A thin-walled aluminum alloy component welding method based on infrared-blue light composite laser

Abstract

The present invention discloses a method for welding thin-walled aluminum alloy components based on infrared-blue light composite laser, which belongs to the field of laser cladding technology. The method comprises the following steps: first, cleaning and drying the surface of the thin-walled aluminum alloy component to be welded to remove the oxide film and impurities on the surface of the thin-walled aluminum alloy component in the area to be welded; then, preheating the area to be welded of the thin-walled aluminum alloy component using a blue light laser; then, using an infrared-blue light composite laser as a heat source, an aluminum alloy welding wire as a filler material, and an inert gas as a shielding gas, welding the thin-walled aluminum alloy component according to a preset welding path; and after welding is completed, remelting and heat-insulating the area to be welded using a blue light laser to complete the welding of the thin-walled aluminum alloy component to be welded. The present invention exhibits significant advantages in terms of improving welding efficiency, improving welding quality, reducing defect rate, and expanding the scope of application of aluminum alloy welding, providing an efficient and reliable solution for thin-walled aluminum alloy welding.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser cladding, and in particular relates to a welding method for thin-walled aluminum alloy components based on infrared-blue light composite laser. Background Art

[0002] Due to its advantages of light weight, high strength, and corrosion resistance, the development of aluminum alloy welding technology is of great significance for achieving complex structural forming, increasing design freedom, and promoting lightweight design. A wide variety of aluminum alloy welding processes are currently available, including infrared laser welding, TIG welding (non-metallic inert gas arc welding), MIG welding (metallic inert gas arc welding), plasma arc welding, friction stir welding, electron beam welding, infrared laser-MIG hybrid welding, and other specialized welding methods. Infrared laser welding, with its concentrated laser beam energy, fast welding speed, and strong shape adaptability, is widely used in thin-walled and complex component manufacturing and precision welding.

[0003] Traditional aluminum alloy laser welding processes usually use a single wavelength infrared laser (1064nm), but aluminum alloy has a low absorption rate for lasers in this band (usually less than 10%). In order to ensure penetration and welding strength, high-power infrared lasers are usually required to increase heat input. This is inconsistent with the fact that thin-walled aluminum alloy components are sensitive to heat input and prone to welding deformation, resulting in some technical difficulties in welding: 1) High reflectivity. Aluminum alloys have a high reflectivity for infrared lasers, resulting in low laser energy utilization and low welding efficiency. High-power infrared laser input can easily lead to the expansion of the heat-affected zone, causing increased residual stress and component deformation, which is especially evident in the welding process of thin-walled aluminum alloy components; 2) Thermal crack tendency. Aluminum alloys have a large thermal expansion coefficient, and thermal stress is easily generated during welding, leading to the formation of thermal cracks; 3) Porosity defects. An oxide film is easily formed on the surface of aluminum alloys, and porosity defects are easily generated during welding, resulting in low weld strength and poor sealing; 4) Aluminum alloys have high thermal conductivity and rapid heat diffusion, making it difficult to control the stability of the molten pool, affecting welding quality. Summary of the Invention

[0004] In order to solve the problems in the prior art, the present invention provides a thin-walled aluminum alloy component welding method based on infrared-blue light composite laser.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention discloses a thin-walled aluminum alloy component welding method based on infrared-blue light composite laser, comprising the following steps:

[0007] 1) Clean and dry the surface of the thin-walled aluminum alloy component to be welded to remove the oxide film and impurities on the surface of the thin-walled aluminum alloy component in the area to be welded, and then use a blue laser to preheat the area to be welded of the thin-walled aluminum alloy component;

[0008] 2) Using infrared-blue light composite laser as heat source, aluminum alloy welding wire as filler material, and inert gas as shielding gas, thin-walled aluminum alloy components are welded according to the preset welding path;

[0009] 3) After welding is completed, the blue light laser is used to remelt and heat-insulate the welding area to complete the welding of the thin-walled aluminum alloy components to be welded.

[0010] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0011] The present invention adopts an infrared-blue light composite laser combined with a preheating-welding-remelting and heat preservation process, which can effectively avoid welding problems caused by the low absorption rate of aluminum alloy to a single infrared laser. The main performances are as follows: 1) The blue light laser effectively reduces the high reflectivity of the aluminum alloy surface to the laser, improves the laser energy utilization rate, and thus greatly improves the welding efficiency; 2) The blue light laser can inhibit the generation of pores during welding, and at the same time synergize with the infrared laser to refine the weld structure, significantly improve the welding quality, and improve the strength and toughness of the weld; 3) Composite laser welding can achieve more precise heat input control, reduce the welding heat affected zone, and reduce the tendency of thermal cracking. It is particularly suitable for thin-walled aluminum alloy materials with high reflectivity, easy oxidation and heat sensitivity. In summary, the infrared-blue light composite laser welding technology has shown significant advantages in improving welding efficiency, improving welding quality, reducing defect rates and expanding the scope of application of aluminum alloy welding, providing an efficient and reliable solution for thin-walled aluminum alloy welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of welding method;

[0013] Figure 2 Schematic diagram of the cross section of infrared-blue composite laser;

[0014] Figure 3 This is a flow chart of the welding method;

[0015] Figure 4 This is the warm-up motion trajectory diagram;

[0016] Figure 5 This is the appearance of the weld after infrared laser welding;

[0017] Figure 6 This is the appearance of the weld after composite laser welding;

[0018] Figure 7This is the cross-sectional view of the weld after infrared laser welding;

[0019] Figure 8 This is the cross-sectional view of the weld after hybrid laser welding. DETAILED DESCRIPTION

[0020] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0021] The purpose of the present invention is to provide a thin-walled aluminum alloy component welding method based on infrared-blue light composite laser, so as to solve the problems of low efficiency and poor quality of aluminum alloy laser welding in the prior art. By introducing blue light laser, the reflectivity of the aluminum alloy surface to the laser is reduced, the energy absorption rate is improved, and the heat input control during the welding process is optimized, the generation of pores is suppressed and the weld structure is refined, thereby significantly improving the welding efficiency, improving the welding quality, and reducing the tendency of thermal cracks. The present invention also designs a preheating process of low-power, large-spot blue light laser, which can uniformly heat the weld area and avoid thermal stress and thermal deformation caused by excessive temperature gradient during welding. The present invention also designs a remelting and heat preservation process to effectively slow down the temperature drop rate after welding, reduce the thermal shrinkage problem of thin-walled aluminum alloy components due to drastic temperature drop, and help improve the shape and position accuracy of the components after welding.

[0022] The schematic diagram of the welding method of thin-walled aluminum alloy components based on infrared-blue light composite laser designed by the present invention is as follows Figure 1 The figure mainly shows a workbench 1, a thin-walled aluminum alloy component to be welded 2, a shielding gas output pipe 3, a blue laser 4, an infrared laser 5, and a wire feed tube 6.

[0023] The workbench 1 provides an installation location for the thin-walled aluminum alloy component 2 to be welded and its fixing fixture, and is in a fixed state during the welding process. The thin-walled aluminum alloy component 2 to be welded includes a welding area. The thin-walled aluminum alloy component 2 to be welded is divided into two units with the welding area as the boundary. After welding is completed, the two units will be fused into one. One end of the shielding gas output pipe 3 is connected to the gas cylinder, and the other end acts on the welding area. The shielding gas output pipe 3 is used to transport the inert gas in the gas cylinder to the welding area to avoid oxidation during the welding process, which affects the welding performance. In a specific embodiment of the present invention, the inert gas is argon or helium.

[0024] The blue laser 4 and infrared laser 5 are coaxially distributed, with their focal points at the same location. They are generated by a blue laser and an infrared laser, respectively, and converged to a single point via optical fiber transmission and optical lens processing. The blue laser 4 is a laser beam with a wavelength range of 450nm-470nm and a maximum power of 500W. The infrared laser 5 is a laser beam with a wavelength range of 800nm-1100nm and a maximum power of 2000W. The output power of both laser beams can be infinitely adjusted within the maximum power range and has independent control capabilities, meaning that during the welding process, both infrared and blue lasers can be output separately, as well as a composite infrared-blue laser output.

[0025] In a specific embodiment of the present invention, the diameter of the blue laser 4 spot at the focus is 2 mm, and the diameter of the infrared laser 5 spot is 1.2 mm. From the cross section of the laser focus, the two are distributed in a ring shape, as shown in FIG. Figure 2 shown.

[0026] One end of the wire duct 6 is connected to the wire feeder. This duct delivers the wire to the laser focal point, providing the necessary material for welding to fill defects and restore the shape and function of thin-walled aluminum alloy components. The shielding gas output pipe 3, blue laser 4, infrared laser 5, and wire duct 6 are fixed relative to each other and connected to the motion actuator in the welding device. The actuator moves along a pre-set trajectory to complete the welding process.

[0027] The welding method process designed by the present invention is as follows Figure 3 As shown, the process mainly includes the steps of clamping, cleaning, preheating, welding, remelting and heat preservation of the thin-walled aluminum alloy component 2 to be welded. The implementation details of each step are as follows.

[0028] Step 1: Clamping the thin-walled aluminum alloy component 2 to be welded. Fix the thin-walled aluminum alloy component 2 to be welded on the workbench 1 using a clamp or other tool to ensure that the thin-walled aluminum alloy component 2 to be welded does not move during the welding process.

[0029] Step 2: Cleaning. A dense aluminum oxide film forms on the surface of aluminum alloys at room temperature. Its melting point is as high as 2050°C, far higher than the melting point of the aluminum alloy itself (approximately 660°C). This oxide film can hinder metal fusion during welding, leading to defects such as lack of fusion and incomplete penetration in the welded area. Therefore, cleaning is necessary to remove the oxide film from the surface of thin-walled aluminum alloy components.

[0030] The cleaning process can be: first, use an alkaline solution to rinse the surface of the thin-walled aluminum alloy component around the welding area to remove the oxide film and impurities on the surface of the thin-walled aluminum alloy component; then use an acidic solution to rinse to neutralize the alkaline solution remaining on the surface of the aluminum alloy; finally, use anhydrous ethanol to clean and dry.

[0031] Specifically, in a specific embodiment of the present invention, the specific steps of cleaning include: using a 10% concentration of sodium hydroxide solution to rinse the surface of the thin-walled aluminum alloy component around the welding area and letting it stand for 5 minutes to remove the oxide film and impurities on the surface to be welded; then using a 10% concentration of nitric acid solution to rinse and let it stand for 3 minutes to neutralize the residual alkaline solution after the sodium hydroxide cleaning; finally, cleaning with anhydrous ethanol and drying naturally or wiping with a clean dry cloth to remove residual moisture after the sodium hydroxide and nitric acid rinsing to prevent the residual moisture from causing pores during the welding process.

[0032] The oxide film on the surface of aluminum alloys has a low electron work function and is prone to electron emission, causing arc drift and affecting welding stability. Removing the oxide film helps maintain arc stability and ensure weld quality. The presence of the oxide film also exacerbates thermal stress during welding and increases the risk of thermal cracking. Removing the oxide film can reduce this tendency and improve the strength and reliability of the weld (i.e., the area to be welded). Furthermore, removing the oxide film makes the welding process easier to control, improving welding efficiency and quality.

[0033] Step 3: Preheating: Use a low-power, large-spot blue laser with a power of 100-200W, a wavelength of 450nm-470nm, and a spot diameter of 4-6mm in combination with a motion actuator to preheat the area to be welded.

[0034] In a specific embodiment of the present invention, the vertical distance between the laser focus and the area to be welded is adjusted by a motion actuator so that the blue laser spot is in a defocused state, and a spot with a diameter of 4 mm can be obtained.

[0035] After the blue laser is turned on, the motion actuator starts to control the blue laser spot to reciprocate along the preset welding path to achieve preheating. At the same time, it also moves a certain amount across the width of the welding path to preheat the welding path, avoiding local overheating or insufficient heating in the area to be welded. In addition, this preheating method can effectively expand the range of the heat-affected zone and achieve a gradient diffusion distribution of heat, thereby effectively avoiding the band-like high-temperature concentrated areas that are easily formed along the straight preheating path. The main advantage of this path is its local repeated heating function, which is particularly significant for improving the temperature field distribution of the material.

[0036] In a specific embodiment of the present invention, the blue laser spot 4 can perform a spiral reciprocating motion along a preset welding path, and the motion trajectory is as follows: Figure 4 As shown, using high-reflectivity aluminum alloy as an example, this preheating path can significantly reduce total heat input by 15-20% compared to a traditional straight path. This feature not only improves energy efficiency but also helps improve the processing characteristics of the material. The width of the welding path can move 10-20 mm.

[0037] Low-power, large-spot blue lasers can effectively reduce the laser beam power density. Combined with the spiral reciprocating motion, this prevents localized overheating or insufficient heating in the weld area, ensuring uniform heating across the weld area. When the surface temperature of the thin-walled aluminum alloy component within a 10-15mm radius around the weld area reaches 150-200°C, the blue laser is turned off, preheating is complete, and the motion actuator moves to the starting point of the preset weld path.

[0038] Preheating can reduce the temperature gradient in the area to be welded and reduce the thermal stress caused by rapid heating and cooling, thereby reducing the risk of deformation and thermal cracking of thin-walled aluminum alloy components during welding.

[0039] Step 4: Welding. The blue laser, infrared laser, gas cylinder, wire feeder, and motion mechanism are simultaneously activated. The focal points of the blue laser 4 and the infrared laser 5 converge at the starting point of the preset welding path. Simultaneously, the aluminum alloy welding wire, passing through the wire feed duct 6, also converges at this starting point. Shielding gas is delivered to the weld through the shielding gas output pipe 3.

[0040] Under the action of infrared-blue light composite laser, the thin-walled aluminum alloy component base material and aluminum alloy welding wire at the starting point melt together to form a molten pool. At the same time, under the action of the motion actuator, the molten pool moves along the preset welding path. After the laser beam moves, the temperature of the melting area behind the molten pool decreases. The melted thin-walled aluminum alloy component base material and aluminum alloy welding wire solidify into one to complete the welding. The moving speed of the motion actuator is 10mm / s.

[0041] Among them, the power of the blue laser in the infrared-blue light composite laser is 350-500w, the wavelength is 450nm-470nm, the power of the infrared laser is 900-1200w, and the wavelength is 800nm-1100nm; the diameter of the light spot that appears when the blue laser is irradiated on the surface of the area to be welded is 2-3mm, and the diameter of the light spot that appears when the infrared laser is irradiated on the surface of the area to be welded is 1.2-2mm, and the center of the light spot irradiated by the blue laser coincides with the center of the light spot irradiated by the infrared laser.

[0042] In a specific embodiment of the present invention, the power of the blue laser 4 is 350W, and the power of the infrared laser 5 is 900W. The two work together to form a ring-shaped composite laser with low power on the outside and high power in the center at the laser focus. The specific power value can be adjusted according to the thickness of the thin-walled aluminum alloy component 2 to be welded.

[0043] The blue laser portion of the infrared-blue hybrid laser reduces infrared laser reflection losses in aluminum alloys, improving energy utilization and enhancing welding efficiency. Furthermore, the large-spot blue laser effectively stabilizes the molten material surrounding the weld pool, improving its fluidity and facilitating the removal of gases and impurities, reducing defects such as porosity and slag inclusions, and improving process stability. After welding is complete, the actuator resets to the starting point of the pre-set weld path.

[0044] Step 5: Remelting and Insulation. This step is similar to the preheating process in step 3. A low-power, large-spot blue laser with a power of 100-200W, a wavelength of 450nm-470nm, and a spot diameter of 4-6mm is used. The blue laser spot is controlled to reciprocate along the preset welding path. At the same time, it is also moved a certain amount across the width of the welding path to ensure that the width of the welding path is also remelted and insulated.

[0045] During the remelting and insulation process, the power of the blue laser is dynamically adjusted according to a preset rate of change. Through this nonlinear power adjustment strategy, the surface temperature of the thin-walled aluminum alloy components within a range of 10-15mm around the welding area is precisely controlled, so that the surface temperature of the thin-walled aluminum alloy components within a range of 10-15mm around the welding area is reduced to 80-100°C within 2-5 minutes, at which time the remelting and insulation treatment is completed; among them, the absolute value of the rate of change is 20W / s-50W / s; the distance moved in the width direction of the welding path can be 10-20mm; the dynamic adjustment includes increasing the power of the blue laser and decreasing the power of the blue laser.

[0046] In a specific embodiment of the present invention, the motion trajectory of the blue laser spot can be Figure 4 The motion trajectory shown remains consistent.

[0047] This step has the effect of slowing down the temperature drop rate of the area to be welded, promoting grain refinement in the area to be welded, reducing welding residual stress, improving the mechanical properties of the area to be welded, and reducing the risk of deformation and cracking of the thin-walled aluminum alloy component 2.

[0048] To verify the advantages of infrared-blue light composite laser in the welding of thin-walled aluminum alloy components, a crack damage with a prefabricated depth of 1mm was preformed on an aluminum alloy (grade: 2024) with a specification of 150*80*2mm. Welding performance tests were carried out using an infrared laser of 1250W and a composite laser with a total power of 1250W (including 900W infrared laser and 350W blue light laser). A comparison was also made in terms of weld appearance, tensile strength, and weld cross-sectional state.

[0049] In both welding processes, except for the different laser modes used in the final welding, the cleaning, preheating, and insulation steps are the same. Figure 5 、 Figure 6 The weld seams after infrared laser and hybrid laser welding are shown in Figure 2. The black arrow in the figure indicates the welding direction. As can be seen from the weld seam appearance images, the weld seam flatness in the infrared laser mode is worse than that in the hybrid laser mode.

[0050] Figure 7 、 Figure 8 The following are cross-sectional views of the welds after infrared laser and hybrid laser welding, respectively. As can be seen from the figures, under the action of infrared laser, a noticeable gap is observed in the middle of the weld, indicating that the substrate materials on both sides of the crack have not completely melted, cooled, and solidified into one piece after welding. Under the action of hybrid laser, no noticeable gap is observed in the weld cross-section, and the substrate penetration depth (D) and cladding layer width (w) are both greater than those obtained with infrared laser, while the cladding layer height (h) is less than those obtained with infrared laser. Furthermore, the tensile strength of the samples obtained under both welding modes was tested according to the room temperature test method for tensile testing of metallic materials (GB / T 228.1-2021). The average tensile strength of the infrared laser welded parts was only 276 MPa, while that of the hybrid laser welded parts was 383 MPa. The welding performance test results show that the weld appearance, cross-sectional state, and tensile strength of the hybrid laser welded components are significantly improved due to the infrared laser, making this method of welding thin-walled aluminum alloy components of practical significance.

[0051] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A thin-walled aluminum alloy component welding method based on infrared-blue light composite laser, characterized in that: The following steps are involved: 1) Clean and dry the surface of the thin-walled aluminum alloy component to be welded to remove the oxide film and impurities on the surface of the thin-walled aluminum alloy component in the area to be welded, and then use a blue laser to preheat the area to be welded of the thin-walled aluminum alloy component; In step 1), the blue laser is used to preheat the area to be welded of the thin-walled aluminum alloy component, including: First, adjust the power of the blue laser to 100-200W, and then adjust the diameter of the spot that appears when the blue laser is irradiated on the surface of the area to be welded to 4-6mm; wherein, the wavelength of the blue laser is 450nm-470nm; The blue laser spot is controlled to reciprocate along the preset welding path. When the surface temperature of the thin-walled aluminum alloy component within a range of 10-15mm around the welding area reaches 150-200℃, the preheating process is considered complete. 2) Using infrared-blue light composite laser as heat source, aluminum alloy welding wire as filler material, and inert gas as shielding gas, thin-walled aluminum alloy components are welded according to the preset welding path; In step 2), the power of the blue laser in the infrared-blue composite laser is 350-500W, and the wavelength is 450nm-470nm, and the power of the infrared laser is 900-1200W, and the wavelength is 800nm-1100nm; the diameter of the light spot that appears when the blue laser is irradiated on the surface of the area to be welded is 2-3mm, and the diameter of the light spot that appears when the infrared laser is irradiated on the surface of the area to be welded is 1.2-2mm, and the center of the light spot irradiated by the blue laser coincides with the center of the light spot irradiated by the infrared laser; 3) After welding is completed, the blue laser is used to remelt and heat-insulate the welding area to complete the welding of the thin-walled aluminum alloy components to be welded; In step 3), after the welding is completed, the blue laser is used to remelt and heat-insulate the welding area, including: First, adjust the power of the blue laser to 100-200W, and then adjust the diameter of the spot that appears when the blue laser is irradiated on the surface of the area to be welded to 4-6mm; wherein, the wavelength of the blue laser is 450nm-470nm; The blue laser spot is controlled to move back and forth along the preset welding path to achieve remelting and insulation treatment. During the remelting and insulation process, the power of the blue laser is dynamically adjusted according to the preset change rate, so that the surface temperature of the thin-walled aluminum alloy components within a range of 10-15mm around the area to be welded is reduced to 80-100℃ within 2-5 minutes, at which time the remelting and insulation treatment is completed; among them, the absolute value of the change rate is 20W / s-50W / s.

2. The thin-walled aluminum alloy component welding method based on infrared-blue light composite laser according to claim 1 is characterized in that: In step 1), the surface of the aluminum alloy to be welded is cleaned and dried, comprising: First, the surface of the thin-walled aluminum alloy component around the welding area is rinsed with an alkaline solution to remove the oxide film and impurities on the surface of the thin-walled aluminum alloy component; then it is rinsed with an acidic solution to neutralize the alkaline solution remaining on the surface of the aluminum alloy; finally, it is cleaned with anhydrous ethanol and dried.

3. The thin-walled aluminum alloy component welding method based on infrared-blue light composite laser according to claim 1 is characterized in that: When the blue laser spot reciprocates along the welding path, it also moves a certain range in the width direction of the welding path so that the width direction of the welding path is also preheated to avoid local overheating or insufficient heating of the area to be welded.

4. The thin-walled aluminum alloy component welding method based on infrared-blue light composite laser according to claim 1 is characterized in that: In step 2), the inert gas is argon or helium.

5. The thin-walled aluminum alloy component welding method based on infrared-blue light composite laser according to claim 1 is characterized in that: When the blue laser spot moves back and forth along the welding path, it also moves a certain range in the width direction of the welding path, so that the width direction of the welding path is also remelted and heat-insulated, slowing down the temperature drop rate of the area to be welded, promoting grain refinement in the area to be welded, reducing the effect of welding residual stress, improving the mechanical properties of the area to be welded, and reducing the risk of deformation and cracking of thin-walled aluminum alloy components.

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