Self-cleaning aluminum alloy welding material preparation method, system and aluminum alloy welding material

Abstract

This invention relates to the field of alloy purification technology, specifically to a method, system, and aluminum alloy welding material for preparation of self-purifying aluminum alloy welding material. The method for preparing the self-purifying aluminum alloy welding material includes the following steps: cold pressing a mixture of aluminum alloy powder and refining agent powder to obtain a cold-pressed billet; hot pressing the cold-pressed billet to obtain a hot-pressed aluminum ingot; removing impurities from the surface of the hot-pressed aluminum ingot, followed by preheating to obtain a preheated ingot; and extruding the preheated ingot into wire. This invention uses powder metallurgy to prepare aluminum alloy welding material with self-purifying function, extending the degassing method of aluminum alloy smelting to the aluminum alloy welding process. This relaxes the strict requirements on the hydrogen content of the aluminum alloy base material, achieving a weld with lower hydrogen content. The method is more efficient, more stable, and less expensive.

Description

Technical Field

[0001] This invention relates to the field of alloy purification technology, and more specifically, to a method, system, and aluminum alloy welding material for preparing self-purifying aluminum alloy welding material. Background Technology

[0002] Aluminum and aluminum alloys possess advantages such as high specific strength, fracture toughness, fatigue strength, and good formability, leading to their widespread application in aerospace, transportation, communications, and electronics industries. They are considered among the most promising environmentally friendly lightweight structural materials. Argon arc welding (argon arc welding), a welding technology with high design freedom, wide applicability, and high material utilization, is widely used in aluminum alloy welding. Due to the numerous applications of aluminum alloys, the requirements for their welding performance are gradually increasing. Among these, hydrogen content determines the fracture toughness, fatigue strength, and corrosion resistance of the weld. Excessive hydrogen content not only leads to defects such as porosity or looseness in the weld but also causes hydrogen embrittlement in high-strength aluminum alloys. Porosity and hydrogen embrittlement in aluminum alloy welds are mainly caused by the difference in solubility of hydrogen atoms in the liquid and solid phases of the aluminum alloy. The maximum solubility of hydrogen atoms in 100g of liquid pure aluminum exceeds 1mL, while the maximum solubility in 100g of solid pure aluminum is only 0.034mL. Due to the huge difference in hydrogen solubility between the liquid and solid phases, dissolved hydrogen in liquid aluminum alloys is difficult to completely precipitate during solidification. Supersaturated gases in aluminum alloys distribute in two ways: one is through the formation of defects such as pores or porosity; the other is by remaining in an unstable supersaturated state within the aluminum alloy, subsequently accumulating at crack tips or inclusions under heating or pressurization conditions, forming hydrogen molecules and leading to hydrogen embrittlement. The hydrogen content in aluminum alloy welds is controlled by adjusting the cleanliness of the welding materials and welding parameters. Since aluminum alloy welding materials are used as weld filler materials, they inevitably affect the hydrogen content of the aluminum alloy weld.

[0003] Currently, the main method for controlling the hydrogen content of aluminum alloy welding materials is to add trace amounts of rare earth elements during the smelting stage to achieve certain degassing and modification effects. For example, prior art one (application number CN201510688002.9) discloses an aluminum alloy refining agent containing cerium, yttrium, and erbium, which believes that rare earth elements can replace and adsorb impurity hydrogen in the melt to form complexes REH2 or REH3 to achieve degassing. Prior art two (application number CN201310011724.1) directly adds rare earth elements to the aluminum alloy composition. Utilizing the relatively active chemical properties of rare earth elements, they readily react with gases (such as hydrogen), nonmetals (such as sulfur), and metals to generate stable compounds with high melting points. At the same time, rare earth elements are highly reactive and can selectively adsorb at the interfaces of growing grains, hindering grain growth and thus leading to grain refinement and modification. The existing technology 3 (CN200510026593.X) removes hydrogen by adding an adsorbent (such as a gas or solid purifier) ​​to the aluminum melt, so that the adsorbent interacts with the aluminum melt chemically, physically or mechanically during the contact process.

[0004] Existing hydrogen removal methods suffer from drawbacks such as limited effectiveness, severe burn-off, and high costs. For example, the current price of rare earth metals Ce and La is 27,000 yuan / ton, and welding materials are susceptible to moisture and contamination during transportation and use, which may still introduce new hydrogen impurities. Inert gas dehydrogenation methods require long reaction times and the flow of the melt, but the short lifespan of the weld pool makes it difficult to provide sufficient dehydrogenation reaction time.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One objective of this invention is to provide a method for preparing self-cleaning aluminum alloy welding materials, thereby addressing the technical problems of existing methods for removing hydrogen from microalloyed welding materials, such as ineffectiveness, severe burn-off, and high cost.

[0007] Another objective of this invention is to provide an aluminum alloy welding material prepared by the aforementioned self-cleaning aluminum alloy welding material, which has a low hydrogen content.

[0008] Another object of the present invention is to provide a system used in the preparation method of the self-cleaning aluminum alloy welding material described above, which has the characteristics of high efficiency and stability.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0010] A method for preparing a self-cleaning aluminum alloy welding material includes the following steps:

[0011] A method for preparing a self-cleaning aluminum alloy welding material includes the following steps:

[0012] A mixture of aluminum alloy powder and refining agent powder is cold-pressed to obtain a cold-pressed billet; the cold-pressed billet is hot-pressed to obtain a hot-pressed aluminum ingot; impurities on the surface of the hot-pressed aluminum ingot are removed, and then it is preheated to obtain a preheated ingot; the preheated ingot is extruded into wire.

[0013] In one embodiment, the refining agent powder is pre-dried at a temperature of 100–250°C for 2–3 hours.

[0014] In one embodiment, the aluminum alloy powder and refining agent powder are mixed using a three-dimensional mixer for 30-60 minutes to obtain the mixture.

[0015] In one embodiment, the particle size of the aluminum alloy powder ranges from 20 to 200 mesh.

[0016] In one embodiment, the average particle size ratio of the aluminum alloy powder to the refining agent powder is (6.5-7.5):1.

[0017] In one embodiment, the mass content of the refining agent powder in the mixture of aluminum alloy powder and refining agent powder is 0.01% to 2%.

[0018] In one embodiment, the aluminum alloy powder is made of at least one of aluminum-silicon, aluminum-magnesium, aluminum-copper, and aluminum-manganese alloys.

[0019] In one embodiment, the refining agent powder comprises a first refining agent and / or a second refining agent.

[0020] In one embodiment, the first refining agent comprises, by mass percentage, 47% KCl, 30% NaCl, and 23% Na3AlF6;

[0021] In one embodiment, the second refining agent comprises, by mass percentage, 8% KCl, 67% MgCl2, 10% CaF2, and 15% MgF2.

[0022] In one embodiment, the diameter of the cold-pressed blank is 50-100 mm.

[0023] In one embodiment, the height-to-diameter ratio of the cold-pressed blank is (1.8 to 2.2):1.

[0024] In one embodiment, the hot pressing process specifically includes: preheating the cold-pressed blank and the hot pressing device used for the hot pressing process respectively; and placing the preheated cold-pressed blank into the preheated hot pressing device for extrusion.

[0025] In one embodiment, during the hot pressing process, the preheating temperature of the cold-pressed blank is 395–405°C, and the holding time is 25–35 min.

[0026] In one embodiment, during the hot pressing process, the preheating temperature of the hot pressing device is 420-520°C, and the holding time is 25-35 minutes.

[0027] In one embodiment, during the hot pressing process, the cold-pressed blank is subjected to a pressure of 480 to 750 MPa.

[0028] In one embodiment, removing impurities from the surface of the hot-pressed aluminum ingot specifically includes: cooling the hot-pressed aluminum ingot and then removing the impurities using mechanical or chemical cleaning methods.

[0029] In one embodiment, the preheating temperature of the preheated ingot is 400–450°C.

[0030] In one embodiment, the extrusion fiber forming process employs an extrusion fiber forming device; the extrusion fiber forming device undergoes a preheating treatment to a temperature of 450–550°C.

[0031] In one embodiment, the initial extrusion pressure during the extrusion fiber forming process is 500-1000 MPa.

[0032] In one embodiment, the method further includes: drawing and mechanically scraping the filament obtained by extrusion.

[0033] The aluminum alloy welding material prepared by the self-cleaning aluminum alloy welding material preparation method described above.

[0034] The system used to implement the preparation method of self-cleaning aluminum alloy welding material as described above includes a cold pressing unit for cold pressing the mixture, a hot pressing unit for hot pressing the cold-pressed billet, and an extrusion wire forming unit for extruding the preheated ingot into wire.

[0035] The cold pressing unit includes a cold pressing device; the cold pressing device includes a cold pressing cylinder and two cold extrusion rods; the hot pressing unit includes a hot pressing device; the hot pressing device includes a hot pressing cylinder, a hot extrusion pad, and a hot extrusion rod; the extrusion filament making unit includes an extrusion filament making device; the extrusion filament making device includes a hot extrusion filament making cylinder, a hot extrusion filament making rod, and an extrusion die.

[0036] In one embodiment, the wire-exiting die plate is provided with a plurality of wire-exiting through holes; the number of wire-exiting through holes is 2 to 15.

[0037] In one embodiment, the shape of the wire outlet hole includes circular and / or square.

[0038] In one embodiment, the system further includes a premixing device for uniformly mixing aluminum alloy powder with refining agent powder to obtain the mixture.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) This invention uses powder metallurgy to prepare aluminum alloy welding materials with self-cleaning function, and innovatively extends the degassing method of aluminum alloy smelting process to the aluminum alloy welding process to obtain welds with lower hydrogen content; it has greater applicability and can relax the strict requirements on the hydrogen content of the aluminum alloy base material itself. Using the welding wire of this invention, it is estimated that aluminum plates with hydrogen content ≤0.5mL / 100g Al can be selected; the method of this invention has the advantages of being more efficient, more stable, and lower in cost.

[0041] (2) The present invention uses powder metallurgy process to prepare composite aluminum alloy welding wire containing refining agent. Since the refining agent is uniformly distributed inside the aluminum alloy welding material, it can ensure that the aluminum alloy welding material has a stable and reliable degassing and impurity removal effect during the welding process, and at the same time avoid the phenomenon that the core or coating of the flux-cored or coated aluminum alloy welding material fails due to moisture during transportation and storage.

[0042] (3) The present invention uses extrusion to prepare wire. By adjusting the shape and size of the extrusion die, the size of the wire can be directly prepared to be closer to the target product. The final product can be obtained by simply drawing and cleaning as needed. The advantage is that it greatly reduces the rolling, drawing and annealing processes in the traditional aluminum alloy wire production process, which can significantly improve production efficiency. Attached Figure Description

[0043] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of the system used in the preparation method of the self-cleaning aluminum alloy welding material of the present invention;

[0045] Figure 2This is a diagram showing the porosity of the weld in Example 1 of X-ray flaw detection.

[0046] Figure 3 A diagram showing the porosity of the weld seam of 4047 solid welding wire under X-ray inspection;

[0047] Figure 4 This is a diagram showing the porosity of the weld in Comparative Example 2, obtained using X-ray flaw detection.

[0048] Figure label:

[0049] 1-Premixing device, 100-Cold pressing device, 2-Cold extrusion rod, 3-Cold pressing cylinder, 4-Cold pressing billet, 200-Hot pressing device, 5-Hot extrusion rod, 6-Hot pressing cylinder, 7-Hot pressing aluminum ingot, 8-Hot pressing pad, 300-Extrusion wire making device, 9-Hot extrusion wire making rod, 10-Hot extrusion wire making cylinder, 11-Wire exiting die, 12-Welding material. Detailed Implementation

[0050] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0051] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] According to one aspect of the present invention, the present invention relates to a method for preparing a self-cleaning aluminum alloy welding material, comprising the following steps:

[0054] A mixture of aluminum alloy powder and refining agent powder is cold-pressed to obtain a cold-pressed billet; the cold-pressed billet is hot-pressed to obtain a hot-pressed aluminum ingot; impurities on the surface of the hot-pressed aluminum ingot are removed, and then it is preheated to obtain a preheated ingot; the preheated ingot is extruded into wire.

[0055] This invention employs powder metallurgy to prepare aluminum alloy welding materials with self-cleaning functions, innovatively extending the degassing method from aluminum alloy smelting to the aluminum alloy welding process to achieve welds with lower hydrogen content. The welding materials of this invention have greater applicability, relaxing the stringent requirements on the hydrogen content of the aluminum alloy base material itself. Using the welding materials of this invention, it is estimated that aluminum plates with a hydrogen content ≤0.5mL / 100g Al can be selected; while existing technologies require the hydrogen content of the base material to be welded to be ≤0.4mL / 100g Al.

[0056] The cold pressing process employed in this invention serves several purposes: (1) it eliminates the interference of air (primarily oxygen) on subsequent extrusion wire production; when loosely packed aluminum powder is directly hot-extruded, the adhesion between aluminum powder particles makes it difficult to expel gas, which ultimately remains inside or on the surface of the welding wire, forming pores or bubbles. At the same time, the air inside the gas causes severe oxidation of the aluminum alloy powder; (2) it increases the density of the billet, transforming the aluminum powder with a large specific surface area into a dense billet with a small specific surface area at room temperature, greatly reducing the area in contact with air and further reducing the oxidation of aluminum powder during subsequent hot extrusion. If aluminum powder is directly hot-pressed without cold pressing, it will cause severe oxidation of the aluminum powder. At the same time, a large amount of gas remains inside the welding material, making the welding material prone to spattering during welding, resulting in an unstable arc, more oxidation inclusions in the weld, and an increase in the number of hydrogen pores.

[0057] This invention, through the aforementioned specific operational steps, yields a composite aluminum alloy welding wire containing a refining agent. Because the refining agent is uniformly distributed within the aluminum alloy welding material, it ensures stable and reliable degassing and impurity removal during welding. Simultaneously, it prevents the failure of flux-cored or coated aluminum alloy welding materials due to moisture absorption during transportation and storage. This invention employs extrusion to prepare the wire. By adjusting the shape and size of the extrusion die, dimensions closer to the target product can be directly produced. Subsequent simple drawing and cleaning are then performed as needed to obtain the final product. The advantage is a significant reduction in the rolling, drawing, and annealing processes required in traditional aluminum alloy wire production, resulting in a substantial improvement in production efficiency.

[0058] Compared to the microalloying method for degassing, this invention offers advantages such as higher efficiency, greater stability, and lower cost. Typically, microalloying involves adding a small amount of rare earth alloying elements during the aluminum alloy welding process. The current mainstream explanation is that rare earth elements readily combine with hydrogen in the molten aluminum alloy to form compounds, thereby solidifying the hydrogen atoms and preventing them from combining to form hydrogen gas and creating pores. However, this method suffers from problems such as ineffective degassing and high cost. Since the mechanism of rare earth elements in degassing aluminum alloys is still unclear, how to efficiently utilize rare earths or other microalloying methods for degassing remains an unsolved problem. Furthermore, rare earth elements are expensive; for example, cerium and lanthanum, rare earth elements with significant degassing effects, cost 25-30 yuan / kg, while commonly used aluminum alloy refining agents cost less than 10 yuan / kg. Moreover, rare earth elements are easily burned off in the molten aluminum alloy. Considering the double burning loss during smelting and welding, increasing the rare earth element content is necessary to ensure effective degassing, further increasing production costs.

[0059] In one embodiment, the refining agent powder is pre-dried at a temperature of 100–250°C, such as 100°C, 120°C, 150°C, 170°C, 190°C, 200°C, 220°C, or 250°C; and for a duration of 2–3 hours, such as 2 hours, 2.2 hours, 2.5 hours, 2.7 hours, or 3 hours. In one embodiment, the refining agent powder is dried using a vacuum drying oven. In one embodiment, the dried refining agent powder is sieved to obtain a refining agent powder with a suitable mesh size range.

[0060] In one embodiment, aluminum alloy powder is subjected to gas-protected ball milling and sieving to obtain brazing filler metal powder with a suitable mesh size range.

[0061] In one embodiment, a three-dimensional mixer is used to mix the aluminum alloy powder and the refining agent powder for a mixing time of 30–60 minutes, such as 30, 35, 40, 45, 50, 55, or 60 minutes, to obtain the mixture. This invention uses a three-dimensional mixer with stirring blades to mix the aluminum alloy powder and the refining agent powder; that is, it employs a dual-motion mixing method, where the external mechanism performs three-dimensional motion while internal blades enhance stirring.

[0062] In one embodiment, the refining agent powder has a particle size of 110-1340 mesh, such as 110 mesh, 200 mesh, 300 mesh, 600 mesh, or 1340 mesh. In another embodiment, the 110-1340 mesh refining agent powder is produced by ball milling the refining agent raw material. In one embodiment, the aluminum alloy powder has a particle size of 20-200 mesh, such as 20 mesh, 50 mesh, 100 mesh, 150 mesh, or 200 mesh. In another embodiment, the aluminum alloy powder includes spherical powder, but non-spherical powder can also be used. The particle size and ratio of the aluminum alloy and refining agent can be appropriately adjusted, in principle ensuring that the two powders are mixed evenly and achieve the degassing effect.

[0063] In one embodiment, the particle size of the refining agent powder is smaller than that of the aluminum alloy powder, allowing the refining agent to be uniformly distributed within the alloy welding material. In another embodiment, the average particle size ratio of the aluminum alloy powder to the refining agent powder is (6.5–7.5):1, for example, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.1:1, 7.2:1, 7.3:1, or 7.4:1. The particle sizes of the refining agent powder and the aluminum alloy powder need to be within a suitable range. If the particle size difference between the refining agent and the aluminum alloy is large, and the particle size of the refining agent is much larger than that of the aluminum-silicon alloy powder, the refining agent cannot be uniformly distributed in the aluminum alloy welding material. Furthermore, large particles of refining agent can easily cause the extruded wire to break, making welding impossible. In one embodiment, the present invention uses a laser particle size analyzer to test the average particle size values ​​of the refining agent powder and the aluminum alloy powder.

[0064] In one embodiment, the mass content of the refining agent powder in the mixture of aluminum alloy powder and refining agent powder is 0.01% to 2%, for example, 0.01%, 0.03%, 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, or 2%. The amount of refining agent powder added in this invention needs to be within a suitable range. If the amount of refining agent added is too low, it cannot effectively remove hydrogen; if the amount of refining agent added is too high, the welding wire strength decreases, the processing performance deteriorates, the wire is prone to breakage, and spatter is easily generated during argon arc welding, which destroys the protective effect of argon gas on the molten pool and affects the weld quality.

[0065] In one embodiment, the aluminum alloy powder is made of at least one of aluminum-silicon, aluminum-magnesium, aluminum-copper, and aluminum-manganese alloys, and other aluminum alloy powders in the prior art may also be selected.

[0066] In one embodiment, the refining agent powder comprises a first refining agent and / or a second refining agent.

[0067] In one embodiment, the first refining agent comprises, by mass percentage, 47% KCl, 30% NaCl, and 23% Na3AlF6. The first refining agent of this invention is used for refining aluminum alloys other than those containing magnesium. Because alloys with a magnesium content ≥2% are prone to "sodium embrittlement," sodium salt refining agents are not permitted for high-magnesium alloys.

[0068] In one embodiment, the second refining agent comprises, by mass percentage, 8% KCl, 67% MgCl2, 10% CaF2, and 15% MgF2.

[0069] In one embodiment, during the cold pressing process, the mixture is subjected to a pressure of 80 to 120 MPa, such as 80 MPa, 85 MPa, 90 MPa, 95 MPa, 100 MPa, 110 MPa, or 120 MPa.

[0070] In one embodiment, the diameter of the cold-pressed blank is 50-100 mm, for example, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, or 100 mm. In another embodiment, the height-to-diameter ratio of the cold-pressed blank is (1.8-2.2):1, for example, 1.8:1, 2:1, or 2.2:1.

[0071] In one embodiment, the hot pressing process specifically includes: preheating the cold-pressed blank and the hot pressing device used for the hot pressing process respectively; and placing the preheated cold-pressed blank into the preheated hot pressing device for extrusion.

[0072] In one embodiment, during the hot pressing process, the preheating temperature of the cold-pressed blank is 395-405℃, such as 395℃, 398℃, 400℃, 402℃, 405℃, etc., and the holding time is 25-35min, such as 30min.

[0073] In one embodiment, during the hot pressing process, the preheating temperature of the hot pressing mold is 420-520°C, such as 420°C, 440°C, 480°C, 520°C, etc., and the holding time is 25-35 minutes, such as 30 minutes.

[0074] In one embodiment, during the hot pressing process, the cold-pressed blank is subjected to a pressure of 480–750 MPa, such as 500 MPa, 550 MPa, 580 MPa, 600 MPa, 620 MPa, 650 MPa, 680 MPa, 700 MPa, 720 MPa, and 750 MPa. The pressure during the hot pressing process of this invention needs to be within a suitable range. If the pressure is too low, the gap between the aluminum alloy powder and the refining agent powder will not be fully sealed, resulting in a lower density of the aluminum alloy welding wire, making the wire prone to breakage. Furthermore, the gas trapped inside the gap will enter the molten pool during welding, increasing the hydrogen content of the weld.

[0075] In one embodiment, during the hot pressing process, the pressure holding time is 3 to 5 minutes, for example, 3.5 minutes, 4 minutes or 4.5 minutes.

[0076] In one embodiment, the diameter of the hot-pressed aluminum ingot is 50-100mm, such as 50mm, 70mm, 80mm or 100mm; and the height is 80-160mm, such as 80mm, 100mm, 120mm or 160mm.

[0077] In one embodiment, removing impurities from the surface of the hot-pressed aluminum ingot specifically includes: cooling the hot-pressed aluminum ingot and then removing the impurities using mechanical or chemical cleaning methods.

[0078] In one embodiment, the preheating temperature of the preheated ingot is 400-450°C, such as 400°C, 420°C, 450°C, etc.

[0079] In one embodiment, the extrusion fiber forming process employs an extrusion fiber forming device; the extrusion fiber forming device undergoes a preheating treatment to a temperature of 450–550°C, such as 450°C, 500°C, 520°C, 550°C, etc.

[0080] In one embodiment, the preheating involved in this invention uses a resistance furnace, but other preheating methods can also be used as long as the desired effect is achieved.

[0081] In one embodiment, during the extrusion fiber production process, the initial extrusion pressure is 500-1000 MPa, such as 500 MPa, 750 MPa, 800 MPa, 850 MPa, 950 MPa, 1000 MPa, etc.

[0082] In one embodiment, the method further includes: drawing and mechanically scraping the filament obtained by extrusion to achieve the required dimensions and surface finish.

[0083] According to another aspect of the present invention, the present invention also relates to aluminum alloy welding materials prepared by the method described above for preparing self-cleaning aluminum alloy welding materials.

[0084] According to another aspect of the present invention, the present invention also relates to a system used in carrying out the preparation method of the self-cleaning aluminum alloy welding material, comprising a cold pressing unit for cold pressing a mixture, a hot pressing unit for hot pressing a cold-pressed billet, and an extrusion wire forming unit for extruding a preheated ingot into wire.

[0085] The cold pressing unit includes a cold pressing device; the cold pressing device includes a cold pressing cylinder and two cold extrusion rods; in one embodiment, the two cold extrusion rods are located at the top and bottom of the cold pressing cylinder, respectively, and the two cold extrusion rods are matched with the inner diameter of the cold pressing cylinder to extrude the material inside; the hot pressing unit includes a hot pressing device; the hot pressing device includes a hot pressing cylinder, a hot extrusion pad, and a hot extrusion rod; in one embodiment, the hot extrusion pad is located at the bottom of the hot pressing cylinder, and the hot extrusion rod is located at the top of the hot extrusion cylinder to extrude the material inside the hot extrusion cylinder; the extrusion wire forming unit includes an extrusion wire forming device; the extrusion wire forming device includes a hot extrusion wire forming cylinder, a hot extrusion wire forming rod, and an extrusion die; in one embodiment, the extrusion die is located at the bottom of the hot extrusion wire forming cylinder, and the hot extrusion wire forming rod is matched with the inner diameter of the hot extrusion wire forming cylinder to extrude the spindle inside to form wire.

[0086] The present invention can prepare aluminum alloy welding materials with low hydrogen content through the above system.

[0087] In one embodiment, the wire-exiting die plate is provided with a plurality of wire-exiting through holes; the number of wire-exiting through holes is 2 to 15, for example 4, 8, 12, 14, etc.

[0088] In one embodiment, the shape of the wire outlet hole includes circular and / or square.

[0089] In one embodiment, the diameter of the circular wire exit hole is 2.8–3.2 mm. In another embodiment, the side length of the square wire exit hole is 1.8–2.2 mm.

[0090] In one embodiment, the system further includes a premixing device for uniformly mixing aluminum alloy powder with refining agent powder to obtain the mixture.

[0091] In a preferred embodiment, a method for preparing a self-cleaning aluminum alloy welding material includes the following steps:

[0092] (a) The refining agent powder is pre-dried at a temperature of 100–250°C for 2–3 hours, and then sieved to obtain a refining agent powder with a particle size of 110–1340 mesh; the aluminum alloy powder is ball-milled and sieved under gas protection to obtain an aluminum alloy powder with a particle size of 20–200 mesh; the aluminum alloy powder and the refining agent powder are mixed evenly using a three-dimensional mixer to obtain a mixture; in the mixture, the mass content of the refining agent powder is 0.01%–2%;

[0093] (b) The mixture from step (a) is subjected to cold pressing to obtain a cold-pressed blank; during the cold pressing process, the mixture is subjected to a pressure of 80-120 MPa; the diameter of the cold-pressed blank is 50-100 mm; and the height-to-diameter ratio of the cold-pressed blank is (1.8-2.2):1.

[0094] (c) The cold-pressed billet is subjected to hot pressing to obtain a hot-pressed aluminum ingot; impurities on the surface of the hot-pressed aluminum ingot are removed, and then preheated to obtain a preheated ingot; wherein, the hot pressing process specifically includes: preheating the cold-pressed billet and the hot pressing device used for the hot pressing process respectively; placing the preheated cold-pressed billet in the preheated hot pressing device for extrusion, wherein the preheating temperature of the cold-pressed billet is 395-405℃, the holding time is 25-35min, the preheating temperature of the hot pressing device is 420-520℃, the holding time is 25-35min; the pressure on the cold-pressed billet is 480-750MPa; and the holding time is 3-5min.

[0095] (d) The preheated ingot is extruded into filaments at a temperature of 400-450°C. The extrusion process is carried out using an extrusion filament device. The extrusion filament device is preheated to a temperature of 450-550°C. During the extrusion process, the initial extrusion pressure is 500-1000 MPa. The filaments obtained from the extrusion process are then drawn and mechanically scraped.

[0096] The following explanation is provided in conjunction with specific embodiments, comparative examples, and accompanying drawings.

[0097] The systems used in the preparation methods of self-cleaning aluminum alloy welding materials in various embodiments of the present invention, such as... Figure 1As shown, the system includes a premixing device 1 for uniformly mixing aluminum alloy powder and refining agent powder to obtain a homogeneous mixture; a cold pressing device 100 for cold pressing the mixture to obtain a cold-pressed billet 4; a hot pressing device 200 for hot pressing the cold-pressed billet 4 to obtain a hot-pressed aluminum ingot 7; and an extrusion wire forming device 300 for extruding the preheated ingot into wire. The cold pressing device 100 includes a cold pressing cylinder 3 and two cold extrusion rods 2; the hot pressing device 200 includes a hot pressing cylinder 6, a hot extrusion rod 5, and a hot pressing pad 8; and the extrusion wire forming device 300 includes a hot extrusion wire forming cylinder 10, a hot extrusion wire forming rod 9, and a wire exiting die 11. The system is used to obtain welding material 12.

[0098] Example 1

[0099] A method for preparing a self-cleaning aluminum alloy welding material includes the following steps:

[0100] (1) The refining agent powder is pre-dried at a temperature of 135℃ for 2.5h, then ground and sieved to obtain 600-mesh refining agent powder; a three-dimensional mixer with stirring blades is used to mix the ground refining agent powder with spherical alloy powder for 30min to obtain mixed powder; wherein, the refining agent, by mass ratio, includes KCl 8%, MgCl2 67%, CaF2 10% and MgF2 15%, and the amount of refining agent added is 0.03%; the spherical aluminum alloy powder is composed of AlSi12 and has a particle size of 90 mesh;

[0101] (2) Place an appropriate amount of mixed powder in a cold pressing device 100 to form a blank, and obtain a cold-pressed blank; the diameter of the cold-pressed blank is 58mm and the height is 120mm.

[0102] (3) The cold-pressed billet is placed in the resistance furnace for preheating. The preheating temperature of the cold-pressed billet is 400℃ and the holding time is 30min. At the same time, the hot pressing device 200, which is about to be hot-pressed into ingots, is preheated and held at a temperature of 450℃.

[0103] (4) The preheated billet is quickly transferred to the hot press cylinder 6 of the hot press device 200 for extrusion and ingot making. The inner diameter of the hot press cylinder is 60mm, the pressure on the billet is 500MPa, and the holding time is 4min.

[0104] (5) Unload the pressure and eject the aluminum ingot that has been hot-pressed and sintered. After the aluminum ingot cools down, it is machined to remove surface impurities. The aluminum ingot is placed in an electric resistance furnace and preheated to 435°C. The extrusion wire making device 300 is preheated to 485°C and kept warm. The inner diameter of the hot extrusion wire making cylinder 10 of the extrusion wire making device 300 is 60mm, and the wire outlet is 4 round holes with a diameter of 3mm.

[0105] (6) Quickly place the preheated aluminum ingot into the hot extrusion wire forming cylinder 10 of the extrusion wire forming device 300. Apply load to the hot extrusion wire forming rod. During the extrusion wire forming process, the initial extrusion pressure is 760MPa. Wires are extruded through the wire exiting hole of the wire exiting die 11. The wire is taken up by the wire taking-up device.

[0106] (7) The extruded filaments are drawn and mechanically scraped to achieve the required size and surface finish.

[0107] Example 2

[0108] A method for preparing self-cleaning aluminum alloy welding material, except that the particle size of the refining agent powder is 1340 mesh and the particle size of the spherical aluminum alloy powder is 200 mesh, and other conditions are the same as in Example 1.

[0109] Example 3

[0110] A method for preparing a self-cleaning aluminum alloy welding material, except that the amount of refining agent added is 0.5%, the chemical composition of the aluminum alloy spherical powder is AlMg4.5Mn0.7, and other conditions are the same as in Example 1.

[0111] Example 4

[0112] A method for preparing a self-cleaning aluminum alloy welding material, wherein the diameter of the cold-pressed blank in step (2) is 98mm and the height is 200mm; the inner diameter of the hot-pressed cylinder 6 in step (4) is 100mm; and the inner diameter of the hot-extruded wire-making cylinder 10 in step (5) is 100mm, the wire outlet hole is 12 holes, and the wire cross-section is a square wire of 2mm×2mm.

[0113] Example 5

[0114] A method for preparing a self-cleaning aluminum alloy welding material, wherein the refining agent, by mass percentage, includes 47% KCl, 30% NaCl, and 23% Na3AlF6; in step (3), the preheating temperature of the cold-pressed billet is 395°C, the holding time is 35 min, and the preheating temperature of the hot pressing device 200 is 430°C; in step (4), the pressure on the billet is 600 MPa, and the holding time is 3.5 min; in step (5), the aluminum ingot is placed in a resistance furnace and preheated to 400°C, and the extrusion wire forming device 300 is preheated to 450°C and held at that temperature, and other conditions are the same as in Example 1.

[0115] Example 6

[0116] A method for preparing a self-cleaning aluminum alloy welding material, wherein in step (3), the preheating temperature of the cold-pressed billet is 405°C and the holding time is 25 min, and the preheating temperature of the hot pressing device 200 is 500°C; in step (4), the pressure value of the billet is 750 MPa and the holding time is 3 min; in step (5), the aluminum ingot is placed in the resistance furnace and preheated to 450°C, and the extrusion wire making device 300 is preheated to 550°C and held at that temperature, and other conditions are the same as in Example 1.

[0117] Example 7

[0118] A method for preparing a self-cleaning aluminum alloy welding material, except that the amount of refining agent added is 2%, the chemical composition of the aluminum alloy spherical powder is AlMg4.5Mn0.7, and other conditions are the same as in Example 1.

[0119] Example 8

[0120] A method for preparing self-cleaning aluminum alloy welding material, except that the particle size of the refining agent powder is 110 mesh and the particle size of the spherical aluminum alloy powder is 20 mesh, and other conditions are the same as in Example 1.

[0121] Example 9

[0122] A method for preparing a self-cleaning aluminum alloy welding material, except that the drying temperature is 250°C and the time is 3 hours, and the ground refining agent powder is mixed with spherical alloy powder for 60 minutes, and other conditions are the same as in Example 1.

[0123] Comparative Example 1

[0124] The preparation method of aluminum alloy welding material is the same as in Example 1, except that in step (1), the aluminum alloy refining agent is ball-milled into 30-mesh powder and the particle size of the spherical aluminum alloy powder is 200 mesh.

[0125] Comparative Example 2

[0126] The preparation method of aluminum alloy welding material is the same as in Example 1, except that the amount of refining agent added in step (1) is 0.001%.

[0127] Comparative Example 3

[0128] The preparation method of aluminum alloy welding material is the same as in Example 1, except that the amount of refining agent added in step (1) is 3%.

[0129] Comparative Example 4

[0130] The preparation method of aluminum alloy welding material is the same as in Example 1, except that the pressure value of the billet in step (4) is 300MPa.

[0131] Comparative Example 5

[0132] The preparation method of aluminum alloy welding material is the same as in Example 1, except that the drying temperature in step (1) is 80°C and the time is 1h, and the ground refining agent powder is mixed with spherical alloy powder for 20min.

[0133] Experimental Example

[0134] The conventional solid welding wire, the welding wire of the embodiment, and the welding wire of the comparative example were respectively used to weld with 6061 base material. The specific operation steps are as follows:

[0135] (1) Check whether the wiring and cooling system of the welding equipment are working properly;

[0136] (2) Select appropriate welding parameters based on the diameter of the welding material and the thickness of the base material. Here, the diameter of the welding rod is 2mm, the thickness of the base material is 5mm, and the welding current is AC, with a current of 90 to 150A.

[0137] (3) Select appropriate tungsten needle size, tungsten electrode diameter of 3mm, nozzle inner diameter of 10mm, and argon flow rate of 10L / min;

[0138] (4) Hold the welding torch in your right hand and bring it close to the base material and start the arc. Keep the arc at an appropriate length. After the base material forms a molten pool, move the welding torch slightly back and hold the welding rod in your left hand to quickly contact the front end of the molten pool. After the welding rod melts into the molten pool, move the welding torch to the front end of the molten pool to complete one welding operation. Continue to work together to repeat the above operations until a complete weld is completed.

[0139] The hydrogen content of the 4047 solid welding wire, the welding wire of the example, and the welding wire of the comparative example, the hydrogen content of the base metal, and the hydrogen content of the weld center area were tested respectively, and the X-ray flaw detection level was evaluated. The results are shown in Table 1.

[0140] Table 1 Test Results

[0141]

[0142] As shown in Table 1, the aluminum alloy welding material obtained by the specific method of this invention has a low hydrogen content. Welding using this aluminum alloy welding material results in a low hydrogen content in the weld, and the X-ray flaw detection rating is Class II. Specifically, the weld porosity in Example 1 of X-ray flaw detection is as follows: Figure 2 As shown; the porosity of the weld seam of 4047 solid welding wire detected by X-ray inspection is as follows. Figure 3 As shown, the flaw detection level is Class III; the weld porosity in Comparative Example 2 obtained by X-ray flaw detection is as follows. Figure 4 As shown, the flaw detection level is Level IV.

[0143] In Comparative Example 1, the particle size of the refining agent powder is much larger than that of the aluminum-silicon alloy powder, which causes the refining agent to be unable to be evenly distributed in the aluminum alloy welding material. At the same time, the large particles of refining agent can easily cause the extruded wire to break, making welding impossible.

[0144] The refining agent content in Comparative Example 2 was too low to effectively remove hydrogen, and the hydrogen content of the resulting welding wire was higher than that of the welding wire in Example 1 of this application.

[0145] The excessive amount of refining agent in Comparative Example 3 resulted in a higher hydrogen content in the welding wire compared to the example, leading to a decrease in wire strength, poorer processing performance, and increased susceptibility to wire breakage. Furthermore, it caused spatter during argon arc welding, which compromised the protective effect of argon gas on the molten pool and affected weld quality.

[0146] In Comparative Example 4, the billet was subjected to lower pressure during hot extrusion ingot forming, which resulted in the gap between the aluminum alloy powder and the refining agent powder not being fully sealed. This ultimately led to a lower density of the aluminum alloy welding wire, making the wire prone to breakage. Furthermore, the gas remaining inside the gap entered the molten pool during welding, increasing the hydrogen content of the weld.

[0147] In Comparative Example 5, the refining agent was dried at a lower temperature and for a shorter time, which resulted in the incomplete removal of moisture from the refining agent. When extruding aluminum welding wire, the moisture in the refining agent would seriously interfere with the welding process, causing spatter. At the same time, the presence of water would lead to the generation of a large number of hydrogen pores in the weld.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a self-cleaning aluminum alloy welding material, characterized in that, Includes the following steps: A mixture of aluminum alloy powder and refining agent powder is cold-pressed to obtain a cold-pressed billet; the cold-pressed billet is hot-pressed to obtain a hot-pressed aluminum ingot; impurities on the surface of the hot-pressed aluminum ingot are removed, and then it is preheated to obtain a preheated ingot; the preheated ingot is extruded into wire. In the mixture of aluminum alloy powder and refining agent powder, the mass content of refining agent powder is 0.01%~2%; during the hot pressing process, the pressure on the cold-pressed billet is 480~750MPa.

2. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The refining agent powder is pre-dried at a temperature of 100~250℃ for 2~3 hours. (2) The aluminum alloy powder and the refining agent powder are mixed using a three-dimensional mixer for 30-60 minutes to obtain the mixture.

3. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The particle size range of the aluminum alloy powder is 20~200 mesh; (2) The average particle size ratio of the aluminum alloy powder to the refining agent powder is (6.5~7.5):

1.

4. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (4): (1) The material of the aluminum alloy powder includes at least one of aluminum-silicon, aluminum-magnesium, aluminum-copper and aluminum-manganese; (2) The refining agent powder includes a first refining agent and / or a second refining agent; (3) By mass percentage, the first refining agent comprises 47% KCl, 30% NaCl, and 23% Na3AlF6; (4) The second refining agent comprises, by mass percentage, 8% KCl, 67% MgCl2, 10% CaF2 and 15% MgF2.

5. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (2): (1) The diameter of the cold-pressed blank is 50~100mm; (2) The height-to-diameter ratio of the cold-pressed billet is (1.8~2.2):

1.

6. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (3): (1) The hot pressing process specifically includes: preheating the cold-pressed blank and the hot pressing device used for the hot pressing process respectively; and placing the preheated cold-pressed blank into the preheated hot pressing device for extrusion. (2) During the hot pressing process, the preheating temperature of the cold-pressed blank is 395~405℃, and the holding time is 25~35min; (3) During the hot pressing process, the preheating temperature of the hot pressing device is 420~520℃ and the heat preservation time is 25~35min.

7. The method for preparing self-cleaning aluminum alloy welding material according to claim 1, characterized in that, It includes at least one of the following features (1) to (5): (1) Removing impurities from the surface of the hot-pressed aluminum ingot, specifically including: cooling the hot-pressed aluminum ingot and then removing the impurities by mechanical or chemical cleaning methods; (2) The preheating temperature of the preheated ingot is 400~450℃; (3) The extrusion fiber forming process is carried out using an extrusion fiber forming device; the extrusion fiber forming device is preheated to a temperature of 450~550℃; (4) During the extrusion fiber production process, the initial extrusion pressure is 500~1000MPa; (5) also includes: drawing and mechanically scraping the filaments obtained by extrusion.

8. The aluminum alloy welding material prepared by the method described in any one of claims 1 to 7.

9. The system used in the method for preparing self-cleaning aluminum alloy welding material according to any one of claims 1 to 7, characterized in that, It includes a cold pressing unit for cold pressing the mixture, a hot pressing unit for hot pressing the cold-pressed billet, and an extrusion wire forming unit for extruding preheated ingots into wire. The cold pressing unit includes a cold pressing device; the cold pressing device includes a cold pressing cylinder and two cold extrusion rods; the hot pressing unit includes a hot pressing device; the hot pressing device includes a hot pressing cylinder, a hot extrusion pad, and a hot extrusion rod; the extrusion filament making unit includes an extrusion filament making device; the extrusion filament making device includes a hot extrusion filament making cylinder, a hot extrusion filament making rod, and an extrusion die.

10. The system according to claim 9, characterized in that, It includes at least one of the following features (1) to (3): (1) The wire-exiting die plate is provided with a plurality of wire-exiting through holes; the number of wire-exiting through holes is 2 to 15; (2) The shape of the wire outlet hole includes circular and / or square; (3) The system further includes a premixing device; the premixing device is used to mix aluminum alloy powder and refining agent powder evenly to obtain the mixture.

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