A method for laser-mig hybrid welding of 7000 series aluminum alloy assisted by electric and magnetic field coupling

Abstract

This invention discloses a laser-MIG composite welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling, belonging to the field of welding technology, including the following steps: (1) Pretreatment of welding samples: The surface of the 7000 series aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, and wiped clean with volatile organic solvent, and then placed in a drying equipment for drying; (2) The 7000 series aluminum alloy plates in step (1) are placed together and fixed by a pressure plate to form a structure to be welded; (3) A horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld are set at the structure to be welded; (4) The structure to be welded is welded using laser-MIG composite welding process. This invention utilizes multi-field coupling assistance of electric field and magnetic field to achieve slag removal and degassing of the high-temperature molten pool, while also having a stirring effect on the molten pool, which can effectively refine the grains, reduce the elemental segregation of 7000 series aluminum alloys, and obtain a high-strength welded joint.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular provides a laser-MIG composite welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling. Background Technology

[0002] 7000 series aluminum alloys are widely used in aerospace, rail transportation, and other industries due to their low density, high specific strength, and good corrosion resistance. However, due to the unique physicochemical properties of 7000 series aluminum alloys, such as high thermal conductivity, high coefficient of thermal expansion, easy formation of oxide film on the surface, large difference in hydrogen solubility between solid and liquid states, and easy formation of low-melting-point eutectic during welding, low-boiling-point elements Mg and Zn are easily lost, resulting in defects such as porosity and cracks, leading to poor weld surface quality and low joint strength.

[0003] Laser-MIG hybrid welding technology is a welding technology that combines two heat sources with different properties: laser and electric arc. It has the advantages of both laser and electric arc welding technologies. The laser has the effect of stabilizing the electric arc, while the addition of the electric arc can not only improve the absorption rate of the aluminum alloy to the laser, but also improve problems such as porosity and cracks caused by excessively fast laser welding speed.

[0004] Initially, electro / magnetic assisted welding technology was commonly used in metal casting processes, and its effectiveness has been proven. It primarily works by controlling the direction of electromagnetic force to influence the flow, heat transfer, and solidification of molten metal, thereby eliminating defects generated during casting. With the development of electro / magnetic assisted welding technology, researchers have applied it to welding. Studies have shown that the addition of electric / magnetic fields significantly affects the flow behavior of the weld pool and the movement of plasma, effectively reducing defects such as weld porosity and thus improving the quality of weld joints. For example, Chinese patent (CN103612019A) discloses a magnetically stirred CO2 laser-TIG arc hybrid welding method that effectively refines grains and improves joint performance; Chinese patent (CN103612019A) also discloses a laser filler wire welding device that uses an external electric and magnetic field to stir the weld pool, creating a strong convection stirring effect within the weld pool and ensuring uniform diffusion of elemental components.

[0005] This invention proposes a laser-MIG composite welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling. Through the synergistic effect of electric field, magnetic field, laser and electric arc, the surface forming quality of weld is improved, the porosity defects inside the weld are reduced, and the strength of the welded joint is increased. Summary of the Invention

[0006] To address the problems of poor weld surface formation quality, numerous internal porosity defects, and low joint strength in existing laser-arc hybrid welding of 7000 series aluminum alloys, this invention provides a laser-MIG hybrid welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling.

[0007] The specific solution adopted in this invention is: a laser-MIG hybrid welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling, the method comprising the following steps:

[0008] (1) Pretreatment of welding test specimens: The surface of the 7000 series aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, and wiped clean with volatile organic solvents, and then put into the drying equipment for drying.

[0009] (2) Place the 7000 series aluminum alloy plates from step (1) together and fix them with pressure plates to form a structure to be welded.

[0010] (3) A horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld are set at the structure to be welded;

[0011] (4) The structure to be welded is welded using a laser-MIG hybrid welding process. In laser-MIG hybrid welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity. Before welding begins, arc-starting plates are set at both ends of the workpiece weld. The material of the arc-starting plates is the same as that of the workpiece. The arc-starting plates and the weld are butt joints without bevels. At the start of welding, welding begins from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece.

[0012] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein, in step (1), the 7000 series aluminum alloys include 7075, 7005, 7050, 7475, etc.

[0013] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloy, wherein in step (1), the thickness of the 7000 series aluminum alloy is 1-6mm.

[0014] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloy, wherein in step (1), when the thickness of the 7000 series aluminum alloy is 1-3mm, no beveling is required; when the thickness is 4-6mm, a beveling is required, and the beveling shape includes "I" shape, "V" shape, and "Y" shape.

[0015] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein, in step (1), the volatile organic solvent includes ethanol and acetone.

[0016] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (1), the drying temperature is 60-80℃ and the drying time is 20-40min.

[0017] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (2), the butt gap is 0, that is, the two plates are completely butted together without leaving any gaps.

[0018] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (3), the horizontal magnetic field perpendicular to the weld is generated by the interaction of rubidium magnets uniformly distributed on both sides of the weld of the aluminum alloy to be welded.

[0019] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloy, wherein in step (3), the longitudinal electric field perpendicular to the weld is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded, and the upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0020] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (4), the laser beam deviates from the central axis by about 5-15° during the welding process, and the angle between the MIG welding gun and the surface of the aluminum alloy plate to be welded is 50-70°.

[0021] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (4), the welding wire used during welding is aluminum-magnesium welding wire, including ER5356, ER5083, and ER5556.

[0022] The electric field and magnetic field coupled assisted laser-MIG composite welding method for 7000 series aluminum alloys, wherein in step (4), during welding, a high-purity inert gas with a mass concentration of not less than 99.99% is used for protection, the front side blowing gas flow rate is 15-20 L / min, and the back protection gas flow rate is 10-15 L / min.

[0023] The advantages of this invention compared to the prior art include:

[0024] 1. This invention sets up electric and magnetic fields during the welding process, and utilizes the Lorentz magnetic force generated by the interaction between the electric / magnetic fields and the flowing conductive molten pool fluid to provide support for the back side of the weld, effectively suppressing the collapse of the weld surface of 7000 series aluminum alloys.

[0025] 2. This invention creates a strong convection stirring effect in the weld pool by setting electric and magnetic fields, which can effectively refine grains and make the various elements in the weld pool diffuse evenly; it also plays a certain role in reducing porosity and impurities, thereby effectively improving the strength of the weld joint. Attached Figure Description

[0026] Figure 1 A schematic diagram of laser-MIG hybrid welding assisted by electric and magnetic field coupling;

[0027] Figure 2 Macroscopic morphology of the weld provided in Example 2;

[0028] Figure 3 Macroscopic morphology of the weld provided for comparison. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0030] This invention provides a laser-MIG hybrid welding method for 7000 series aluminum alloys assisted by electric field and magnetic field coupling, the method comprising the following steps:

[0031] (1) Pretreatment of welding test specimens: The surface of the 7000 series aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, and wiped clean with volatile organic solvents, and then put into the drying equipment for drying.

[0032] (2) Place the 7000 series aluminum alloy plates from step (1) together and fix them with pressure plates to form a structure to be welded.

[0033] (3) A horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld are set at the structure to be welded;

[0034] (4) The structure to be welded is welded using a laser-MIG hybrid welding process. In laser-MIG hybrid welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity. Before welding begins, arc-starting plates are set at both ends of the workpiece weld. The material of the arc-starting plates is the same as that of the workpiece. The arc-starting plates and the weld are butt joints without bevels. At the start of welding, welding begins from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece.

[0035] In step (1), the 7000 series aluminum alloys include 7075, 7005, 7050, 7475, etc.

[0036] In step (1), the thickness of the 7000 series aluminum alloy is 1-6mm.

[0037] In step (1), when the thickness of the 7000 series aluminum alloy is 1-3mm, no beveling is required; when the thickness is 4-6mm, beveling is required, and the beveling shape includes "I", "V" and "Y".

[0038] In step (1), the volatile organic solvents include ethanol and acetone.

[0039] In step (1), the drying temperature is 60-80℃ and the drying time is 20-40min.

[0040] In step (2), the welding is performed with a gap of 0, meaning that the two plates are completely joined together without leaving any gaps.

[0041] In step (3), the horizontal magnetic field perpendicular to the weld is generated by the interaction of rubidium magnets uniformly distributed on both sides of the aluminum alloy weld to be welded.

[0042] In step (3), the longitudinal electric field perpendicular to the weld is provided by a capacitor consisting of two copper electrodes placed above and below the aluminum alloy to be welded, and the upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0043] In step (4), the laser beam deviates from the central axis by about 5-15° during the welding process, and the angle between the MIG welding gun and the surface of the aluminum alloy plate to be welded is 50-70°.

[0044] In step (4), the welding wire used during welding is aluminum-magnesium welding wire, including ER5356, ER5083, and ER5556.

[0045] In step (4), during welding, a high-purity inert gas with a mass concentration of not less than 99.99% is used for protection, with a front side blowing gas flow rate of 15-20 L / min and a back protection gas flow rate of 10-15 L / min.

[0046] The present invention will be further described below with reference to specific embodiments.

[0047] Example 1

[0048] This embodiment provides a laser-MIG hybrid welding method for 1mm thick 7005-T6 aluminum alloy assisted by electric field and / or magnetic field coupling, specifically including:

[0049] (1) Pretreatment of welding test specimens: The surface of the 7005-T6 aluminum alloy plate to be welded (1 mm thick) and the area around the weld seam (25 mm) are ground to remove the oxide film. No beveling is required. The plate is then wiped clean with acetone and placed in an 80℃ drying equipment for 30 minutes to dry.

[0050] (2) Place the 7005-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form a structure to be welded.

[0051] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0052] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7005-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 5° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 50°; the laser power is 1000W, the welding speed is 24mm / s, the defocusing amount is 0, the wire spacing is 2mm, the welding current is 80A, the welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.05T, and the electric field strength is 2000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 15L / min on the front side and 10L / min on the back side.

[0053] In this embodiment, the weld surface is well formed, without forming defects such as undercut and spatter. The tensile strength of the welded specimen is 357.8 MPa, and the weld strength coefficient is 68.1%.

[0054] Example 2

[0055] This embodiment provides a laser-MIG hybrid welding method for 3mm thick 7075-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0056] (1) Pretreatment of welding test specimens: The surface of the 7075-T6 aluminum alloy plate to be welded (3mm thick) and the area around the weld seam (25mm) are ground to remove the oxide film. No beveling is required. The plate is then wiped clean with ethanol and placed in an 80℃ drying equipment for 30 minutes to dry.

[0057] (2) Place the 7075-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0058] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0059] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7075-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 10° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 60°; the laser power is 2800W, the welding speed is 30mm / s, the defocusing amount is -1, the wire spacing is 2mm, the welding current is 100A, the welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.08T, and the electric field strength is 4000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 18L / min on the front side and 12L / min on the back side.

[0060] The macroscopic morphology of the weld in this embodiment is as follows: Figure 2 As shown, the weld surface is well formed, without forming defects such as undercut and spatter. The tensile strength of the welded specimen is 385.8 MPa, and the weld strength coefficient is 70.8%.

[0061] Example 3

[0062] This embodiment provides a laser-MIG hybrid welding method for 6mm thick 7050-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0063] (1) Pretreatment of welding test specimens: The surface of the 6mm thick 7050-T6 aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, a "Y" shaped bevel is opened, and it is wiped clean with acetone, and then placed in an 80℃ drying equipment for 30 minutes to dry.

[0064] (2) Place the 7050-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0065] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0066] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7050-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 15° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 70°; the laser power is 4500W, the welding speed is 30mm / s, the defocusing amount is -2, the wire spacing is 1mm, the welding current is 160A, the welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.2T, and the electric field strength is 15000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 20L / min on the front side and 15L / min on the back side.

[0067] In this embodiment, the weld surface has good formation, with no forming defects such as undercut and spatter. The tensile strength of the welded specimen is 376.5 MPa, and the weld strength coefficient is 67.2%.

[0068] Example 4

[0069] This embodiment provides a laser-MIG hybrid welding method for 4mm thick 7005-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0070] (1) Pretreatment of welding test specimens: The surface of the 4mm thick 7005-T6 aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, an "I" shaped bevel is opened, and it is wiped clean with acetone and then placed in an 80℃ drying equipment for 30 minutes to dry.

[0071] (2) Place the 7005-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form a structure to be welded.

[0072] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0073] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7005-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 12° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 65°; the laser power is 3200W, the welding speed is 20mm / s, the defocusing amount is -1, the wire spacing is 2mm, the welding current is 140A, the welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.14T, and the electric field strength is 8000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 18L / min on the front side and 16L / min on the back side.

[0074] In this embodiment, the weld surface has good formation, with no forming defects such as undercut and spatter. The tensile strength of the welded sample is 343.2 MPa, and the weld strength coefficient is 65.4%.

[0075] Example 5

[0076] This embodiment provides a laser-MIG hybrid welding method for 5mm thick 7075-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0077] (1) Pretreatment of welding test specimens: The surface of the 5mm thick 7075-T6 aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, a "V" shaped bevel is opened, and it is wiped clean with acetone, and then placed in an 80℃ drying equipment for 30 minutes to dry.

[0078] (2) Place the 7075-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0079] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0080] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7075-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 10° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 60°; the laser power is 3700W, the welding speed is 25mm / s, the defocusing amount is -2, the wire spacing is 1mm, the welding current is 140A, the welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.15T, and the electric field strength is 11000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 17L / min on the front side and 15L / min on the back side.

[0081] In this embodiment, the weld surface is well formed, without forming defects such as undercut and spatter. The tensile strength of the welded sample is 374.2 MPa, and the weld strength coefficient is 68.7%.

[0082] Example 6

[0083] This embodiment provides a laser-MIG hybrid welding method for 2mm thick 7050-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0084] (1) Pretreatment of welding test specimens: The surface of the 2mm thick 7050-T6 aluminum alloy plate to be welded and the area around the weld 25mm should be ground to remove the oxide film, without beveling, and wiped clean with acetone, and then placed in an 80℃ drying equipment for 30 minutes to dry.

[0085] (2) Place the 7050-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0086] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0087] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7050-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 8° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 55°; the laser power is 1700W, the welding speed is 30mm / s, the defocusing amount is 0, the wire spacing is 1mm, the welding current is 80A, the welding wire used is ER5356 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.08T, and the electric field strength is 3000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 18L / min on the front side and 16L / min on the back side.

[0088] In this embodiment, the weld surface is well formed, without forming defects such as undercut and spatter. The tensile strength of the welded sample is 394.7 MPa, and the weld strength coefficient is 70.5%.

[0089] Example 7

[0090] This embodiment provides a laser-MIG hybrid welding method for 3mm thick 7475-T6 aluminum alloy assisted by electric field and magnetic field coupling, specifically including:

[0091] (1) Pretreatment of welding test specimens: The surface of the 3mm thick 7475-T6 aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film. No beveling is required. The plate is wiped clean with acetone and then placed in an 80℃ drying equipment for 30 minutes to dry.

[0092] (2) Place the 7475-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0093] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded. Two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded. The N pole of one rubidium magnet is placed opposite to the S pole of the other rubidium magnet. A longitudinal electric field perpendicular to the weld is set at the structure to be welded. It is provided by a capacitor composed of two copper electrodes set above and below the aluminum alloy to be welded. The upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

[0094] (4) The structure to be welded is welded using laser-MIG composite welding process. Before welding begins, 7475-T6 aluminum alloy is set at both ends of the workpiece weld as arc-starting plates, which are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece. During welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; the laser beam deviates from the central axis by about 10° during the welding process, and the angle between the MIG welding torch and the surface of the aluminum alloy plate to be welded is 50°; the laser power is 2400W, the welding speed is 20mm / s, the defocusing amount is -1, the wire spacing is 1mm, the welding current is 100A, the welding wire used is ER5356 aluminum alloy welding wire with a diameter of 1.2mm, the magnetic field strength is 0.12T, and the electric field strength is 5000V / m; high-purity argon gas with a mass concentration of 99.9% is used for protection on both sides, with a gas flow rate of 18L / min on the front side and 16L / min on the back side.

[0095] In this embodiment, the weld surface has good formation, with no forming defects such as undercut and spatter. The tensile strength of the welded sample is 472.1 MPa, and the weld strength coefficient is 72.6%.

[0096] Comparative Example

[0097] This comparative example provides a laser-MIG hybrid welding method for 3mm thick 7075-T6 aluminum alloy, specifically including:

[0098] (1) Pretreatment of welding test specimens: The surface of the 7075-T6 aluminum alloy plate to be welded (3mm thick) and the area around the weld seam (25mm) are ground to remove the oxide film. No beveling is required. The plate is then wiped clean with ethanol and placed in an 80℃ drying equipment for 30 minutes to dry.

[0099] (2) Place the 7075-T6 aluminum alloy plates from step (1) with zero gap and fix them with pressure plates to form the structure to be welded.

[0100] (3) The structure to be welded was welded using a laser-MIG composite welding process. Before welding, 7075-T6 aluminum alloy was placed at both ends of the workpiece weld as arc-starting plates, with a butt joint without bevel. At the start of welding, welding began from the starting end of the arc-starting plate on one side of the workpiece and ended when welding reached the end of the arc-starting plate on the other side of the workpiece. During welding, the laser was in front and the arc was behind, and the arc welding method was DC reverse polarity. The laser beam deviated from the central axis by about 10° during the welding process, and the angle between the MIG welding gun and the surface of the aluminum alloy plate to be welded was 60°. The laser power was 2800W, the welding speed was 25mm / s, the defocusing amount was 0, the wire spacing was 2mm, the welding current was 120A, and the laser did not oscillate. The welding wire used was ER5356 aluminum alloy welding wire with a diameter of 1.2mm. High-purity argon gas with a mass concentration of 99.9% was used for protection on both sides, with a gas flow rate of 18L / min on the front side and 12L / min on the back side.

[0101] The macroscopic morphology of the comparative weld is as follows: Figure 3 As shown, the weld front collapsed and there was spatter on the back, indicating poor forming quality. The tensile strength of the welded specimen was 304.7 MPa, and the weld strength coefficient was 56.1%.

[0102] The above description is only one specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention are covered within the protection scope of the present invention.

Claims

1. A laser-MIG hybrid welding method for 7000 series aluminum alloys assisted by electric and magnetic field coupling, characterized in that, Includes the following steps: (1) Pretreatment of welding test specimens: The surface of the 7000 series aluminum alloy plate to be welded and the area around the weld 25mm are ground to remove the oxide film, and wiped clean with volatile organic solvents, and then put into the drying equipment for drying. (2) Place the 7000 series aluminum alloy plates from step (1) together and fix them with pressure plates to form a structure to be welded. (3) A horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld are set at the structure to be welded; (4) The structure to be welded is welded using laser-MIG composite welding process; during laser-MIG composite welding, the laser is in front and the arc is behind, and the arc welding method is DC reverse polarity; before welding begins, arc-starting plates are set at both ends of the workpiece weld, the material of the arc-starting plates is the same as the material of the workpiece, and the arc-starting plates and the weld are butt joints without bevels. When welding begins, welding starts from the starting end of the arc-starting plate on one side of the workpiece and ends when welding reaches the end of the arc-starting plate on the other side of the workpiece.

2. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (1), the 7000 series aluminum alloys include 7075, 7005, 7050, and 7475.

3. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (1), the thickness of the 7000 series aluminum alloy is 1-6 mm.

4. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (1), when the thickness of the 7000 series aluminum alloy is 1-3mm, no beveling is required; when the thickness is 4-6mm, beveling is required, and the beveling shape includes "I", "V" and "Y".

5. The electric field and magnetic field coupled-assisted laser-MIG composite welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (1), the volatile organic solvents include ethanol and acetone.

6. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (1), the drying temperature is 60-80℃ and the drying time is 20-40min.

7. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (2), the gap between the two plates is 0, meaning that the two plates are completely joined together without any gaps.

8. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (3), the horizontal magnetic field perpendicular to the weld is generated by the interaction of rubidium magnets uniformly distributed on both sides of the aluminum alloy weld to be welded.

9. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (3), the longitudinal electric field perpendicular to the weld is provided by a capacitor consisting of two copper electrodes placed above and below the aluminum alloy to be welded, and the upper copper electrode has a small hole so that the laser can pass through and act on the surface of the base material.

10. The electric field and magnetic field coupled-assisted laser-MIG composite welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (4), the laser beam deviates from the central axis by 5-15° during the welding process, and the angle between the MIG welding gun and the surface of the aluminum alloy plate to be welded is 50-70°.

11. The electric field and magnetic field coupled-assisted laser-MIG hybrid welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (4), the welding wire used during welding is aluminum-magnesium welding wire, including ER5356, ER5083, and ER5556.

12. The electric field and magnetic field coupled-assisted laser-MIG composite welding method for 7000 series aluminum alloys according to claim 1, characterized in that: In step (4), during welding, a high-purity inert gas with a mass concentration of not less than 99.99% is used for protection. The flow rate of the front side blowing gas is 15-20 L / min, and the flow rate of the back shielding gas is 10-15 L / min.

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