Electron beam welding method for aluminum alloy
Through the double-gun electron beam welding method, the metal flow and temperature field of the molten pool are accurately controlled, and the problems of pores and residual stress of the welds of 7-Series aluminum alloy are solved, achieving stability and performance improvement of weld elongation.
Patent Information
- Application Number
- CN202510770043.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-10
- Publication Date
- 2025-07-25
AI Technical Summary
When the existing electron beam welding method is welded 7-type aluminum alloy, the weld structure has more pores and thick weld structure, and the residual stress on weld welding is difficult to eliminate, resulting in the weld elongation rate not meeting the use requirements.
The double-gun electron beam welding method is used, the main gun is welded, and the secondary gun is preheated before welding and local heat treatment after welding. By accurately controlling the flow and temperature field of the molten pool metal, the generation of pores is suppressed, the dendrites are refined, and the residual stress is eliminated.
The stability and consistency of weld elongation have been improved, and the technical requirements of special components have been met. The weld elongation is greater than 3.5%, and the welding performance has been significantly improved.
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of aluminum alloy welding, and relates to an electron beam welding method for aluminum alloy, specifically an electron beam welding method for 7-series aluminum alloy. Technical Background
[0002] Due to characteristics such as high energy density, small heat affected zone, and small distortion, electron beam welding has been widely used in the fields of aviation, aerospace, etc. In conventional welding, the mechanical properties of aluminum alloy welded joints are greatly lost, while the tensile strength of electron beam welded joints is generally 60% - 65% of the tensile strength of the base material, and the elongation rate is generally 1.5% - 3.5%.
[0003] In some aerospace usage scenarios, more and more stringent requirements are put forward for the structure of the weld seam of 7-series aluminum alloy welded joints, the porosity in the welding area, and the elongation rate. Additionally, due to the large and complex workpieces, the workpieces cannot be directly stress-relieved and annealed as a whole after welding. The conventional electron beam welding method results in a large fluctuation range of elongation rate, and cannot meet the technical requirement of elongation rate greater than 3%.
[0004] Therefore, there is an urgent need to provide a new electron beam welding method for 7-series aluminum alloy to overcome the problems that the weld seam structure of 7-series aluminum alloy components welded by the existing electron beam welding has more pores, the weld seam structure is coarse, and it is difficult to completely eliminate the welding residual stress of the weld seam, resulting in the elongation rate of the weld seam after welding of the components often not meeting the usage index requirements. Summary of the Invention
[0005] During the electron beam welding process, the molten metal in the weld pool is strongly bombarded by the high-energy electron beam, resulting in a large amount of metal evaporation. The counter-shock action of the metal vapor forces the surface of the liquid metal to sink to form a "keyhole". During this process, the molten metal in the weld pool undergoes complex mass transfer and heat transfer flows with the superposition of temperature field and flow field. At the same time, the cooling process of the molten metal is the self-thermal conduction of the aluminum alloy base material under a large temperature gradient. The cooling rate is fast, and the molten metal solidifies rapidly, easily forming a welding molten pool with a large depth-width ratio. During the welding process, the molten metal in the weld pool reaches an approximate balance under the action of the electron beam energy input, heat conduction, radiation, and evaporation energy. Under the combined action of the recoil pressure, surface tension, shear force, and hydrostatic pressure, the flow of the molten metal in the weld pool tends to a steady flow. At the same time, under the combined action of the above factors, it determines the morphology, size, and growth direction of the internal structure of the weld seam. By precisely controlling the melting and solidification behavior of the molten metal in the weld pool, the generation of pores in the weld pool is inhibited; through the stirring action of the metal flow in the weld pool, the dendritic structure in the weld seam is refined, and an ideal microstructure inside the joint is obtained, thereby achieving excellent welding performance.
[0006] The technical solution adopted by the present invention is an electron beam welding method for 7-series aluminum alloy, and the specific steps are as follows: Use a double-gun electron beam to weld the aluminum alloy. Among them, the main gun uses a power of 20KW - 300KW for electron beam welding, and the sub-gun uses a power of 1KW - 20KW for on-line local auxiliary heat treatment of the weld seam; the main gun is used to weld the weld seam, and the sub-gun is used for local preheating of the workpiece before electron beam welding to improve the temperature field of the molten pool, realize the steady-state flow of the molten pool metal and on-line local vacuum stress relief annealing after electron beam welding to eliminate welding stress;
[0007] In some preferred embodiments, during the electron beam welding process of the main gun, a fixed gun and fixed focus method is adopted. That is, during the welding process, the 7-series aluminum alloy workpiece to be welded is placed in the vacuum cavity, and the chuck height is adjusted to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process.
[0008] In some preferred embodiments, during the electron beam welding process of the main gun, the aluminum alloy workpiece moves in a closed cavity, and the welding speed is 50mm / min - 800mm / min.
[0009] In some preferred embodiments, during the electron beam welding process of the main gun, the steady-state flow of the molten pool metal is kept controllable, promoting the overflow of gas in the molten pool, effectively reducing the pores in the weld structure; through the stirring action of the metal flow in the molten pool, the dendritic structure in the weld is refined, and the mechanical properties of the weld structure are improved.
[0010] In some preferred embodiments, during the electron beam welding process of the sub-gun, local preheating treatment is performed on the area to be welded of the base metal before welding, and the preheating time is 1s - 5s; on-line local heat treatment is performed on the weld seam after welding, and the heating and holding time is 1s - 5s.
[0011] In some preferred embodiments, when the sub-gun performs on-line local heat treatment on the weld seam with an electron beam, the heating electron beam spot is 1mm - 3mm larger than the weld width.
[0012] In some preferred embodiments, the aluminum alloy is 7-series aluminum alloy, preferably 7075 aluminum alloy.
[0013] In some preferred embodiments, the aluminum alloy has a plate structure; preferably, the thickness of the plate is 50 - 800mm; for example, it can be 100mm, 150mm, 180mm, 200mm, 220mm, 250mm, 280mm, 300mm, 330mm, 350mm, 360mm, 380mm, 400mm, 420mm, 450mm, 480mm, 500mm, 550mm, 600mm, 650mm, 700mm, 750mm, 800mm.
[0014] Second aspect, the present invention provides an electron beam welding method for aluminum alloy, comprising the following steps:
[0015] 1) Prepare an electron beam welding machine, the electron beam welding machine is a double-gun welding machine, wherein the main gun is used for electron beam welding of aluminum alloy, and the secondary gun is used for local preheating of the workpiece before electron beam welding and local on-line vacuum heat treatment after electron beam welding of the weld seam;
[0016] 2) Place the aluminum alloy plate to be welded into the vacuum chamber, adjust the height of the chuck of the electron beam welding machine according to the thickness of the plate to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process;
[0017] 3) Turn on the secondary gun to perform electron beam preheating, with a heating power of 1KW - 20KW for preheating; the preheating time of the aluminum alloy workpiece to be welded is 1s - 5s;
[0018] 4) Turn on the main gun, and the electron beam starts welding, with a welding power of 20KW - 300KW, and the moving speed of the workpiece during the electron beam welding process is 50mm / min - 800mm / min;
[0019] 5) After welding is completed, turn on the secondary gun, and use the electron beam to perform on-line local heat treatment on the weld seam, with a heat treatment heating power of 1KW - 20KW, a heating holding time of 1s - 5s, and the heating electron beam spot being 1mm - 3mm larger than the weld seam width.
[0020] Third aspect, the present invention further provides an aluminum alloy obtained by welding with the electron beam welding method described above. Preferably, the aluminum alloy is a 7-series aluminum alloy, and more preferably 7075 aluminum alloy.
[0021] In some preferred embodiments, the elongation of the aluminum alloy weld seam obtained by the welding is not less than 3.5%; preferably not less than 3.8 - 4.2%;
[0022] In some preferred embodiments, the tensile strength of the aluminum alloy obtained by the welding is 330 - 350MPa or more, preferably 338 - 350MPa or more.
[0023] The beneficial effects of the present invention are at least as follows:
[0024] The present invention realizes the direct influence on the weld width and penetration by controlling key process parameters such as the electron beam welding power, i.e., the heat input per unit time, the welding speed, and the welding focal length. By precisely controlling the above factors, on the one hand, the precise control of the welding penetration and width is achieved, effectively improving the steady-state flow of the metal in the welding pool, suppressing the generation of pores while ensuring the full overflow of gases, and reducing the generation of post-weld tissue pores. On the other hand, the flow behavior of the liquid metal is regulated through the electron beam stirring effect, reducing the heat transfer and mass transfer gradients of the metal inside the welding pool, achieving the growth in all directions into fine and uniform dendritic structures, suppressing dendritic growth, and further improving the weld structure and properties.
[0025] The electron beam on-line local heat treatment technology is a technology in which the electron beam performs defocused scanning heating on a small area of the workpiece in the form of a line or surface heat source for heat treatment.
[0026] By preheating the weld to be welded on the workpiece, the cooling gradient of the molten metal in the weld pool can be effectively improved, thereby achieving the purpose of improving the temperature field of the molten metal in the weld pool.
[0027] By performing on-line electron beam heating local stress relief annealing heat treatment on the workpiece weld, the residual stress in the weld structure is further eliminated, and the structure and properties of the weld are improved.
[0028] The elongation of the obtained welds is greater than 3.5%, and the consistency and stability of the indexes are significantly improved, fully meeting the index requirements of a certain special component. Specific embodiments
[0029] To make the purpose, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0030] Embodiment 1
[0031] Combined with 7075 aluminum alloy, a thick plate of 200 mm, the specific implementation process of welding is used to further elaborate on the present invention in detail:
[0032] 1. The electron beam welder is a double-gun welding machine. The main gun is used for electron beam welding of the 7075 plate, and the secondary gun is used for local preheating of the workpiece before electron beam welding and local on-line vacuum heat treatment after electron beam welding of the weld.
[0033] 2. Place the 7075 aluminum alloy plate to be welded into the vacuum cavity, with a plate thickness of 200 mm. Adjust the chuck height to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process.
[0034] 3. Turn on the sub-gun to preheat the electron beam with a heating power of 10 kW for preheating; the preheating time for the aluminum alloy workpiece to be welded is 5 s.
[0035] 4. Turn on the main gun and the electron beam starts welding with a welding power of 35 KW. During the electron beam welding process, the moving speed of the workpiece is 400 mm / min.
[0036] 5. After welding is completed, turn on the sub-gun and use the electron beam to perform on-line local heat treatment on the weld seam. The heat treatment heating power is 16 kW, the heating holding time is 5 s, and the heating electron beam spot is 3 mm larger than the weld width; welding is completed.
[0037] After welding is completed, take 3 tensile specimens at the welded joint to test the mechanical properties of the welded joint. See Table 1 below for details. The elongation of the obtained weld seams is all greater than 3.5%. The consistency and stability of the indicators are significantly improved, fully meeting the index requirements of a certain special component.
[0038] Table 1
[0039] Number Tensile strength / MPa Elongation / % 1 340 3.8 2 342 4.0 3 338 3.9
[0040] Example 2
[0041] Combined with 7075 aluminum alloy with a plate thickness of 400 mm, the specific implementation process of welding is used to further elaborate on the present invention in detail:
[0042] 1. The electron beam welder is a double-gun welding machine. The main gun is used for electron beam welding of 7075 plates, and the sub-gun is used for local preheating of the workpiece before electron beam welding and local on-line vacuum heat treatment of the electron beam weld seam after welding.
[0043] 2. Place the 7075 aluminum alloy plate to be welded into the vacuum chamber with a plate thickness of 400 mm, adjust the height of the chuck to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process.
[0044] 3. Turn on the sub-gun to preheat the electron beam with a heating power of 20 kW for preheating; the preheating time for the aluminum alloy workpiece to be welded is 5 s.
[0045] 4. Turn on the main gun and the electron beam starts welding with a welding power of 300 KW. During the electron beam welding process, the moving speed of the workpiece is 800 mm / min.
[0046] 5. After welding is completed, turn on the sub-gun and use the electron beam to perform on-line local heat treatment on the weld seam. The heat treatment heating power is 20 kW, the heating holding time is 5 s, and the heating electron beam spot is 3 mm larger than the weld width; welding is completed.
[0047] After welding, three tensile specimens were taken at the welded joint to test the mechanical properties of the welded joint. See Table 2 below for details. The elongation of the obtained welds was greater than 3.5%, and the consistency and stability of the indicators were significantly improved, fully meeting the requirements of a certain special component.
[0048] Table 2
[0049] Number Tensile strength / MPa Elongation / % 1 345 3.9 2 344 4.2 3 340 4.0
[0050] Example 3
[0051] Combined with 7075 aluminum alloy with a plate thickness of 100 mm, the specific implementation process of welding is used to further elaborate on the present invention in detail:
[0052] 1. The electron beam welder is a double-gun welding machine. The main gun is used for electron beam welding of 7075 plates, and the sub-gun is used for local preheating of the workpiece before electron beam welding and local on-line vacuum heat treatment after electron beam welding of the weld.
[0053] 2. Place the 7075 aluminum alloy plate to be welded into the vacuum chamber with a plate thickness of 100 mm, adjust the height of the chuck to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process.
[0054] 3. Turn on the sub-gun for electron beam preheating with a heating power of 1 kW for preheating; the preheating time of the aluminum alloy workpiece to be welded is 5 s.
[0055] 4. Turn on the main gun, and the electron beam starts welding with a welding power of 20 KW. The moving speed of the workpiece during electron beam welding is 50 mm / min.
[0056] 5. After welding is completed, turn on the sub-gun and use the electron beam to perform on-line local heat treatment on the weld. The heat treatment heating power is 1 kW, the heating holding time is 5 s, and the heating electron beam spot is 1 mm larger than the weld width; welding is completed.
[0057] After welding, three tensile specimens were taken at the welded joint to test the mechanical properties of the welded joint. See Table 3 below for details. The elongation of the obtained welds was greater than 3.5%, and the consistency and stability of the indicators were significantly improved, fully meeting the requirements of a certain special component.
[0058] Table 3
[0059] Number Tensile strength / MPa Elongation / % 1 349 4.0 2 350 4.2 3 343 4.2
Claims
1. An electron beam welding method for aluminum alloy, characterized in that, The aluminum alloy is welded by using a double-gun electron beam. The main gun performs electron beam welding with a power of 20KW - 300KW, and the secondary gun performs on-line local auxiliary heat treatment on the weld seam with a power of 1KW - 20KW.
2. The electron beam welding method for an aluminum alloy according to claim 1, characterized in that, During the electron beam welding process of the main gun, a fixed gun and fixed focus method is adopted.
3. A method for electron beam welding of an aluminum alloy according to claim 1, characterized in that, During the electron beam welding process of the main gun, the aluminum alloy moves in a sealed cavity, and the welding speed is 50mm / min - 800mm / min.
4. A method for electron beam welding of an aluminum alloy according to claim 1, characterized in that, During the electron beam welding process of the secondary gun, the area to be welded of the base material before welding is locally preheated, and the preheating time is 1s - 5s; preferably, on-line local heat treatment is performed on the weld seam after welding, and the heating holding time is 1s - 5s.
5. A method for electron beam welding of an aluminum alloy according to claim 1, characterized in that, When the secondary gun performs on-line local heat treatment on the weld seam by using an electron beam, the heating electron beam spot is 1mm - 3mm larger than the weld seam width.
6. A method for electron beam welding of an aluminum alloy according to any one of claims 1 to 5, characterized in that, The aluminum alloy is a 7-series aluminum alloy, preferably 7075 aluminum alloy.
7. A method for electron beam welding of an aluminum alloy according to any one of claims 1 to 6, characterized in that, The aluminum alloy is in a plate structure; preferably, the thickness of the plate is 50 - 800mm; preferably 100 - 400mm; more preferably 300mm.
8. An electron beam welding method for an aluminum alloy, comprising the following steps: 1) Prepare an electron beam welding machine. The electron beam welding machine is a double-gun welding machine, where the main gun is used for electron beam welding of the aluminum alloy, and the secondary gun is used for local preheating of the workpiece before electron beam welding and local on-line vacuum heat treatment of the electron beam weld seam. 2) Place the aluminum alloy plate to be welded into the vacuum cavity, adjust the height of the chuck of the electron beam welding machine according to the plate thickness to ensure that the focal length of the workpiece to be welded remains unchanged during the welding process. 3) Turn on the secondary gun and perform electron beam preheating with a heating power of 1KW - 20KW for preheating. The preheating time of the aluminum alloy workpiece to be welded is 1s - 5s. 4) Turn on the main gun, and the electron beam starts welding with a welding power of 20KW - 300KW. During the electron beam welding process, the moving speed of the workpiece is 50mm / min - 800mm / min. 5) After welding is completed, turn on the secondary gun and perform on-line local heat treatment on the weld seam with an electron beam. The heat treatment heating power is 1KW - 20KW, the heating holding time is 1s - 5s, and the heating electron beam spot is 1mm - 3mm larger than the weld seam width.
9. An aluminum alloy welded by using the electron beam welding method according to any one of claims 1 - 8.
10. The aluminum alloy according to claim 9, wherein, The weld elongation rate of the aluminum alloy obtained by the welding is not less than 3.5%; preferably not less than 3.8 - 4.2%; the tensile strength of the aluminum alloy obtained by the welding is 330 - 350MPa or more, preferably 338 - 350MPa or more.