Active magnesium alloy welding wire and preparation method and application thereof

Abstract

The invention relates to the technical field of welding wires, in particular to an active magnesium alloy welding wire and a preparation method and application thereof. The active magnesium alloy welding wire comprises magnesium alloy and an active agent dispersed and filled in the magnesium alloy. Wherein the activating agent comprises ZnCl2, TiO2 and CeO2 according to the mass ratio of (40-45): (40-45): (10-20), and the mass ratio of the magnesium alloy to the activating agent is (10-20): 1. When the active magnesium alloy welding wire is adopted for active welding, wire filling is easy, uniform and attractive welding seams can be formed, the welding penetration depth is obviously increased, welding passes can be reduced during thick plate welding, welding deformation is restrained, and the joint performance is improved.

Description

Technical Field

[0001] This invention relates to the field of welding wire technology, and more specifically, to an active magnesium alloy welding wire, its preparation method, and its application. Background Technology

[0002] Magnesium alloys possess advantages such as low density and high specific strength, making them widely used in aerospace and automotive electronics fields. In engineering applications, besides some thin-plate welding, magnesium alloys are frequently used for thick-plate welding. Due to their high thermal conductivity, magnesium alloys exhibit shallow penetration during welding, especially when welding thick plates, requiring multi-layer, multi-pass welding. However, because magnesium alloys have a low melting point, multi-layer, multi-pass welding can lead to severe overheating of the weld joint, significantly degrading its performance. Activating flux TIG welding (A-TIG welding) is a welding method that involves coating the base metal surface with an activator before welding. Under the same welding parameters, compared to conventional TIG welding, the activator causes arc contraction and increases arc force, ultimately increasing weld penetration. However, the traditional method of coating the base metal with an activator suffers from drawbacks such as difficulty in filler wire application and poor weld formation during active welding.

[0003] Therefore, it is of great significance to provide a composite magnesium alloy welding wire with a built-in activator that can increase the penetration depth and reduce the number of welding passes, while overcoming the problems of difficult wire filling and difficult weld formation during active welding.

[0004] Patent CN200710010464.0 proposes a method for composite active magnesium alloy welding wire, which uses flux-cored welding wire technology to uniformly encapsulate the activator in the welding wire, or coats the surface of solid magnesium alloy welding wire with the activator, and then dries it before use. Patent CN200910261249.7 discloses a method for applying activator to active welding wire, using polyethylene glycol with a molecular weight of 2000-20000 as a binder. The activator is mixed evenly with polyethylene glycol and heated into a paste, then applied through a constant-temperature material cylinder. The activator is then evenly distributed on the surface of the welding wire using a wire drawing die, and finally air-dried at room temperature or coated onto the surface of the welding wire using a drying oven. Patent CN201811227684.3 discloses a method for welding carbon nanotube-reinforced aluminum / magnesium alloy thick plates, using a pure aluminum outer sheath to wrap a mixture of carbon nanotubes and composite active flux to create a novel active welding wire for welding aluminum or magnesium alloy thick plates.

[0005] It is evident that the commonly used method in the production of activated welding wire is to coat the surface of magnesium alloy welding wire with an activator. This is achieved by mixing the activator with a binder and then coating the wire surface manually or mechanically. While this method is low-cost and relatively easy to implement, it suffers from drawbacks such as binder contamination of the activator, poor coating adhesion, difficulty in controlling the activator content, and the activator adhering to the welding wire surface, which hinders automated welding. Although improvements can be made in the binder composition and the shape of the welding wire surface, such as the use of polyethylene glycol as a binder or a non-circular cross-section design mentioned in the aforementioned patent CN200910261249.7, the prepared activated welding wire still struggles to meet the requirements of mechanical wire feeding or automated equipment. Under external forces (the welding wire surface is subjected to compression during machining or wire filling), the activator on the welding wire surface can still detach, leading to unstable welding results.

[0006] Another production method for activated welding wire is similar to the preparation process of flux-cored welding wire. This involves encapsulating and sealing the activator in a magnesium or aluminum alloy sheath, followed by a drawing process to produce the wire. However, magnesium alloys have poor plasticity, leading to asynchronous deformation of the activator core and the metal sheath during rolling. Furthermore, the proportion of activator in different locations is difficult to control, resulting in issues such as powder leakage, powder breakage, or hollow areas, leading to unstable activity and a low yield rate. Moreover, the preparation of the magnesium alloy sheath is difficult and complex due to its poor plasticity, ultimately resulting in high production costs for activated welding wire and limiting its development and application.

[0007] Furthermore, existing technologies also employ vacuum encapsulation-evacuation sealing-hot extrusion or hot isostatic pressing to prepare active welding wire. However, after practical verification, this process suffers from problems such as difficulty in sealing after evacuation, low efficiency, and reduced vacuum levels, making it difficult to guarantee the purity of the magnesium alloy after hot pressing. Moreover, the vacuum encapsulation method requires advanced welding techniques, has low production efficiency, and results in unstable weld seal quality.

[0008] In view of this, the present invention is hereby proposed. Summary of the Invention

[0009] The primary objective of this invention is to provide an active magnesium alloy welding wire. When using this active magnesium alloy welding wire, it facilitates wire filling during active welding, produces uniform and aesthetically pleasing welds, and significantly increases weld penetration. This reduces the number of welding passes in thick plate welding, suppresses welding deformation, and improves joint performance. It solves the problems of difficult wire filling and poor weld formation during active welding associated with traditional methods that involve coating the base material with an activator.

[0010] The second objective of this invention is to provide a method for preparing active magnesium alloy welding wire. This method employs a cold isostatic pressing-hot extrusion ingot forming process. Cold isostatic pressing removes most of the air from the powder at room temperature. Then, the hot extrusion process utilizes the venting operation and the addition of ZnCl2 activator to remove the oxide film, further reducing the oxygen content in the active magnesium alloy welding wire. This achieves the goals of easy operation, reliability, high efficiency, low cost, short process flow, and more stable quality. It solves the problems of existing methods using vacuum encapsulation-evacuation sealing-hot extrusion or hot isostatic pressing, such as difficulty in sealing after evacuation, low efficiency, reduced vacuum level leading to difficulty in ensuring the purity of the magnesium alloy after hot pressing, high requirements for welding technology, low production efficiency, and unstable weld sealing quality. Furthermore, hot extrusion wire forming completely fixes the uniform mixing state of the magnesium alloy and activator; ultrasonic drawing reduces the diameter, significantly reducing the drawing force and the number of drawing passes, improving surface finish, and making the diameter more uniform. The final active magnesium alloy welding wire has a uniform and densely embedded activator inside. The activator is uniformly sealed inside the welding wire, preventing contact with air and mechanical devices during transportation and use, thus avoiding contamination and detachment. This method is simple to operate, cost-controllable, technologically mature, and produces more stable quality, effectively meeting the needs of automated magnesium alloy welding. Compared to the traditional process of coating the surface of solid welding wire with activator, this invention eliminates the need for manual activator coating, significantly improving production efficiency and allowing for precise and quantitative control of activator dosage, effectively saving costs and reducing environmental pressure. It solves problems such as binder contamination of activator, uncontrollable dosage of activator applied manually, activator adhering to the welding wire surface hindering automated welding, and activator detachment leading to unstable welding results and low efficiency. It also eliminates phenomena such as activator leakage, broken powder, hollow cores, or uneven activator distribution found in flux-cored welding wires, and addresses the challenges of complex processing of magnesium alloy outer sheaths.

[0011] A third objective of this invention is to provide the application of active magnesium alloy welding wire or active magnesium alloy welding wire prepared according to the preparation method of active magnesium alloy welding wire in welding.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0013] The present invention first provides an active magnesium alloy welding wire, comprising a magnesium alloy and an activator dispersed and filled inside the magnesium alloy; wherein the activator comprises ZnCl2, TiO2 and CeO2 in a mass ratio of 40-45:40-45:10-20; and the mass ratio of the magnesium alloy to the activator is 10-20:1.

[0014] Furthermore, the magnesium alloy includes AZ61 magnesium alloy and / or AZ31B magnesium alloy.

[0015] Furthermore, the diameter of the active magnesium alloy welding wire is 1.6–2.4 mm.

[0016] The present invention further provides a method for preparing the above-mentioned active magnesium alloy welding wire, comprising the following steps: cold isostatic pressing of a mixed powder containing magnesium alloy and activator into a billet, hot extrusion into an ingot, wire making, and ultrasonic drawing to reduce the diameter, thereby obtaining the active magnesium alloy welding wire.

[0017] Furthermore, the particle size of the mixed powder is 100-300 mesh.

[0018] Furthermore, the blank obtained by the cold isostatic pressing is cylindrical in shape, with a diameter of 90-150 mm and a height of 100-300 mm.

[0019] Furthermore, the relative density of the blank obtained by the cold isostatic pressing is 90% to 95%.

[0020] Furthermore, the hot extrusion temperature of the hot extrusion ingot is 330–360°C.

[0021] Furthermore, the extrusion ratio of the hot extrusion ingot is 5 to 10:1.

[0022] Furthermore, after the hot extrusion ingot forming and before the wire forming, the following steps are also included: cutting the bar obtained by the hot extrusion ingot forming and then turning it to obtain a semi-finished ingot; wherein the thickness of the turning is 1 to 2 mm.

[0023] Furthermore, the temperature for spinning the yarn is 340–360°C.

[0024] Furthermore, the extrusion ratio of the filament is 100-200:1.

[0025] Furthermore, the ultrasonic frequency for the ultrasonic drawing diameter reduction is 14–16 kHz.

[0026] Furthermore, the ultrasonic drawing reduction diameter reduction has a drawing compression ratio of 3 to 9:1.

[0027] Furthermore, after the ultrasonic drawing and diameter reduction, the method further includes the steps of scraping and sizing the welding wire obtained after the ultrasonic drawing and diameter reduction.

[0028] The present invention also provides the application of the above-mentioned active magnesium alloy welding wire or the active magnesium alloy welding wire prepared by the above-mentioned method in welding.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The active magnesium alloy welding wire provided by the present invention is easy to fill during welding, can form a uniform and beautiful weld, and significantly increases the welding penetration. It can reduce the number of welding passes when welding thick plates, suppress welding deformation, and improve joint performance. It solves the problems of difficult filling of wire and difficult weld formation during active welding in the traditional method of coating the base material with activator.

[0031] (2) The active magnesium alloy welding wire provided by the present invention is easy to obtain, cheap, environmentally friendly, does not have side effects on the welding process, and can simplify the welding process and improve production efficiency.

[0032] (3) The preparation method of the active magnesium alloy welding wire provided by the present invention adopts a cold isostatic pressing billet-hot extrusion ingot method. Through cold isostatic pressing, most of the air in the powder is first removed at room temperature. Then, the oxygen content in the active magnesium alloy welding wire is further reduced by utilizing the venting operation during hot extrusion and the addition of ZnCl2 activator to remove the oxide film. This achieves the goals of easy operation, reliability, high efficiency, low cost, short process flow, and more stable quality. It solves the problems of existing technologies using vacuum encapsulation-evacuation sealing-hot extrusion or hot isostatic pressing, such as difficulty in sealing after evacuation, low efficiency, reduced vacuum degree leading to difficulty in ensuring the purity of the magnesium alloy after hot pressing, high requirements for welding technology, low production efficiency, and unstable welding seal quality.

[0033] (4) The preparation method of the active magnesium alloy welding wire provided by the present invention completely fixes the uniform mixing state of magnesium alloy and activator through hot extrusion wire forming; then, ultrasonic drawing reduces the diameter, significantly reduces the drawing force, significantly reduces the number of drawing passes, improves the surface finish, and makes the diameter more uniform; the final active magnesium alloy welding wire has a uniform and densely embedded activator inside. The activator is uniformly sealed inside the welding wire, avoiding contact with air and mechanical devices during transportation and use, and will not cause pollution or shedding. This method is simple to operate, cost-controllable, mature in process, and more stable in quality, which can well meet the needs of automated magnesium alloy welding. Compared with the traditional process of coating the surface of solid welding wire with activator, the present invention does not require manual coating of activator, which not only greatly improves production efficiency, but also allows for precise and quantitative control of the amount of activator, effectively saving costs and reducing environmental pressure. It solves the problems of binder contamination of activator, uncontrollable dosage of activator when manually applied, activator adhering to the surface of welding wire which is not conducive to automated welding, and activator easy to fall off, resulting in unstable welding effect and low efficiency. It also eliminates the phenomenon of activator leakage, broken powder and hollow, or uneven distribution of activator in flux-cored welding wire. In addition, it solves the problems of high processing difficulty and complex process of magnesium alloy outer skin.

[0034] (5) The preparation method of active magnesium alloy welding wire provided by the present invention adopts ultrasonic drawing process, which can effectively avoid the situation that the welding wire is difficult to draw due to insufficient processing performance caused by the composite of active agent, and greatly improve production efficiency. Attached Figure Description

[0035] 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.

[0036] Figure 1 A cross-sectional microstructure diagram of the active magnesium alloy welding wire prepared in Example 1 of this invention;

[0037] Figure 2 Another cross-sectional microstructure of the active magnesium alloy welding wire prepared in Example 1 of this invention;

[0038] Figure 3 A cross-sectional microstructure diagram of the active magnesium alloy welding wire prepared in Comparative Example 1 provided by the present invention;

[0039] Figure 4 Another cross-sectional microstructure diagram of the active magnesium alloy welding wire prepared in Comparative Example 1 provided by the present invention. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0041] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0042] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0043] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0044] In a first aspect, the present invention provides an active magnesium alloy welding wire comprising a magnesium alloy and an activator dispersed and filled within the magnesium alloy.

[0045] Magnesium alloy is used as the sealant metal.

[0046] Understandably, the active magnesium alloy welding wire is filamentous. Using filamentous composite welding wire with its own activator facilitates wire filling and can form a uniform and aesthetically pleasing weld.

[0047] It is understandable that magnesium alloys are formed from magnesium alloy powder. During preparation, the activator and magnesium alloy powder are evenly dispersed together. Therefore, the activator in the active magnesium alloy welding wire is evenly sealed inside the magnesium alloy or the welding wire.

[0048] The activator comprises ZnCl2, TiO2, and CeO2 in a mass ratio of 40–45 (e.g., 40, 41, 42, 43, 44, or 45): 40–45 (e.g., 40, 41, 42, 43, 44, or 45): 10–20 (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20). At this ratio, the activator interacts significantly with the electric arc, causing the arc to contract, thereby significantly increasing the weld penetration. Furthermore, this activator is readily available, inexpensive, environmentally friendly, and does not produce any side effects on the welding process.

[0049] TiO2 possesses advantages such as being non-toxic, having optimal opacity, whiteness, and brightness. It also exhibits a high dielectric constant, excellent electrical properties, and semiconductor characteristics. Its conductivity increases rapidly with temperature, and it is highly sensitive to oxygen deficiency.

[0050] ZnCl2 not only has good activity and can significantly increase melting depth, but it can also be used as a film removal component to remove small amounts of oxides generated by hot extrusion; at the same time, ZnCl2 is harmless to the environment and human body.

[0051] The oxygen element in rare earth oxide CeO2 can alter the surface energy of liquid metal, causing a change in the surface tension gradient of the molten pool and thus increasing the weld penetration. Furthermore, the rare earth element Ce can refine the microstructure and remove hydrogen. In other words, CeO2 not only increases weld penetration but also effectively purifies the molten pool, refines the grain structure, and improves weld performance.

[0052] ZnCl2, TiO2, and CeO2 have large atomic radii and high electron affinity, allowing this activator to interact significantly with the electric arc, causing it to contract and thus significantly increasing the weld penetration. Furthermore, this activator is readily available, inexpensive, environmentally friendly, and does not produce any side effects on the welding process.

[0053] The mass ratio of the magnesium alloy to the activator is 10–20:1, for example, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1. This effectively increases the weld penetration of the magnesium alloy, reduces the number of welding passes in thick plate welding, suppresses welding deformation, and improves joint performance.

[0054] The active magnesium alloy welding wire provided by this invention is a composite magnesium alloy welding material with its own activator. This active magnesium alloy welding wire overcomes the shortcomings of the traditional method of coating the base material with activator, which has the disadvantages of difficult wire filling and difficult weld formation during active welding. Compared with the traditional method of coating the base material with activator, the active magnesium alloy welding wire of this invention is easy to fill with wire during active welding, can form a uniform and beautiful weld, and significantly increases the welding penetration. It can reduce the number of welding passes when welding thick plates, suppress welding deformation, improve joint performance, simplify the welding process, and improve production efficiency.

[0055] In some specific implementations, the magnesium alloy is determined based on the actual base material being welded, with the principle being to ensure that the alloy composition of the welding wire is consistent with that of the base material.

[0056] In some specific embodiments, the magnesium alloy includes AZ61 magnesium alloy and / or AZ31B magnesium alloy.

[0057] Among them, AZ61 magnesium alloy has a tendency to resist cracking and can be used to weld aluminum-containing magnesium alloys, making it widely applicable.

[0058] In some specific embodiments, the diameter of the active magnesium alloy welding wire is 1.6–2.4 mm, including but not limited to any one of 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, and 2.4 mm, or a range between any two. Specifically, the diameter of the active magnesium alloy welding wire can be selected according to the thickness of the welding plate, and various specifications of welding wire can be prepared to adapt to the welding requirements of base materials of different thicknesses.

[0059] Secondly, the present invention provides a method for preparing the above-mentioned active magnesium alloy welding wire, comprising the following steps: cold isostatically pressing a mixed powder containing magnesium alloy and activator into a billet to obtain a billet. Then, the billet is preheated and hot-extruded into an ingot (or hot-extruded into a rod) to obtain an ingot. The ingot is then hot-extruded into a wire to obtain a wire. Finally, the wire is ultrasonically drawn to reduce its diameter to obtain the active magnesium alloy welding wire.

[0060] This invention uses powder metallurgy to prepare active magnesium alloy welding wire. First, the magnesium alloy powder and the activator powder are mixed evenly to ensure the uniform distribution of the activator in the welding wire. Then, the wire is sequentially subjected to cold isostatic pressing, hot extrusion ingot making, wire making, and ultrasonic drawing for diameter reduction.

[0061] Cold isostatic pressing effectively increases the density of the billet while minimizing the oxidation of magnesium alloy powder by air. Hot extrusion further increases the density, resulting in a semi-finished ingot that closely resembles a metallic material. Since magnesium alloys are highly susceptible to oxidation, especially at high temperatures, the process of this invention significantly reduces the likelihood of oxidation of magnesium alloy powder at high temperatures compared to common direct hot pressing and sintering methods. Furthermore, ZnCl2, one of the activators in this invention, not only acts as an activator but also serves as a flux removal component in magnesium alloy brazing. ZnCl2 effectively removes the oxide film on the surface of the magnesium alloy, thus even if the cold isostatically pressed billet is slightly oxidized during hot extrusion, the activator ZnCl2 can effectively remove the oxide film.

[0062] This invention employs a cold isostatic pressing-hot extrusion method for billet preparation. Through cold isostatic pressing, over 95% of the air in the powder is expelled at room temperature. Then, the venting process during hot extrusion and the addition of ZnCl2 activator further reduce the oxygen content in the active magnesium alloy welding wire, achieving the goals of easy operation, reliability, high efficiency, low cost, short process flow, and more stable quality (high product density, isotropy, and good microstructure consistency). This solves the problems of existing methods using vacuum encapsulation-evacuation sealing-hot extrusion or hot isostatic pressing, which suffer from difficulties in sealing after evacuation, low efficiency, reduced vacuum levels leading to difficulties in ensuring the purity of the magnesium alloy after hot pressing, high welding technology requirements, low production efficiency, and unstable weld seal quality.

[0063] Furthermore, hot extrusion wire forming completely fixes the uniform mixing state of the magnesium alloy and activator. Ultrasonic drawing then reduces the wire diameter, significantly decreasing the drawing force and the number of drawing passes, improving surface finish, and resulting in a more uniform diameter. The final active magnesium alloy welding wire has a smooth magnesium alloy surface and a uniformly and densely embedded activator inside. The activator is uniformly sealed inside the welding wire, preventing contact with air and mechanical devices during transportation and use, thus avoiding contamination and shedding. Compared to the traditional process of coating the surface of solid welding wire with activator, this invention eliminates the need for manual activator coating, greatly improving production efficiency and allowing for precise and quantitative control of activator dosage, effectively saving costs and reducing environmental impact. It eliminates the problems of binder contamination of activator, uncontrollable dosage of activator applied manually, activator adhering to the welding wire surface which is not conducive to automated welding, and activator easy to fall off, resulting in unstable welding effect and low efficiency. At the same time, it also eliminates the phenomenon of activator leakage, broken powder and hollow, or uneven distribution of activator, which are similar to flux-cored welding wire. It solves the problems of high processing difficulty and complex process of magnesium alloy outer skin. The cost is controllable, the quality stability is good, and it can well meet the needs of automated welding of magnesium alloy.

[0064] It is understandable that magnesium alloys have only 3 geometric slip systems and 2 independent slip systems at room temperature, resulting in low plasticity. They can usually only be hot drawn. The addition of composite activators in this invention further exacerbates the insufficient drawing performance of composite magnesium alloy welding wires. However, ultrasonic drawing offers significant advantages: it can greatly reduce drawing force, significantly reduce the number of drawing passes, achieve high surface finish, and produce uniform diameters. It is particularly suitable for fine and brittle wires and certain composite materials. Moreover, ultrasonic drawing requires low ultrasonic power and can be easily modified from ordinary drawing equipment, making it easy to implement in industrial production.

[0065] In other words, ultrasonic drawing process can effectively avoid the situation where the welding wire is difficult to draw due to insufficient machinability caused by activator composite, and greatly improve production efficiency.

[0066] In some specific embodiments, the preparation method of the mixed powder containing magnesium alloy and activator includes: vacuum drying magnesium alloy powder and activator, then mixing the activator and magnesium alloy powder in a certain proportion, and placing them in a vacuum ball mill mixer for mixing under vacuum or gas protection, wherein the mixing time can be 20 to 60 minutes.

[0067] In some specific embodiments, the particle size of the mixed powder is 100-300 mesh, including but not limited to the values ​​of any one of 100 mesh, 150 mesh, 200 mesh, 250 mesh, and 300 mesh, or any range between two of them. This particle size range can effectively ensure that the magnesium alloy powder and the activator powder are fully mixed, while the powder particle specific surface area is moderate, which can effectively reduce the degree of oxidation of the powder during subsequent pressing processing.

[0068] In some specific embodiments, the blank obtained by cold isostatic pressing is cylindrical in shape. The diameter of the blank is 90-150 mm, including but not limited to any one of 90 mm, 100 mm, 110 mm, 120 mm, 130 mm, 140 mm, and 150 mm, or a range between any two. The height of the blank is 100-300 mm, including but not limited to any one of 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 230 mm, 250 mm, 270 mm, and 300 mm, or a range between any two.

[0069] In some specific embodiments, the relative density of the billet obtained by the cold isostatic pressing is 90% to 95%, including but not limited to the point value of any one of 90%, 91%, 92%, 93%, 94%, and 95%, or the range between any two.

[0070] In some specific embodiments, the mixed powder is loaded into an elastic mold in a specified amount and transferred to a cold isostatic pressing device for pressing. Cold isostatic pressing can remove air from the billet and, to some extent, prevent air oxidation.

[0071] Cold isostatic pressing (COP) is more efficient and stable than the encapsulation and vacuuming method. The process of filling powder, encapsulating, and vacuuming is not only complex and inefficient, but also makes it difficult to guarantee quality stability, heavily relying on the airtightness of the encapsulation and the degree of vacuuming. Furthermore, compared to hot isostatic pressing, COP avoids rapid oxidation of the powder during high-temperature compression, minimizes oxidation during compression at room temperature, significantly improves density, and reduces oxidation during subsequent extrusion rod making.

[0072] In some specific embodiments, the hot extrusion temperature of the hot extrusion ingot is 330 to 360°C, for example, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C or 360°C.

[0073] In some specific implementations, the billet is preheated in a resistance furnace at a temperature of 300°C for 60 minutes. Simultaneously, the hot extrusion die is preheated at 330–360°C. Preheating the billet in the furnace improves efficiency, allowing for the simultaneous preheating of multiple billets and ensuring continuous, high-efficiency production. If the preheating temperature is too low, the extrusion pressure increases, placing higher demands on the die and equipment; if the preheating temperature is too high, the extruded material may crack. The preheated billet is then quickly transferred to the extrusion die, maintaining the die temperature at the hot extrusion temperature for hot extrusion.

[0074] In some specific embodiments, the extrusion ratio of the hot extrusion ingot is 5 to 10:1, including but not limited to any one of 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1, or any range between two of them. If the extrusion ratio is too high, it may result in the ingot not being extruded or damage to the mold.

[0075] In some specific embodiments, after the hot extrusion ingot forming and before the wire forming, the following steps are also included: cutting the bar obtained by the hot extrusion ingot forming and then turning it to obtain a semi-finished ingot.

[0076] The thickness of the turning process is 1 to 2 mm, including but not limited to the point value of any one of 1 mm, 1.2 mm, 1.3 mm, 1.5 mm, 1.8 mm, and 2 mm, or the range between any two.

[0077] Turning before hot extrusion wire cutting can remove the aluminum foil coating and surface defects on the spindle surface, namely the surface oxide defect layer formed during the hot extrusion of the billet.

[0078] It is understandable that the surface temperature of the bar stock is high after extrusion through the die, making it easy to react with oxygen in the air to form MgO. At the same time, the surface of the bar stock will be contaminated with debris and scratches during the cutting process, forming an oxide defect layer.

[0079] Understandably, the length of bars produced by continuous hot extrusion can reach several meters or even tens of meters, so they need to be cut to facilitate subsequent processing.

[0080] In some specific embodiments, the wire forming is hot extrusion wire forming, and the hot extrusion wire forming temperature is 340-360°C, for example 340°C, 345°C, 350°C, 355°C, or 360°C. However, if the hot extrusion wire forming temperature is too high, the extruded metal material is prone to cracking or even breakage.

[0081] In some specific implementations, the semi-finished ingot is preheated, for example, at a preheating temperature of 320°C, and then hot extrusion is performed to produce fibers.

[0082] In some specific embodiments, the extrusion ratio of the filaments is 100-200:1, including but not limited to any one of 100:1, 120:1, 130:1, 150:1, 180:1, and 200:1, or a range between any two. If the extrusion ratio is too low, the extruded filaments will not have sufficient density, resulting in insufficient filament strength, breakage, and affecting subsequent processing.

[0083] In some specific embodiments, the extruded filament is subjected to room temperature ultrasonic drawing to reduce its diameter according to the target size. The ultrasonic frequency for ultrasonic drawing to reduce the diameter is 14-16 kHz, preferably 15 kHz. When ultrasonic waves are used for drawing within this frequency range, the drawing force can be significantly reduced, the number of drawing passes can be significantly reduced, the surface finish can be high, and the diameter can be uniform.

[0084] In some specific embodiments, the ultrasonic drawing compression ratio for diameter reduction is 3 to 9:1, including but not limited to the point value of any one of 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, and 9:1, or the range between any two.

[0085] In some specific embodiments, after the ultrasonic drawing and diameter reduction, the welding wire obtained after the ultrasonic drawing and diameter reduction is further subjected to mechanical scraping and polycrystalline die sizing to remove defects and oil stains on the surface of the welding wire and improve the surface finish.

[0086] Thirdly, the present invention provides the application of the above-mentioned active magnesium alloy welding wire or the active magnesium alloy welding wire prepared according to the above-mentioned method for preparing active magnesium alloy welding wire in welding.

[0087] The active magnesium alloy welding wire and its preparation method provided by this invention have broad application prospects, such as in aerospace, automotive electronics and other fields.

[0088] When using this active magnesium alloy welding wire, it is easy to fill the wire, can form a uniform and beautiful weld, and the weld penetration depth is significantly increased. It can reduce the number of welding passes when welding thick plates, suppress welding deformation, improve joint performance, simplify the welding process, and improve production efficiency.

[0089] Furthermore, the above preparation method is simple to operate, reliable, efficient, low-cost, and has a short process flow. The resulting product has high density, isotropy, and good microstructure consistency, which can meet the requirements of automated welding of magnesium alloys.

[0090] 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.

[0091] Example 1

[0092] The method for preparing the active magnesium alloy welding wire provided in this embodiment includes the following steps:

[0093] (1) The AZ61 magnesium alloy powder and the activator were vacuum dried respectively, wherein the AZ61 magnesium alloy powder was used as the filler metal and the activator was ZnCl2, TiO2 and CeO2 in a mass ratio of 40:40:20.

[0094] (2) Mix AZ61 magnesium alloy powder and activator in a mass ratio of 10:1 and place them in a vacuum ball mill mixer. Mix them under an argon atmosphere for 30 minutes. The particle size of the mixed powder obtained after mixing is 100 mesh.

[0095] (3) The mixed powder is loaded into an elastic mold and transferred to a cold isostatic pressing device for pressing into a blank. The resulting blank is... A cylindrical blank (shaped like a cylinder) with a diameter of 120mm and a height of 250mm has a relative density of 90%. The purpose of cold isostatic pressing is to remove air from the blank and to isolate it from oxidation to a certain extent.

[0096] (4) Place the prepared billet into the resistance furnace for preheating. The preheating temperature is 300℃ and the preheating holding time is 60min. At the same time as preheating the billet, preheat the hot extrusion ingot mold at a temperature of 350℃.

[0097] (5) Quickly transfer the preheated billet to the extrusion briquette mold, keep the mold temperature at 350°C, and perform hot extrusion briquette making with an extrusion ratio of 5:1.

[0098] (6) After cutting the semi-finished bar obtained by hot extrusion, it is machined into a semi-finished ingot with a cutting length of 120mm and a machining thickness of 1.5mm.

[0099] (7) Preheat the semi-finished ingot to 320°C; then extrude it at 350°C with an extrusion ratio of 100:1.

[0100] (8) Based on the target size, the extruded filament is subjected to room temperature ultrasonic drawing to reduce the diameter. The drawing compression ratio is 5:1 and the ultrasonic frequency is 15kHz.

[0101] (9) The ultrasonically drawn welding wire is mechanically scraped and sized using a polycrystalline die to obtain an active AZ61 magnesium alloy welding wire with the following specifications: (diameter) 2.0mm.

[0102] Example 2

[0103] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in Example 1, except that: in step (2), the mass ratio of AZ61 magnesium alloy powder to activator is 20:1, and the particle size of the mixed powder obtained after mixing is 300 mesh.

[0104] Example 3

[0105] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in embodiment 1, except that in step (5), the extrusion ratio of hot extrusion rod is 10:1.

[0106] Example 4

[0107] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in embodiment 1, except that in step (7), the extrusion ratio of the extrusion wire is 200:1.

[0108] Example 5

[0109] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in Example 1, except that in step (2), the mass ratio of AZ61 magnesium alloy powder to activator is 15:1.

[0110] Example 6

[0111] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in Example 1, except that in step (1), the mass ratio of ZnCl2, TiO2 and CeO2 is 45:45:10.

[0112] Example 7

[0113] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in Example 1, except that in step (1), the mass ratio of ZnCl2, TiO2 and CeO2 is 42:42:16.

[0114] Example 8

[0115] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in embodiment 1, except that: in step (8), the drawing compression ratio of ultrasonic drawing is 9:1.

[0116] Example 9

[0117] The method for preparing the active magnesium alloy welding wire provided in this embodiment includes the following steps:

[0118] (1) The AZ61 magnesium alloy powder and the activator were vacuum dried respectively, wherein the AZ61 magnesium alloy powder was used as the filler metal and the activator was ZnCl2, TiO2 and CeO2 in a mass ratio of 41:41:18.

[0119] (2) Mix AZ61 magnesium alloy powder and activator in a mass ratio of 12:1 and place them in a vacuum ball mill mixer. Mix them under an argon atmosphere for 40 minutes. The particle size of the mixed powder is 250 mesh.

[0120] (3) The mixed powder is loaded into an elastic mold and transferred to a cold isostatic pressing device for pressing into a blank. The resulting blank is... A cylindrical blank (shaped like a cylinder) with a diameter of 90mm and a height of 150mm has a relative density of 95%. The purpose of cold isostatic pressing is to remove air from the blank and to isolate it from oxidation to a certain extent.

[0121] (4) Place the prepared billet into the resistance furnace for preheating. The preheating temperature is 300℃ and the preheating holding time is 60min. At the same time as preheating the billet, preheat the hot extrusion ingot mold at a temperature of 330℃.

[0122] (5) Quickly transfer the preheated billet to the extrusion briquette mold, keep the mold temperature at 330°C, and perform hot extrusion briquette making with an extrusion ratio of 8:1.

[0123] (6) After cutting the semi-finished bar obtained by hot extrusion, it is machined into a semi-finished ingot with a cutting length of 120mm and a machining thickness of 2mm.

[0124] (7) Preheat the semi-finished ingot to 320°C; then extrude it at 360°C with an extrusion ratio of 150:1.

[0125] (8) Based on the target size, the extruded filament is subjected to room temperature ultrasonic drawing to reduce the diameter. The drawing compression ratio is 3:1 and the ultrasonic frequency is 15.5kHz.

[0126] (9) The ultrasonically drawn welding wire is mechanically scraped and sized using a polycrystalline die to obtain an active AZ61 magnesium alloy welding wire with the following specifications: (Diameter) 2.2mm.

[0127] Example 10

[0128] The preparation method of the active magnesium alloy welding wire provided in this embodiment is basically the same as that in embodiment 9, except that in steps (1) and (2), AZ61 magnesium alloy powder is replaced with AZ31B magnesium alloy powder.

[0129] Comparative Example 1

[0130] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (2), the mass ratio of AZ61 magnesium alloy powder to activator is 5:1.

[0131] Comparative Example 2

[0132] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (2), the mass ratio of AZ61 magnesium alloy powder to activator is 30:1.

[0133] Comparative Example 3

[0134] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (5), the extrusion ratio of hot extrusion rod is 3:1.

[0135] Comparative Example 4

[0136] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (7), the extrusion ratio of the extrusion wire is 50:1.

[0137] Comparative Example 5

[0138] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (1), the mass ratio of ZnCl2, TiO2 and CeO2 is 60:30:10.

[0139] Comparative Example 6

[0140] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (1), the mass ratio of ZnCl2, TiO2 and CeO2 is 10:70:20.

[0141] Comparative Example 7

[0142] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, except that in step (1), the mass ratio of ZnCl2, TiO2 and CeO2 is 10:10:80.

[0143] Comparative Example 8

[0144] The preparation method of the active magnesium alloy welding wire provided in this comparative example is basically the same as that in Example 1, the only difference is that CeO2 is not added to the activator in step (1), that is, the mass ratio of ZnCl2 and TiO2 is 50:50.

[0145] Experimental Example

[0146] Welding was performed using the active magnesium alloy welding wires prepared in each embodiment and comparative example. The welding parameters were as follows: welding speed 300 mm / min, welding current 100 A, shielding gas flow rate 10 L / min, and the base material was AZ61 magnesium alloy plate of 200 mm × 150 mm × 5 mm. After welding, the weld seam was cut and sampled. By macroscopic observation of the weld seam cross-section, the penetration depth of different magnesium alloy welding wires was statistically analyzed. The mechanical properties of the weld joint were tested according to GB / T2651-2008 "Tension Test Method for Welded Joints" to obtain the tensile strength and elongation of the weld joint. The test results are shown in Table 1 below.

[0147] Table 1. Test results of melt depth, tensile strength and elongation.

[0148]

[0149]

[0150] The cross-sectional microstructure of the active magnesium alloy welding wire prepared in Example 1 is shown in the figure below. Figure 1 and Figure 2 As shown. The cross-sectional microstructure of the active magnesium alloy welding wire prepared in Comparative Example 1 is shown in the figure. Figure 3 and Figure 4 As shown. See also Figures 1-4 The white area represents the AZ61 magnesium alloy matrix, while the black blocky areas represent the activator. In Example 1, the mass ratio of magnesium alloy to activator was 10:1. The black activator was evenly distributed within the magnesium alloy matrix with a moderate density, which is beneficial for subsequent processing of the composite welding wire. In Comparative Example 1, the mass ratio of magnesium alloy to activator was 5:1, meaning the activator content was doubled. This resulted in a significant increase in the density of the black blocky areas and an increase in large, agglomerated black areas. While this increased the weld penetration to some extent, excessive penetration could lead to hot cracks and porosity, thus reducing mechanical properties. Furthermore, the excessive presence of activator in the welding wire structure also reduced the wire's plastic deformation capacity and machinability.

[0151] As can be seen from Table 1, the welding penetration depth of the active magnesium alloy welding wires prepared using each embodiment is significantly increased, and the tensile strength and elongation of the weld joint are high.

[0152] In contrast, Comparative Example 1, due to its excessively high proportion of activator, although the penetration depth increased, it was highly susceptible to hot cracking and porosity during welding, resulting in a decrease in the mechanical properties of the weld joint.

[0153] In Comparative Example 2, the low proportion of activator resulted in a significant reduction in penetration depth and a decrease in the mechanical properties of the weld joint.

[0154] In Comparative Example 3, the low extrusion ratio during hot extrusion resulted in insufficient density of the bar stock, leading to gaseous impurities in the extruded wire. This caused spatter and oxidation during welding, reducing the mechanical properties of the weld joint.

[0155] Comparative Example 4 shows that the extrusion ratio of the extrusion wire is too high, resulting in a discontinuous extrusion process, low extrusion efficiency, and easy die blockage. Although it does not have a critical impact on the performance of the welding wire, it increases the processing difficulty and requires high-end equipment.

[0156] In Comparative Example 5, the content of ZnCl2 was significantly higher than that of TiO2, which weakened the grain refinement effect of TiO2. However, the higher content of ZnCl2 could increase the weld penetration depth. However, relative to the optimal ratio, the weld penetration depth was slightly lower, and the overall mechanical properties of the weld decreased.

[0157] In Comparative Example 6, the TiO2 content was significantly higher than the ZnCl2 content, which weakened the increase in weld penetration. However, the TiO2 particles' effect on microstructure refinement compensated to some extent for the impact of insufficient weld penetration on mechanical properties.

[0158] In Comparative Example 7, the excessive CeO2 content led to a reduction in the proportion of activator, which was insufficient to increase the weld penetration depth. Although CeO2 has a certain effect on increasing penetration depth, its main function is to purify the molten pool and refine the microstructure grains to improve weld performance. Therefore, the weld penetration depth was insufficient, which limited the mechanical properties of the weld joint.

[0159] Comparative Example 8 showed that the absence of CeO2 resulted in increased weld porosity and decreased strength and plasticity.

[0160] It is evident that the present invention, using activators with specific compositions and dosages, can significantly increase weld penetration, suppress weld deformation, and improve joint performance. Furthermore, by employing specific preparation parameters, the mechanical properties of the weld joint can be further enhanced.

[0161] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can 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, without departing from the spirit and scope of the present invention; and these 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; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. An active magnesium alloy welding wire, characterized in that, Includes a magnesium alloy and an active agent dispersed and filled inside the magnesium alloy; The active agent comprises ZnCl2, TiO2 and CeO2 in a mass ratio of 40-45:40-45:10-20; The mass ratio of the magnesium alloy to the activator is 10-20:

1.

2. The active magnesium alloy welding wire according to claim 1, characterized in that, The magnesium alloys include AZ61 magnesium alloy and / or AZ31B magnesium alloy.

3. The active magnesium alloy welding wire according to claim 1, characterized in that, The diameter of the active magnesium alloy welding wire is 1.6 to 2.4 mm.

4. The method for preparing the active magnesium alloy welding wire according to any one of claims 1 to 3, characterized in that, Includes the following steps: The active magnesium alloy welding wire is obtained by cold isostatic pressing of a mixed powder containing magnesium alloy and activator into a billet, hot extrusion into an ingot, wire making, and ultrasonic drawing to reduce the diameter.

5. The method for preparing the active magnesium alloy welding wire according to claim 4, characterized in that, The particle size of the mixed powder is 100-300 mesh.

6. The method for preparing the active magnesium alloy welding wire according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The blank obtained by cold isostatic pressing is cylindrical in shape, with a diameter of 90-150 mm and a height of 100-300 mm. (2) The relative density of the blank obtained by cold isostatic pressing is 90% to 95%.

7. The method for preparing the active magnesium alloy welding wire according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The hot extrusion temperature of the hot extrusion ingot is 330-360℃; (2) The extrusion ratio of the hot extrusion ingot is 5 to 10:1; (3) After the hot extrusion ingot making and before the wire making, the following steps are also included: after cutting the bar obtained by the hot extrusion ingot making, it is turned to obtain a semi-finished ingot; wherein the thickness of the turning is 1 to 2 mm.

8. The method for preparing the active magnesium alloy welding wire according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The temperature for making the yarn is 340-360℃; (2) The extrusion ratio of the filament is 100-200:

1.

9. The method for preparing the active magnesium alloy welding wire according to claim 4, characterized in that, At least one of the following conditions must be met: (1) The ultrasonic frequency of the ultrasonic drawing diameter reduction is 14-16 kHz. (2) The ultrasonic drawing reduction ratio is 3 to 9:1; (3) After the ultrasonic drawing and diameter reduction, the method further includes the step of scraping and sizing the welding wire obtained after the ultrasonic drawing and diameter reduction.

10. The application of the active magnesium alloy welding wire according to any one of claims 1 to 3 or the active magnesium alloy welding wire prepared by the preparation method according to any one of claims 4 to 9 in welding.

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