A titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling

Abstract

The present invention relates to the technical field of titanium alloy welding. The present invention provides a titanium alloy welding method coupled with arc, laser and ultrasonic multi-energy fields, the welding method comprising: step S1: treating the surface of a substrate to be welded and performing matching assembly and fixing; step S2: starting an arc-laser composite welding device for welding; step S3: synchronously starting an ultrasonic vibration device to vibrate the substrate to be welded and the arc welding wire during the welding process, respectively, and the vibration frequency and amplitude of the substrate to be welded are coordinated with the laser's travel trajectory and laser power according to a preset logic; step S4: after welding, turning off the arc-laser composite welding device; step S5: after a first preset time, turning off the wire vibration device, and after a second preset time, turning off the substrate vibration device. The present invention adjusts the Marangoni flow behavior in the weld through the coupling welding setting of multiple energy fields, refines the weld grains, and improves the mechanical properties of the welded joint.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy welding, and in particular to a titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling. Background Art

[0002] Titanium alloy has the advantages of good corrosion resistance, sound permeability and high specific strength, and is called "marine alloy". With the wide application of titanium alloy in aerospace, shipbuilding and other fields, the research on titanium alloy welding technology has gradually heated up. At present, the commonly used titanium alloy welding technologies include electron beam welding and TIG welding. Electron beam welding can obtain good joint quality, but it needs to be carried out in a vacuum chamber. Large titanium alloy structural parts cannot be electron beam welded due to size limitations. TIG welding method is widely used in titanium alloy welding, but the welding efficiency and quality are not high, which cannot meet the requirements of large titanium alloy structures for high-quality and efficient welded joints.

[0003] Arc-laser hybrid welding has attracted attention as an efficient welding method. Due to the high viscosity and low thermal conductivity of titanium alloy materials, defects such as pores are very likely to appear inside the weld joint during arc-laser welding, and finger-shaped penetration is also likely to appear in the weld joint, which seriously affects the mechanical properties of the weld joint, making this technology unable to be used in the welding of titanium alloy structural parts with high mechanical properties requirements. In addition, the superposition of the high energy density heat input of the laser and the heat input of the arc makes the metallurgy, solidification, and phase change of the welding process more complicated. At the same time, the finger-shaped molten pool formed during the welding process will also lead to reduced performance. During the welding process, due to the accumulation of heat and the directionality of heat dissipation, the formed structure is prone to coarse grains, which further affects the performance of the welded joint.

[0004] At present, the existing methods for controlling the morphology and performance of the organization are mainly intervened by adding grain refiners, stirring the molten pool with a magnetic field, and other methods. Zou et al. published "Refinement of the grain structure of additive manufactured titanium alloys via epitaxial recrystallization enabled by rapid heat treatment" in the journal Scripta Materialia, which uses a rapid heat treatment method to achieve the regulation of titanium alloy grains. MJ Bermingham et al. published "Promoting the columnar to equiaxed transition and grain refinement of titanium alloys during additive manufacturing" in the journal Acta Materialia, which proposed a method of adding alloying elements to refine the grains of titanium alloys. Chinese patent CN201611214847.5 discloses a "manufacturing process method of multi-energy field coupling of arc, laser, and magnetic field", which optimizes the organization and performance of the welded joint by the method of multi-energy field coupling of arc, laser, and magnetic field. However, the non-magnetic characteristics of titanium alloys make it difficult to achieve the expected magnetic field effect, making it impossible to use it for titanium alloy welding.

[0005] By adding alloying elements as grain refiners, the purpose of controlling coarse grains in the formed structure can be achieved, but new elements are also introduced, which may lead to a decrease in other properties. Traditional arc-laser hybrid welding joints are prone to "finger-like" penetration, resulting in the performance of the welded joint failing to meet the use requirements. Refining grains through the stirring effect of a magnetic field is an earlier method of use, but the alternating magnetic field will affect the stability of the arc during the welding process, and the non-magnetic characteristics of titanium alloys make it difficult to achieve the expected magnetic field effect. Summary of the invention

[0006] The present invention aims to control the flow and solidification of molten pool metal through multi-energy field coupling to avoid "finger-like" melting depth and eliminate internal defects such as pores. At the same time, it refines the welding grain morphology and improves the uniformity of organization and performance, providing technical support for the efficient and high-quality manufacturing of titanium alloy thick plate welding, profiles, annular ribs and other structures.

[0007] The present invention discloses a titanium alloy welding method by coupling multiple energy fields of arc, laser and ultrasound. The welding device used in the welding method comprises an arc-laser composite welding device and two or more ultrasonic vibration devices. The two or more ultrasonic vibration devices at least comprise a substrate vibration device and a welding wire vibration device. The substrate vibration device is used to vibrate the substrate to be welded during the welding process, and the welding wire vibration device is used to vibrate the arc welding wire. The welding method comprises:

[0008] Step S1: Preparation before welding: Process the surface of the substrate to be welded to make it meet the welding requirements, and assemble and fix the substrate to be welded according to the welding process requirements;

[0009] Step S2: starting the arc-laser hybrid welding device to perform welding, wherein the laser oscillates and welds along a preset trajectory;

[0010] Step S3: synchronously starting the ultrasonic vibration device with the arc-laser hybrid welding device to vibrate the substrate to be welded and the arc welding wire in the welding process, respectively, wherein the substrate to be welded vibrates back and forth in the length direction of the weld, and the arc welding wire vibrates back and forth in the wire feeding direction, and the vibration frequency and amplitude of the substrate to be welded cooperate with the laser travel trajectory and laser power according to a preset logic;

[0011] Step S4: After welding is completed, the arc-laser hybrid welding device is turned off;

[0012] Step S5: After the arc-laser hybrid welding device is turned off for a first preset time, the welding wire vibration device is turned off, and after the second preset time, the substrate vibration device is turned off.

[0013] Through the oscillating welding of the laser and the vibration of the substrate to be welded and the arc welding wire, the Marangoni flow behavior in the welding process can be effectively eliminated, thereby eliminating the finger-shaped penetration. In addition, the high-frequency vibration of the arc welding wire can make the molten droplet at the end of the arc welding wire detach from the arc welding wire and enter the molten pool under lower heat input, thereby improving the molten droplet transition efficiency during arc welding, reducing the molten droplet size, reducing spatter, reducing heat input, and improving weld formation. Combined with the ultrasonic vibration of the substrate, it promotes the escape of gas in the molten pool, realizes the control of internal defects of titanium alloy, and can also significantly refine the columnar crystal structure formed in the traditional arc-laser composite welding joint, thereby significantly improving the impact toughness of the welded joint.

[0014] Furthermore, the preset trajectory in step S2 is an ∞-shaped trajectory.

[0015] By setting the above-mentioned running trajectory, the laser can swing periodically during the welding process, which is convenient for melting the metal at the front end of the molten pool on the one hand, and guides the molten pool on the other hand, adjusts the temperature field of the molten pool, improves the fluidity of the molten pool, promotes the escape of pores inside the molten pool, reduces the temperature gradient in the length direction of the molten pool, promotes the spreading of molten metal and the wetting of the side walls, and achieves good forming of the weld. It can also improve the fluidity of the molten pool, improve the surface tension gradient of the molten pool, improve the Marangoni flow behavior of the liquid metal inside the molten pool, promote the escape of pores inside the molten pool, avoid the occurrence of unfusion and internal pores, and cooperate with the effect of ultrasonic vibration to effectively break up the coarse dendrites in the molten pool, refine the weld grains, and significantly improve the impact toughness of the welded joint.

[0016] Further, step S1 includes:

[0017] Step S11: mechanically polishing the surface of the substrate to be welded, using acetone and alcohol solvents in combination with ultrasonic cleaning to remove oil stains, and placing it to dry for later use;

[0018] Step S12: Place the cleaned and dried substrate to be welded on a workbench and fix it with a clamp.

[0019] The above arrangement ensures the cleanliness of the surface of the substrate 400 to be welded, prevents the oil therein from contaminating the molten pool during welding, and ensures the quality of the joint during welding.

[0020] Further, step S2 includes:

[0021] Step S21: starting the protective gas delivery device to protect the welding area;

[0022] Step S22: Start the arc welding gun and the laser welding gun, and perform welding in a protective gas atmosphere, with the laser in front and the arc in the back during welding.

[0023] The shielding gas is argon, which is not easy to react chemically with titanium alloy during welding, and can play a good protective role on the weld, prevent the weld from oxidation and impurity intrusion, and ensure the quality of the weld.

[0024] Furthermore, during welding, the angle between the laser and the advancing direction of the weld is between 75° and 85°, and the angle between the arc welding wire and the advancing direction of the weld is between 100° and 110°.

[0025] By setting the laser angle, the laser energy can act more concentratedly on the weld, reducing reflection losses, increasing the penetration width, and reducing the thermal impact on the surrounding substrates to be welded, reducing the width of the heat-affected zone, thereby reducing the risk of deformation of the substrates to be welded and degradation of mechanical properties; by setting the arc welding wire angle, the molten droplet can be more stably transferred to the molten pool, reducing spatter and improving the weld quality; by coordinating the angles of the laser and arc welding wire, the energy distribution of the substrate to be welded and the arc welding wire can be optimized under ultrasonic vibration, the stability of the molten droplet transition can be improved, welding defects can be reduced, and the weld formation can be improved, thereby significantly improving the welding quality and efficiency.

[0026] Furthermore, the power of the laser welding gun is 7-14 kW, the frequency of substrate vibration is 80-100 kHz, and the amplitude is 12-20 μm.

[0027] The high energy density provided by higher laser power can achieve deep penetration, while ultrasonic vibration helps to break up and discharge gas and inclusions in the molten pool. The combination of the two can significantly improve the purity and penetration of the weld.

[0028] Furthermore, the vibration frequency of the arc welding wire is 60-80 kHz, and the amplitude is 15-18 μm.

[0029] The above-mentioned setting of the vibration parameters of the substrate 400 to be welded and the arc welding wire 300 unexpectedly promotes the dynamic release of thermal stress during welding, realizes the self-balance of thermal stress, reduces welding residual stress, and reduces welding deformation. In addition, the vibration of the arc welding wire 300 significantly reduces the size of the molten droplet, reduces the heat input of arc welding, and the smaller molten droplets are dispersed and fall into the molten pool, destroying the distribution state of the surface tension of the molten pool, thereby further curbing the Marangoni flow and avoiding the occurrence of finger-shaped molten pools. In addition, the smaller and more dispersed molten droplets formed during the vibration of the arc welding wire 300 not only improve the problem of difficult transition of titanium alloy molten droplets, but also promotes the uniform distribution of elements in the molten pool, significantly reducing the phenomenon of component segregation in the weld, and improving the corrosion resistance and fatigue life of the joint.

[0030] Furthermore, the laser emitted by the laser welding gun is a flat-top laser.

[0031] The flat-top laser has a uniform light intensity distribution, avoiding the problem of local overheating caused by the excessive central energy of the traditional Gaussian laser, making the weld depth and width more consistent. Its sharp edge helps to reduce the width of the heat-affected zone, thereby solving the uneven performance of the upper and lower thick plate welding joints. Combined with the corresponding motion trajectory and the vibration of the substrate and arc welding wire 300, the Marangoni flow behavior of the metal inside the molten pool is effectively regulated, so that the uniformity of the weld reaches an extremely high level, and the residual stress in the weld is greatly reduced, which significantly improves the overall quality of the weld.

[0032] Furthermore, the vibration frequency and amplitude of the substrate to be welded in step S3 cooperate with the trajectory and power of the laser according to the following preset logic:

[0033] The frequency, amplitude and laser power of the ultrasonic vibration of the substrate to be welded are periodically adjusted according to the operating law of the laser oscillation. When the laser swings forward to the front end of the ∞-shaped track, the frequency and amplitude of the ultrasonic vibration are reduced and the laser power is increased; when the laser swings backward to the middle of the ∞-shaped track and the laser swings to a position close to the rear end of the ∞-shaped track, the frequency and amplitude of the ultrasonic vibration are increased and the laser power is reduced.

[0034] Through the above settings, when the laser is close to the front end of the ∞-shaped track, increasing the laser power can ensure the melting of the metal of the substrate 400 to be welded at the front end of the molten pool, and the lower vibration frequency and amplitude can prevent the splashing of the molten metal generated at the laser action point, thereby ensuring the quality of the welded joint; when the laser is close to the middle and rear ends of the ∞-shaped track, lowering the laser frequency and increasing the vibration frequency and amplitude can reduce the temperature gradient at the front end of the molten pool solidification, reduce the risk of finger-like melting depth caused by Marangoni flow behavior, and break the columnar crystals to achieve the effect of grain refinement.

[0035] Further, in step S5, the first preset time is 0.5 to 2 seconds, and the second preset time is 10 to 15 seconds.

[0036] Through the above-mentioned arrangement, the molten droplets at the top of the arc welding wire 300 can fall into the molten pool evenly and dispersedly, and the molten pool keeps vibrating, so as to release the thermal stress of the molten pool and discharge impurities such as pores, thereby avoiding the formation of coarse dendrites at the end of the weld, thereby ensuring the quality of the weld joint and thus ensuring the mechanical properties of the weld joint.

[0037] Compared with the prior art, the titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling described in the present invention has the following advantages:

[0038] 1. The present invention uses arc, laser, and ultrasonic multi-energy field coupling welding settings to eliminate pores and defects in the weld while adjusting the Marangoni flow behavior in the weld to avoid the formation of finger-shaped penetration. It also eliminates coarse dendrites in traditional arc laser composite welding joints, significantly improving the mechanical properties of the welded joints;

[0039] 2. Through laser oscillation, arc welding wire vibration, and substrate vibration during welding, the heat input of the weld is significantly reduced, the droplet transition is improved, the residual stress and welding deformation are reduced, the uniformity of the weld metal is improved, the local segregation is improved, and the mechanical properties of the weld joint are improved;

[0040] 3. Through the swing of the laser preset trajectory, the Marangoni flow behavior of the molten pool is improved, the molten pool is guided, and the good formation of the weld is achieved;

[0041] 4. Through the use of flat-top laser and the setting of its swing trajectory, the Marangoni flow behavior inside the molten pool is effectively improved, the formation of finger-shaped melting depth in the transmission arc laser hybrid welding method is avoided, and the problem of uneven performance of thick plate welding joints is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A schematic diagram of the welding state of the titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling according to an embodiment of the present invention;

[0043] Figure 2 Schematic diagram of the metallographic structure of the TC4 titanium alloy welded joint obtained by the conventional arc-laser welding method;

[0044] Figure 3 Another schematic diagram of the metallographic structure of the TC4 titanium alloy welded joint obtained by the conventional arc-laser welding method;

[0045] Figure 4 A schematic diagram of the metallographic structure of a TC4 titanium alloy welded joint obtained by the titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling according to an embodiment of the present invention;

[0046] Figure 5 Another schematic diagram of the metallographic structure of a TC4 titanium alloy welded joint obtained by the titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling as described in an embodiment of the present invention.

[0047] Description of reference numerals:

[0048] 100. Laser welding gun; 200. Arc welding gun; 300. Arc welding wire; 400. Base plate to be welded. DETAILED DESCRIPTION

[0049] To make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0050] A titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] This embodiment provides a titanium alloy welding method using arc, laser, and ultrasonic multi-energy field coupling. Figure 1 As shown, the welding device used in the welding method includes an arc-laser hybrid welding device and two or more ultrasonic vibration devices, the two or more ultrasonic vibration devices at least include a substrate vibration device and a welding wire vibration device, the substrate vibration device is used to vibrate the substrate 400 to be welded during the welding process, and the welding wire vibration device is used to vibrate the arc welding wire 300; the welding method includes:

[0053] Step S1: Preparation before welding: Process the surface of the substrate 400 to be welded to meet the welding requirements, and assemble and fix the substrate 400 to be welded according to the welding process requirements;

[0054] Step S2: starting the arc-laser hybrid welding device to perform welding, wherein the laser oscillates and welds along a preset trajectory;

[0055] Step S3: The ultrasonic vibration device is started synchronously with the arc-laser hybrid welding device to vibrate the substrate 400 to be welded and the arc welding wire 300 in the welding process, respectively, wherein the substrate 400 to be welded vibrates back and forth in the length direction of the weld, and the arc welding wire 300 vibrates back and forth in the wire feeding direction, and the vibration frequency and amplitude of the substrate 400 to be welded are coordinated with the laser travel trajectory and laser power according to a preset logic;

[0056] Step S4: After welding is completed, the arc-laser hybrid welding device is turned off;

[0057] Step S5: After the arc-laser hybrid welding device is turned off for a first preset time, the welding wire vibration device is turned off, and after the second preset time, the substrate vibration device is turned off.

[0058] The study found that the finger-shaped molten pool formed by traditional arc-laser hybrid welding is mainly caused by the Marangoni flow behavior of the metal solution inside the molten pool. The Marangoni flow behavior refers to the presence of a large surface tension gradient in the molten pool during welding, which results in an additional pressure difference in the molten pool pointing to the area with higher surface tension. This pressure difference drives the solution in the molten pool to flow along the surface tension gradient in an attempt to eliminate the tension difference, thereby forming a Marangoni flow. This flow is usually unstable. In addition, the high viscosity of titanium alloys and the difficulty of droplet transition make the high energy density heat input of the laser and the heat input of the arc superimposed during arc and laser welding, which easily produces coarse grain defects, making the metallurgy, solidification, and phase change of the welding process more complicated. The finger-shaped molten pool formed by the Marangoni flow will also lead to performance degradation, seriously affecting the performance of titanium alloy welded joints. In the present application, through the swing welding of the laser and the vibration of the substrate 400 to be welded and the arc welding wire 300, the Marangoni flow behavior in the welding process can be effectively eliminated, thereby eliminating the finger-shaped penetration. In addition, the high-frequency vibration of the arc welding wire 300 can make the molten droplet at the end of the arc welding wire 300 separate from the arc welding wire 300 and enter the molten pool under low heat input, improve the molten droplet transition efficiency during arc welding, reduce the molten droplet size, reduce spatter, reduce heat input, improve weld formation, and cooperate with the ultrasonic vibration of the substrate to promote the escape of gas in the molten pool, realize the control of internal defects of the titanium alloy, and can also significantly refine the columnar crystal structure formed in the traditional arc-laser composite welding joint, thereby significantly improving the impact toughness of the welded joint. The welding structure obtained by the welding method provided in this embodiment has a dense internal structure, few defects, refined grains, and good joint morphology, and has good application prospects in the efficient construction of large structures such as ships. Optionally, the substrate vibration device is arranged between the workbench and the substrate 400 to be welded, so as to realize the overall vibration of the substrate 400 to be welded during the welding forming process.

[0059] As an embodiment of the present invention, step S1 includes:

[0060] Step S11: mechanically polishing the surface of the substrate 400 to be welded, using acetone and alcohol solvents in combination with ultrasonic cleaning to remove oil stains, and placing it to dry for later use;

[0061] Step S12: Place the cleaned and dried substrate 400 to be welded on a workbench and fix it with a clamp.

[0062] The above arrangement ensures the cleanliness of the surface of the substrate 400 to be welded, prevents the oil therein from contaminating the molten pool during welding, and ensures the quality of the joint during welding.

[0063] The preset trajectory in step S2 is an ∞-shaped trajectory.

[0064] By setting the above-mentioned running track, the laser is periodically oscillated during the welding process, which is convenient for melting the metal at the front end of the molten pool on the one hand, and guides the molten pool on the other hand, adjusts the temperature field of the molten pool, improves the fluidity of the molten pool, promotes the escape of pores inside the molten pool, reduces the temperature gradient in the length direction of the molten pool, promotes the spreading of molten metal and the wetting of the side wall, and achieves good forming of the weld. It can also improve the fluidity of the molten pool, improve the surface tension gradient of the molten pool, improve the Marangoni flow behavior of the liquid metal inside the molten pool, promote the escape of pores inside the molten pool, avoid the occurrence of unfused and internal pores, and cooperate with the effect of ultrasonic vibration to effectively break the coarse dendrites in the molten pool, refine the weld grains, and significantly improve the impact toughness of the welded joint. Among them, the specific parameters of the ∞-shaped track need to be set according to the specific conditions such as the size of the substrate to be welded, and are no longer limited here.

[0065] In this embodiment, step S2 includes:

[0066] Step S21: starting the protective gas delivery device to protect the welding area;

[0067] Step S22: Start the arc welding gun 200 and the laser welding gun 100, and perform welding in a protective gas atmosphere, with the laser in front and the arc in the back during welding.

[0068] Optionally, the protective gas is argon.

[0069] Argon does not easily react chemically with titanium alloy during welding, and can provide good protection for the weld, preventing oxidation and impurity intrusion in the weld, thereby ensuring weld quality. It should be noted that a corresponding gas shield is provided on the upper side of the substrate to be welded, and the gas shield is used to limit the flow of shielding gas, thereby ensuring a pure argon atmosphere during welding.

[0070] As one embodiment, during welding, the angle between the laser and the advancing direction of the weld is between 75° and 85°, and the angle between the arc welding wire 300 and the advancing direction of the weld is between 100° and 110°.

[0071] By setting the laser angle, the laser energy can act more concentratedly on the weld, reducing reflection losses, increasing the penetration width, and reducing the thermal impact on the surrounding substrate 400 to be welded, reducing the width of the heat-affected zone, thereby reducing the risk of deformation of the substrate to be welded and degradation of mechanical properties; by setting the angle of the arc welding wire 300, the molten droplet can be more stably transferred to the molten pool, reducing spatter and improving the quality of the weld; by coordinating the angles of the laser and the arc welding wire 300, the substrate to be welded and the arc welding wire 300 can optimize the energy distribution, improve the stability of the molten droplet transition, reduce welding defects, and improve the weld formation under the condition of ultrasonic vibration, thereby significantly improving the welding quality and efficiency.

[0072] In this embodiment, the power of the laser welding gun 100 is 7-14 kW, the frequency of the substrate vibration is 80-100 kHz, the amplitude is 12-20 μm, and the vibration frequency of the arc welding wire 300 is 60-80 kHz, the amplitude is 15-18 μm. In this embodiment, the high energy density provided by the higher laser power can achieve deep penetration, while the ultrasonic vibration helps to break up and discharge the gas and inclusions in the molten pool. The combination of the two can significantly improve the purity and penetration of the weld. In addition, the substrate 400 to be welded and the arc welding wire 300, through the setting of the above-mentioned vibration parameters, unexpectedly promote the dynamic release of thermal stress during welding, achieve self-balance of thermal stress, reduce welding residual stress, and reduce welding deformation. In addition, the vibration of the arc welding wire 300 significantly reduces the size of the molten droplet, reduces the heat input of the arc welding, and the smaller molten droplets are dispersed and fall into the molten pool, destroying the distribution state of the surface tension of the molten pool, thereby further curbing the Marangoni flow and avoiding the appearance of a finger-shaped molten pool. In addition, the smaller and dispersed molten droplets formed during the vibration of the arc welding wire 300 not only improve the problem of difficult transition of titanium alloy molten droplets, but also promote the uniform distribution of elements in the molten pool, significantly reducing the phenomenon of component segregation in the weld, and improving the corrosion resistance and fatigue life of the joint. It should be noted that appropriate process parameters such as current, voltage, defocusing amount, etc. can also be set according to the size and joint form of the substrate 400 to be welded, which will not be elaborated here.

[0073] Preferably, the laser emitted by the laser welding gun 100 is a flat-top laser. The flat-top laser has a uniform light intensity distribution, which avoids the local overheating problem caused by the excessive central energy of the traditional Gaussian laser, making the weld depth and weld width more consistent, and its sharp edge helps to reduce the width of the heat-affected zone, thereby solving the unevenness of the upper and lower performance of the thick plate welding joint. Combined with the corresponding motion trajectory and the vibration of the substrate and the arc welding wire 300, the Marangoni flow behavior of the metal inside the molten pool is effectively regulated, so that the uniformity of the weld reaches an extremely high level, and the residual stress in the weld is greatly reduced, which significantly improves the overall quality of the weld.

[0074] The vibration frequency and amplitude of the substrate 400 to be welded in step S3 cooperate with the trajectory and power of the laser according to the following preset logic:

[0075] The frequency, amplitude and laser power of the ultrasonic vibration of the substrate 400 to be welded are periodically adjusted according to the operating law of the laser oscillation. When the laser swings forward to near the front end of the ∞-shaped trajectory, the frequency and amplitude of the ultrasonic vibration are reduced and the laser power is increased; when the laser swings backward to near the middle of the ∞-shaped trajectory and the laser swings to a position near the rear end of the ∞-shaped trajectory, the frequency and amplitude of the ultrasonic vibration are increased and the laser power is reduced.

[0076] It should be noted that the front end of the ∞-shaped trajectory refers to the end of the ∞-shaped trajectory close to the welding forward direction. It can be seen that the ∞-shaped trajectory refers to the end of the ∞-shaped trajectory away from the welding forward direction. Through the above settings, when the laser is close to the front end of the ∞-shaped trajectory, increasing the laser power can ensure the melting of the metal of the substrate 400 to be welded at the front end of the molten pool, and the lower vibration frequency and amplitude can prevent the splash of molten metal generated at the laser action point, thereby ensuring the quality of the welded joint; when the laser is close to the middle and rear end of the ∞-shaped trajectory, reducing the laser frequency and increasing the vibration frequency and amplitude can reduce the temperature gradient at the front end of the molten pool solidification, reduce the risk of finger-shaped melting depth caused by Marangoni flow behavior, and break the columnar crystals to achieve the effect of grain refinement, thereby Figure 2 and Figure 3 It can be seen that there is an obvious finger-shaped penetration in the joint of the conventional arc-laser hybrid welding of titanium alloy, which seriously affects the mechanical properties of the connection between the weld and the substrate 400 to be welded. From the joint photos and metallographic photos, it can be seen that there are a large number of coarse columnar crystals in the welded joint, and its metallographic structure is martensite and β transformation structure. Figure 4 and Figure 5 It can be seen that in the weld joint obtained by the titanium alloy welding method coupled with arc, laser and ultrasonic multi-energy fields provided in this embodiment, the weld and the substrate 400 to be welded have a natural transition, there is no finger-like penetration, and the mechanical properties of the weld joint are significantly improved. It can be seen from the joint photos and the process photos that there are no coarse columnar crystals in the weld joint, and its metallographic structure is mainly α lamellar structure and transformed β structure, which significantly improves the degree of grain refinement in the weld joint and improves the mechanical properties of the weld joint.

[0077] As an optional embodiment, in step S5, the first preset time is 0.5 to 2 seconds, and the second preset time is 10 to 15 seconds. Through the above settings, the molten droplets at the top of the arc welding wire 300 can fall into the molten pool evenly and dispersedly, and the molten pool keeps vibrating, keeps the thermal stress of the molten pool released, and discharges impurities such as pores, avoids the formation of thick dendrites at the end of the weld, thereby ensuring the quality of the weld joint, thereby ensuring the mechanical properties of the weld joint.

[0078] The arc, laser, and ultrasonic multi-energy coupling welding method provided in this embodiment is a welding method performed by organically combining arc, laser, and ultrasound, which gives full play to their respective advantages in the welding process. Without increasing heat input, it can not only effectively reduce defects such as unfusion and porosity inside the weld joint, but also effectively refine the grains, avoid the "finger-like" penetration depth of traditional arc-laser composite welding, and improve joint performance.

[0079] The metal welding joints prepared by the multi-energy field coupling method can obtain high-quality welding joints by adjusting process parameters and selecting reasonable welding methods during the welding process of different metal materials.

[0080] Example 2

[0081] In this embodiment, TC4 titanium alloy is used as the substrate to be welded, and the arc welding wire specification used for arc welding is φ1.2 mm. The TC4 titanium alloy substrate includes the following chemical components by mass fraction: 5.5-6.5% Al, 2.5-3.5% Nb, 1.5-2.5% Zr, 0.6-1.5% Mo, 0.25% Fe, 0.15% Si, 0.10% C, 0.05% N, 0.015% H, 0.15% O, and the remainder is Ti.

[0082] The surface of the TC4 titanium alloy substrate is mechanically polished, ultrasonically cleaned with acetone and alcohol solvent to remove oil stains, dried and set aside, and then the cleaned substrate to be welded is measured and placed on the workbench, fixed with a clamp and set aside; the welding process parameters are set according to the size of the test plate, and argon gas is used for protection during the welding process to ensure that the surface of the welded joint is silver-white; the arc, laser, and ultrasonic multi-energy field coupling welding process provided in Example 1 is used for welding. The joint structure is analyzed using a metallographic microscope. The comparison results of the welded joint obtained by the welding method provided in Example 1 and the welded joint obtained by traditional arc-laser composite welding are shown as follows: Figure 2-Figure 5 shown.

[0083] like Figure 2 , Figure 3 As shown in the figure, the titanium alloy joint of the conventional arc-laser hybrid welding shows a "finger-like" penetration depth, with a large number of columnar crystal structures perpendicular to the length of the weld. Figure 4 , Figure 5 The metallographic structure of the TC4 titanium alloy welded joint obtained by the arc, laser, and ultrasonic multi-energy coupling welding method provided in Example 1. By comparison, it is found that the multi-energy coupling welding structure can effectively refine the grains and effectively avoid the "finger-like" penetration. The length and number of columnar crystals in the weld are compared with Figure 2 , Figure 3 The microstructure is significantly reduced, the structure is finer and more uniform, and there are no defects such as pores. The metallographic structure is mainly α-lamellar structure and transformed β-structure, which significantly improves the mechanical properties of the welded joint.

[0084] The mechanical properties of the welded joint obtained by welding TC4 titanium alloy by conventional arc-laser welding and the welding method provided in Example 1 and the TC4 titanium alloy base material are compared in Table 1.

[0085] Table 1 Mechanical properties of TC4 titanium alloy joints under different welding methods

[0086]

[0087] It can be seen from Table 1 that the strength, i.e., impact toughness, of the TC4 welded joint obtained by conventional arc-laser hybrid welding is lower than that of the base material. The strength of the TC4 titanium alloy welded joint obtained by the arc, laser, and ultrasonic multi-energy coupling welding method provided in Example 1 is equivalent to that of the base material, and the impact toughness is slightly higher than that of the base material. It can be seen that the welding method provided in this embodiment can improve the strength and impact toughness of the welded joint compared with the conventional arc-laser welding method, especially the impact toughness is greatly improved, so that the strength and impact toughness can match the base material, thereby ensuring the quality of the welded joint and enabling it to meet the use requirements.

[0088] It should be noted that all the terms used in the present invention for directional and positional indications, such as: "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "tail end", "head end", "center", etc., are only used to explain the relative position relationship, connection status, etc. between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which both A and B are satisfied.

[0089] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0090] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A titanium alloy welding method using arc, laser and ultrasonic multi-energy field coupling, characterized in that: The welding device used in the welding method includes an arc-laser hybrid welding device and two or more ultrasonic vibration devices, the two or more ultrasonic vibration devices at least include a substrate vibration device and a welding wire vibration device, the substrate vibration device is used to vibrate the substrate to be welded during the welding process, and the welding wire vibration device is used to vibrate the arc welding wire; the welding method includes: Step S1: Preparation before welding: Process the surface of the substrate to be welded to make it meet the welding requirements, and assemble and fix the substrate to be welded according to the welding process requirements; Step S2: starting the arc-laser hybrid welding device to perform welding, wherein the laser oscillates and welds along a preset trajectory, and the preset trajectory is an ∞-shaped trajectory; Step S3: Synchronously start the ultrasonic vibration device with the arc-laser hybrid welding device to vibrate the substrate to be welded and the arc welding wire in the welding process, respectively, wherein the substrate to be welded reciprocates in the length direction of the weld, and the arc welding wire reciprocates in the wire feeding direction, and the vibration frequency and amplitude of the substrate to be welded cooperate with the laser travel trajectory and laser power according to the following preset logic: periodically adjust the frequency, amplitude and laser power of the ultrasonic vibration of the substrate to be welded according to the operating law of the laser swing, when the laser swings forward to the front end of the ∞-shaped trajectory, reduce the frequency and amplitude of the ultrasonic vibration, and increase the laser power; when the laser swings backward to the middle of the ∞-shaped trajectory and the laser swings to a position close to the rear end of the ∞-shaped trajectory, increase the frequency and amplitude of the ultrasonic vibration, and reduce the laser power; through the swing welding of the laser and the vibration of the substrate to be welded and the arc welding wire, the Marangoni flow behavior in the welding process can be effectively eliminated, thereby eliminating the finger-shaped penetration; Step S4: After welding is completed, the arc-laser hybrid welding device is turned off; Step S5: After the arc-laser hybrid welding device is turned off for a first preset time, the welding wire vibration device is turned off, and after the second preset time, the substrate vibration device is turned off.

2. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 1 is characterized in that: Step S1 includes: Step S11: mechanically polishing the surface of the substrate to be welded, using acetone and alcohol solvents in combination with ultrasonic cleaning to remove oil stains, and placing it to dry for later use; Step S12: Place the cleaned and dried substrate to be welded on a workbench and fix it with a clamp.

3. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 1 is characterized in that: Step S2 includes: Step S21: starting the protective gas delivery device to protect the welding area; Step S22: Start the arc welding gun and the laser welding gun, and perform welding in a protective gas atmosphere, with the laser in front and the arc in the back during welding.

4. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 1, characterized in that: During welding, the angle between the laser and the advancing direction of the weld is 75°~85°, and the angle between the arc welding wire and the advancing direction of the weld is 100°~110°.

5. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 3, characterized in that: The power of the laser welding gun is 7-14 kW, the frequency of substrate vibration is 80-100 kHz, and the amplitude is 12-20 μm.

6. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 1, characterized in that: The vibration frequency of the arc welding wire is 60-80kHz, and the amplitude is 15-18μm.

7. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 3 is characterized in that: The laser emitted by the laser welding gun is a flat-top laser.

8. The titanium alloy welding method of arc, laser and ultrasonic multi-energy field coupling as claimed in claim 1, characterized in that: In step S5, the first preset time is 0.5 to 2 seconds, and the second preset time is 10 to 15 seconds.

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