Electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method

Abstract

The invention discloses an electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method, which belongs to the technical field of welding, and comprises the following steps: (1) pretreatment of a welding sample: polishing the surface to be welded of a 7000 series aluminum alloy plate to be welded and a 25mm area around a welding seam to remove an oxidation film, and wiping the surface and the area by adopting a volatile organic solvent; then putting into drying equipment for drying; (2) the 7000 series aluminum alloy plates in the step (1) are placed in a butt joint mode and fixed through a pressing plate, and a to-be-welded structure is formed; (3) arranging a horizontal magnetic field perpendicular to the weld joint and a longitudinal electric field perpendicular to the weld joint at the structure to be welded; and (4) the to-be-welded structure is welded through the laser-MIG composite welding technology. By means of multi-field coupling assistance of the electric field and the magnetic field, deslagging and degassing of the high-temperature molten pool can be achieved, meanwhile, the molten pool is stirred, grains can be effectively refined, element segregation of 7000 series aluminum alloy is reduced, and a high-strength welding joint is obtained.

Description

Technical Field

[0001] The invention relates to the technical field of welding, and in particular provides an electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method. Background Art

[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 physical and chemical properties of 7000 series aluminum alloys, such as high thermal conductivity, large thermal expansion coefficient, easy formation of oxide film on the surface, large difference in solubility of solid and liquid hydrogen, easy formation of low melting point eutectic during welding, etc., low boiling point elements Mg and Zn are burned, and defects such as pores and cracks are prone to occur, resulting in 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 arc. It has the advantages of both laser and arc welding technologies. The laser has the function of stabilizing the arc, and the addition of the arc can not only increase the absorption rate of the aluminum alloy to the laser, but also improve problems such as pores and cracks caused by the excessively fast laser welding speed.

[0004] At the beginning of the development of electric / magnetic assisted technology, it was often used in the metal casting process. Its role has been proven. It mainly affects the flow, heat transfer and solidification process of liquid metal by controlling the direction of electromagnetic force to eliminate defects generated in casting. With the development of electric / magnetic assisted technology, researchers have applied electromagnetic technology to welding. Studies have shown that the addition of electric / magnetic fields has a significant effect on the flow behavior of the welding molten pool and the movement of plasma, and can effectively reduce defects such as welding pores, thereby improving the quality of welded joints. For example, Chinese patent (CN103612019A) discloses a magnetically stirred CO2 laser-TIG arc composite welding method, which effectively refines grains and improves joint performance; Chinese patent (CN103612019A) discloses a laser wire welding device that uses an external electric field and magnetic field to stir the welding molten pool, which can form a strong convection stirring effect in the welding molten pool, so that the element components in the welding molten pool are evenly diffused.

[0005] The present invention proposes an electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, which improves the surface forming quality of the weld, reduces the internal porosity defects of the weld, and improves the strength of the weld joint through the synergistic effect of the electric field, magnetic field, laser and arc. Summary of the invention

[0006] In view of the problems in the prior art of poor weld surface forming quality, many porosity defects inside the weld and low weld joint strength in the laser-arc hybrid welding of 7000 series aluminum alloys, the present invention provides an electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method.

[0007] The specific scheme adopted by the present invention is: an electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method, the method comprising the following steps: (1) Pretreatment of welding specimens: Grind the surface of the 7000 series aluminum alloy plate to be welded and the 25mm area around the weld to remove the oxide film, wipe it clean with a volatile organic solvent, and then put it in a drying equipment for drying; (2) placing the 7000 series aluminum alloy plates obtained in step (1) in a butt-jointed manner and fixing them with a pressing plate to form a structure to be welded; (3) setting a horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld at the structure to be welded; (4) The structure to be welded is welded by a laser-MIG hybrid welding process. In laser-MIG hybrid welding, the laser is in front and the arc is in the back, and the arc welding method is DC reverse connection. Before welding begins, arc-starting plates are set at both ends of the weld of the workpiece. The material of the arc-starting plates is consistent with the material of the workpiece, and the arc-starting plates and the weld are butt-jointed without grooves. At the beginning of welding, welding starts from the starting end of the arc-starting plate on one side of the workpiece, and ends when welding to the end of the arc-starting plate on the other side of the workpiece.

[0008] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (1), the 7000 series aluminum alloy includes 7075, 7005, 7050, 7475, etc.

[0009] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (1), the thickness of the 7000 series aluminum alloy is 1-6 mm.

[0010] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (1), when the thickness of the 7000 series aluminum alloy is 1-3 mm, no groove is opened; when the thickness is 4-6 mm, a groove is opened, and the groove shapes include "I" shape, "V" shape, and "Y" shape.

[0011] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein in step (1), the volatile organic solvent includes ethanol and acetone.

[0012] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (1), the drying temperature is 60-80° C., and the drying time is 20-40 minutes.

[0013] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (2), the butt gap is 0, that is, the two plates are completely butt-jointed, and welding is performed in a manner that leaves no gap.

[0014] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method, 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 aluminum alloy weld to be welded.

[0015] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method, wherein, in step (3), the longitudinal electric field perpendicular to the weld is provided by a capacitor consisting of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the laser to pass through and act on the surface of the base material.

[0016] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, 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°.

[0017] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, wherein, in step (4), during welding, the welding wire used is aluminum-magnesium welding wire, including ER5356, ER5083, and ER5556.

[0018] The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG composite welding method, 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 to 20 L / min, and the back protection gas flow rate is 10 to 15 L / min.

[0019] Compared with the prior art, the beneficial effects of the present invention include:

[0020] 1. The present invention sets an electric / magnetic field during the welding process, and utilizes the Lorentz magnetic force generated by the interaction between the electric / magnetic field and the flowing conductive molten pool fluid to support the back of the weld, thereby effectively suppressing the collapse of the welding surface of the 7000 series aluminum alloy.

[0021] 2. The present invention forms a strong convection stirring effect in the welding pool by setting up an electric / magnetic field, which can effectively refine the grains and at the same time allow the various element components in the welding pool to diffuse evenly; it also plays a certain improvement role in reducing pores and impurities, thereby effectively improving the strength of the weld joint. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of electric / magnetic field coupling assisted laser-MIG hybrid welding; Figure 2 The weld macroscopic morphology provided in Example 2; Figure 3 Macroscopic morphology of the weld provided for comparison. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0024] The present invention provides a laser-MIG hybrid welding method for 7000 series aluminum alloy assisted by electric / magnetic field coupling, the method comprising the following steps: (1) Pretreatment of welding specimens: Grind the surface of the 7000 series aluminum alloy plate to be welded and the 25mm area around the weld to remove the oxide film, wipe it clean with a volatile organic solvent, and then put it in a drying equipment for drying; (2) placing the 7000 series aluminum alloy plates obtained in step (1) in a butt-jointed manner and fixing them with a pressing plate to form a structure to be welded; (3) setting a horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld at the structure to be welded; (4) The structure to be welded is welded by a laser-MIG hybrid welding process. In laser-MIG hybrid welding, the laser is in front and the arc is in the back, and the arc welding method is DC reverse connection. Before welding begins, arc-starting plates are set at both ends of the weld of the workpiece. The material of the arc-starting plates is consistent with the material of the workpiece, and the arc-starting plates and the weld are butt-jointed without grooves. At the beginning of welding, welding starts from the starting end of the arc-starting plate on one side of the workpiece, and ends when welding to the end of the arc-starting plate on the other side of the workpiece.

[0025] In the step (1), the 7000 series aluminum alloy includes 7075, 7005, 7050, 7475, etc.

[0026] In the step (1), the thickness of the 7000 series aluminum alloy is 1-6 mm.

[0027] In the step (1), when the thickness of the 7000 series aluminum alloy is 1-3 mm, no groove is formed; when the thickness is 4-6 mm, a groove is formed, and the groove shapes include "I" shape, "V" shape, and "Y" shape.

[0028] In the step (1), the volatile organic solvent includes ethanol and acetone.

[0029] In the step (1), the drying temperature is 60-80° C. and the drying time is 20-40 min.

[0030] In the step (2), the butt gap is 0, that is, the two plates are completely butt-jointed and welded without leaving any gap.

[0031] In the step (3), a 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.

[0032] In the step (3), the longitudinal electric field perpendicular to the weld is provided by a capacitor consisting of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the laser to pass through and act on the surface of the base material.

[0033] In the 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°.

[0034] In the step (4), during welding, the welding wire used is aluminum-magnesium welding wire, including ER5356, ER5083, and ER5556.

[0035] In the 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 to 20 L / min, and the back protection gas flow rate is 10 to 15 L / min.

[0036] The present invention is further described below in conjunction with specific embodiments.

[0037] Example 1 This embodiment provides a method for laser-MIG hybrid welding of 7005-T6 aluminum alloy with a thickness of 1 mm assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding samples: The surface of the 7005-T6 aluminum alloy plate to be welded 1 mm thick and the 25 mm area around the weld were ground to remove the oxide film, without opening the groove, and wiped clean with acetone, and then placed in an 80 ° C drying equipment for 30 minutes for drying.

[0038] (2) The 7005-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0039] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0040] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding begins, 7005-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding begins, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates from the central axis by about 5° 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°; the laser power is 1000W, the welding speed is 24mm / s, the defocus amount is 0, the light wire spacing is 2mm, and the welding current is 80A. The welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.05T, and an electric field strength of 2000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 15L / min, and the back gas flow rate is 10L / min.

[0041] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 357.8 MPa, and the weld strength coefficient is 68.1%.

[0042] Example 2 This embodiment provides a laser-MIG hybrid welding method for 3 mm thick 7075-T6 aluminum alloy assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding samples: The surface of the 7075-T6 aluminum alloy plate to be welded 3 mm thick and the 25 mm area around the weld were ground to remove the oxide film, without opening the groove, and wiped clean with ethanol, and then placed in an 80 ° C drying equipment for 30 minutes for drying.

[0043] (2) The 7075-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0044] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0045] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding, 7075-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding starts, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates 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 is 60°; the laser power is 2800W, the welding speed is 30mm / s, the defocus amount is -1, the filament spacing is 2mm, and the welding current is 100A. The welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.08T, and an electric field strength of 4000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 18L / min, and the back gas flow rate is 12L / min.

[0046] The macroscopic morphology of the weld in this embodiment is as follows Figure 2 As shown in the figure, the weld surface is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 385.8MPa and the weld strength coefficient is 70.8%.

[0047] Example 3 This embodiment provides a 6 mm thick 7050-T6 aluminum alloy laser-MIG hybrid welding method assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding specimens: The surface of the 6 mm thick 7050-T6 aluminum alloy plate to be welded and the 25 mm area around the weld were ground to remove the oxide film, a "Y"-shaped groove was opened, and it was wiped clean with acetone and then placed in an 80 °C drying equipment for 30 min for drying.

[0048] (2) The 7050-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0049] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0050] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding, 7050-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding starts, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates from the central axis by about 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 70°; the laser power is 4500W, the welding speed is 30mm / s, the defocus amount is -2, the light wire spacing is 1mm, and the welding current is 160A. The welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.2T, and an electric field strength of 15000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 20L / min, and the back gas flow rate is 15L / min.

[0051] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 376.5 MPa, and the weld strength coefficient is 67.2%.

[0052] Example 4 This embodiment provides a 4 mm thick 7005-T6 aluminum alloy laser-MIG hybrid welding method assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding specimens: The surface of the 4 mm thick 7005-T6 aluminum alloy plate to be welded and the 25 mm area around the weld were ground to remove the oxide film, an "I"-shaped groove was opened, and it was wiped clean with acetone and then placed in an 80 °C drying equipment for 30 min for drying.

[0053] (2) The 7005-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0054] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0055] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding begins, 7005-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding begins, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates from the central axis by about 12° during the welding process, and the angle between the MIG welding gun 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 defocus amount is -1, the filament spacing is 2mm, and the welding current is 140A. The welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.14T, and an electric field strength of 8000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 18L / min, and the back gas flow rate is 16L / min.

[0056] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 343.2 MPa, and the weld strength coefficient is 65.4%.

[0057] Example 5 This embodiment provides a laser-MIG hybrid welding method for 5 mm thick 7075-T6 aluminum alloy assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding specimens: The surface of the 5 mm thick 7075-T6 aluminum alloy plate to be welded and the 25 mm area around the weld were ground to remove the oxide film, a "V"-shaped groove was opened, and it was wiped clean with acetone and then placed in an 80 °C drying equipment for 30 min for drying.

[0058] (2) The 7075-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0059] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0060] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding, 7075-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding starts, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates 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 is 60°; the laser power is 3700W, the welding speed is 25mm / s, the defocus amount is -2, the light wire spacing is 1mm, and the welding current is 140A. The welding wire used is ER5083 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.15T, and an electric field strength of 11000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 17L / min, and the back gas flow rate is 15L / min.

[0061] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 374.2 MPa, and the weld strength coefficient is 68.7%.

[0062] Example 6 This embodiment provides a 2 mm thick 7050-T6 aluminum alloy laser-MIG hybrid welding method assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding samples: The surface of the 2 mm thick 7050-T6 aluminum alloy plate to be welded and the 25 mm area around the weld were polished to remove the oxide film, without opening the groove, and wiped clean with acetone, and then placed in an 80 ° C drying equipment for 30 min for drying.

[0063] (2) The 7050-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0064] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0065] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding, 7050-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding starts, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates from the central axis by about 8° during the welding process, and the angle between the MIG welding gun 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 defocus amount is 0, the light wire spacing is 1mm, and the welding current is 80A. The welding wire used is ER5356 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.08T, and an electric field strength of 3000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 18L / min, and the back gas flow rate is 16L / min.

[0066] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 394.7 MPa, and the weld strength coefficient is 70.5%.

[0067] Example 7 This embodiment provides a method for laser-MIG hybrid welding of 3 mm thick 7475-T6 aluminum alloy assisted by electric / magnetic field coupling, specifically comprising: (1) Pretreatment of welding specimens: The surface of the 3 mm thick 7475-T6 aluminum alloy plate to be welded and the 25 mm area around the weld were ground to remove the oxide film, without opening the groove, and wiped clean with acetone, and then placed in an 80 ° C drying equipment for 30 minutes for drying.

[0068] (2) The 7475-T6 aluminum alloy plates of step (1) are placed in a zero-gap butt-jointed manner and fixed by a pressing plate to form a structure to be welded.

[0069] (3) A horizontal magnetic field perpendicular to the weld is set at the structure to be welded, and two rubidium magnets are evenly distributed on both sides of the weld of the aluminum alloy to be welded, and 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, and is provided by a capacitor composed of two copper electrodes arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the passage of laser to act on the surface of the base material.

[0070] (4) The structure to be welded is welded by using a laser-MIG hybrid welding process. Before welding, 7475-T6 aluminum alloy is set at both ends of the workpiece weld as an arc starter plate, which is butt-jointed with the weld without a groove. When welding starts, welding starts from the starting end of the arc starter plate on one side of the workpiece and ends when welding to the end of the arc starter 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 connection; the laser beam deviates 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 is 50°; the laser power is 2400W, the welding speed is 20mm / s, the defocus amount is -1, the filament spacing is 1mm, and the welding current is 100A. The welding wire used is ER5356 aluminum alloy welding wire with a diameter of 1.2mm, a magnetic field strength of 0.12T, and an electric field strength of 5000V / m; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 18L / min, and the back gas flow rate is 16L / min.

[0071] The weld surface of this embodiment is well formed without forming defects such as undercut and spatter. The tensile strength of the weld sample is 472.1 MPa, and the weld strength coefficient is 72.6%.

[0072] Comparative Example This comparative example provides a 3 mm thick 7075-T6 aluminum alloy laser-MIG composite welding method, which specifically includes: (1) Pretreatment of welding samples: The surface of the 7075-T6 aluminum alloy plate to be welded 3 mm thick and the 25 mm area around the weld were ground to remove the oxide film, without opening the groove, and wiped clean with ethanol, and then placed in an 80 ° C drying equipment for 30 minutes for drying.

[0073] (2) The 7075-T6 aluminum alloy plates of step (1) are placed in a butt joint with zero gap and fixed by a pressing plate to form a structure to be welded.

[0074] (3) The structure to be welded is welded by laser-MIG composite welding process. Before welding, 7075-T6 aluminum alloy is set as arc-starting plates at both ends of the weld of the workpiece, and the weld is butted without groove. At the beginning of welding, welding starts from the starting end of the arc-starting plate on one side of the workpiece, and ends when welding to 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 in the back, and the arc welding method is DC reverse connection; the laser beam deviates 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 is 60°; the laser power is 2800W, the welding speed is 25mm / s, the defocusing amount is 0, the light wire spacing is 2mm, the welding current is 120A, the laser does not swing, and the welding wire used is ER5356 aluminum alloy welding wire with a diameter of 1.2mm; high-purity argon gas with a mass concentration of 99.9% is used for front and back protection, the front gas flow rate is 18L / min, and the back gas flow rate is 12L / min.

[0075] The macroscopic morphology of the weld in this comparative example is as follows Figure 3 As shown, the front of the weld collapsed, there was spatter on the back, the forming quality was poor, the tensile strength of the welded sample was 304.7 MPa, and the weld strength coefficient was 56.1%.

[0076] The above is only a specific implementation 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 any technician familiar with the technical field within the technical scope disclosed by the present invention are all covered by the protection scope of the present invention.

Claims

1. An electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method, characterized in that: The steps include: (1) Pretreatment of welding specimens: Grind the surface of the 7000 series aluminum alloy plate to be welded and the 25mm area around the weld to remove the oxide film, wipe it clean with a volatile organic solvent, and then put it in a drying equipment for drying; (2) placing the 7000 series aluminum alloy plates obtained in step (1) in a butt-jointed manner and fixing them with a pressing plate to form a structure to be welded; (3) setting a horizontal magnetic field perpendicular to the weld and a longitudinal electric field perpendicular to the weld at the structure to be welded; (4) The structure to be welded is welded by a laser-MIG hybrid welding process; during laser-MIG hybrid welding, the laser is in front and the arc is in the back, and the arc welding method is DC reverse connection; before welding, arc-starting plates are set at both ends of the weld of the workpiece, the material of the arc-starting plates is consistent with the material of the workpiece, and the arc-starting plates and the weld are butt-jointed without grooves. At the beginning of welding, welding starts from the starting end of the arc-starting plate on one side of the workpiece, and ends when welding to the end of the arc-starting plate on the other side of the workpiece.

2. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method according to claim 1, characterized in that: In step (1), the 7000 series aluminum alloy includes 7075, 7005, 7050, 7475, etc.

3. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method 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 / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method according to claim 1, characterized in that: In step (1), when the thickness of the 7000 series aluminum alloy is 1-3 mm, no groove is formed; when the thickness is 4-6 mm, a groove is formed, and the groove shapes include "I" shape, "V" shape, and "Y" shape.

5. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method according to claim 1, characterized in that: In step (1), the volatile organic solvent includes ethanol and acetone.

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

7. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method according to claim 1, characterized in that: In step (2), the butt joint gap is 0, that is, the two plates are completely butt jointed and welded without leaving any gap.

8. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method 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 evenly distributed on both sides of the aluminum alloy weld to be welded.

9. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method 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 arranged above and below the aluminum alloy to be welded, and a small hole is opened in the upper copper electrode to facilitate the laser to pass through and act on the surface of the base material.

10. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method according to claim 1, characterized in that: 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°.

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

12. The electric / magnetic field coupling assisted 7000 series aluminum alloy laser-MIG hybrid welding method 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 front side blowing gas flow rate is 15 to 20 L / min, and the back protection gas flow rate is 10 to 15 L / min.

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