Dissimilar metal power modulation galvanometer laser welding method

Abstract

The invention belongs to the technical field of welding, and discloses a dissimilar metal power modulation galvanometer laser welding method which comprises the following steps: finely cleaning a 6061 aluminum alloy and a 304 stainless steel plate by using acetone, and then airing for more than 20 minutes; the aluminum steel sheet is assembled, pressed and fixed on a welding test platform in a steel-up-aluminum-down mode; the position of the welding test platform is adjusted, argon serves as welding protection gas, and a protection gas nozzle is arranged to be aligned with a welding pool area; laser welding parameters are set, a laser power modulation mode is set to be a gradient power mode, and the gradient power mode is to regulate and control phase point laser power in a circular scanning track in the advancing direction of a welding seam; a welding test is carried out in the mode that a galvanometer laser head is fixed and a welding test platform is moved, and a laser and the welding test platform are synchronously started and stopped; and the protective gas is started 5 seconds before the laser is started, and after the laser is stopped, the protective gas is stopped lagging for 10 seconds so as to continuously protect the welding seam and prevent oxidation.

Description

Technical Field

[0001] The present invention belongs to but is not limited to the field of welding technology, and in particular relates to a power-modulated galvanometer laser welding method for dissimilar metals. Background Art

[0002] In recent years, due to the need for environmental protection and energy conservation, automobile lightweighting has become the mainstream trend of the world's automobile industry. The key to a car's fuel consumption lies in the engine's exhaust volume and the total weight of the car. Under the condition of keeping the overall structure and performance of the car unchanged, reducing the weight of the car itself can improve maneuverability and stability, reduce fuel consumption, and reduce exhaust emissions. Scientific research data shows that if the weight of the entire vehicle is reduced by 10%, fuel consumption can be reduced by 6%-8%; and using lightweight alloys to replace part of the body steel structure is the most effective way to lightweight a car. At present, many automobile manufacturers have begun to use a large amount of aluminum alloys for body structure manufacturing. For example, the aluminum alloy content in the body structure of Cadillac CT6 has reached 64%, which is 99kg lighter than the pure steel structure body. Audi, Volkswagen, Honda and other major brands all use a large amount of aluminum alloys, so the manufacture of automobile body structures involves a large number of aluminum-steel dissimilar metal structures. Connection.

[0003] The great differences between aluminum and steel in thermophysical properties such as density and melting point bring great challenges to the welding of aluminum-steel dissimilar metals. The difficulty of laser welding of aluminum-steel dissimilar metals is that the solute in the molten pool is easy to segregate to form a solute-enriched area, which causes solidification cracks; due to the large differences in physical properties such as thermal conductivity and linear expansion coefficient between aluminum and steel, the cooling and shrinkage during welding are not synchronized, which is easy to produce large stress. In addition, a hard and brittle intermetallic compound layer (IMCs) is easy to form at the aluminum-steel interface during welding, which seriously affects the mechanical properties of the welded joint. Therefore, it is of great theoretical and application value to study the welding technology of aluminum-steel dissimilar metals and improve the welding quality of dissimilar metals.

[0004] In view of the above problems, the present invention proposes a gradient power modulation galvanometer laser welding method, which provides a good solution for dissimilar metal welding. It can realize power modulation and change the energy distribution on the weld surface, and has a high molten pool control capability. The gradient power heat source mode is adopted to weld the aluminum-steel lap joint, and the laser beam can stir the molten pool, which has the effect of improving the segregation of weld elements, accelerating the gas escape in the molten pool, and reducing defects such as weld pores and cracks. In addition, laser welding with different power modulation modes can limit the generation of IMC by changing the energy distribution on the weld surface of the aluminum-steel joint and regulating the interface thermal field distribution, and improve the uniformity of the thickness of the intermetallic compound layer at the interface of dissimilar metals, improve the structural heterogeneity, and improve the mechanical properties of the weld joint.

[0005] In view of the above analysis, the technical problems that need to be solved urgently in the prior art are:

[0006] (1) The thermal conductivity and linear expansion coefficient of aluminum and steel are quite different. The cooling and shrinkage during welding are not synchronized, which can easily generate large stress and become the origin of crack initiation.

[0007] (2) The solute in the welding pool is easy to segregate to form a solute-rich area, which causes solidification cracks;

[0008] (3) Laser welding keyhole has poor stability and is prone to defects such as spatter, undercut, and pores;

[0009] (4) A hard and brittle Fe-Al intermetallic compound layer is easily generated at the laser welding interface of aluminum and steel dissimilar metals, which seriously affects the mechanical properties of the welded joint;

[0010] (5) Laser welding cools down quickly, which causes hydrogen in the molten pool to have no time to escape, thus forming porosity defects. Summary of the invention

[0011] In view of the problems existing in the prior art, the present invention provides a power-modulated galvanometer laser welding method for dissimilar metals, which adopts a gradient power heat source mode to weld aluminum-steel lap joints. It can realize laser power modulation, change the energy distribution of the molten pool, and match with a variety of scanning curves of the galvanometer laser, which greatly improves the molten pool regulation capability.

[0012] The present invention is implemented as follows: a dissimilar metal power modulation galvanometer laser welding method, comprising:

[0013] Step 1: Use acetone to carefully clean the 6061 aluminum alloy and 304 stainless steel plates to remove dirt, oil and other impurities on the surface, and then let them stand for more than 20 minutes to allow the acetone to completely evaporate;

[0014] Step 2, assembling the aluminum-steel sheet in the form of steel on top and aluminum on the bottom and pressing and fixing it on the welding test platform;

[0015] Step 3, adjust the position of the welding test platform and place the stainless steel surface to be welded at a position where the laser beam defocus amount is -1;

[0016] Step 4, using argon gas with a purity of 99.99% as welding shielding gas, with a gas flow rate of 10 L / min, and setting the shielding gas nozzle to be aimed at the welding pool area and at a 45° angle with the plane of the test plate;

[0017] Step 5, set the laser welding parameters: average laser power 3kW, welding speed 10mm / s, scanning trajectory circular, scanning amplitude 0.5mm,

[0018] Step 6, set three scanning frequencies to 100 Hz, 150 Hz, and 200 Hz, numbered G1, G2, and G3 respectively;

[0019] Step 7, set the laser power modulation mode to the gradient power mode. The gradient power mode is to adjust the laser power of 36 phase points in the circular scanning trajectory along the forward direction of the weld. The laser power in the middle is high and the laser power on both sides is symmetrically reduced. The maximum power and the minimum power are 4kW and 2kW respectively, the average power is 3kW, and the power gradient is 50%;

[0020] Step 8, the galvanometer laser head is fixed and the welding test platform is moved to perform the welding test, and the laser and the welding test platform are started and stopped synchronously;

[0021] Step 9: The shielding gas is turned on 5 seconds before the laser is started. After the laser stops, the shielding gas is stopped for 10 seconds to continue to protect the weld and prevent oxidation.

[0022] Furthermore, the dimensions of the 6061 aluminum alloy and 304 stainless steel plates are both 100×50×2 mm.

[0023] The further welding equipment adopts a full-range power modulation laser welding system with the dual functions of "laser galvanometer + power modulation".

[0024] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0025] First, the present invention provides a power-modulated galvanometer laser welding method for aluminum-steel dissimilar metals. In the gradient power mode, the energy distribution of the weld and the interface thermal field distribution are regulated to reduce the thickness of the intermetallic compound layer at the aluminum-steel interface.

[0026] At the same time, the intermetallic compound layer structure changes from a large number of randomly distributed lamellar structures to uniformly dispersed fine needle-like structures, which improves the uniformity of the structure and the mechanical properties of the welded joint.

[0027] In addition, modulating the laser beam to strengthen the stirring of the molten pool can accelerate the escape of gas in the molten pool and reduce the porosity defects in the weld;

[0028] By precisely controlling the movement trajectory and power of the laser beam, the temperature of the welding area is evenly distributed to avoid local overheating or rapid cooling, thereby reducing thermal stress and crack risks;

[0029] As the scanning frequency increases, the stirring effect of the laser beam is strengthened, the flow rate of the molten pool is accelerated, which has the effect of improving element segregation, while being able to refine the grains and improve the microstructure and mechanical properties of the weld.

[0030] Second, the expected benefits and commercial value after the transformation of the technical solution of the present invention are as follows: the power-modulated galvanometer laser welding method of aluminum-steel dissimilar metals of the present invention can effectively improve the welding quality and tensile shear strength of aluminum-steel dissimilar metal welding joints, and from the perspective of improving welding quality, it improves the connection strength and safety performance of the automobile body, and provides a new technical solution for automobile lightweight design and new aluminum-steel structure manufacturing.

[0031] The technical solution of the present invention solves a technical problem that people have been eager to solve but have never succeeded in solving: the technical solution of the present invention provides a new aluminum-steel dissimilar metal laser welding method, which effectively improves the bonding strength of the aluminum-steel dissimilar metal interface, successfully limits the formation of interface intermetallic compounds by regulating the interface energy field distribution, reduces the thickness of the intermetallic compound layer, and at the same time improves the interface organization morphology and uniformity, thereby improving the mechanical properties of the welded joint.

[0032] Third, the present invention solves a series of technical problems existing in the prior art in the welding of dissimilar metals. The traditional welding method of aluminum alloy and stainless steel dissimilar metals is very likely to cause welding cracks, poor bonding strength, and a large heat-affected zone due to the large difference in thermal expansion coefficient and melting point between the two, which seriously affects the welding quality and the mechanical properties of the joint. In addition, the conventional welding process lacks precise control of temperature and power, which easily causes uneven penetration, welding deformation and oxidation, reducing the stability and controllability of the welding process.

[0033] The present invention achieves precise adjustment of laser power, scanning frequency and scanning trajectory by introducing laser galvanometer and power modulation technology, so that the laser acts evenly on the interface between aluminum alloy and stainless steel during welding. This control method not only effectively reduces the heat affected zone of the weld and reduces the concentration of thermal stress during welding, but also significantly improves the density and strength of the welded joint, and improves the welding quality and reliability of the joint. In addition, by setting the delayed stop of the protective gas, the problem of weld oxidation is effectively prevented, and the integrity of the welding surface is ensured.

[0034] In industrial applications, the present invention significantly improves the efficiency and automation of dissimilar metal welding. Through the combination of power gradient modulation and galvanometer control, the power, frequency and other parameters can be intelligently adjusted during the welding process, thereby achieving precise welding. Compared with traditional methods, this invention not only reduces the error rate in the welding process and saves material costs, but also reduces the dependence on manual operation, providing a more stable welding technology for large-scale automated production.

[0035] The significant technical progress of the present invention is that the collaborative work of the laser galvanometer and power modulation solves the problem of the inability to stably weld aluminum alloy and stainless steel in the prior art. Through intelligent and automated welding process optimization, the present invention has the advantages of high precision and high efficiency, and is suitable for high-demand fields such as aerospace and automobile manufacturing. This technological breakthrough further expands the application scope of dissimilar metal welding and has broad market prospects and application value.

[0036] Fourth, the power-modulated galvanometer laser welding method for dissimilar metals proposed in the present invention adopts a unique laser parameter setting and a precise power modulation mode to solve the problems encountered in the welding of 6061 aluminum alloy and 304 stainless steel plates, such as large differences in material thermal expansion, easy cracking, and insufficient joint strength. In the prior art, due to the significant differences in the thermal physical properties of dissimilar metals, traditional welding methods often lead to uneven internal structures of welds, unstable welding quality, and easy thermal cracking, which seriously affects the service life of the joints. The present invention effectively controls the heat input of the weld zone by adjusting the laser power and optimizing the welding parameters, significantly improving the welding quality and reliability.

[0037] The key parameters in the present invention include 3kW average laser power, 10mm / s welding speed, circular scanning trajectory and 0.5mm scanning amplitude. Combined with three sets of laser scanning frequencies of different frequencies (100Hz, 150Hz and 200Hz), the formation of the molten pool and the heat distribution can be accurately controlled under different welding conditions. By controlling the scanning frequency, the present invention adjusts the size and depth of the molten pool at different welding speeds and power densities, making the welding molten pool more uniform and reducing the cracks and pores caused by local overheating. The combination of these parameters makes the internal structure of the weld more compact and the strength of the welded joint is significantly improved.

[0038] In addition, the power modulation mode of the present invention adopts a gradient power mode to accurately adjust the laser power of 36 phase points within a circular scanning trajectory. By setting a mode with high power in the middle and gradually decreasing power on both sides, a power change between a maximum of 4kW and a minimum of 2kW is achieved, forming a 50% power gradient. This power distribution mode concentrates the welding heat in the center area of ​​the weld, effectively controls the temperature of the edge heat-affected zone, thereby reducing thermal stress concentration and reducing the probability of deformation and cracking during welding. This power modulation strategy ensures a high-quality, uniform weld structure in dissimilar metal welding and improves the weld quality.

[0039] Compared with traditional methods, the present invention has achieved significant technological progress in industrial applications, especially in high-end manufacturing fields such as aerospace, automobile manufacturing and other application scenarios, the welding accuracy and strength are significantly improved. By setting high-purity argon protection and optimized laser parameters, the welding process reduces oxidation, the weld surface is smooth and well-formed, and the oxidation problem of dissimilar metal welding is effectively solved. The present invention significantly improves welding efficiency, reduces the incidence of welding defects, and extends the service life of the welded joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of a method for dissimilar metal power modulation galvanometer laser welding provided by an embodiment of the present invention;

[0041] Figure 2 The circular scanning trajectory phase point power control and gradient power waveform diagram provided by the embodiment of the present invention

[0042] Figure 3 1 is a diagram of energy distribution of weld cross sections under different laser modes provided in an embodiment of the present invention; wherein (a) single laser welding Gaussian heat source mode, (b) conventional galvanometer laser welding mode, (c) gradient power mode, and (d) weld surface energy distribution under gradient power mode;

[0043] Figure 4 : is a morphology diagram of an aluminum-steel welded joint under a gradient power mode provided by an embodiment of the present invention; wherein (a) the surface and back morphology, (b) the cross-sectional morphology;

[0044] Figure 5 These are microstructure diagrams of the joint interface under different welding modes provided by the embodiments of the present invention; wherein, (a) is a conventional galvanometer mode, and (b) is a gradient power mode. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0046] like Figure 1 As shown, the dissimilar metal power modulation galvanometer laser welding method provided by the embodiment of the present invention includes:

[0047] Step 1: Use acetone to carefully clean the 6061 aluminum alloy and 304 stainless steel plates to remove dirt, oil and other impurities on the surface, and then let them stand for more than 20 minutes to allow the acetone to completely evaporate;

[0048] Step 2, assembling the aluminum-steel sheet in the form of steel on top and aluminum on the bottom and pressing and fixing it on the welding test platform;

[0049] Step 3, adjust the position of the welding test platform and place the stainless steel surface to be welded at a position where the laser beam defocus amount is -1 mm;

[0050] Step 4, using argon gas with a purity of 99.99% as welding shielding gas, with a gas flow rate of 10 L / min, and setting the shielding gas nozzle to be aimed at the welding pool area and at a 45° angle with the plane of the test plate;

[0051] Step 5, set the laser welding parameters: average laser power 3kW, welding speed 10mm / s, scanning trajectory circular, scanning amplitude 0.5mm,

[0052] Step 6, set three scanning frequencies to 100 Hz, 150 Hz, and 200 Hz, numbered G1, G2, and G3 respectively;

[0053] Step 7, set the laser power modulation mode to the gradient power mode. The gradient power mode is to adjust the laser power of 36 phase points in the circular scanning trajectory along the forward direction of the weld. The laser power in the middle is high and the laser power on both sides is symmetrically reduced. The maximum power and the minimum power are 4kW and 2kW respectively, the average power is 3kW, and the power gradient is 50%;

[0054] Step 8, the galvanometer laser head is fixed and the welding test platform is moved to perform the welding test, and the laser and the welding test platform are started and stopped synchronously;

[0055] Step 9: The shielding gas is turned on 5 seconds before the laser is started. After the laser stops, the shielding gas is stopped for 10 seconds to continue to protect the weld and prevent oxidation.

[0056] The following is a detailed description of the working principle of this dissimilar metal power modulated galvanometer laser welding method:

[0057] 1. Material preparation and cleaning

[0058] When welding dissimilar metals, the cleaning of the surfaces of 6061 aluminum alloy and 304 stainless steel is crucial. In step 1, acetone is used to clean the surfaces of aluminum and steel to remove surface oil and impurities to ensure that the surfaces of the two metals can fully contact during welding and achieve good welding quality. The cleaned materials must be left to air for at least 20 minutes to ensure that the acetone is completely volatilized and to avoid any residues that interfere with the welding effect.

[0059] 2. Test panel assembly and laser beam alignment

[0060] In step 2, the thin plates are assembled and fixed on the welding platform using a "steel on top and aluminum on bottom" structure, which is to use gravity and pressure to ensure the close fit of the two plates. Then in step 3, the defocus amount of the laser beam is accurately set to focus the laser at a position 1mm away from the stainless steel surface. This defocus setting ensures that the laser penetrates deep enough during the welding process, so that the welding heat is evenly distributed at the steel-aluminum interface, which helps to form a high-quality dissimilar metal weld.

[0061] 3. Shielding gas setting and nozzle angle

[0062] Argon protection during welding is essential to prevent oxidation and reduce welding defects. In step 4, argon with a purity of 99.99% is used, and the gas flow is set to 10L / min, which can effectively cover the molten pool and block the oxygen in the air. The gas nozzle is aimed at the molten pool at a 45° angle to ensure that the gas is evenly distributed in the welding area, further optimizing the protection effect. The delayed closing design of the shielding gas continues to protect the weld after welding is completed, ensuring that the weld will not come into contact with the air during cooling, thereby avoiding oxidation.

[0063] 4. Laser power modulation and frequency setting

[0064] In steps 5 to 7, the system achieves high-quality welding results by precisely controlling the laser power and frequency. The average laser power is set to 3kW, and combined with a 0.5mm circular scanning trajectory, the welding heat can be evenly distributed in the molten pool to avoid local overheating. By setting three frequencies (100Hz, 150Hz, 200Hz), the laser galvanometer can produce different molten pool sizes and depths to meet different welding requirements. The power gradient mode further optimizes the distribution of the laser in the forward direction of the weld. By regulating the power of 36 phase points within the circular trajectory, a power mode with high in the middle and low on both sides is adopted to ensure that the welding intensity in the center of the molten pool is maximum. At the same time, the power on both sides gradually decreases, reducing the width of the heat-affected zone and improving welding efficiency.

[0065] 5. Synchronous movement of galvanometer laser and welding platform

[0066] In step 8, the welding test was conducted with a fixed galvanometer laser head and a moving welding platform. The position of the laser head remained unchanged, and the smooth movement of the welding platform allowed the laser to be precisely controlled on the welding path. This method can better coordinate the power modulation of the galvanometer laser head and the alignment of the welding path, reduce the error caused by the frequent movement of the galvanometer laser head, and improve the welding accuracy. The synchronous start and stop of the laser and the welding platform further enhances the welding control, making the molten pool formation process stable and reliable.

[0067] 6. Delayed shutdown of protective gas

[0068] In step 9, the delayed closing time of the shielding gas is set, that is, after the laser stops, the shielding gas is delayed for 10 seconds before stopping. This design ensures that after welding, the weld can continue to be protected by argon gas during the cooling stage, avoiding oxidation of the weld at high temperature and improving the anti-oxidation effect of the welding area. At the same time, the reasonable setting of the delayed closing time also prevents excessive consumption of gas.

[0069] 7. Accurate temperature control and power distribution

[0070] The power modulation mode and the setting of the galvanometer frequency in the present invention effectively control the distribution of metal temperature during laser welding. By regulating the power at 36 phase points, a stable and solid molten pool can be generated between stainless steel and aluminum alloy, making the weld uniform and crack-free. At the same time, combined with different scanning frequencies, the welding process can adapt to the thermophysical properties of different metals and achieve high-quality welding.

[0071] 8. Apply effects

[0072] Through the above-mentioned power modulation and galvanometer control, the method effectively solves the problem of heat influence in the welding of dissimilar metals, optimizes the quality of the weld, and improves the welding stability and oxidation resistance. The welding method of the present invention is suitable for scenes with high requirements for welding precision in the field of high-end manufacturing, such as automobile manufacturing and aerospace industries, and has significant industrial application value.

[0073] Furthermore, the dimensions of the 6061 aluminum alloy and 304 stainless steel plates are both 100×50×2 mm.

[0074] Furthermore, the welding equipment adopts a full-range power modulation laser welding system with dual functions of "laser galvanometer + power modulation".

[0075] Figure 2 The power control diagram of 36 phase points of the circular scanning track in the full-range power modulation galvanometer laser welding and the laser power waveform diagram in the gradient power mode. In the gradient power mode, the laser beam uses a circular scanning track to weld along the weld. By regulating the power of the 36 phase points in the circular scanning track, the gradient power mode with high in the middle and low on both sides is used for welding, and the molten pool regulation and weld formation control capabilities are enhanced.

[0076] Figure 3 This is the energy distribution diagram of the weld cross section under different laser modes. Figure 3 (a) is the energy distribution diagram of the weld cross section in single laser welding Gaussian heat source mode; Figure 3 (b) is the energy distribution diagram of the weld cross section in conventional galvanometer laser welding mode; Figure 3 (c) is the energy distribution diagram of the weld cross section under gradient power mode. Figure 3(d) is the energy distribution diagram of the weld surface under the gradient power mode. Compared with the single laser welding Gaussian heat source mode and the conventional galvanometer laser welding mode, the energy distribution on the weld surface under the gradient power mode is more uniform, which changes the thermal field distribution at the weld edge and interface, reduces the gradient change, and reduces the thickness of the intermetallic compound layer at the aluminum-steel interface. At the same time, the intermetallic compound layer structure changes from a large number of randomly distributed lamellar structures to uniformly dispersed fine needle-like structures, which improves the uniformity of the structure and the mechanical properties of the welded joint. In addition, under the gradient power mode, the laser beam adopts a circular scanning trajectory to weld along the circumferential weld. By adjusting the power of the 36 phase points in the circular scanning trajectory, a gradient power mode with high in the middle and low on both sides is adopted for welding. The rotating laser beam stirs the molten pool, intensifies the flow of the molten pool, promotes gas escape, reduces the power at the edge of the molten pool, reduces the generation of defects such as undercut and spatter, and makes the weld surface more uniform.

[0077] Figure 4 The surface morphology and cross-sectional morphology of the lap joint welded with steel on top and aluminum on the bottom are shown in the figure. The aluminum-steel interface bonding width has a significant effect on the tensile shear performance of the aluminum-steel lap joint. Therefore, increasing the weld width and depth helps to increase the interface bonding width. The continuously rotating laser beam of the galvanometer laser enhances the stirring effect of the molten pool and also has a positive effect on increasing the weld width. Compared with traditional single laser welding, the galvanometer laser welding joint has a significantly increased molten width, which significantly improves the tensile shear strength of the joint.

[0078] Figure 5 The microstructure diagram of the aluminum-steel welded joint interface under different welding modes. Figure 5 (a) is the microstructure diagram of the aluminum-steel welding joint interface under conventional galvanometer laser mode. Figure 5 (b) is the microstructure diagram of the aluminum-steel weld joint interface under the gradient power laser mode. It can be seen from the figure that the thickness of the intermetallic compound layer at the aluminum-steel weld joint interface under the gradient power laser mode is significantly smaller than that under the conventional galvanometer laser mode, indicating that changing the energy distribution on the weld surface of the aluminum-steel joint through the gradient power modulation mode has played a role in limiting the generation of IMCs. At the same time, the intermetallic compound layer organization changes from a large number of randomly distributed lamellar organizations to uniformly dispersed fine needle-like organizations, which improves the organization uniformity. In addition, according to the test results of the joint tensile shear performance, the tensile shear strength of the conventional galvanometer laser mode joint is 100MPa, and the tensile shear strength of the gradient power laser mode joint is 142MPa, and the tensile shear strength of the joint is significantly improved.

[0079] The specific application field of the present invention is the automobile manufacturing field, and related products include the connection between aluminum alloy components and steel components in the lightweight body structure of automobiles; in addition, the fields of aerospace, transportation, electronic equipment, etc. involving the welding and manufacturing of aluminum-steel dissimilar metals can all use this technical solution for welding, such as welding of aircraft structures and engine components, welding of ship and railway structure components, welding of electronic equipment housing components, etc.

[0080] The following are two specific embodiments to illustrate the practical application of the present invention in welding of dissimilar metals:

[0081] Example 1: Aluminum-steel dissimilar metal welding in automobile manufacturing

[0082] In the automobile manufacturing process, aluminum alloy and stainless steel are commonly used structural materials, used in body frames, engine components and other parts. Since aluminum alloy is light and stainless steel is corrosion-resistant, the combination can optimize the weight and durability of the vehicle body. However, welding between aluminum and steel dissimilar metals is difficult, and traditional welding methods easily lead to cracks and brittle joints in the welding area, affecting the strength and service life of the joint.

[0083] 1. Use acetone to clean the surface of aluminum alloy and stainless steel to remove oil stains.

[0084] 2. Assemble the cleaned and dried aluminum alloy and stainless steel in a "steel on top, aluminum on bottom" structure and fix them on the welding platform.

[0085] 3. Aim the argon nozzle at the welding area and use shielding gas to prevent oxidation.

[0086] 4. Set the laser power to 3kW, the scanning trajectory to a circle with an amplitude of 0.5mm, and the galvanometer laser head to scan at a frequency of 100Hz.

[0087] 5. Apply gradient power modulation, with high power in the middle and gradually decreasing power on both sides, to ensure smooth power distribution in the welding area.

[0088] 6. Start the laser system and shielding gas, and after welding is completed, delay turning off the shielding gas for 10 seconds to prevent oxidation of the weld.

[0089] This welding method allows aluminum and steel materials to form a uniform and stable welding interface, with no cracks or brittleness in the weld. Using this welding technology, automakers can reduce vehicle weight and improve fuel economy while maintaining material strength and corrosion resistance.

[0090] Example 2: Dissimilar metal welding of aluminum and titanium alloys in aerospace

[0091] In the aerospace field, aluminum alloys and titanium alloys are widely used due to their light weight and high strength. Aluminum-titanium dissimilar metal welding can effectively reduce the weight of aircraft and enhance the structural strength. However, there are large physical and chemical differences between titanium alloys and aluminum alloys, and the welding process is prone to thermal cracking and poor bonding.

[0092] 1. Clean the aluminum and titanium alloy surfaces with acetone and dry.

[0093] 2. Fix the aluminum alloy and titanium alloy on the welding platform in a "titanium on top and aluminum on bottom" structure to ensure that the titanium alloy is in the defocused position of the laser beam.

[0094] 3. Use argon as the shielding gas, maintain the gas flow rate at 10L / min, and aim at the welding area at an angle of 45°.

[0095] 4. Set the laser parameters to an average power of 4 kW, a scanning speed of 8 mm / s, a frequency of 200 Hz, and set the distribution of high power in the middle and low power on both sides in the gradient power mode, with a power range of 2 kW to 5 kW.

[0096] 5. Start the laser and gas protection system. After welding is completed, the protective gas is delayed to stop for 10 seconds to ensure that the weld is not oxidized.

[0097] This welding method creates a high-strength, crack-free weld between dissimilar metals such as aluminum and titanium. Aerospace companies can use this process to improve structural strength and durability, and achieve lighter, more energy-efficient aircraft designs.

[0098] In the description of the present invention, unless otherwise specified, "plurality" means two or more than two; the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention 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 operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0099] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for welding dissimilar metals by power modulation galvanometer laser, characterized in that: include: Step 1: Use acetone to clean the 6061 aluminum alloy and 304 stainless steel plates to remove surface impurities, and leave them in the air for at least 20 minutes to ensure that the acetone evaporates; Step 2, assemble the aluminum alloy and stainless steel plates in the form of "steel on top and aluminum on bottom", and press and fix them on the welding test platform; Step 3, adjusting the welding platform so that the stainless steel surface to be welded is at a focal position where the defocus amount of the laser beam is -1; Step 4, use argon gas with a purity of 99.99% as the shielding gas, set the gas flow rate to 10L / min, and aim the shielding gas nozzle at a 45° angle to the welding plane and toward the welding pool.

2. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: The laser welding parameters were set to an average power of 3 kW, a welding speed of 10 mm / s, a circular scanning trajectory, a scanning amplitude of 0.5 mm, and three groups of scanning frequencies were set to 100 Hz, 150 Hz, and 200 Hz, numbered G1, G2, and G3.

3. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: The laser power modulation mode adopts the gradient power mode. The power is adjusted at 36 phase points within the circular scanning trajectory. The laser power is set to be high in the middle and gradually decrease on both sides. The maximum power is 4kW, the minimum power is 2kW, the average power is 3kW, and the power gradient is 50%.

4. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: The welding equipment is a full-range power modulation laser welding system with dual functions of "laser galvanometer + power modulation". The welding operation is completed by keeping the galvanometer laser head stationary and the welding test platform moving.

5. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: The shielding gas is turned on 5 seconds before the laser is started and stopped 10 seconds after the laser is stopped to prevent oxidation of the weld and ensure the surface quality of the welding area.

6. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: The welding process is equipped with an intelligent control system for real-time monitoring of the temperature and morphology of the weld, and dynamically adjusting the laser power, scanning frequency and trajectory according to the monitoring data to meet the needs of welding different thicknesses and materials and improve welding accuracy.

7. The dissimilar metal power modulation galvanometer laser welding method according to claim 1, characterized in that: Further integration with the industrial robot system can realize the automated welding process. By controlling the robot to move the welding platform, welding tasks at different positions and angles can be completed to meet the needs of complex industrial environments.

8. The dissimilar metal power modulated galvanometer laser welding method according to claim 7, characterized in that: The robot system is linked with the laser welding system to ensure that the welding path and parameters are automatically adjusted in real time to achieve consistent welding quality and weld stability, reduce human operation errors, and improve welding efficiency.

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