A method and apparatus for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled materials.

Abstract

This invention discloses a method and apparatus for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material, belonging to the field of superalloy technology. The invention involves forming a consumable electrode inner layer from the molybdenum-containing scrap recycled material and then wrapping it with an outer layer to create a double-layer consumable electrode; the resulting double-layer consumable electrode is then subjected to electroslag remelting to prepare a molybdenum-containing superalloy ingot. The outer layer of the consumable electrode is formed by pressing a mixture containing aluminum particles, molybdenum oxide powder, and molybdenum-containing scrap recycled material, with the mass ratio of molybdenum in the molybdenum oxide powder to the aluminum particles being 1.4–1.5:1. This method, by preparing a consumable electrode with a double-layer structure for electroslag remelting, not only ensures the purity of the obtained molybdenum-containing superalloy ingot but also increases the proportion of molybdenum-containing scrap recycled material added.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy technology, and more specifically, to a method and apparatus for smelting molybdenum-containing high-temperature alloy raw materials using low-molybdenum scrap high-temperature alloy recycled materials. Background Technology

[0002] High-temperature alloys possess excellent comprehensive properties such as high-temperature strength, oxidation resistance, corrosion resistance, fatigue resistance, and fracture toughness, making them an important material widely used in aviation, aerospace, petroleum, chemical, and shipbuilding industries. Currently, commonly used smelting processes for high-temperature alloys include vacuum induction remelting, electroslag remelting, and vacuum arc remelting. Regardless of the process used, the electrodes require surface stripping before proceeding to the next step. For example, before entering arc remelting after electroslag remelting, the surface of the electroslag ingot needs to be machined; subsequent forging products also require surface machining. How to recycle and utilize the shavings from machining is crucial for reducing the production cost of high-temperature alloys.

[0003] A search revealed existing patents addressing these issues, primarily involving physical treatment of recycled materials or vacuum reaction melting after physical treatment. For example, Chinese invention patent application number 2023113934013 discloses a method for purifying recycled high-chromium cast nickel-based superalloy materials, specifically outlining surface treatment, vacuum melting, and casting. However, the purity of metal ingots prepared via vacuum melting still requires further improvement.

[0004] Existing technologies also include recycling recycled materials using induction melting (including vacuum / non-vacuum induction melting) combined with electroslag remelting. For example, Chinese invention patent application No. 2022116482884 discloses a method for refining carbonitrides in GH4169 alloy by controlling the amount of recycled material added. Specifically, it discloses selecting virgin pure GH4169 material and recycled material as raw materials for alloy preparation; the amount of recycled material added to the raw materials is 10~50wt%; the raw materials are sequentially subjected to vacuum induction melting, electroslag remelting, and vacuum arc remelting to obtain VAR consumable ingots. Although the above methods can better remove inclusions in the recycled material, the proportion of recycled material added to the smelting raw materials in this application is relatively low, and the utilization rate of recycled material still needs to be further improved.

[0005] The same problems exist for molybdenum-containing high-temperature alloy scrap. Furthermore, existing methods for alloying molybdenum-containing high-temperature alloys primarily involve directly adding elemental molybdenum during induction melting and electroslag remelting, which is costly. While existing patents also mention adding a certain amount of molybdenum oxide and minerals to the slag pool and relying on slag refining for direct alloying, achieving molybdenum enrichment, this smelting method suffers from poor process stability. Summary of the Invention

[0006] To address the technical problems in existing technologies where the purity of the resulting high-temperature alloy is low or the proportion of recycled material is low when using molybdenum-containing scrap for smelting molybdenum-containing superalloys, this invention provides a method and apparatus for smelting molybdenum-containing superalloys using molybdenum-containing scrap. This invention directly fabricates the molybdenum-containing scrap into a consumable electrode with a double-layer structure for electroslag remelting, and then smelts it using electroslag remelting technology. This not only ensures the purity of the resulting molybdenum-containing superalloy but also increases the proportion of molybdenum-containing scrap added.

[0007] In addition, the present invention can effectively solve the technical problem of poor process stability when molybdenum-containing high-temperature alloys are subjected to molybdenum-enrichment alloying treatment in the prior art.

[0008] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0009] The first aspect of this invention provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material, comprising: forming an inner layer of a consumable electrode from the molybdenum-containing scrap recycled material, and wrapping an outer layer of a consumable electrode around the inner layer to form a double-layer consumable electrode; and electroslag remelting the obtained double-layer consumable electrode to prepare a molybdenum-containing superalloy ingot; wherein the outer layer of the consumable electrode is formed by pressing a mixture containing aluminum particles, molybdenum oxide powder and molybdenum-containing scrap recycled material, and the mass ratio of molybdenum element in the molybdenum oxide powder to the mass of aluminum particles is 1.4~1.5:1.

[0010] This invention prepares a double-layer consumable electrode by compression molding and applies it to electroslag remelting, optimizing its composition. On one hand, electroslag remelting improves the purity of the resulting high-temperature alloy ingot, allowing it to be directly used to prepare new high-temperature alloy ingots through vacuum melting and electroslag remelting without adding a certain proportion of virgin refined material, increasing the utilization rate of recycled materials and reducing smelting costs. On the other hand, it enables molybdenum alloying during electroslag remelting, significantly reducing the cost of molybdenum addition. Molybdenum oxide powder in the outer layer of the consumable electrode reacts with aluminum particles to generate elemental molybdenum and aluminum oxide. The resulting elemental molybdenum can alloy the high-temperature alloy. Due to the skin effect of the current, the reduction reaction of molybdenum oxide by the aluminum particles in the outer layer is better promoted, achieving molybdenum alloying during electroslag remelting. Conversely, directly mixing and pressing molybdenum oxide, aluminum particles, and molybdenum-containing scrap recycled material into a consumable electrode is detrimental to the uniformity of the reduction reaction of molybdenum oxide by aluminum particles throughout the electrode, and also reduces the molybdenum yield. It should also be noted that the inclusion of molybdenum-containing scrap recycled material in the outer layer of the consumable electrode in this invention is necessary. Specifically, the mass ratio of molybdenum to aluminum particles in the molybdenum oxide powder in the outer layer of the consumable electrode is 1.4~1.5:1. This ratio is chosen for the following reasons: firstly, the aluminum particles can fully reduce the molybdenum oxide; secondly, the remaining aluminum particles can play a deoxidizing role; and thirdly, the mass proportion of aluminum particles cannot be too large, otherwise it may lead to aluminum waste and potentially contaminate the resulting high-temperature alloy liquid. Within the above-mentioned range of proportions, the conductivity of the outer layer will be poor. Moreover, as the reduction reaction between molybdenum oxide and aluminum particles proceeds, its conductivity will further deteriorate. Therefore, it is necessary to add scraped high-temperature alloy recycled material to the outer layer of the consumable electrode to improve its conductivity.

[0011] Furthermore, as electroslag remelting proceeds, the alumina in the slag pool gradually decreases due to the high temperature. Failure to replenish alumina in time will lead to process instability and increased power consumption. However, adding room-temperature alumina directly into the slag pool from the outside will cause drastic temperature fluctuations, disrupting the remelting process. At this point, the alumina generated from molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode is at a very high temperature. As the electrode descends into the remelting slag pool, its impact on the slag pool temperature is negligible.

[0012] Furthermore, the aluminum particles in the outer layer of the consumable electrode have a particle size of 0.5~1mm, and the molybdenum oxide powder has a particle size of 800~1000 mesh. The total mass of the molybdenum oxide powder and aluminum particles is denoted as A, and the mass of the scrap-like high-temperature alloy return material is denoted as B, with the mass ratio of A to B being 1~2:1. Limiting the particle size of the aluminum particles and molybdenum oxide powder will further reduce the conductivity of the outer layer, potentially even forming a non-conductive outer layer of the consumable electrode. However, the above particle size selection is based on fully considering the rate of the reduction reaction of aluminum particles with molybdenum oxide powder. Further reducing the particle size of the aluminum particles or increasing the particle size of the molybdenum oxide powder, or using a combination of both, while slightly improving the conductivity of the outer layer, would hinder the reaction of aluminum particles with molybdenum oxide. The specific impacts are as follows: Increasing the particle size of molybdenum oxide reduces the rate of molybdenum oxide reduction; further reducing the particle size of aluminum particles results in a lower initial reaction rate due to the dense alumina film on the outer surface of the aluminum particles; as the reaction proceeds, the increased heat leads to more vigorous subsequent reactions, which is detrimental to the stability of the aluminum-molybdenum oxide reaction, causing drastic temperature fluctuations and consequently hindering the stability of the electroslag remelting process. Therefore, the conductivity of the outer layer of the consumable electrode is controlled by limiting the proportion of recycled high-temperature alloy chips. However, higher conductivity of the outer layer is not always better. Higher conductivity and lower resistivity result in lower heat generation, which is detrimental to the molybdenum oxide reduction reaction. Therefore, the amount of molybdenum-containing recycled chip material in the outer layer should not be too high.

[0013] Furthermore, the consumable electrode is also wrapped with a steel shield. Because the steel shield prevents the volatilization of molybdenum oxide, the molybdenum yield is increased, further reducing costs.

[0014] Furthermore, the length of the molybdenum-containing scrap recycled material used in the outer layer of the consumable electrode is 2-4 mm, and the thickness is 1-2 mm; the length of the molybdenum-containing scrap recycled material used in the inner layer of the consumable electrode is 2-6 mm, and the thickness is 1-2 mm. By selecting a shorter length of molybdenum-containing scrap recycled material for the outer layer of the consumable electrode, which has a relatively higher resistance, and selecting a longer length of molybdenum-containing scrap recycled material for the inner layer, which has a relatively lower resistance, the difference in resistivity between the outer and inner layers is adjusted, thereby controlling the heat generation of the outer layer to be greater than that of the inner layer. During the smelting process, the voltage is generally adjusted to keep the current relatively constant, but the smelting current inevitably fluctuates within a certain range. The range of current parameter variation indicates whether the smelting process is stable.

[0015] Furthermore, the mass ratio of the outer layer to the inner layer of the consumable electrode is 5-15:100. This ratio is set based on a comprehensive consideration of molybdenum enrichment and the stability of the remelting process, specifically as follows: When the mass ratio of the outer layer to the inner layer of the consumable electrode is too low, the increase in molybdenum content is extremely limited, and the amount of alumina generated is also relatively small, which has little significance for replenishing the slag pool. Conversely, if the ratio is too high, more alumina will be generated and enter the slag pool; a certain amount of alumina in the slag pool is beneficial to the stability of the remelting process, but if the alumina exceeds a certain range, it will cause drastic fluctuations in smelting parameters, especially the current, and may even interrupt the smelting process.

[0016] Furthermore, the electroslag remelting specifically includes the following steps: S1, arc initiation and slag formation: the arc initiation electrode and the arc-starting material are pressed together, electricity is applied, and then slag material is added to begin slag formation; S2, remelting stage: as the slag material melts, the double-layer consumable electrode is gradually inserted into the slag pool and melts, and remelting begins; S3, refining stage: after the metal consumable electrode has been remelted, the double-layer consumable electrode is replaced with a graphite electrode to continue heating and refining; S4, casting and molding: after refining, it is cast into an alloy ingot of a specified size.

[0017] Furthermore, the arc-starting electrode used in S1 is prepared from molybdenum-containing scrap recycled material, and its diameter is 1 / 3 to 1 / 2 of the diameter of the double-layer consumable electrode; its height is 5 mm to 10 mm; and / or the arc-starting material used in the electroslag remelting includes molybdenum-containing scrap recycled material and calcium fluoride, with a mass ratio of 3 to 5:1.

[0018] The arc-initiating electrode is made from molybdenum-containing scrap recycled material, further increasing the amount and utilization rate of recycled material. The diameter of the arc-initiating electrode is smaller than that of the double-layer consumable electrode, resulting in a lower current density at this point, which is more conducive to arc initiation.

[0019] Furthermore, the power supply used for arc initiation and slag remelting in S1 is an industrial frequency AC power supply; and / or the electroslag remelting is carried out in a crucible, and the power supply used for the refining stage in step S3 is a low frequency power supply with a frequency of 0.1~0.5Hz.

[0020] The refining stage uses a low-frequency power supply with a frequency of 0.1~0.5Hz. Electroslag remelting is carried out in a crucible, where the consumable electrode melts upon heating, forming a high-temperature molten metal in the crucible. The use of a low-frequency power supply in the refining stage subjects the molten steel in the crucible to a greater electromagnetic force, promoting convection of the alloy liquid, expanding the slag-metal contact area, and maximizing the removal of inclusions from the recycled material, further improving the purity of the product obtained from smelting using the recycled material.

[0021] Furthermore, a second aspect of the present invention provides an apparatus for the above-described smelting method, comprising a graphite electrode, a bottom electrode, a crucible, and a double-layer consumable electrode for use in any of the above-described smelting methods. The crucible contains, from bottom to top, a connected bottom electrode, an arc-starting material, an arc-starting electrode, and a double-layer consumable electrode. The graphite electrode is used to replace the double-layer consumable electrode during the refining stage, and has a steel tube inside. A gap exists between the inner wall of the graphite electrode and the outer wall of the steel tube, forming a second air intake channel. The steel tube is a hollow tube, forming a first air intake channel inside. The side wall of the steel tube has multiple spaced-apart pores for connecting the first air intake channel and the second air intake channel.

[0022] Furthermore, the first intake channel is used to introduce methane at 0.11~0.13MPa; the second intake channel is used to introduce argon at 0.13~0.15MPa, and the pressure of the gas introduced into the first intake channel is less than the pressure of the gas introduced into the second intake channel.

[0023] Considering the resistance of the atmosphere and slag pool, the gas pressure in the first inlet channel is selected to be 0.11~0.13MPa to ensure that methane can smoothly enter the slag pool. Furthermore, the CH4 introduced through the first inlet channel decomposes into carbon and hydrogen at high temperature, diffusing and deoxidizing the molten slag to further purify the high-temperature alloy return material. However, the generated carbon tends to accumulate on the inner wall of the steel pipe. Therefore, argon gas at a slightly higher pressure is introduced into the second inlet channel. The argon gas blows away the carbon powder adhering to the inner wall of the steel pipe through the pores, thus avoiding clogging and ensuring smooth blowing.

[0024] Furthermore, the air holes are inclined upwards along the inner wall of the steel pipe toward its outer wall, and the angle between the axial direction of a single air hole and the vertical direction is 10~20°.

[0025] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0026] (1) This invention designs a double-layer consumable electrode. Specifically, the inner layer of the consumable electrode is made from molybdenum-containing scrap recycled material, and an outer layer of the consumable electrode is wrapped around it. The purity of the recycled material is improved by electroslag remelting. Furthermore, the outer layer of the consumable electrode is made by pressing a mixture containing aluminum particles, molybdenum oxide powder, and molybdenum-containing scrap recycled material. The conductivity of the outer layer is changed by adding molybdenum-containing scrap recycled material. The particle size of the aluminum particles and molybdenum oxide powder is selected to promote the overall performance of aluminum particles reducing molybdenum oxide powder. At the same time, the alumina byproduct of the reaction between aluminum particles and molybdenum oxide powder can supplement the alumina in the slag pool, and has a smaller impact on the stability of electroslag remelting compared to the added alumina. Furthermore, the amount of molybdenum generated can be adjusted by controlling the amount of aluminum particles and molybdenum oxide powder in the outer layer, thereby achieving the adjustment of the molybdenum content in the high-temperature alloy ingot obtained by remelting.

[0027] (2) The present invention further optimizes the specific process of electroslag remelting, which is carried out in a crucible, and adds a subsequent refining stage to further improve the purity of the product obtained by smelting using recycled materials. Furthermore, the internal design of the graphite electrode used in the refining stage is optimized, and a first air inlet channel and a second air inlet channel are set. The first air inlet channel is used to introduce methane, and the second air inlet channel blows air into the first air inlet channel through the air hole in the steel pipe, thereby avoiding carbon powder accumulation and ensuring smooth air blowing. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the arc-starting stage of the melting device in an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram of the remelting stage of the smelting apparatus in an embodiment of the present invention.

[0030] Figure 3 This is a schematic diagram of the refining stage of the smelting apparatus in an embodiment of the present invention.

[0031] Label Explanation:

[0032] 1. Industrial frequency AC power supply;

[0033] 2-1. Outer layer of consumable electrode; 2-2. Inner layer of consumable electrode;

[0034] 3. Crucible;

[0035] 4. Arc starting material;

[0036] 5. Arc-initiating electrode;

[0037] 6. Bottom water tank;

[0038] 7. Bottom electrode;

[0039] 8. High temperature alloy liquid;

[0040] 9. Slag pit;

[0041] 10. Low-frequency power supply;

[0042] 11. Graphite electrode;

[0043] 12. Steel pipes;

[0044] 13. First air intake passage;

[0045] 14. Second air intake channel. Detailed Implementation

[0046] To further understand the content of this invention, the invention will be described in detail with reference to the embodiments.

[0047] Example 1

[0048] This embodiment provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material. The molybdenum content in the recycled material is 0.5%. The specific steps are as follows:

[0049] (i) Preparation of Consumable Electrode: The inner layer 2-2 of the consumable electrode is formed by pressing back the molybdenum-containing recycled material from machining. The length of the recycled material is 4-6 mm and the thickness is 1-2 mm, calculated based on the mass of the inner layer 2-2 as 100%. The inner layer 2-2 can also be formed by melt casting; the specific forming process is not limited by pressing. The outer layer 2-1 of the consumable electrode is formed by pressing a mixture of aluminum granules, molybdenum oxide, and the recycled material from machining onto the outside of the inner layer 2-2. The more detailed process parameters for the outer layer 2-1 of the consumable electrode are as follows: 7.5% of the mass of the turned molybdenum-containing scrap recycled material is used, with a length of 2-3 mm and a thickness of 1-2 mm; 5.36% of the mass of molybdenum oxide powder is used, with a particle size of 1000 mesh, ground from molybdenum oxide clinker, containing 56% molybdenum, or 3.00% molybdenum; 2.14% of the mass of aluminum powder is used, with a particle size of 0.5 mm; that is, the mass ratio of molybdenum in the molybdenum oxide powder to the aluminum particles is 1.40, meaning the ratio of the total mass of aluminum particles and molybdenum oxide powder in the outer layer to the amount of turned molybdenum-containing scrap recycled material is 1. From the above mass ratios, it can be seen that the mass ratio of the outer layer 2-1 to the inner layer 2-2 of the consumable electrode is 15:100.

[0050] The double-layer consumable electrode is also wrapped with a steel cover, preferably made of stainless steel, with a thickness of 0.5 mm.

[0051] The consumable electrode prepared in this embodiment has a diameter of 300 mm, a height of 2 m, and a mass of approximately 1060 kg, of which the inner layer has a mass of approximately 922 kg.

[0052] (ii) Electroslag remelting

[0053] The device used for electroslag remelting in this embodiment includes a power supply, a graphite electrode 11, an arc-initiating electrode 5, a crucible 3, a bottom electrode 7, a bottom water tank 6, and a double-layer consumable electrode. Inside the crucible 3, the bottom electrode 7, the arc-initiating material 4, the arc-initiating electrode 5, and the double-layer consumable electrode are arranged sequentially from bottom to top. The double-layer consumable electrode, the arc-initiating electrode 5, the arc-initiating material 4, and the bottom electrode 7 are arranged coaxially along the height direction. The connection relationship between the components is as follows: Figures 1-3 As shown.

[0054] Referring to the diagram, the equipment used for electroslag remelting is assembled. The specific steps of electroslag remelting are as follows:

[0055] S1, Arc ignition and slag removal: Press the arc ignition electrode 5 and the arc ignition material 4 together, turn on the power, and then add slag material to start slag removal;

[0056] S2, Remelting Stage: As the slag melts, the double-layer consumable electrode is gradually inserted into the slag pool 9 and melts, and remelting begins;

[0057] S3, Refining stage: After the metal consumable electrode is remelted, the double-layer consumable electrode is replaced with graphite electrode 11 and the refining is continued.

[0058] S4, Casting: After refining, the alloy is cast into an alloy ingot of a specified size.

[0059] Following S4, the resulting alloy ingot is forged, cut into raw materials, and polished before being added to a vacuum induction furnace for smelting according to the high-temperature alloy smelting process.

[0060] The arc-initiating material 4 is a mixture of molybdenum-containing scrap return material from machining and calcium fluoride, with a mass ratio of 4:1.

[0061] The diameter of the arc-initiating electrode 5 is smaller than the outer diameter of the double-layer consumable electrode, and its outer diameter is preferably 1 / 3 to 1 / 2 of the outer diameter of the double-layer consumable electrode. The height is preferably in the range of 5mm to 10mm.

[0062] The power supply used in the arc initiation, slag formation, and remelting stages is preferably an industrial frequency AC power supply 1.

[0063] The power supply used in the refining stage is preferably a low-frequency power supply 10, with a frequency preferably between 0.1 and 0.5 Hz. The graphite electrode 11 used in the refining stage has a structure referenced from [reference needed]. Figure 3 As shown, the graphite electrode 11 is a hollow graphite electrode, and a steel tube 12 is provided inside it. There is a gap between the inner wall of the graphite electrode 11 and the outer wall of the steel tube 12, which forms a second air intake channel 14. The steel tube 12 is a hollow tube, and a first air intake channel 13 is formed inside it. The side wall of the steel tube is provided with a plurality of spaced air holes, which are used to connect the first air intake channel 13 and the second air intake channel 14. More specific parameters are as follows:

[0064] The inner diameter of the steel pipe 12 is preferably 10~20mm, and its wall thickness is preferably 10~15mm. Its material is preferably 314 stainless steel.

[0065] The bottom of the steel pipe 12 is preferably 20-40mm above the bottom of the graphite electrode 11, which can effectively prevent the high-temperature slag pool from damaging the steel pipe 12 and extend the service life of the steel pipe 12.

[0066] The distance between the outer wall of the steel pipe 12 and the inner wall of the graphite electrode 11 is preferably 2~5mm, that is, the size of the second air intake channel 14 is preferably 2~5mm.

[0067] The first air inlet channel 13 is used to introduce methane at 0.12 MPa, and the second air inlet channel 14 is used to introduce argon at 0.14 MPa.

[0068] Argon gas with slightly higher pressure is introduced into the second air inlet channel 14 and blown downward along the hole wall into the first air inlet channel 13, so that the carbon powder accumulated on the inner wall of the steel pipe 12 enters the slag pool downward, thereby better avoiding the blockage of the steel pipe 12.

[0069] The vents are inclined upward along the inner wall of the steel pipe 12 towards the outer wall. The angle between the axial direction of a single vent and the vertical direction is preferably in the range of 10~20°, and its diameter can be selected in the range of 2~4mm.

[0070] Multiple vents are spaced apart along the axial direction of the steel pipe 12, forming a single row of vents. The single row of vents can consist of 4 to 6 vents arranged in a circumferential circular array along the steel pipe 12. Adjacent vents in the single row are spaced 30 to 50 mm apart along the height direction. Methane entering the first intake channel 13 decomposes into carbon at high temperatures, but the temperature is too low at 500-600 mm and above in the steel pipe to decompose the methane. Therefore, the single row of vents extends upwards from the bottom of the side wall of the steel pipe 12 to 500-600 mm.

[0071] The high-temperature alloy ingot obtained in this embodiment has a molybdenum content of 3.10% and a yield of 96.90%, which is significantly higher than the molybdenum content of the returned high-temperature alloy chips. Furthermore, compared with the original high-temperature alloy obtained by electroslag remelting, the composition of the remaining alloys in the obtained high-temperature alloy ingot shows inclusion contents of grades A0.5, B1.0, C0, and D1.0. In addition, the variation in current parameters during the smelting process is ≤±4%, indicating a stable smelting process that is conducive to ensuring the smooth progress of the remelting process.

[0072] Comparative Example 1

[0073] This comparative example provides a method for smelting molybdenum-containing high-temperature alloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that: a homogenized material containing aluminum particles, molybdenum oxide, and machined molybdenum-containing scrap recycled material is pressed into a single-layer consumable electrode, wherein the mass ratio of aluminum particles, molybdenum oxide powder, and machined molybdenum-containing scrap recycled material used in the single-layer consumable electrode is 2.14:5.36:107.5; and the obtained single-layer consumable electrode is subjected to electroslag remelting, with the remaining operation steps being basically the same.

[0074] The high-temperature alloy ingot obtained by this comparative smelting had a molybdenum content of 2.65% and a yield of 82.9%. Furthermore, the variation in current parameters during the smelting process was ≤±6%, indicating a relatively stable smelting process.

[0075] Comparative Example 2

[0076] This comparative example provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that, based on the mass of the inner layer of the consumable electrode being 100%, no machined molybdenum-containing scrap recycled material is added to the outer layer of the consumable electrode. The mass ratio of aluminum particles, molybdenum oxide powder, and machined molybdenum-containing scrap recycled material in the double-layer consumable electrode is 2.14:5.36:100; the remaining operations are basically the same.

[0077] The high-temperature alloy ingot obtained from this comparative smelting had a molybdenum content of 2.4% and a yield of 70.6%. Furthermore, the current parameter fluctuated by ≥10% during the smelting process, indicating poor stability of the smelting process.

[0078] Comparative Example 3

[0079] This comparative example provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that, based on the mass of the inner layer of the consumable electrode being 100%, the total mass of molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode is equal to 0.5 times the mass of the scrap superalloy recycled material. That is, the total mass of molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode and the mass of the scrap superalloy recycled material are 5.36:2.14:15. The remaining operations are basically the same.

[0080] The high-temperature alloy ingot obtained by this comparative smelting had a molybdenum content of 2.17% and a yield of 72.3%. Furthermore, the current parameter fluctuated by ≥±10% during the smelting process, indicating poor stability of the smelting process.

[0081] Comparative Example 4

[0082] This comparative example provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that, based on the mass of the inner layer of the consumable electrode being 100%, the total mass of molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode is equal to 2.5 times the mass of the scrap superalloy recycled material. That is, the total mass of molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode and the mass of the scrap superalloy recycled material are 5.36:2.14:3. The remaining operations are basically the same.

[0083] The high-temperature alloy ingot obtained from this comparative smelting had a molybdenum content of 2.12% and a yield of 64.0%. Furthermore, the variation in current parameters during the smelting process was approximately ±12%, indicating poorer stability of the smelting process.

[0084] Comparative Example 5

[0085] This comparative example provides a method for smelting molybdenum-containing high-temperature alloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that the particle size of the molybdenum oxide powder and the aluminum particles used are 1000 mesh, while the rest of the operations are basically the same.

[0086] The high-temperature alloy ingot obtained from this comparative smelting process had a molybdenum content of 2.43% and a yield of 76%. Furthermore, the variation in current parameters during the smelting process was ≤±8%, indicating a relatively stable smelting process.

[0087] Comparative Example 6

[0088] This comparative example provides a method for smelting molybdenum-containing high-temperature alloys using molybdenum-containing scrap recycled material. The difference from Example 1 is that the particle size of the molybdenum oxide powder used is 0.5 mm, and the particle size of the aluminum particles is 0.5 mm. The rest of the operations are basically the same.

[0089] The high-temperature alloy ingot obtained by this comparative smelting had a molybdenum content of 2.25% and a yield of 70.3%. Furthermore, the current parameter fluctuated by ≥±10% during the smelting process, indicating poor stability of the smelting process.

[0090] Comparative Example 7

[0091] This comparative example provides a method for smelting molybdenum-containing high-temperature alloys using molybdenum-containing scrap return material. The difference from Example 1 is that the outer layer of the consumable electrode is not covered with a steel cover, while the rest of the operation is basically the same.

[0092] The high-temperature alloy ingot obtained by this comparative smelting had a molybdenum content of 2.66% and a yield of 83.1%. Furthermore, the variation in current parameters during the smelting process was ≤±6%, indicating a relatively stable smelting process.

[0093] Example 2

[0094] This embodiment provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap return material. The molybdenum content in the molybdenum-containing scrap return material is 2.5%. The specific steps are as follows:

[0095] (I) Preparation of consumable electrode

[0096] The inner layer 2-2 of the consumable electrode is formed by pressing back the molybdenum-containing recycled material from turning, wherein the length of the recycled material is 4-6 mm and the thickness is 1-2 mm; the mass of the inner layer of the consumable electrode is calculated as 100%.

[0097] The outer layer 2-1 of the consumable electrode is formed by pressing a mixture of aluminum granules, molybdenum oxide, and molybdenum-containing recycled material from machining onto the outside of the inner layer of the consumable electrode. More detailed process parameters for the outer layer 2-1 are as follows: the mass of the molybdenum-containing recycled material from machining is 3.33%, with a length of 2-4 mm and a thickness of 1-2 mm; the mass of molybdenum oxide powder is 4.82%, which is made by grinding molybdenum oxide clinker with a particle size of 800 mesh, containing 56% molybdenum (2.70% by mass); the amount of aluminum powder is 1.85%, with a particle size of 1 mm; the mass ratio of molybdenum in the molybdenum oxide powder to the aluminum granules is 1.46; and the ratio of the total mass of aluminum granules and molybdenum oxide powder in the outer layer to the mass of the molybdenum-containing recycled material from machining is 2.

[0098] As can be seen from the above mass ratio, the mass ratio of the outer layer 2-1 of the consumable electrode to the inner layer 2-2 of the consumable electrode is 10:100.

[0099] A steel cover, preferably made of stainless steel, is wrapped around the double-layer consumable electrode. The thickness of the steel cover is 1.0 mm.

[0100] The consumable electrode prepared in this embodiment has a diameter of 400 mm, a height of 2 m, and a mass of approximately 1890 kg, of which the inner layer has a mass of approximately 1718 kg.

[0101] (ii) Electroslag remelting

[0102] The apparatus used for electroslag remelting in this embodiment is basically the same as that in Embodiment 1. The specific steps of electroslag remelting are different from those in Embodiment 1 in that: the arc-starting material 4 is a mixture of spun molybdenum-containing scrap return material and calcium fluoride, with a mass ratio of 3:1; the first gas inlet channel 13 is used to introduce methane at 0.11 MPa; the second gas inlet channel 14 is used to introduce argon at 0.13 MPa; the remaining steps are basically the same.

[0103] The high-temperature alloy ingot obtained in this embodiment has a molybdenum content of 4.65% and a yield of 93.0%, which is significantly higher than the molybdenum content of the returned high-temperature alloy chips. Furthermore, compared with the original high-temperature alloy ingot obtained by electroslag remelting, the inclusion content in the obtained high-temperature alloy ingot is A0.5, B1.0, C0, and D1.0. In addition, the current parameter variation during the smelting process is ≤±4%, indicating a stable smelting process.

[0104] Example 3

[0105] This embodiment provides a method for smelting molybdenum-containing superalloys using molybdenum-containing scrap return material. The molybdenum content in the molybdenum-containing scrap return material is 2.5%. The specific steps are as follows:

[0106] (I) Preparation of consumable electrode

[0107] The inner layer 2-2 of the consumable electrode is formed by pressing back the molybdenum-containing recycled material from the turning process. The length of the recycled material is 4-6 mm and the thickness is 1-2 mm. The mass of the inner layer 2-2 of the consumable electrode is calculated as 100%.

[0108] A mixture of aluminum granules, molybdenum oxide, and molybdenum-containing recycled machining scrap is pressed onto the outside of the inner layer 2-2 of the consumable electrode to form the outer layer 2-1. More detailed process parameters for the outer layer 2-1 are as follows: the mass of the molybdenum-containing recycled machining scrap is 1.66%, with a length of 2-3 mm and a thickness of 1-2 mm; the mass of molybdenum oxide powder is 2.41%, which is made by grinding molybdenum oxide clinker with a particle size of 1000 mesh, containing 56% molybdenum (i.e., 1.35% molybdenum by mass); the amount of aluminum powder is 0.93%, with a particle size of 0.5 mm; that is, the mass ratio of molybdenum in the molybdenum oxide powder to the aluminum granules is 1.45, and the ratio of the total mass of aluminum granules and molybdenum oxide powder in the outer layer to the amount of molybdenum-containing recycled machining scrap is 2.

[0109] As can be seen from the above mass ratio, the mass ratio of the outer layer 2-1 of the consumable electrode to the inner layer 2-2 of the consumable electrode is 5:100.

[0110] A steel cover, preferably made of stainless steel, is wrapped around the double-layer consumable electrode. The thickness of the steel cover is 1.0 mm.

[0111] The consumable electrode prepared in this embodiment has a diameter of 400 mm, a height of 2 m, and a mass of approximately 1890 kg, of which the inner layer has a mass of approximately 1794 kg.

[0112] (ii) Electroslag remelting

[0113] The apparatus and specific steps used in this embodiment of electroslag remelting are basically the same as those in Embodiment 2.

[0114] The high-temperature alloy ingot obtained in this embodiment has a molybdenum content of 3.58% and a yield of 94.7%, which is significantly higher than the molybdenum content of the returned high-temperature alloy chips. Furthermore, compared with the original high-temperature alloy ingot obtained by electroslag remelting, the inclusion content in the obtained high-temperature alloy ingot is A0.5, B1.0, C0, and D1.0. In addition, the current parameter variation during the smelting process is ≤±4%, indicating a stable smelting process.

[0115] Example 4

[0116] This embodiment provides a method for smelting molybdenum-containing superalloys using molybdenum-containing recycled mill scrap. The molybdenum content in the recycled mill scrap is 1.0%. The specific steps are as follows:

[0117] (I) Preparation of consumable electrode

[0118] The inner layer 2-2 of the consumable electrode is formed by pressing back the molybdenum-containing recycled material from the turning process. The length of the recycled material is 4-6 mm and the thickness is 1-2 mm. The mass of the inner layer 2-2 of the consumable electrode is calculated as 100%.

[0119] A mixture of aluminum granules, molybdenum oxide, and molybdenum-containing recycled shavings from machining is pressed onto the outside of the inner layer 2-2 of the consumable electrode to form the outer layer 2-1. More detailed process parameters for the outer layer 2-1 are as follows: the mass of the recycled shavings containing molybdenum is 6%, with a length of 2-3 mm and a thickness of 1-2 mm; the mass of molybdenum oxide powder is 6.43%, which is made by grinding molybdenum oxide clinker with a particle size of 800 mesh, containing 56% molybdenum (3.60% by mass); the amount of aluminum powder is 2.57%, with a particle size of 0.8 mm; that is, the mass ratio of molybdenum in the molybdenum oxide powder to the aluminum granules is 1.40, which means the ratio of the total mass of aluminum granules and molybdenum oxide powder in the outer layer to the amount of recycled shavings containing molybdenum is 1.5.

[0120] As can be seen from the above mass ratio, the mass ratio of aluminum particles in the outer layer 2-1 of the consumable electrode to that in the inner layer 2-2 of the consumable electrode is 15:100.

[0121] A steel shield, preferably made of stainless steel, is wrapped around the double-layer consumable electrode, with a thickness of 0.8 mm. The consumable electrode prepared in this embodiment has a diameter of 500 mm, a height of 2 m, and a mass of approximately 3000 kg, of which the inner layer weighs approximately 2608 kg.

[0122] (ii) Electroslag remelting

[0123] The apparatus used for electroslag remelting in this embodiment is basically the same as that in Embodiment 1, and the specific steps of electroslag remelting are basically the same as those in Embodiment 1. The difference is that the arc-starting material 4 is a mixture of spun molybdenum-containing scrap return material and calcium fluoride, with a mass ratio of 5:1; the first gas inlet channel 13 is used to introduce methane at 0.13 MPa; the second gas inlet channel 14 is used to introduce argon at 0.15 MPa; the remaining steps are basically the same.

[0124] The high-temperature alloy ingot obtained in this embodiment has a molybdenum content of 4.06% and a yield of 95.5%, which is significantly higher than the molybdenum content of the returned high-temperature alloy chips. Furthermore, compared with the high-temperature alloy obtained from the original electroslag remelting, the inclusion content in the obtained high-temperature alloy ingot is A0.5, B1.0, C0, and D1.0. In addition, the current parameter variation during the smelting process is ≤±4%, indicating a stable smelting process.

Claims

1. A method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material, characterized in that, include: The molybdenum-containing scrap recycled material is used to form the inner layer of the consumable electrode (2-2), and the outer layer of the consumable electrode (2-1) is wrapped around it to form a double-layer consumable electrode; The obtained double-layer consumable electrode is electroslag remelted to prepare a molybdenum-containing high-temperature alloy ingot; wherein the outer layer (2-1) of the consumable electrode is formed by pressing a mixture containing aluminum particles, molybdenum oxide powder and molybdenum-containing scrap return material, and the mass ratio of molybdenum element in the molybdenum oxide powder to the mass of aluminum particles is 1.4~1.5:

1.

2. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to claim 1, characterized in that, The aluminum particles in the outer layer (2-1) of the self-consumable electrode have a particle size of 0.5~1mm, and the molybdenum oxide powder has a particle size of 800~1000 mesh; the total mass of molybdenum oxide powder and aluminum particles is denoted as A, the mass of the scrap high-temperature alloy return material is denoted as B, and the mass ratio of A to B is 1~2:

1.

3. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to claim 1, characterized in that, The outer layer (2-1) of the self-consuming electrode is also wrapped with a steel cover.

4. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to any one of claims 1-3, characterized in that, The length of the molybdenum-containing scrap recycled material used in the outer layer (2-1) of the consumable electrode is 2-4 mm and the thickness is 1-2 mm; the length of the molybdenum-containing scrap recycled material used in the inner layer (2-2) of the consumable electrode is 2-6 mm and the thickness is 1-2 mm.

5. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to any one of claims 1-3, characterized in that, The mass ratio of the outer layer (2-1) of the self-consuming electrode to the inner layer (2-2) of the self-consuming electrode is 5~15:

100.

6. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to any one of claims 1-3, characterized in that, The electroslag remelting specifically includes the following steps: S1, Arc ignition and slag removal: Press the arc ignition electrode (5) and the arc ignition material (4) together, turn on the power, and then add slag material to start slag removal; S2, Remelting stage: As the slag melts, the double-layer consumable electrode is gradually inserted into the slag pool (9) and melts, and remelting begins; S3, Refining stage: After the metal consumable electrode is remelted, the double-layer consumable electrode is replaced with a graphite electrode (11) and heated for refining. S4, Casting: After refining, the alloy is cast into an alloy ingot of a specified size.

7. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to claim 6, characterized in that, The arc-starting electrode (5) used in S1 is prepared from molybdenum-containing scrap return material, and its diameter is 1 / 3 to 1 / 2 of the diameter of the double-layer consumable electrode, and its height is 5 mm to 10 mm. The arc-starting material (4) used in S1 includes molybdenum-containing scrap return material and calcium fluoride, with a mass ratio of 3 to 5:

1.

8. The method for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to claim 6, characterized in that, The power supply used for arc initiation and slag formation in S1 is an industrial frequency AC power supply (1). And / or the electroslag remelting is carried out in a crucible (3), and the power supply used in the refining stage of step S3 is a low-frequency power supply (10) with a frequency of 0.1~0.5Hz.

9. An apparatus for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material, characterized in that, The system includes a graphite electrode (11), a bottom electrode (7), a crucible (3), and a double-layer consumable electrode as described in any one of claims 1-8. The crucible (3) is arranged from bottom to top with the bottom electrode (7), the arc-starting material (4), the arc-starting electrode (5), and the double-layer consumable electrode connected in sequence. The graphite electrode (11) is used to replace the double-layer consumable electrode in the refining stage, and it is provided with a steel tube (12) inside. There is a gap between the inner wall of the graphite electrode (11) and the outer wall of the steel tube (12), and the gap forms a second air intake channel (14). The steel tube (12) is a hollow tube, and a first air intake channel (13) is formed inside. The side wall of the steel tube (12) is provided with a plurality of air holes distributed at intervals, and the air holes are used to connect the first air intake channel (13) and the second air intake channel (14).

10. The apparatus for smelting molybdenum-containing superalloys using molybdenum-containing scrap recycled material according to claim 9, characterized in that, The first air inlet channel (13) is used to introduce methane at 0.11~0.13MPa; the second air inlet channel (14) is used to introduce argon at 0.13~0.15MPa, and the pressure of the gas introduced into the first air inlet channel (13) is less than the pressure of the gas introduced into the second air inlet channel (14); And / or the pores are inclined upward along the inner wall of the steel pipe (12) towards the outer wall, and the angle between the axial direction of a single pore and the vertical direction is 10~20°.

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