A method for preparing an alloy material for an induction furnace, a purification device thereof, and a method for using the same

Abstract

The application discloses a preparation method of alloy material for an induction furnace, a purification device and a use method thereof, and belongs to the technical field of special metallurgy. The preparation method of the alloy material comprises the following steps: high-temperature alloy return material in the form of shavings is compressed under high pressure to form a cylindrical metal consumable electrode; then, the metal consumable electrode is subjected to remelting treatment under an oxidizing atmosphere and an oxidizing slag system; after the remelting is completed, vacuum refining is carried out in a vacuum induction furnace; during the refining process, a high-purity carbon tube with holes is used to perform deoxidation, denitrification and dehydrogenation treatment on the alloy melt; after the refining is completed, the alloy melt is poured into a steel ingot with a specified specification, and used as a raw material for smelting high-purity base material. The method can realize efficient recycling of a large amount of high-temperature alloy return material, effectively reduce the content of harmful gas in the high-temperature alloy return material, and finally prepare super-pure alloy material for the induction furnace.

Description

Technical Field

[0001] This invention belongs to the field of special metallurgical technology, and more specifically, relates to a method for preparing low-nitrogen, low-oxygen, and low-hydrogen alloy materials for induction furnaces using high-temperature alloy recycled materials, a purification device, and a method for using them. Background Technology

[0002] High-temperature alloys are widely used in key fields such as aviation, aerospace, petroleum, chemical industry, and shipbuilding due to their excellent comprehensive properties, including high-temperature strength, oxidation resistance, corrosion resistance, fatigue resistance, and fracture toughness. Currently, common smelting processes for high-temperature alloys include vacuum induction melting, electroslag remelting, and vacuum arc remelting. Regardless of the process used, surface treatment of the electrodes or intermediate products is usually required before proceeding to the next stage. For example, electroslag ingots after electroslag remelting need to be machined and peeled before vacuum arc remelting, and forged products also require surface machining. These processes generate a large amount of machining chips, i.e., shaving-like high-temperature alloy reclaimed material.

[0003] Efficiently recycling and utilizing the aforementioned recycled materials is crucial for reducing the production cost of high-temperature alloys. However, high-temperature alloys typically contain high levels of reactive alloying elements such as aluminum (Al) and titanium (Ti). Directly using recycled materials for vacuum induction melting presents the following technical challenges: First, the surface of high-temperature alloy return materials is prone to oxidation during turning, storage, and transportation, and they become contaminated with non-metallic inclusions, oil, and other pollutants. Simultaneously, the return materials themselves contain a significant amount of original inclusions (such as oxides and nitrides). These inclusions, when directly introduced into the smelting system, significantly reduce the purity of the alloy, and are difficult to completely remove even with subsequent refining. Second, Al and Ti in the return materials are easily oxidized during smelting, generating large amounts of non-metallic inclusions such as Al₂O₃ and TiO₂, further deteriorating the alloy's cleanliness. Furthermore, one of the important functions of vacuum induction melting is the removal of nitrogen (N) from molten steel; however, Ti has a strong affinity for N, forming stable TiN, which inhibits nitrogen removal, making it extremely difficult to obtain ultra-low nitrogen materials.

[0004] Therefore, existing technologies make it difficult to achieve large-scale recycling of high-temperature alloy recycled materials. In production practice, only a small amount of recycled materials can usually be added, and the main raw materials are still pure metals or new materials, resulting in high production costs. Summary of the Invention

[0005] To address the challenges of large-scale recycling of existing high-temperature alloy scrap and the relatively high manufacturing cost of high-temperature alloys, this invention provides a method for preparing alloy materials for induction furnaces. This method enables efficient and clean utilization of high-temperature alloy scrap and effectively reduces the content of harmful gases (nitrogen, oxygen, and hydrogen) and inclusion levels in the alloy, thereby significantly lowering the manufacturing cost of high-temperature alloys.

[0006] In addition, the present invention also provides a purification device for preparing the above-mentioned alloy material for induction furnace. By optimizing the structure of the purification device, deep deoxidation, denitrification and dehydrogenation are achieved under vacuum conditions during the refining process, thereby obtaining ultra-pure alloy material for induction furnace with low nitrogen, low oxygen and low hydrogen.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides a method for preparing alloy material for induction furnaces using recycled high-temperature alloy material, comprising the following steps: (1) The high-temperature alloy return material in the shape of shavings is compressed under high pressure to make a cylindrical metal consumable electrode; (2) The consumable electrode is subjected to electroslag remelting under an oxidizing atmosphere and an oxidizing slag system; (3) After grinding and dividing the remelted ingot obtained by electroslag remelting in step (2), it is added to a vacuum induction furnace for vacuum refining. During the refining process, a perforated high-purity carbon tube is used as a purification device to deoxidize, denitrify and dehydrogenate the alloy melt. The purification device is directly inserted into the alloy liquid and argon gas is introduced into the high-purity carbon tube, while electromagnetic stirring is carried out simultaneously. (4) After refining, the alloy material is cast into steel ingots to obtain alloy material for induction furnace. The contents of gas and impurities in the alloy material simultaneously meet the following requirements: oxygen content TO≤45ppm, nitrogen content N≤35ppm, hydrogen content H≤1.2ppm; maximum size of inclusions ≤20 micrometers.

[0008] This invention directly compresses high-temperature alloy scrap in the form of shavings into cylindrical consumable electrodes under high pressure. These electrodes are then electroslag remelted in an oxidizing atmosphere and FeO-containing oxidizing slag system to effectively remove reactive elements such as Al and Ti. The remelted ingot is then vacuum induction refined. During the refining process, a high-purity carbon tube with a perforated structure is inserted into the alloy liquid, and argon gas is introduced along with electromagnetic stirring. This achieves deep deoxidation, denitrification, and dehydrogenation under vacuum conditions. This solution solves the technical problems in existing technologies where high-temperature alloy scrap is difficult to directly recycle due to its high Al and Ti content, easily forms oxide inclusions, and is difficult to denitrify. It enables large-scale, high-efficiency recycling of scrap, ultimately obtaining ultra-pure induction furnace alloy material with low nitrogen, low oxygen, and low hydrogen content, significantly reducing the production cost of high-temperature alloys.

[0009] As one possible embodiment of the first aspect of this invention, the length of the shaving-like high-temperature alloy return material is controlled to be ≤250mm and the thickness to be ≤3mm. This design is because if the return material size exceeds the limit, the material sheets will not be able to mesh tightly during high-pressure compression, resulting in insufficient compaction density of the manufactured consumable electrode and increased internal porosity. In the subsequent electroslag remelting process, the loose electrode will significantly increase resistance, causing uneven current distribution and localized overheating, forcing a substantial increase in smelting energy consumption and a decrease in efficiency. Therefore, strictly limiting the size of the high-temperature alloy return material is not only a prerequisite for ensuring the structural integrity of the consumable electrode but also a key process measure for achieving stable and efficient operation of electroslag remelting. High-pressure compression (nominal pressure between 1000 tons and 6000 tons) is used during manufacturing, resulting in a metal consumable electrode with a diameter of 200-400mm, a height of 3000-4000mm, and a density ≥4g / cm³. If the electrode diameter exceeds 400mm or the height exceeds 4000mm, it will significantly increase the tonnage requirements of the pressing equipment and the complexity of the mold, drastically increasing the difficulty of electrode forming. Secondly, excessively large electrodes will lead to a significant extension of the melting time during electroslag remelting. Prolonged high-temperature action can easily cause thermal decomposition and volatilization loss of the slag components, disrupting the initial design ratio of the slag system and thus weakening its refining effect on the alloy liquid. If the electrode size is below this range, the amount of metal fed in a single melting will be too small, resulting in low production efficiency and failing to meet the economic requirements of industrial mass production. Regarding density, only when the density of the shavings after high-pressure compression reaches or exceeds this level will the gaps between the shavings be fully eliminated, the metal particles achieve tight mechanical meshing, and the porosity inside the electrode be reduced to an acceptable level, ensuring a dense and uniform overall structure. Electrodes that meet this density requirement can maintain a low and stable resistance value during subsequent electroslag remelting, effectively avoiding local overheating or abnormal heating caused by a loose structure, thereby ensuring the thermal efficiency and process stability of the melting process. Conversely, if the density does not meet the standard, it indicates that the pressing is not solid, which will directly threaten the smooth operation of electroslag remelting and product quality.

[0010] As one possible implementation of the first aspect of the present invention, in step (2), the oxidizing atmosphere is O2; the composition of the oxidizing slag system by mass percentage includes: 65%~70% CaF2, 25%~30% Al2O3, and 0%~5% FeO.

[0011] As one possible implementation of the first aspect of the present invention, in the electroslag remelted ingot obtained in step (2), Al≤0.003% and Ti≤0.003%.

[0012] It should be noted that directly using high-temperature alloy return materials to manufacture high-temperature alloys has several drawbacks. First, the non-metallic inclusions, oil stains, and original inclusions (oxides, nitrides, etc.) carried by the high-temperature alloy return materials will directly enter the smelting system, significantly reducing the purity of the alloy, which is difficult to completely remove even with subsequent refining. Second, the Al and Ti in the high-temperature alloy return materials are easily oxidized during the smelting process, generating a large amount of non-metallic inclusions such as Al2O3 and TiO2, further deteriorating the purity of the alloy. Therefore, in this invention, when using high-temperature alloy return materials, the high-temperature alloy return materials pressed into metal consumable electrodes are directly subjected to electroslag remelting under an oxidizing atmosphere and an oxidizing slag system. The flow rate of the oxidizing atmosphere is 50 L / min to 100 L / min, the weight of the slag system is 5% to 10% of the electrode weight, and the remelting time is 2 to 6 hours. It is worth emphasizing that the fundamental reason why the industry generally finds it difficult to conceive of using consumable electrodes made from recycled high-temperature alloy materials and employing oxidizing atmospheres and slag systems for remelting is that this approach directly overturns the core technical logic and operational conventions of electroslag remelting (ESR) technology. In the industry consensus, ESR is a secondary refining technology aimed at purifying and cleansing metals. Therefore, one of the core logics of its process design is to minimize the loss of easily oxidized elements (such as Al, Ti, and Si). From an operational perspective, many processes add deoxidizers such as Al, Si, and Ca during remelting. If an oxidizing atmosphere is used simultaneously, the deoxidizer will preferentially react with oxygen in the atmosphere and be consumed, rendering the deoxidation operation ineffective. To control the loss of Ti, TiO2 is usually added to the slag system to reduce its activity, thereby "stabilizing" Ti in the alloy. However, actively adopting an oxidizing slag system means abandoning this strategy of "protecting" elements through slag system design. Therefore, most researchers in the industry could not come up with this solution because it requires a reverse way of thinking: to transform oxidation reactions, which are traditionally regarded as "defects," into a "tool" for the selective and precise removal of Al and Ti.

[0013] This invention involves electroslag remelting of metal consumable electrodes directly made from recycled materials under an oxidizing atmosphere and oxidizing slag system. Through optimized process operation and parameter design, the Al content in the electroslag remelted ingot is effectively controlled to ≤0.003%, thus facilitating the vacuum carbon deoxidation reaction. In subsequent vacuum induction melting, carbon (C) is used as the deoxidizer, with the reaction formula [C] + [O] → CO(g). The unique advantage of this reaction is that the product CO is an insoluble gas in molten steel and can be rapidly removed under vacuum conditions, achieving "residue-free" deoxidation without introducing any solid inclusions. If the Al content in the molten steel after electroslag remelting is high, Al will preferentially combine with O to form stable solid Al₂O₃ inclusions during the vacuum induction refining stage. At this point, the carbon-oxygen reaction is significantly inhibited because the oxygen potential is preempted by Al. Therefore, reducing Al to ≤0.003% is essentially a pre-purification of the molten steel, ensuring that subsequent carbon can react directly and efficiently with oxygen, fully utilizing the gas self-extraction advantage of vacuum carbon deoxidation. The purpose of using Ti ≤ 0.003% is to reduce the burden on the vacuum denitrification reaction. Titanium is a recognized strong nitrogen-fixing element, exhibiting an extremely strong affinity for nitrogen at high temperatures. This significantly reduces the activity of nitrogen in molten steel, effectively "locking" nitrogen atoms within the solid solution, making it difficult for them to freely diffuse to the liquid surface and escape. In the high-temperature, low-pressure environment of vacuum melting, if the Ti content is too high, the denitrification reaction will face extremely high kinetic barriers, and even with extended vacuum time, the nitrogen content will be difficult to reduce to the target level. Therefore, oxidizing and removing Ti to ≤ 0.003% during the electroslag remelting stage is equivalent to prematurely releasing the "chemical lock" on nitrogen atoms, creating the necessary compositional prerequisite for efficient denitrification in the subsequent vacuum refining process.

[0014] As one possible implementation of the first aspect of the present invention, step (3) specifically includes the following steps: (3-1) The remelted ingots after grinding and dividing are heated and melted in a vacuum induction furnace; the heating temperature is 1450℃~1500℃ and the time is 4h~8h; (3-2) Insert a perforated high-purity carbon tube into the molten alloy and introduce argon gas into the tube. Simultaneously, refine the alloy using electromagnetic stirring, controlling the pressure inside the vacuum induction furnace to 2 Pa to 8 Pa and the superheat of the molten alloy to 30 to 50 °C. Controlling the pressure inside the vacuum chamber is crucial for the refining effect. Excessive pressure will inhibit the carbon-oxygen reaction, leading to a decrease in deoxidation efficiency. Furthermore, excessive pressure will accelerate the escape rate of argon bubbles from the molten steel, shortening their travel time and thus weakening the stirring and degassing effects of argon gas.

[0015] (3-3) The refined alloy liquid is tested. When the carbon content in the alloy liquid is 0.05%~0.08%, the high-purity carbon tube is removed. In the vacuum induction melting refining stage, the high-purity carbon tube is inserted into the alloy liquid. This utilizes the chemical reaction between carbon and dissolved oxygen [C]+[O]→CO(g) to generate CO gas under vacuum conditions, which then escapes, thereby achieving deep deoxidation without residue or inclusions. The timing of removing the carbon tube is based on the real-time carbon content in the alloy liquid reaching 0.05%~0.08%. This range is not randomly selected but takes into account the thoroughness of deoxidation and the compliance requirements of the final composition. If the carbon content in the alloy liquid is below 0.05% when the carbon tube is removed, it means that the activity of carbon in the system has been significantly reduced, and the chemical driving force of the carbon-oxygen reaction has been greatly weakened. At this time, even if the vacuum degree and temperature conditions meet the requirements, the reaction rate will become extremely slow, and it will be impossible to reduce the oxygen to the target level within a reasonable refining time. These residual oxygen particles will react with reactive elements in the alloy during subsequent solidification to form oxide inclusions, severely impairing the purity and mechanical properties of the material. If the carbon nanotubes are removed too late, resulting in a carbon content exceeding 0.08% in the molten alloy, although the oxygen content can be reduced to a lower level, excessive carbon will remain in the alloy matrix. Most high-temperature alloys have strict upper limits on the final carbon content. Excessive carbon content will directly lead to unqualified alloy composition in the entire furnace, failing to meet product standards, resulting in material scrap or requiring expensive dilution and remelting.

[0016] (3-4) Continue refining for 20-30 minutes, then raise the temperature of the alloy liquid (melting point of the alloy liquid + (80-120℃)) and cast.

[0017] In one possible implementation of the first aspect of the present invention, in step (3-1), the flow rate of argon gas introduced is 10 L / h to 500 L / h, and the electromagnetic stirring is performed for 10 to 30 seconds every 10 minutes, excluding the stirring time within the 10-minute interval. In the vacuum induction refining process, electromagnetic stirring and the introduction of argon gas through a high-purity carbon tube are not isolated operations, but rather have a significant synergistic relationship. The combination of the two mainly improves the efficiency of degassing, removal of non-metallic inclusions, and homogenization of composition and temperature by optimizing fluid flow and improving thermodynamic and kinetic conditions. Specifically, argon gas, as an inert gas, does not participate in the reaction; its mechanism of action is physical stirring: during the rising of bubbles, it agitates the molten metal, providing an interface for the CO reaction, promoting the CO reaction, and carrying dissolved hydrogen, nitrogen, and other gases, as well as non-metallic inclusions, to the surface, thereby achieving the purpose of degassing and removal of non-metallic inclusions. Electromagnetic stirring utilizes an alternating electromagnetic field to generate an induced current in the molten metal, which then interacts with the magnetic field to generate an electromagnetic force that drives the movement of the molten metal. This is a non-contact stirring method that generates a powerful and controllable rotating flow, achieving homogenization of composition and temperature throughout the molten pool and promoting the collision, aggregation, and flotation of inclusions. The synergistic effect of electromagnetic stirring optimizes the flow field and improves stirring efficiency. The rotational force generated by electromagnetic stirring causes bubbles that originally rise vertically to ascend in a spiral shape, significantly extending their travel and residence time in the molten steel. This not only allows for more efficient carrying of gas and inclusions but also expands the stirring range from a localized bubble plume area to the entire molten pool, greatly improving overall stirring efficiency. Simultaneously, the rotating electromagnetic force breaks down large bubbles into smaller ones, significantly increasing the total surface area of ​​the bubbles and thus significantly enhancing their ability to adsorb inclusions and carry gas. Argon stirring provides the driving force for bubbles and reactions, but its stirring effect is limited; electromagnetic stirring provides powerful global stirring and dispersion capabilities. Combining the two fully leverages their respective advantages and compensates for each other's shortcomings, producing a refining effect of "1+1>2".

[0018] Furthermore, with argon continuously providing the refining "power," electromagnetic stirring is periodically activated to "strongly regulate" the molten pool, breaking up any potential compositional or temperature stratification and more effectively dispersing and distributing bubbles. This intermittent, strong stirring ensures refining effectiveness while avoiding risks such as furnace lining erosion caused by excessive stirring, making it an optimized strategy for achieving efficient and stable refining.

[0019] In a second aspect, the present invention provides a purification apparatus, wherein the purification apparatus adopts a perforated high-purity carbon tube as the main structure, and the lower part and bottom of the high-purity carbon tube wall extend radially outward to form annular carbon layers, namely a first carbon layer and a second carbon layer, which are parallel to each other. An argon gas inlet hole is processed in the middle of the high-purity carbon tube wall, and the argon gas inlet hole is connected to an argon gas inlet pipe. A cavity communicating with the argon gas inlet hole is processed in both the first carbon layer and the second carbon layer, and an outlet hole communicating with the cavity is processed on the surface of both the first carbon layer and the second carbon layer, so that the argon gas blown in from the argon gas inlet hole can be discharged from the outlet hole of the first carbon layer and the second carbon layer. The advantages of setting up a first and second carbon layer are that, by dispersing the blowing positions along the longitudinal direction of the molten pool, the synergistic enhancement of bubble refining and carbon deoxidation reactions in space is achieved. The lower layer of bubbles, due to its longer travel distance, improves degassing and inclusion removal efficiency, while the upper layer of bubbles fills the refining blind spot in the middle. Simultaneously, the double-layered orifices expand the reaction interface between the carbon tube and the molten steel, promoting a more uniform carbon-oxygen reaction over a greater depth range and effectively shortening the oxygen diffusion path. With the aid of electromagnetic stirring, the double-layered bubble plume generates a more complex spiral upward flow field, breaking the local stagnation zones easily formed by single-layer blowing, significantly improving the uniformity of the molten pool composition and temperature. Furthermore, this structure also has a gas path backup function to prevent refining interruption due to single-layer blockage, while dispersing gas flow scouring and reaction consumption, extending the service life of the carbon tube. Essentially, this design upgrades the high-purity carbon tube from a single gas supply channel to a multi-level reaction-stirring composite functional body, maximizing the synergistic effect of its physical stirring and chemical deoxidation.

[0020] As a possible embodiment of the second aspect of the present invention, the vent holes of the first carbon layer include a first radial vent hole, a first axial vent hole, and a second axial vent hole. The first radial vent hole includes multiple sets of vent holes spaced apart along the vertical surface of the first carbon layer. The multiple sets of vent holes are arranged parallel to each other, and the multiple small holes of each set of vent holes are evenly distributed along the circumference of the first carbon layer. The first axial vent hole includes multiple sets of vent holes spaced apart along the upper horizontal surface of the first carbon layer. The second axial vent hole includes multiple sets of vent holes spaced apart along the lower horizontal surface of the first carbon layer. The first axial vent hole and the second axial vent hole are symmetrically arranged, and the multiple small holes of each set of vent holes are concentrically distributed with the center of the high-purity carbon tube as the axis.

[0021] By configuring the vents on the first carbon layer as described above, this design achieves all-round three-dimensional stirring of the molten pool by constructing a three-dimensional vent network consisting of a first radial vent, a first axial vent, and a second axial vent on the first carbon layer. The radial vents are parallel to the vertical plane and uniformly distributed circumferentially, forcing the molten steel to generate lateral convection, while the axial vents are concentrically distributed along the upper and lower horizontal planes, driving vertical flow. The multi-dimensional turbulence formed by the two effectively eliminates the flow dead zone caused by traditional unidirectional air blowing, significantly improving the electromagnetic stirring effect. The mixing achieves global uniformity in penetration depth and molten pool composition and temperature. Simultaneously, these three-dimensionally distributed pores extend the carbon-oxygen reaction interface from local point sources to the entire immersion depth, creating low CO partial pressure micro-regions around each pore opening. This greatly promotes the diffusion of dissolved oxygen to the pore surface and its reaction to generate CO, thereby improving carbon deoxidation efficiency to a comprehensive body-to-body purification level. Furthermore, the dispersed layout of numerous pores evenly distributes the total gas volume and reaction consumption, reducing the single-pore flow rate and local erosion rate, making the wear of carbon nanotubes more uniform in all directions, and significantly extending their service life.

[0022] In one possible embodiment of the second aspect of the present invention, the vents of the second carbon layer include a second radial vent, a third axial vent, and a fourth axial vent. The second radial vent comprises multiple sets of vents spaced apart along the vertical surface of the second carbon layer, the multiple sets of vents being arranged parallel to each other, and the plurality of small holes in each set of vents being uniformly distributed along the circumference of the second carbon layer. The third axial vent comprises multiple sets of vents spaced apart along the horizontal surface of the second carbon layer, the multiple sets of vents being concentrically distributed with the center of the high-purity carbon tube as the axis. The fourth axial vent comprises multiple vents arrayed along the entire bottom circumference of the second carbon layer.

[0023] By configuring the vents on the second carbon layer as described above, the design of the vents in the second carbon layer further enhances the stirring and reaction efficiency of the bottom molten pool based on the first carbon layer. The second radial vents are parallel to the vertical plane and evenly distributed circumferentially, driving horizontal convection in the molten steel. The third axial vents are concentrically distributed along the upper horizontal plane, providing vertical upward airflow. The fourth axial vents are arranged in a circular array along the entire bottom circumference. This densely distributed bottom structure is particularly crucial, as it can form a uniform bubble curtain at the bottom of the molten pool, effectively preventing the formation of a stagnant zone at the bottom and forcing the bottom... The molten steel participates in circulating convection, significantly improving the penetration depth and coverage of the electromagnetic stirring throughout the molten pool. Simultaneously, this layout extends the carbon-oxygen reaction interface to the entire bottom region and lower sidewalls of the carbon nanotube, allowing the deoxidation reaction to begin intensively at the lowest point of the molten pool. The generated CO bubbles continuously adsorb oxygen and inclusions as they rise, achieving layer-by-layer deep purification from the bottom up. Furthermore, the porous structure of the bottom circumferential array significantly disperses the gas flow rate through individual pores, reducing concentrated scouring and localized reaction consumption at the bottom of the carbon nanotube, resulting in more uniform erosion and effectively extending its service life. In summary, the vent configuration of the second carbon layer effectively complements the first carbon layer, addressing the stirring dead zone and insufficient deoxidation in the bottom molten pool, further improving the uniformity and purity of vacuum induction refining.

[0024] As a possible embodiment of the second aspect of the present invention, the multiple sets of air holes in the first radial air outlet are of the same size, with a diameter of 0.5mm to 1mm and evenly spaced, preferably in three sets. Similarly, the multiple sets of air holes in the first and second axial air outlets are of the same size, with a diameter of 0.5mm to 1mm and evenly spaced, preferably in three sets. Likewise, the multiple sets of air holes in the second radial air outlet are of the same size, with a diameter of 0.5mm to 1mm and evenly spaced, preferably in three sets. The multiple sets of air holes in the third axial air outlet are of the same size, with a diameter of 0.5mm to 1mm and evenly spaced, preferably in three sets. All the air holes in the fourth axial air outlet are of the same size, with a diameter of 0.5mm to 1mm and arranged in an array. The diameters of all the air holes satisfy 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, and 1mm.

[0025] By optimizing the number and size of pores, the advantages are that the smaller bubbles have a larger specific surface area and a slower rising velocity, extending their residence time in the molten steel and enhancing their ability to carry adsorbed gases and inclusions. Simultaneously, each tiny bubble forms a low CO partial pressure micro-region, constructing dense carbon-oxygen reaction active sites on the carbon nanotube surface, significantly improving deoxidation efficiency. The evenly spaced and uniformly distributed pores, along with the optimal three-group configuration, ensure the discretization and symmetry of the airflow in the circumferential direction, preventing bubble aggregation or flow deviation, resulting in uniform force on the molten pool and optimal flow field coupling with electromagnetic stirring, while also preventing liquid surface skewing and slag entrapment. Furthermore, this combination of pore size and number avoids clogging or large bubble problems while ensuring sufficient air permeability, and the multiple groups of pores disperse reaction consumption and airflow scouring, uniformizing carbon nanotube wear and significantly extending its service life. This parameter optimization achieves the best balance between refining efficiency, flow field stability, and component durability.

[0026] As a possible embodiment of the second aspect of the present invention, the diameter D of the first carbon layer and the second carbon layer is 2 / 3 to 3 / 4 of the inner diameter of the crucible. The advantages of this design are: this ratio ensures that the carbon layer occupies the mainstream core area in the molten steel, which ensures that the pores on the surface of the carbon tube can cover most of the cross-section of the molten pool, so that the reaction between the bubbles and carbon and oxygen can be fully spread in the radial range, avoiding insufficient stirring or deoxidation blind spots in the edge molten pool due to the small diameter; at the same time, the diameter of the carbon layer is smaller than the inner diameter of the crucible, leaving enough annular space to provide a smooth upward and backflow channel for the overall circulation convection of the molten pool driven by electromagnetic stirring, preventing short circuits or local erosion caused by the narrow distance between the carbon tube and the crucible wall; in addition, this ratio also takes into account the structural strength and mechanical stability of the carbon tube itself, avoiding the large diameter that would lead to a sharp increase in the weight of the carbon tube, difficulty in installation, or deformation and breakage at high temperature.

[0027] As a possible embodiment of the second aspect of the present invention, the high-purity carbon tube, by mass percentage, contains C ≥ 99.0% and S ≤ 0.03%. The fundamental reason for limiting the sulfur content in the high-purity carbon tube to ≤ 0.03% is that when the carbon tube participates in the CO reaction as a deoxidizer in molten steel, its surface is continuously consumed and corroded. If the carbon tube itself contains a high amount of sulfur, as the reaction proceeds, sulfur will be continuously released from the carbon tube matrix and dissolved into the molten steel, thereby causing sulfur contamination of the alloy, resulting in excessive sulfur content and decreased purity in the final product. When the sulfur content is controlled below 0.03%, even if the carbon tube undergoes a certain degree of corrosion during the refining process, the total amount of sulfur it brings into the molten steel is extremely limited, and it has almost no detectable impact on the final sulfur content and cleanliness of the alloy, which can be considered a safe engineering threshold. Therefore, the setting of this upper limit for sulfur content is a key quality red line set to prevent the carbon tube from acting as an impurity source and contaminating the molten steel, provided that the carbon tube has sufficient deoxidation reactivity.

[0028] A third aspect of the present invention provides a method of using the above-described purification apparatus, specifically comprising: Ten minutes after the start of vacuum refining, the purification device is inserted into the alloy liquid. When the carbon content in the alloy liquid is 0.05% to 0.08%, the purification device is removed.

[0029] As a possible embodiment of the third aspect of the present invention, the distance H between the upper surface of the first carbon layer of the purification device and the surface of the alloy liquid is controlled to be 150mm~300mm, while the depth of the high-purity carbon tube immersed in the alloy liquid is controlled to be 50%~80% of the total depth of the alloy liquid. The two together constitute an optimized combination of "upper layer limiting + lower layer deep immersion". Specifically, the upper layer limiting ensures that the bubbles released from the upper layer pores have sufficient travel length to fully adsorb gases and inclusions, while avoiding bubbles getting too close to the liquid surface and causing splashing or slag entrapment; the lower layer deep immersion ensures that the bottom pores can reach the bottom area of ​​the molten pool, effectively eliminating the bottom stirring dead zone, while avoiding excessive immersion that hinders the bottom circulation. The core synergistic effect of simultaneous control lies in the fact that they jointly define the effective longitudinal reaction zone between the upper and lower pore layers. When this zone occupies 50% to 80% of the liquid depth, the lower layer bubbles meet the upper layer bubble group during their ascent, resulting in gas merging and redispersing, forming a strong longitudinal turbulent mixing effect. This significantly shortens the diffusion path of oxygen and inclusions from various regions of the molten pool to the carbon nanotube surface. At the same time, this longitudinal span allows the rotating flow field of the electromagnetic stirring to be continuously disturbed by the multi-layer bubble group, maximizing the radial and axial momentum exchange and effectively eliminating the longitudinal gradient of molten pool composition and temperature. This combined design of "upper limit limiting to prevent splashing, lower limit deep immersion to eliminate dead zones, and strong coupling of longitudinal span" essentially upgrades the carbon nanotube into a three-dimensional gas-liquid stirring reaction tower spanning the entire height of the molten pool. Its comprehensive refining effect is far superior to the simple superposition of controlling the two separately.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) By using an oxidizing atmosphere and an oxidizing slag system containing FeO in the electroslag remelting stage, the present invention can significantly reduce the content of Al and Ti elements, which are relatively low and inexpensive, in high-temperature alloy return materials to Al≤0.003% and Ti≤0.003%. Since Al and Ti are strong nitride-forming elements, the significant reduction in their content eliminates the inhibitory effect on vacuum denitrification. At the same time, it avoids the generation of stable Al2O3 and TiO2 inclusions during carbon deoxidation, creating favorable conditions for fully utilizing the advantages of carbon deoxidation and denitrification in subsequent vacuum induction refining. It effectively overcomes the defects in the prior art where the high content of inclusions in the high-temperature alloy return materials and the active elements such as Al and Ti contained therein easily lead to the generation of a large number of non-metallic inclusions during the melting process and inhibit the denitrification reaction, thus making it impossible to use a large amount of return materials and only pure materials can be used. This significantly reduces the production cost of high-temperature alloys.

[0031] (2) This invention utilizes a metal consumable electrode made from high-temperature alloy recycled material for electroslag remelting. During the remelting process, the oxidizing slag system used not only removes Al and Ti but also has excellent adsorption and dissolution capabilities for non-metallic inclusions, especially effectively removing large-particle oxide inclusions originally present in the high-temperature alloy recycled material. Although the final oxide content of the electroslag ingot is high under an oxidizing atmosphere, these oxides are mainly formed during the remelting solidification process; these inclusions will decompose and release oxygen during the subsequent vacuum melting process, and are ultimately removed through carbon deoxidation. Meanwhile, the large-particle, difficult-to-decompose inclusions in the raw material have been removed during the electroslag remelting stage, thereby significantly reducing the purification burden of subsequent vacuum refining.

[0032] (3) In the vacuum induction refining process, this invention uses a porous carbon rod inserted into the molten steel to generate CO gas through the deoxidation reaction of carbon under vacuum conditions. The product does not leave any non-metallic inclusions. Compared with carbon powder floating on the surface (carbon powder has low density, is easily carried away by the vacuum pumping system, and has low reaction efficiency), the carbon rod is directly immersed deep into the molten steel, resulting in high carbon utilization and no pollution. Combined with the fact that Al and Ti have been reduced to ≤0.003% in the electroslag remelting stage, the generation of stable oxides is avoided. Therefore, ultra-low oxygen, low nitrogen, and low hydrogen ultra-pure alloy smelting can be achieved simultaneously without the need to add active metal deoxidizers.

[0033] (4) The purification device designed in this invention uses a porous high-purity carbon tube as the main structure, and optimizes the structure and distribution of the gas outlet holes on the carbon tube. The high-purity carbon tube with a multi-layer, multi-directional gas outlet hole structure is designed as the purification device. During the vacuum refining process, the argon gas introduced into the high-purity carbon tube can be ejected from the tiny gas outlet holes at different heights and angles of the carbon tube, thereby forming a large number of dispersed bubbles in the alloy liquid. On the one hand, it strongly stirs the melt and promotes the renewal of the carbon-oxygen reaction interface. On the other hand, the bubbles carry the removed gas products to float and escape, which significantly accelerates the deoxidation, denitrification and dehydrogenation processes. The method of directly adding carbon powder cannot achieve directional and controllable bubble stirring, and it is easy to agglomerate on the liquid surface or slag layer, resulting in poor kinetic conditions. In addition, the periodic electromagnetic stirring further enhances the uniformity of the melt and the reaction kinetics, making the refining process fast and efficient, and shortening the smelting cycle.

[0034] (5) The present invention directly recycles the shavings-shaped turning material after pressing it into electrodes. Through the combined process of electroslag remelting and vacuum refining, the inclusions in the original high-temperature return material and those generated during the smelting process are effectively removed, and the Al and Ti contents are significantly reduced. At the same time, the purification device designed in this invention is used to finally prepare ultra-pure induction furnace alloy material with low nitrogen, low oxygen and low hydrogen. It can be used as a high-quality raw material for smelting high-purity master material, significantly reducing the production cost of high-temperature alloys, and has outstanding economic benefits and resource recycling value. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the vacuum induction furnace of the present invention; Figure 2 This is a schematic diagram of the purification apparatus of the present invention; Figure 3 for Figure 2 Sectional view of point AA′ at point A in the middle; Figure 4 for Figure 2 Cross-sectional view of BB′ at point B in the middle.

[0036] In the picture: 1. Argon gas blowing tube; 2. High-purity carbon tube; 2-1. First carbon layer; 2-2. Second carbon layer; 3. Molten alloy; 4. Vacuum melting chamber; 5. Crucible; 6. Induction coil; 7-1, First radial vent; 7-2, First axial vent; 7-3, Second axial vent; 7-4, Second radial vent; 7-5, Third axial vent; 7-6, Fourth axial vent. Detailed Implementation

[0037] It should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify 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. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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 will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] Example 1 like Figure 1 As shown, a method for preparing an alloy material for an induction furnace according to this embodiment includes the following steps: Step S1: Select a high-temperature alloy return material with a length of about 240mm and a thickness of about 2.5mm, and press it into a metal consumable electrode with a diameter of 300mm, a height of 3500mm, and a density of 5g / cm³ using a device with a nominal pressure of 2000 tons.

[0041] Step S2: Electroslag remelting is performed in oxygen and an oxidizing slag system (65% CaF2, 30% Al2O3, 4% FeO, with the balance being unavoidable impurities). The flow rate of the oxidizing atmosphere is 50 L / min to 100 L / min, and the weight of the oxidizing slag system is 8% of the electrode weight. The electroslag remelting time is 3 h, and the Al content and Ti content in the resulting electroslag remelted ingot are controlled to be 0.0025% and 0.0025%, respectively.

[0042] Step S3: Melt the polished and divided remelted ingots at 1480℃ for 6 hours in a vacuum induction furnace. Specifically, refer to... Figure 1 The vacuum melting chamber 4 of the vacuum induction furnace is equipped with a crucible 5, which contains molten alloy liquid 3. An induction coil 6 is fitted on the outer surface of the crucible 5 to facilitate electromagnetic stirring during subsequent vacuum refining.

[0043] After vacuum refining for 10 minutes, the purification device of the present invention is inserted into the alloy liquid 3, and argon gas is introduced into the high-purity carbon tube of the purification device at a flow rate of 100 L / h. At the same time, electromagnetic stirring is carried out, with stirring for 20 seconds every 10 minutes. The stirring time is not included in the 10-minute interval.

[0044] Specifically, in combination Figure 2 The purification device uses a perforated high-purity carbon tube 2 as its main structure. The lower part and bottom of the tube wall extend radially outward to form annular carbon layers, namely a first carbon layer 2-1 and a second carbon layer 2-2. The diameter D of the first carbon layer 2-1 and the second carbon layer 2-2 is the same, and D is 2 / 3 to 3 / 4 of the inner diameter of the crucible. The first carbon layer 2-1 and the second carbon layer 2-2 are parallel to each other. An argon gas inlet hole is machined in the middle of the tube wall of the high-purity carbon tube 2, and the argon gas inlet hole is connected to an argon gas inlet pipe 1. Both the first carbon layer 2-1 and the second carbon layer 2-2 have cavities communicating with the argon gas inlet hole, and both the first carbon layer 2-1 and the second carbon layer 2-2 have outlet holes communicating with the cavities, allowing argon gas blown in from the argon gas inlet hole to exit from the outlet holes of the first carbon layer 2-1 and the second carbon layer 2-2. The diameter of all outlet holes is 0.6 mm.

[0045] Combination Figure 2 and Figure 3 The first carbon layer 2-1 has vents including a first radial vent 7-1, a first axial vent 7-2, and a second axial vent 7-3. The first radial vent 7-1 includes three sets of vents spaced apart along the vertical surface of the first carbon layer 2-1. The three sets of vents are arranged parallel to each other on the vertical sidewall of the first carbon layer 2-1, and each set of vents has 10 small holes evenly distributed along the circumference of the first carbon layer 2-1. The first axial vent 7-2 includes vents along the vertical surface of the first carbon layer 2-1. The second axial air outlet 7-3 includes three sets of air outlets spaced apart along the horizontal plane below the first carbon layer 2-1. The first axial air outlet 7-2 and the second axial air outlet 7-3 are symmetrically arranged, and the three sets of air outlets are concentrically distributed with the center of the high-purity carbon tube 2 as the axis. That is, the inner ring of the first axial air outlet 7-2 or the second axial air outlet 7-3 is provided with 12 small holes, the middle ring is provided with 18 small holes, and the outer ring is provided with 24 small holes.

[0046] Combination Figure 2 and Figure 4 The second carbon layer 2-2 has three sets of vents: a second radial vent 7-4, a third axial vent 7-5, and a fourth axial vent 7-6. The second radial vent 7-4 comprises three sets of vents spaced apart along the vertical plane of the second carbon layer 2-2, with the three sets arranged parallel to each other. Each set of vents has 10 small holes evenly distributed along the circumference of the second carbon layer 2-2. The third axial vent 7-5 comprises three sets of vents spaced apart along the horizontal plane of the second carbon layer 2-2, concentrically distributed with the center of the high-purity carbon tube 2 as the axis. The inner ring has 12 small holes, the middle ring has 18 small holes, and the outer ring has 24 small holes. The fourth axial vent 7-6 comprises multiple vents arranged in a circular array along the entire bottom circumference of the second carbon layer 2-2, with the numbers from the outer ring to the inner ring being 24, 18, 12, 8, and 2, for a total of 64 small holes.

[0047] During vacuum refining, the pressure inside the vacuum induction furnace is controlled at 5 Pa, and the superheat of the alloy liquid is 40°C. The purification device is immersed in the alloy liquid 3 to a depth of 60% of the total depth of the alloy liquid 3, and the distance H between the upper surface of the first carbon layer 2-1 and the surface of the alloy liquid 3 is 200 mm. When the carbon content in the alloy liquid 3 is detected to be 0.06%, the purification device is removed and refining continues for 25 minutes.

[0048] Step S4: After refining, the alloy liquid is heated and cast into steel ingots to obtain alloy material (alloy ingot) for induction furnace.

[0049] The gas and impurity contents in the prepared alloy ingot for induction furnace are as follows: oxygen content TO 35ppm, nitrogen content N 28ppm, hydrogen content H 0.3ppm; the maximum size of inclusions does not exceed 13 micrometers.

[0050] Example 2 The main difference between this embodiment and Embodiment 1 is that the method for preparing alloy material for induction furnaces is as follows: In step S1, the length of the shaving-shaped high-temperature alloy return material is 250mm, the thickness is 3mm, the diameter of the metal consumable electrode is 400mm, and the height is 4000mm. In step S2, the flow rate of the oxidizing atmosphere is 100 L / min, the weight of the oxidizing slag system is 10% of the electrode weight, and the electroslag remelting time is 6 h. In step S3, the vacuum induction furnace is heated to 1500℃ for 4 hours, the pressure inside the vacuum induction furnace is controlled at 2Pa, and the superheat of the alloy liquid is 30℃. The purification device is immersed in the alloy liquid 3 to a depth of 50% of the total depth of the alloy liquid 3, and the distance H between the upper surface of the first carbon layer (2-1) and the surface of the alloy liquid 3 is 300mm. The diameter of all the vent holes of the purification device is 0.5 mm, and the flow rate of argon gas is 10 L / h. The electromagnetic stirring is performed for 30 seconds every 10 minutes, and the stirring time is not included in the 10-minute interval. When the carbon content in the alloy liquid 3 is detected to be 0.05%, the purification device is removed and refining is continued for 20 minutes.

[0051] The gas and impurity contents in the prepared alloy material for induction furnace are as follows: oxygen content TO 39ppm, nitrogen content N 32ppm, hydrogen content H 1.0ppm; the maximum size of inclusions does not exceed 17 micrometers.

[0052] Example 3 The main difference between this embodiment and Embodiment 1 is that the method for preparing alloy material for induction furnaces is as follows: In step S1, the length of the shaving-shaped high-temperature alloy return material is 250 mm, the thickness is 3 mm, the diameter of the metal consumable electrode is 200 mm, the height is 3000 mm, and the density is 4 g / cm³. In step S2, the flow rate of the oxidizing atmosphere is 50 L / min, the weight of the oxidizing slag system is 5% of the electrode weight, the electroslag remelting time is 2 h, and the Al content and Ti content in the resulting electroslag remelted ingot are controlled to be 0.003% and 0.003%, respectively. In step S3, the vacuum induction furnace is heated to 1450℃ for 8 hours, the pressure inside the vacuum induction furnace is controlled at 8Pa, and the superheat of the alloy liquid is 50℃. The purification device is immersed in the alloy liquid 3 to a depth of 80% of the total depth of the alloy liquid 3, and the distance H between the upper surface of the first carbon layer 2-1 and the surface of the alloy liquid 3 is 150mm. The diameter of all the vent holes of the purification device is 1 mm, and the flow rate of argon gas is 500 L / h. The electromagnetic stirring is performed for 10 seconds every 10 minutes, and the stirring time is not included in the 10-minute interval. When the carbon content in the alloy liquid 3 is detected to be 0.08%, the purification device is removed and refining is continued for 30 minutes.

[0053] The gas and impurity contents in the prepared alloy ingot for induction furnace are as follows: oxygen content TO 45ppm, nitrogen content N 35ppm, hydrogen content H 1.2ppm; the maximum size of inclusions does not exceed 20 micrometers.

[0054] Comparative Example 1 The main difference between this comparative example and Example 1 is that in step S2, the metal consumable electrode compressed from the high-temperature alloy return material in step S1 is directly subjected to electroslag remelting treatment, using a slag system of 60%CaF2+20%Al2O3+20%CaO, without introducing oxygen. All other operations are the same as in Example 1.

[0055] During the operation, it was found that due to insufficient oxidation reaction in the electroslag remelting stage, the Al and Ti contents in the alloy could not be effectively reduced and remained at a high level. After subsequent vacuum induction melting, the resulting alloy ingot had an oxygen content of 50 ppm, a nitrogen content of 75 ppm, a hydrogen content of 1.2 ppm, and an inclusion size of up to 45 micrometers.

[0056] Comparative Example 2 The main difference between this comparative example and Example 1 is that the density of the metal consumable electrode formed by high-temperature alloy return material after high-pressure compression in step S1 is 2.54 g / cm³, while the rest of the settings are the same as in Example 1.

[0057] During operation, it was found that the power consumption per ton of steel during the electroslag remelting process was more than 30% higher than normal, and it would cause the consumable electrode to over-oxidize. As a result, after vacuum induction melting, the resulting alloy ingot had an oxygen content of more than 60 ppm (TO), a nitrogen content of 48 ppm (N), a hydrogen content of 1.4 ppm (H), and the largest inclusion size reached 40 micrometers.

[0058] Comparative Example 3 The main difference between this comparative example and Example 1 is that in step S2, the oxidizing slag system of Example 1 is used during electroslag remelting, but oxygen is not introduced, and the Al content in the electroslag remelted ingot is 0.005%. All other settings are the same as in Example 1.

[0059] During the operation, it was found that insufficient oxidation resulted in high levels of Ti and Al in the electroslag ingot, which weakened the denitrification and large inclusion removal capabilities of the vacuum induction process. After vacuum induction melting, the resulting alloy ingot had an oxygen content of 50 ppm (T.O), a nitrogen content of 65 ppm (N), a hydrogen content of 2.2 ppm (H), and the largest inclusion size reached 35 micrometers.

[0060] Comparative Example 4 The main difference between this comparative example and Example 1 is that in step S3, a conventional high-purity carbon tube with a central hole is used to introduce argon gas. The diameter of the central hole is the same as that of the argon gas inlet hole of the high-purity carbon tube 2 in Example 1. At the same time, the high-purity carbon tube in this comparative example is removed when the carbon content in the alloy liquid reaches 0.04% in real time. All other settings are the same as in Example 1.

[0061] Using this device leads to a reduction in the ability of argon to stir and remove gases as a "vacuum chamber"; at the same time, the low carbon content will cause the alloy liquid to over-oxidize, and the final alloy ingot has an oxygen content of 50 ppm, a nitrogen content of 60 ppm, a hydrogen content of 2.5 ppm, and an inclusion size of up to 30 micrometers.

[0062] Comparative Example 5 The main difference between this comparative example and Example 1 is that in step S3, the high-purity carbon tube 2 is removed when the carbon content in the alloy liquid reaches 0.09% in real time, and electromagnetic stirring is not used during the entire vacuum refining process. All other settings are the same as in Example 1.

[0063] Since most high-temperature alloys require low carbon content, when the target carbon content is set at 0.09%, the proportion of pure metal feed needs to be increased to dilute the carbon brought in by the recycled material, which directly leads to an increase in production costs. At the same time, due to the lack of electromagnetic stirring, the stirring kinetics of the molten metal pool deteriorates, resulting in an oxygen content (TO) of 52 ppm, a nitrogen content (N) of 58 ppm, a hydrogen content (H) of 2.0 ppm, and an inclusion size of up to 28 micrometers in the resulting alloy ingot.

[0064] Comparative Example 6 The main difference between this comparative example and Example 1 is that in step S3, the high-purity carbon tube 2 is immersed to a depth of 90% of the total depth of the alloy liquid 3, and the distance H between the upper surface of the first carbon layer 2-1 of the purification device and the surface of the alloy liquid 3 is 350 mm. All other settings are the same as in Example 1.

[0065] The high-purity carbon tube 2 was inserted too deeply, and the first carbon layer 2-1 of the purification device was too high above the surface of the alloy liquid 3. The stirring effect at the bottom of the alloy liquid 3 was suppressed, and the degassing kinetics of the upper metal liquid were also weakened. As a result, the oxygen content TO in the obtained alloy ingot increased to 50 ppm, the nitrogen content N to 42 ppm, the hydrogen content H to 1.8 ppm, and the maximum size of the inclusions reached 25 micrometers.

[0066] Comparative Example 7 The main difference between this comparative example and Example 1 is that in step S3, the high-purity carbon tube 2 is immersed to a depth of 40% of the total depth of the alloy liquid 3, and the distance H between the upper surface of the first carbon layer 2-1 of the purification device and the surface of the alloy liquid 3 is 100mm. All other settings are the same as in Example 1.

[0067] When the high-purity carbon tube 2 is inserted too shallowly, and the height of the first carbon layer 2-1 of the purification device from the surface of the alloy liquid 3 is insufficient, the stirring effect at the bottom of the alloy liquid 3 is also suppressed; the rising path of the argon bubbles is shortened, and the gas-liquid contact time is reduced, thereby reducing the efficiency of degassing and inclusion removal. As a result, the oxygen content TO in the obtained alloy ingot reaches 52 ppm, the nitrogen content N 45 ppm, and the hydrogen content H 2.0 ppm, and the maximum size of the inclusions is 25 micrometers.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing an alloy material for an induction furnace, characterized in that: Includes the following steps: S1. High-temperature alloy recycled material is directly compressed into metal consumable electrodes; S2. The metal consumable electrode is subjected to electroslag remelting treatment under an oxidizing atmosphere and an oxidizing slag system. S3. After grinding and dividing the remelted ingot obtained after electroslag remelting in step S2, it is added to a vacuum induction furnace for vacuum refining. During the refining process, a perforated high-purity carbon tube is used as a purification device to deoxidize, denitrify and dehydrogenate the alloy melt. The purification device is directly inserted into the alloy liquid and argon gas is introduced into the high-purity carbon tube, while electromagnetic stirring is used. S4. After refining, the material is cast into steel ingots to obtain alloy material for induction furnaces.

2. The method for preparing alloy material for induction furnaces according to claim 1, characterized in that: In step S2, the flow rate of the oxidizing atmosphere is 50 L / min to 100 L / min; The oxidizing slag system comprises, by mass percentage: 65%~70% CaF2, 25%~30% Al2O3, and 0%~5% FeO, with the weight of the oxidizing slag system being 5%~10% of the electrode weight; the electroslag remelting time is 2h~6h.

3. The method for preparing alloy material for induction furnaces according to claim 2, characterized in that: In step S2, the obtained electroslag remelted ingot contains Al ≤ 0.003% and Ti ≤ 0.003%.

4. The method for preparing alloy material for induction furnaces according to any one of claims 1-3, characterized in that: In step S3, the high-purity carbon tube contains C ≥ 99.0% and S ≤ 0.03%.

5. The method for preparing alloy material for induction furnaces according to claim 4, characterized in that: In step S3, the flow rate of argon gas is 10L / h to 500L / h, and the electromagnetic stirring is performed for 10s to 30s every 10 minutes. The stirring time is not included in the 10-minute interval.

6. A purification apparatus for use in the method according to any one of claims 1-5, characterized in that, The purification device is used in the refining process to deoxidize, denitrify, and dehydrogenate the alloy melt, wherein: The purification device uses a perforated high-purity carbon tube (2) as the main structure. The lower part and bottom of the high-purity carbon tube (2) extend radially outward along its tube wall to form an annular carbon layer, which are the first carbon layer (2-1) and the second carbon layer (2-2), respectively. The first carbon layer (2-1) and the second carbon layer (2-2) are parallel to each other; The high-purity carbon tube (2) has an argon gas inlet hole in the middle of its tube wall. The argon gas inlet hole is connected to the argon gas inlet tube (1). The first carbon layer (2-1) and the second carbon layer (2-2) are both machined with cavities that communicate with the argon gas inlet hole. The surfaces of the first carbon layer (2-1) and the second carbon layer (2-2) are both machined with gas outlet holes that communicate with the cavity.

7. The purification apparatus according to claim 6, characterized in that, The vents of the first carbon layer (2-1) include a first radial vent (7-1), a first axial vent (7-2), and a second axial vent (7-3), wherein: The first radial air outlet (7-1) includes multiple sets of air holes spaced apart along the vertical surface of the first carbon layer (2-1). The multiple sets of air holes are arranged parallel to each other, and the multiple small holes of each set of air holes are evenly distributed along the circumferential direction of the first carbon layer (2-1). The first axial vent (7-2) includes multiple sets of vents spaced apart along the horizontal plane of the first carbon layer (2-1), and the second axial vent (7-3) includes multiple sets of vents spaced apart along the horizontal plane of the first carbon layer (2-1). The first axial vent (7-2) and the second axial vent (7-3) are symmetrically arranged, and each set of vents is concentrically distributed with the center of the high-purity carbon tube (2) as the axis.

8. The purification apparatus according to claim 6, characterized in that, The second carbon layer (2-2) has vents including a second radial vent (7-4), a third axial vent (7-5), and a fourth axial vent (7-6), wherein: The second radial air outlet (7-4) includes multiple sets of air holes spaced apart along the vertical plane of the second carbon layer (2-2). The multiple sets of air holes are arranged parallel to each other, and the multiple small holes of each set of air holes are evenly distributed along the circumferential direction of the second carbon layer (2-2). The third axial vent (7-5) includes multiple sets of vents spaced apart along the horizontal plane of the second carbon layer (2-2), with the multiple sets of vents concentrically distributed with the center of the high-purity carbon tube (2) as the axis; The fourth axial vent (7-6) includes multiple vents arranged in a circular array along the entire bottom circumference of the second carbon layer (2-2).

9. The purification apparatus according to claim 6, characterized in that, The first carbon layer (2-1) and the second carbon layer (2-2) have the same diameter D, which is 2 / 3 to 3 / 4 of the inner diameter of the crucible, and the vent holes on the surface of the first carbon layer (2-1) and the second carbon layer (2-2) have a diameter of 0.5 mm to 1 mm.

10. A method of using the purification apparatus as described in any one of claims 6-9, characterized in that: During vacuum refining, the purification device is inserted, and the purification device is immersed in the alloy liquid (3) to a depth of 50% to 80% of the total depth of the alloy liquid (3), and the distance H between the upper surface of the first carbon layer (2-1) and the surface of the alloy liquid (3) is 150 mm to 300 mm; when the carbon content in the alloy liquid (3) is 0.05% to 0.08%, the purification device is removed.

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