cleaning.

[0043] In step S1, the aluminum metal sheet can be directly fixed above or below the copper metal sheet. Accordingly, the aluminum metal sheet and the copper metal sheet can be stacked one above the other or one above the other. The stacking of the aluminum metal sheet and the copper metal sheet is suitable for applications with strict requirements on the heat-affected zone, but the bonding strength between the two may be insufficient. The stacking of the copper metal sheet and the aluminum metal sheet is suitable for applications requiring high bonding strength, but it is necessary to prevent overheating of the aluminum. Figure 1 The diagram shows the situation where aluminum metal sheets and copper metal sheets are stacked one above the other, which can ensure that the weld joint has matching strength and plasticity.

[0044] S2. Combine the blue laser, point infrared laser and ring infrared laser and focus them on the welding position on the surface of the workpiece to be welded to form a composite laser beam.

[0045] In some embodiments of the present application, in step S2, a blue laser and an infrared tunable mode laser are used to emit a blue laser, a point infrared laser (central infrared beam) and a ring infrared laser (ring infrared beam), which are then combined by a welding head. For example, the laser used is a beam mode tunable laser, Shanghai Feibo Laser Technology Co., Ltd., equipment model: YDFL-2000 / 4000-PAM+; and a blue laser, Guangdong Guangdong-Hong Kong-Macao Greater Bay Area Hard Technology Innovation Research Institute, model: BLF-455-800-2 (subsequent embodiments and comparative examples use the same equipment and will not be repeated here). In other embodiments, other lasers that can emit blue lasers, point infrared lasers and ring infrared lasers can also be used. They can be single lasers or different lasers can be used in combination.

[0046] The focusing method is to adjust the distance between the focus of each laser beam and the welding site so that the waist position of each laser beam is located at the welding site on the same plane, forming a composite laser beam. The "waist position" is the point where the energy and quality of the beam emitted by the laser are optimal. The waists of the above three laser beams (blue laser, point infrared laser and ring infrared laser) coincide. Figure 1 The weld site shown is the top surface of the aluminum sheet metal.

[0047] In some embodiments of the present application, the composite laser beam refers to the laser beam formed by combining and focusing the above three laser beams (blue laser, point infrared laser and ring infrared laser). During the welding process, the composite laser beam remains in the combined and focused state. In the composite laser beam formed, the radius of the blue laser is 0.8-1 mm, the diameter of the point infrared laser is 0.01-0.05 mm, the diameter of the ring infrared laser is 0.1-0.3 mm, and the center energy density is >10 6 W / mm 2, to achieve a keyhole welding mode. The dimensions of each laser beam are based on the dimensions of each laser beam on the same plane being welded (for example, the upper surface of an aluminum sheet). The dimensions refer to the outer diameter. The energy density at the center of the composite laser beam is primarily determined by the point infrared laser. The energy density of the remaining beams is much lower than that of the point infrared laser. Therefore, the energy density of the point infrared laser can be adjusted to control the energy density at the center of the composite laser beam.

[0048] S3. The composite laser beam is kept in an oscillating manner to weld the workpiece. During the welding process, the surface of the aluminum metal plate or the copper metal plate is preheated by a blue laser, a keyhole welding (also called keyhole welding) mode is formed by a central infrared laser, and a ring infrared laser is used to stabilize the keyhole and reduce spatter.

[0049] During the welding process, the oscillation frequency and amplitude of the composite laser beam are adjusted to keep the composite laser beam oscillating and swinging. At the same time, the welding speed is controlled by a robotic arm to form a continuous weld. The swing mode of the composite laser beam includes at least one of ∞ type, 8 type, and O type, that is, the waist position of the three overlapping laser beams maintains a high-frequency vibration of "∞ type, 8 type, O type".

[0050] During the welding process, the power of the three laser beams is set separately, and the dissimilar metals are welded at a predetermined welding speed. The process parameters include the welding speed and the power of the three laser beams.

[0051] In some embodiments of the present application, the welding process parameters are: the power of the blue light laser is 100-300 W, the power of the point infrared laser is 500-1000 W, and the power of the ring infrared laser is 500-1000 W; the amplitude of the oscillation is 0.5-2 mm, and the frequency is 50-200 Hz; the welding speed is 10-100 mm / s, and the defocus is 0-0.5 mm.

[0052] In some embodiments of the present application, in step S3, an inert medium is used to protect the welding area during the welding process; optionally, the flow rate of the inert medium is 5-15 L / min.

[0053] In addition, an embodiment of the present application provides an aluminum-copper welded joint, which is manufactured using the aluminum-copper dissimilar metal composite laser welding method of the aforementioned embodiment. The aluminum-copper welded joint includes aluminum metal plates and copper metal plates stacked and welded together. The porosity in the weld is <0.5 vol.%, the shear strength is 80-110 MPa, and the elongation is 6%-8%.

[0054] The features and performance of the present application are further described in detail below with reference to the embodiments.

[0055] Example 1

[0056] This embodiment provides a method for laser welding of aluminum-copper dissimilar metal composites, the steps of which are as follows:

[0057] S1. Place the plates to be welded: an aluminum plate on a copper plate, grind it with sandpaper, scrub it with acetone, clean it with ultrasonic cleaning, and dry it, and then fix it with a welding fixture, wherein the aluminum plate is overlapped on top of the copper plate.

[0058] S2. The semiconductor blue laser and the infrared point-ring beam adjustable mode laser emit blue laser, point infrared laser (central infrared beam) and ring infrared laser (ring infrared beam), which are combined through a welding head so that multiple laser beams are focused onto the upper surface of the aluminum metal plate to form a composite laser beam.

[0059] S3. Control the welding head to keep the light beam oscillating for welding. The laser oscillation mode is "∞" type. The process parameters are as follows: blue laser power is 100 W, central infrared laser power is 600 W, outer ring infrared laser power is 700 W, amplitude is 0.5 mm, oscillation frequency is 150 Hz, welding speed is 30 mm / s, defocus amount is 0 mm, and flow rate of inert medium is 15 L / min. The above process parameters are used to achieve high reflectivity aluminum-copper dissimilar metal connection to produce an aluminum-copper welding joint.

[0060] The macrostructure and shear properties of the brazed joint at the weld are as follows: Figure 2 and Figure 3 As shown, the weld porosity (ratio of pore area to weld area in the metallographic photograph) was calculated using Image-ProPlus software. The weld of the aluminum-copper welded joint obtained in this example had low porosity (<0.5 vol.%), fine grain structure, a thin brittle layer at the aluminum-copper interface, low brittle phase content, a maximum shear strength of 110 MPa, and an elongation of 6%.

[0061] Example 2

[0062] This embodiment provides a method for laser welding of aluminum-copper dissimilar metal composites, the steps of which are as follows:

[0063] S1. Grind the plate to be welded with sandpaper, scrub with acetone, and ultrasonically clean and dry it, and fix the aluminum and copper dissimilar metals with a welding fixture, wherein the aluminum metal is above the copper metal.

[0064] S2. The semiconductor blue laser and the infrared point-ring beam adjustable mode laser emit blue laser, point infrared laser (central infrared beam) and ring infrared laser (ring infrared beam), and combine them through the welding head so that the multiple laser beams are focused on the overlapping upper surface of the dissimilar metals.

[0065] S3. Control the welding head to keep the light beam oscillating. The laser oscillation mode is "8" type. The process parameters are as follows: blue laser power is 200 W, central infrared laser power is 700 W, outer ring infrared laser power is 800 W, amplitude is 1.0 mm, oscillation frequency is 100 Hz, welding speed is 50 mm / s, defocus is 0.2 mm, and flow rate of inert medium is 10 L / min. An aluminum-copper welding joint is obtained.

[0066] The weld macrostructure and shear properties of the brazed joint are as follows: Figure 4 and Figure 5 As shown, the weld porosity was calculated using Image-Pro Plus software (the ratio of the pore area to the weld area in the metallographic photograph). The weld porosity of the aluminum-copper welded joint obtained in this embodiment was low (<0.5 vol.%), the grain structure was fine, the brittle layer at the aluminum-copper interface was thin, the brittle phase content was low, the maximum shear strength was 105 MPa, and the elongation was 7%.

[0067] Example 3

[0068] This embodiment provides a method for laser welding of aluminum-copper dissimilar metal composites, the steps of which are as follows:

[0069] S1. Grind the plate to be welded with sandpaper, scrub with acetone, and ultrasonically clean and dry it, and fix the aluminum and copper dissimilar metals with a welding fixture, wherein the aluminum metal is above the copper metal;

[0070] S2, using a semiconductor blue laser and an infrared point-ring beam adjustable mode laser to emit a blue laser, a point infrared laser (central infrared beam), and a ring infrared laser (ring infrared beam), and combining the beams through a welding head so that the multiple laser beams are focused onto the overlapping upper surface of the dissimilar metals;

[0071] S3. Control the welding head to keep the light beam oscillating. The laser oscillation mode is "o" type. The process parameters are as follows: blue laser power is 300 W, central infrared laser power is 600 W, outer ring infrared laser power is 800 W, amplitude is 1.5 mm, oscillation frequency is 70 Hz, welding speed is 70 mm / s, defocus is 0.4 mm, and flow rate of inert medium is 5 L / min to obtain an aluminum-copper welding joint.

[0072] The macrostructure and shear properties of the brazed joint at the weld are as follows: Figure 6 and Figure 7As shown in FIG5 , the weld porosity was calculated using Image-ProPlus software (the ratio of the pore area to the weld area in the metallographic photograph). The weld porosity of the aluminum-copper welded joint obtained in this embodiment was low (<0.5 vol.%), the grain structure was fine, the brittle layer at the aluminum-copper interface was thin, the brittle phase content was low, the maximum shear strength was 100 MPa, and the elongation was 8%.

[0073] Comparative Example 1

[0074] This comparative example provides an aluminum-copper dissimilar metal composite laser welding method. The steps are different from those in Example 1 in that: a point infrared laser (central infrared beam) and a ring infrared laser (annular infrared beam) are emitted, but a blue light laser is not included, and finally an aluminum-copper welded joint is produced.

[0075] The porosity of the weld of the obtained aluminum-copper welded joint is 7.5 vol.%, the maximum shear strength is 60 MPa, and the elongation is 2%.

[0076] Comparative Example 2

[0077] This comparative example provides an aluminum-copper dissimilar metal composite laser welding method. The steps described differ from those in Example 1 in that: blue laser and ring infrared laser (ring infrared beam) are emitted, but point infrared laser (central infrared beam) is not included, and finally an aluminum-copper welded joint is produced.

[0078] The porosity of the weld of the obtained aluminum-copper welded joint is 2.5 vol.%, the maximum shear strength is 90 MPa, and the elongation is 6%.

[0079] Comparative Example 3

[0080] This comparative example provides an aluminum-copper dissimilar metal composite laser welding method. The steps differ from those in Example 1 in that: a blue laser and a point infrared laser (central infrared beam) are emitted, but a ring infrared laser (annular infrared beam) is not included, and finally an aluminum-copper welded joint is produced.

[0081] The porosity of the weld of the obtained aluminum-copper welded joint is 4.5 vol.%, the maximum shear strength is 80 MPa, and the elongation is 4%.

[0082] In summary, the aluminum-copper dissimilar metal composite laser welding method and the aluminum-copper welding joint of the embodiment of the present application can reduce the porosity in the weld and improve the mechanical properties and ductility of the weld.

[0083] The above description is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for laser welding of aluminum-copper dissimilar metal composites, characterized in that: It includes the following steps: S1. Stacking an aluminum metal sheet and a copper metal sheet on top of each other and fixing them relatively to each other to obtain a workpiece to be welded, wherein the thickness of the aluminum metal sheet is 0.1-1 mm, and the thickness of the copper metal sheet is 0.1-1 mm; S2, combining the blue laser, the point infrared laser and the ring infrared laser, and focusing them on the welding position on the upper surface of the aluminum metal plate to form a composite laser beam, wherein the radius of the blue laser is 0.8-1 mm, the diameter of the point infrared laser is 0.01-0.05 mm, the diameter of the ring infrared laser is 0.1-0.3 mm, and the central energy density is greater than 10 6 W / mm 2 ; S3, welding the parts to be welded by keeping the composite laser beam in an oscillating manner.

2. The aluminum-copper dissimilar metal composite laser welding method according to claim 1, characterized in that: The aluminum metal includes aluminum or an aluminum alloy, and the copper metal includes copper or a copper alloy.

3. The aluminum-copper dissimilar metal composite laser welding method according to claim 1, characterized in that: In step S1, the aluminum metal plate and the copper metal plate are polished, cleaned, dried, stacked, and fixed with a welding fixture.

4. The aluminum-copper dissimilar metal composite laser welding method according to claim 1, characterized in that: In step S2, a blue laser and an infrared tunable mode laser are used to emit blue laser, point infrared laser and ring infrared laser, and the beams are combined through a welding head; And / or, the distance between the focus of each laser beam and the welding site is adjusted so that the beam waist of each laser beam is located at the welding site to form the composite laser beam.

5. The aluminum-copper dissimilar metal composite laser welding method according to claim 1, characterized in that: The oscillation mode of the composite laser beam includes at least one of an ∞ type, an 8 type, and an o type.

6. The aluminum-copper dissimilar metal composite laser welding method according to claim 1 or 5, characterized in that: The welding process parameters are as follows: the power of the blue laser is 100-300 W, the power of the point infrared laser is 500-1000 W, and the power of the ring infrared laser is 500-1000 W; the amplitude of the oscillation is 0.5-2 mm, and the frequency is 50-200 Hz; the welding speed is 10-100 mm / s, and the defocus is 0-0.5 mm.

7. The aluminum-copper dissimilar metal composite laser welding method according to claim 1, characterized in that: In step S3, an inert medium is used to protect the welding area during the welding process.

8. The aluminum-copper dissimilar metal composite laser welding method according to claim 7, characterized in that: The flow rate of the inert medium is 5-15 L / min.

9. An aluminum-copper welding joint, characterized in that: It is made using the aluminum-copper dissimilar metal composite laser welding method described in any one of claims 1 to 8, the aluminum-copper welded joint comprises aluminum metal plates and copper metal plates stacked and welded together, the porosity in the weld is <0.5 vol.%, the shear strength is 80-110 MPa, and the elongation is 6%-8%.

Images