A laser-MIG arc composite filler wire welding method for high-strength aluminum alloys

Abstract

This invention relates to the field of welding technology, specifically to a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys. The method includes the following steps: adjusting the welding posture so that the laser beam, a first welding wire, and a second welding wire all act on the same molten pool, wherein the first welding wire achieves droplet transfer under the action of MIG arc welding, and the second welding wire achieves droplet transfer under the radiation heating of the laser beam and the induction heating of the heating device; determining the weld width on both sides of the laser-MIG arc composite welding joint without the second welding wire; determining the wire feeding speed of the second welding wire based on the weld width on both sides of the weld joint; and performing laser-MIG arc composite filler wire welding on the high-strength aluminum alloy according to the wire feeding speed of the second welding wire and the laser-MIG arc composite welding parameters without the second welding wire. The purpose of this laser-MIG arc composite filler wire welding method for high-strength aluminum alloys is to solve the problem of easy cracking during the fusion welding process of high-strength aluminum alloys.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and specifically to a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys. Background Technology

[0002] Laser welding boasts advantages such as low heat input, high welding speed, minimal thermal damage to materials, ease of flexible operation when combined with robotic arms, and the ability to weld in atmospheric environments, leading to its increasing applications in aerospace, transportation, and other fields. However, the high precision required for pre-welding assembly and the inability to precisely adjust the chemical composition of the weld joint limit its further application to some extent.

[0003] By adding welding wire or electric arc during the laser welding process, i.e., using laser filler wire welding or laser-arc hybrid welding, the limitations of high assembly precision before self-fusion laser welding can be overcome, and the chemical composition of the welded joint can be appropriately adjusted by using filler wire. Therefore, it has gained increasingly wider application.

[0004] In laser-arc hybrid welding, simultaneously adding filler wire is an effective method to improve deposition efficiency. Patent applications 202211556587.5 and 202211557459.2 propose using double wires in laser and single or two TIG arc hybrid welding processes to solve the problem of sidewall fusion in narrow gap welding and improve deposition efficiency. Patent application 201811243168.X proposes accelerating molten pool stirring through laser beam scanning in laser-hot wire MIG hybrid welding, thereby improving the concave back side of the weld to a full state. Patent application 202110448624.X proposes an empirical formula for laser-TIG arc hybrid hot welding process and wire feed speed.

[0005] High-strength aluminum alloys are prone to cracking during the fusion welding process. Although conventional methods such as filler wire or adding an electric arc can have a certain restraining effect on cracking, the improvement effect is not ideal.

[0006] For the fusion welding of high-strength aluminum alloys, it is necessary to improve the weld formation or weld fullness by feeding wire, and also to control the crack sensitivity of the base material during melting and resolidation and improve the mechanical properties of the joint by controlling the composition of the welding wire, thereby expanding the engineering application of fusion welded structures of high-strength aluminum alloys.

[0007] Therefore, the inventors have provided a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys. Summary of the Invention

[0008] (1) Technical problems to be solved

[0009] This invention provides a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys, solving the technical problem that high-strength aluminum alloys are prone to cracking during the fusion welding process.

[0010] (2) Technical solution

[0011] This invention provides a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys, comprising the following steps:

[0012] The welding posture is adjusted so that the laser beam, the first welding wire, and the second welding wire act together on the same molten pool. The first welding wire achieves droplet transfer through jet transfer under the action of MIG arc welding, while the second welding wire achieves droplet transfer through short-circuit transfer under the radiation heating of the laser beam and the induction heating of the heating device.

[0013] Determine the weld width on both sides of the laser-MIG arc hybrid welding joint when the second filler wire is not used;

[0014] The wire feeding speed of the second welding wire is determined based on the weld width on both sides of the weld joint.

[0015] Based on the wire feeding speed of the second welding wire and the laser-MIG arc composite welding parameters when the second welding wire is not filled, laser-MIG arc composite filler wire welding is performed on high-strength aluminum alloy.

[0016] Furthermore, the laser beam is a scanning galvanometer laser beam with a circular scanning trajectory, a scanning amplitude of 0–1.5 mm, and a scanning frequency of 30–200 Hz.

[0017] Furthermore, the welding current of the MIG arc is 40–80 A.

[0018] Furthermore, the diameters of both the first and second welding wires range from 0.8 to 1.6 mm.

[0019] Furthermore, the focal spot diameter of the laser beam is 0.15–0.6 mm, and the angle between the laser beam and the normal of the welding surface is within the range of ±10°.

[0020] Furthermore, the angles between the first welding wire, the second welding wire, and the welding surface are all 30 to 60°.

[0021] Furthermore, the first welding wire is selected from welding wires with added reinforcing elements of a set content, wherein the reinforcing elements include at least one of Mg, Er, Zr and Sc.

[0022] Furthermore, the second welding wire is selected from welding wires with a high Si content.

[0023] Furthermore, the arc distance between the first welding wire and the laser beam is 2.0 to 5.0 mm.

[0024] Furthermore, the distance between the second welding wire and the laser beam filament is 0.25 to 0.75 times the diameter of the second welding wire.

[0025] (3) Beneficial effects

[0026] In summary, this invention, by combining the preset requirements for the reinforcement height on both sides of the weld joint cross-section, forms an empirical formula for the wire feeding speed of the second welding wire, facilitating the determination of the second welding wire feeding speed. Through the dual feeding of the first and second welding wires, a full weld formation is achieved. Simultaneously, the use of hot wire feeding at the front end of the molten pool, under the combined heat of the laser and arc, further promotes the melting of the second welding wire and the transfer of molten droplets to the molten pool. Under the stirring effect of the laser beam, alloying elements diffuse more rapidly within the molten pool, which not only facilitates the escape of porosity defects in the molten pool but also further inhibits the growth of columnar crystals and promotes the formation of equiaxed crystals, thus achieving better welding results. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of a laser-MIG arc composite filler wire welding structure provided in an embodiment of the present invention.

[0030] In the picture:

[0031] 1-Laser beam; 2-MIG welding torch; 3-First welding wire; 4-Second welding wire; 5-Inert gas shield; 6-MIG arc; 7-Heating device; 8-Heating power source; 9-Molten pool; 10-Weld metal; 11-Base material. Detailed Implementation

[0032] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments.

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0034] In the description of this invention, it should be understood that the terms "upper," "lower," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0035] Figure 1 This is a schematic flowchart of a laser-MIG arc composite filler wire welding method for high-strength aluminum alloys provided by an embodiment of the present invention. The method may include the following steps:

[0036] S100. Adjust the welding posture so that the laser beam, the first welding wire, and the second welding wire work together in the same molten pool. The first welding wire achieves droplet transfer through jet transfer under the action of MIG arc welding, while the second welding wire achieves droplet transfer through short-circuit transfer under the radiation heating of the laser beam and the induction heating of the heating device.

[0037] Specifically, the welding posture includes continuously feeding the second welding wire 4, heated by the heating device 7, to the front end of the molten pool 9 formed by the laser-MIG arc off-axis composite welding; the laser beam 1 is basically in a normal position to the welding plane, and the second welding wire 4 and the MIG welding torch 2 are positioned on the front and rear sides of the laser beam 1, respectively; the MIG welding torch 2 continuously feeds the first welding wire 3, such as... Figure 2 As shown, the central axis of the first welding wire 3, the laser beam 1, and the second welding wire 4 are in the same plane.

[0038] In this process, the laser beam 1, the melting electrode (first welding wire 3), and the continuously heated second welding wire 4 all act together on and around the same molten pool. The defocusing amount Δ between the focal point of the laser beam 1 and the welding surface is... f ±2mm, the focal spot diameter of the laser beam Ø L The laser beam 1 has a diameter of 0.15mm to 0.6mm, and the angle between the laser beam 1 and the normal to the welding surface ranges from ±10°. The angle between the first welding wire 3 and the second welding wire 4 and the welding surface is 30° to 60°. The preset arc distance between the first welding wire 3 and the laser beam 1 is D. LA The preset filament spacing between the second welding wire 4 and the laser beam 1 is D. LW The diameter of the first welding wire 3 is Ø1, and the diameter of the second welding wire 4 is Ø2. Ø1 and Ø2 may be equal or unequal, depending on actual needs, and both are within the range of 0.8mm to 1.6mm.

[0039] The heating device 7 and the wire feeding mechanism of the second welding wire 4 are both connected to the hot wire power supply 8 to provide a power source for the wire feeding mechanism and a heat source for the heating device 7. The heating device 7 is preferably a hot wire heating device.

[0040] The arc distance D between the first welding wire 3 and the laser beam 1 LA The distance D between the second welding wire 4 and the laser beam 1 is 2.0–5.0 mm. LW It is 0.25 to 0.75 times the diameter of the second welding wire Ø2. (The last part, "Ø," appears to be incomplete and possibly refers to a different component or part.) L The increase of D LW The corresponding increase.

[0041] S200. Determine the weld width on both sides of the laser-MIG arc hybrid welding joint when the second filler wire is not used.

[0042] Specifically, laser-MIG arc hybrid welding without the second welding wire 4 can be performed using either flat plate surfacing or butt welding. A corresponding relationship is established between each set of welding process parameters and the front weld width (FW) and back weld width (BW) of the laser-MIG arc hybrid weld obtained without the second welding wire 4. The weld formation should be free of leaks and uneven weld width; weld collapse is permissible.

[0043] S300. Determine the wire feeding speed of the second welding wire based on the weld width on both sides of the weld joint.

[0044] Specifically, except for the wire feeding speed of the second welding wire 4 v 2. Except for the hot wire temperature, other welding parameters are the same as in step S100, and the wire feeding speed of the second welding wire 4 is... v 2. Determine according to formula (1):

[0045] (1)

[0046] In the formula, FW is the front weld width of the laser-MIG arc hybrid welded joint without the second welding wire 4, and BW is the back weld width of the laser-MIG arc hybrid welded joint without the second welding wire 4; △h1 is the preset front reinforcement height of the welded joint, which is 0.5mm to 2.0mm; △h2 is the preset back reinforcement height of the welded joint, which is 0.5mm to 2.5mm. v w For welding speed, v 1 represents the wire feeding speed of the first welding wire 3. v 2 is the wire feeding speed of the second welding wire 4; Ø1 is the diameter of the first welding wire 3, and Ø2 is the diameter of the second welding wire 4.

[0047] S400. Based on the wire feeding speed of the second welding wire and the laser-MIG arc composite welding parameters when the second welding wire is not filled, laser-MIG arc composite filler wire welding is performed on high-strength aluminum alloy.

[0048] Specifically, before welding, the workpieces to be welded need to be assembled. The specific requirements are as follows: the local assembly gap should not be greater than △x, and the value of △x is 30%·δ or 0.5mm (δ is the wall thickness of the base material to be welded; when welding dissimilar thicknesses, δ is the smaller base material wall thickness), and the smaller value should be taken; the assembly misalignment should not be greater than △y, and the value of △y is 20%·δ or 0.3mm, and the smaller value should be taken.

[0049] Based on the weld width requirements on both sides of the weld joint, set the welding speed, laser power, MIG welding current, and wire feed speed of the second welding wire 4. v 2. Arc spacing D LA and filament spacing D LW wait.

[0050] Heating device 7 employs a high-frequency induction heating principle, eliminating interference from bypass current magnetic fields and thus preventing magnetic blow. This makes it more suitable for heating low-resistivity welding wires and allows for precise temperature control. Under the radiative heating of laser beam 1 and the high-frequency induction heating of heating device 7, the second welding wire 4 achieves droplet transfer via a short-circuit transfer method. Under the action of pulsed MIG arc welding, the first welding wire 3 achieves droplet transfer via a jet transfer method.

[0051] In some optional embodiments, the laser beam 1 is a scanning galvanometer laser beam with a circular scanning trajectory, a scanning amplitude of 0–1.5 mm, and a scanning frequency of 30–200 Hz. It should be noted that the laser beam 1 includes both conventional laser beams and scanning galvanometer laser beams. The scanning galvanometer laser beam can accelerate the flow of the molten pool, which is more conducive to the melting of the second welding wire 4, the transfer of molten droplets to the molten pool, the diffusion of alloying elements within the molten pool, and the escape of porosity defects in the molten pool, thus achieving better welding results.

[0052] In some optional implementations, the welding current of the MIG arc is 40–80 A. For the MIG arc, while ensuring the energy coupling of the composite welding (i.e., normal composite arc operation and good weld formation), the welding current is selected as low as possible, within the range of 40 A–80 A. When the welding current is 40 A–80 A, the Ø1 of the first welding wire 3 is 1.2 mm. Under the integrated adjustment of the aluminum welding machine, the corresponding wire feeding speed of the first welding wire 3 is… v 1 is 2.6m / min to 4.8m / min. More preferably, the welding current is selected within the range of 40A to 60A, corresponding to the wire feeding speed of the first welding wire 3. v 1 is 2.6m / min~3.6m / min.

[0053] In some optional embodiments, the first welding wire is selected from welding wires with added reinforcing elements of a predetermined content, including at least one of Mg, Er, Zr, and Sc. Specifically, the first welding wire 3 is preferably an ER5356 welding wire rich in Mg, or an ER5356 welding wire with added content of other reinforcing elements; the reinforcing elements include, but are not limited to, Er, Zr, and Sc; when Er is added, the mass percentage of Er ranges from 0.10% to 0.30%; when Zr is added, the mass percentage of Zr ranges from 0.15% to 0.30%; when Sc is added, the mass percentage of Sc ranges from 0.10% to 0.20%. When the first welding wire 3 has added reinforcing elements, it transitions into the liquid molten pool, which leads to a relatively increased probability of heterogeneous nucleation in the molten pool, which can further refine the grains and improve the strength of the weld joint, and to a certain extent suppress welding cracks.

[0054] In some alternative embodiments, the second welding wire is selected from those rich in Si. Specifically, the second welding wire 4 is preferably selected from ER4043 or ER4047 welding wires rich in Si. By introducing a higher Si content into the liquid molten pool, the fluidity of the molten pool 9 is increased, thereby suppressing welding cracks.

[0055] The different functions of the first and second welding wires are proposed. The first welding wire, by adding Mg-rich elements or other strengthening elements, transitions into the liquid molten pool, further increasing the compositional supercooling and heterogeneous nucleation probability of the molten pool 9, thereby further refining the grains and improving the strength of the welded joint, and suppressing welding cracks to a certain extent. The second welding wire, by adding Si-rich elements, transitions into the liquid molten pool, increasing the fluidity of the liquid molten pool, thereby suppressing welding cracks.

[0056] Example 1

[0057] Taking 3mm thick 7050 high-strength aluminum alloy as an example, its laser-MIG arc composite filler wire welding method includes the following steps:

[0058] S100: Adjust or confirm the welding posture and laser-MIG arc hybrid welding parameters. Specifically, a fiber laser is selected as the laser source, and the defocusing distance Δ between the laser beam 1 and the welding surface is set. f The focal spot diameter of the laser beam is Ø, which is 0mm. L The laser beam is 0.28 mm thick, and the angle between the laser beam 1 and the normal to the welding surface is within the range of 8°. The angles between the first welding wire 3 and the second welding wire 4 and the welding surface are both 45°. The preset arc distance D between the first welding wire 3 and the laser beam 1 is... LA Select 4.0m, and set the preset filament spacing D between the second welding wire 4 and the laser beam 1. LWThe diameter is selected as 0.50·Ø2, which is 0.6mm. The diameter Ø1 of the first welding wire 3 and the diameter Ø2 of the second welding wire 4 are equal and both are selected as 1.2mm. The laser beam 1 adopts a scanning galvanometer laser beam, with a circular scanning trajectory, a scanning amplitude of 0.5mm, and a scanning frequency of 50Hz. On the basis of ensuring the energy coupling of the composite welding (i.e., normal composite arc and good weld formation), the welding current is selected as low as possible. Under this welding condition, the MIG welding current is selected as 50A. Under the integrated adjustment of the aluminum welding machine, the corresponding wire feeding speed of the first welding wire 3 is... v 1 is 3.2 m / min. The wire feeding speed of the second welding wire 4 is... v 2 is 0 m / min, meaning the second welding wire 4 is not used yet. The first welding wire 3 is an ER5356 welding wire with a high Mg content. Welding speed v w Select 1.5m / min and 3000W laser power.

[0059] S200: Establish the correlation between the laser-MIG arc hybrid welding process parameters and the weld width on both sides of the weld joint when the second welding wire 4 is not filled. That is, under the welding process parameters selected in step S100, obtain the front weld width FW and back weld width BW of the laser-MIG arc hybrid weld when the second welding wire 4 is not filled. The weld formation should be free of weld leaks and uneven weld width, and weld collapse is permissible. Wherein, FW = 4.6mm, BW = 3.6mm.

[0060] S300: Assemble the workpieces to be welded. Ensure that the local assembly gap is no greater than △x, where △x is 0.5mm; and that the assembly misalignment is no greater than △y, where △y is 0.3mm.

[0061] S400: Set welding process parameters. The second welding wire 4 is an ER4043 welding wire with a high Si content. Except for the wire feed speed of the second welding wire 4... v 2. Except for the hot wire temperature, other welding parameters are the same as in step S100. The preset front reinforcement height Δh1 of the weld joint is 1.0 mm, and the preset back reinforcement height Δh2 of the weld joint is 1.5 mm. The wire feeding speed of the second welding wire 4 is calculated using formula (1). v 2 is set to 3.4 m / min. The preheating temperature of the second welding wire 4 is adjusted to 500℃ by high-frequency induction heating of the hot wire heating device 7.

[0062] S500: Welding is performed. Based on the set welding process parameters, high-strength aluminum alloy laser-MIG arc composite filler wire welding is performed under inert gas protection. Under the radiant heating of the laser beam 1 and the high-frequency induction heating of the hot wire heating device 7, the second welding wire 4 achieves droplet transfer via a short-circuit transfer method. Under the action of pulsed MIG arc welding, the first welding wire 3 achieves droplet transfer via a jet transfer method. Furthermore, by using a hot wire feed at the front end of the molten pool, the heating effect of the laser beam, especially the scanning galvanometer laser beam, is more conducive to the melting of the second welding wire 4 and the transfer of droplets to the molten pool, the diffusion of alloying elements in the molten pool, and the escape of porosity defects in the molten pool, thus achieving better welding results.

[0063] S600: Quality Inspection. X-ray inspection of welded joints.

[0064] The geometric dimensions of the welded joint cross-section were measured and found to be largely as expected. The welded joint exhibited good shape and a full weld, with defects such as porosity and cracks well controlled. In the as-welded state, the tensile strength of the welded joint reached over 70% of that of the base material. To further improve the mechanical properties of the welded joint, a solution-aging heat treatment process can be used. After heat treatment, the tensile strength of the welded joint can reach over 90% of that of the base material. In summary, the welding method of this invention is reasonable and feasible, and is particularly suitable for high-quality welding of 7XXX and 2XXX series high-strength aluminum alloys such as 7050 and 2024.

[0065] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0066] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A laser-MIG arc composite filler wire welding method for high-strength aluminum alloys, characterized in that, The method includes the following steps: The welding posture is adjusted so that the laser beam, the first welding wire, and the second welding wire act together on the same molten pool. The first welding wire achieves droplet transfer through jet transfer under the action of MIG arc welding, while the second welding wire achieves droplet transfer through short-circuit transfer under the radiation heating of the laser beam and the induction heating of the heating device. Determine the weld width on both sides of the laser-MIG arc hybrid welding joint when the second filler wire is not used; The wire feeding speed of the second welding wire is determined based on the weld width on both sides of the weld joint. Based on the wire feeding speed of the second welding wire and the laser-MIG arc composite welding parameters when the second welding wire is not filled, laser-MIG arc composite filler wire welding is performed on high-strength aluminum alloy.

2. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The laser beam is a scanning galvanometer laser beam with a circular scanning trajectory, a scanning amplitude of 0–1.5 mm, and a scanning frequency of 30–200 Hz.

3. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The welding current of the MIG arc is 40–80A.

4. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The diameters of both the first and second welding wires range from 0.8 to 1.6 mm.

5. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The focal spot diameter of the laser beam is 0.15–0.6 mm, and the angle between the laser beam and the normal of the welding surface is within the range of ±10°.

6. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The angles between the first welding wire, the second welding wire, and the welding surface are both 30° to 60°.

7. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The first welding wire is selected from welding wires with added reinforcing elements of a set content, the reinforcing elements including at least one of Mg, Er, Zr and Sc.

8. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The second welding wire is selected from those with a high Si content.

9. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The arc distance between the first welding wire and the laser beam is 2.0 to 5.0 mm.

10. The laser-MIG arc composite filler wire welding method for high-strength aluminum alloys according to claim 1, characterized in that, The distance between the second welding wire and the laser beam is 0.25 to 0.75 times the diameter of the second welding wire.

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