Method and device for smelting molybdenum-containing high-temperature alloy by utilizing molybdenum-containing scrap-shaped return scrap

Abstract

The invention discloses a method and a device for smelting molybdenum-containing high-temperature alloy by utilizing molybdenum-containing scrap-shaped return scrap, and belongs to the technical field of high-temperature alloy. According to the method, the consumable electrode inner layer is formed by the molybdenum-containing scrap-shaped return scrap, and the consumable electrode outer layer wraps the consumable electrode inner layer, so that the double-layer consumable electrode is formed; the obtained double-layer consumable electrode is subjected to electroslag remelting, and a molybdenum-containing high-temperature alloy ingot is prepared; wherein the consumable electrode outer layer is formed by pressing a uniformly mixed material containing aluminum particles, molybdenum oxide powder and molybdenum-containing scrap-shaped return scraps, and the mass ratio of the molybdenum element in the molybdenum oxide powder to the aluminum particles is (1.4-1.5): 1. According to the scheme, the consumable electrode with the double-layer structure for electroslag remelting is prepared, so that the purity of the obtained molybdenum-containing high-temperature alloy ingot can be guaranteed, and meanwhile, the adding amount proportion of the molybdenum-containing scrap-shaped return scrap can be increased.

Description

Technical Field

[0001] The present invention relates to the technical field of superalloys, and more specifically, to a method and device for smelting molybdenum-containing superalloy raw materials by using low-molybdenum chip-shaped superalloy return materials. Background Art

[0002] Superalloys have comprehensive properties such as good high-temperature strength, oxidation resistance, corrosion resistance, fatigue resistance, and fracture toughness, and are an important material widely used in aviation, aerospace, petroleum, chemical industry, and ships. Currently, the commonly used smelting processes for superalloys include vacuum induction, electroslag remelting, and vacuum consumable. No matter which of the above processes is adopted, before entering the next process, the electrode needs to be peeled, for example, before the electroslag remelting is completed and entering the consumable remelting, the surface of the electroslag ingot needs to be turned; subsequent products obtained by forging also need to be surface-turned. How to recycle the turned chip-shaped shavings is crucial for reducing the production cost of superalloys.

[0003] After retrieval, to solve the above problems, relevant patents have been disclosed in the prior art, which mainly perform physical treatment on the return materials, or perform vacuum reaction melting after physical treatment. For example, the Chinese invention patent application case with the application number 2023113934013 discloses a method for purifying and smelting high-chromium cast nickel-based superalloy return materials, which specifically discloses the surface treatment, vacuum melting, and pouring of the return materials. However, the purity of the metal ingot prepared by the vacuum melting method still needs to be further improved.

[0004] In the prior art, there is also a method of recycling return materials by using induction melting (including vacuum / non-vacuum induction melting) plus electroslag remelting. For example, the Chinese invention patent application case with the application number 2022116482884 discloses a method for controlling the addition amount of return materials to refine carbides and nitrides in GH4169 alloy, which specifically discloses selecting GH4169 brand-new pure materials and return materials as raw materials for preparing alloys; the addition amount of return materials in the raw materials is 10-50 wt%; the raw materials are sequentially subjected to vacuum induction melting, electroslag remelting, and vacuum arc remelting to obtain VAR consumable ingots. Although the above method can better remove inclusions in the return materials, the addition ratio of return materials in the smelting raw materials of this application case is relatively low, and the utilization rate of return materials still needs to be further improved.

[0005] For molybdenum-containing superalloy waste materials, the above problems also exist. In addition, the existing molybdenum-containing superalloys are mainly alloyed with molybdenum by directly adding elemental molybdenum during induction melting and electroslag remelting, resulting in high costs. Although existing patents also add a certain amount of molybdenum oxide and minerals to the slag pool and rely on slag refining to directly alloy, thereby realizing molybdenum addition treatment. However, the process stability of this smelting method is poor. Summary of the Invention

[0006] When using molybdenum-containing chip-shaped return materials in the smelting process of molybdenum-containing superalloys in the prior art, the purity of the obtained superalloys is relatively low, or the proportion of the addition of return materials is relatively low. The present invention provides a method and device for smelting molybdenum-containing superalloys using molybdenum-containing chip-shaped return materials. By directly forming the molybdenum-containing chip-shaped return materials into a consumable electrode with a double-layer structure for electroslag remelting, and then smelting through the electroslag remelting technology, not only can the purity of the obtained molybdenum-containing superalloy be ensured, but also the proportion of the addition of molybdenum-containing chip-shaped return materials can be increased.

[0007] In addition, the present invention can also effectively solve the technical problem of poor process stability when performing molybdenum addition alloying treatment on molybdenum-containing superalloys in the prior art.

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

[0009] In a first aspect of the present invention, there is provided a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials, including: forming a consumable electrode inner layer from the molybdenum-containing chip-shaped return materials, and wrapping a consumable electrode outer layer outside it to form a double-layer consumable electrode; and subjecting the obtained double-layer consumable electrode to electroslag remelting to prepare a molybdenum-containing superalloy ingot; wherein, the consumable electrode outer layer is formed by pressing a mixed material containing aluminum particles, molybdenum oxide powder, and molybdenum-containing chip-shaped return materials, and the mass ratio of molybdenum element in the used molybdenum oxide powder to the mass of aluminum particles is 1.4 - 1.5:1.

[0010] The present invention prepares a double-layer consumable electrode by pressing molding, applies the double-layer consumable electrode to electroslag remelting, and optimizes the composition of the double-layer consumable electrode. On the one hand, the purity of the prepared superalloy ingot can be improved through electroslag remelting, so that the superalloy ingot can be directly used to prepare a new superalloy ingot through vacuum melting and electroslag remelting without adding a certain proportion of new pure materials, improving the proportion of recycled materials used subsequently and reducing the smelting cost. On the other hand, molybdenum alloying treatment can also be carried out during the electroslag remelting process, which can significantly reduce the cost of molybdenum addition. In the outer layer of the consumable electrode, molybdenum oxide powder reacts with aluminum particles to form elemental molybdenum and aluminum oxide, and the formed elemental molybdenum can alloyize the superalloy with molybdenum. Due to the skin effect of the current, it can better promote the reduction reaction of aluminum particles in the outer layer to molybdenum oxide, realizing molybdenum alloying treatment during the electroslag remelting process. On the contrary, if molybdenum oxide, aluminum particles, and molybdenum-containing chip-shaped recycled materials are directly mixed and pressed into a consumable electrode, it is not conducive to the uniformity of the reduction reaction of aluminum particles in the consumable electrode to molybdenum oxide, and will also reduce the molybdenum recovery rate. It should also be noted that the necessity of including molybdenum-containing chip-shaped recycled materials in the outer layer of the consumable electrode in the present invention. Among them, the mass ratio of molybdenum element in molybdenum oxide powder to the mass of aluminum particles in the outer layer of the consumable electrode is 1.4-1.5:1, and the dosage ratio of the two is considered as follows: First, the aluminum particles can fully reduce the molybdenum oxide; second, the remaining part of the aluminum particles can play a deoxidizing role; third, the mass ratio of the aluminum particles cannot be too large, otherwise it may cause waste of aluminum and may pollute the obtained superalloy liquid. Within the range of the above dosage ratio, the conductivity of the outer layer will be reduced. Moreover, as the reduction reaction of molybdenum oxide and aluminum particles proceeds, its conductivity will become worse. Therefore, it is necessary to add chip-shaped superalloy recycled materials to the outer layer of the consumable electrode to improve the conductivity of the outer layer of the consumable electrode.

[0011] In addition, as the electroslag remelting progresses, the alumina in the slag pool will gradually decrease under the action of high temperature. If alumina is not replenished in time, on the one hand, the process will be unstable; on the other hand, the power consumption will increase. However, if normal-temperature alumina is directly added to the slag pool from the outside, the temperature of the slag pool will fluctuate violently, and then the remelting process will be damaged. At this time, the alumina generated by the molybdenum oxide powder and aluminum particles in the outer layer of the consumable electrode has a very high temperature, and as the electrode descends into the remelting slag pool, the influence on the temperature of the slag pool can be almost ignored.

[0012] Further, the particle size of the aluminum particles in the outer layer of the consumable electrode is 0.5 - 1 mm, the particle size of the molybdenum oxide powder is 800 - 1000 mesh. The total mass of the molybdenum oxide powder and the aluminum particles is denoted as A, and the mass of the chip-shaped superalloy return material is B, and the mass ratio of A to B is 1 - 2:1. The limitation of the particle size of the aluminum particles and the molybdenum oxide powder will further reduce the poor conductivity of the outer layer and even form a non-conductive outer layer of the consumable electrode. However, the above particle size selection is based on fully considering the reduction reaction rate of the molybdenum oxide powder by the aluminum particles. If the particle size of the aluminum particles is further reduced, or the particle size of the molybdenum oxide powder is increased, or a combination of the above two methods is used, although the conductivity of the outer layer will be slightly improved, it will be unfavorable for the reaction of the aluminum particles with the molybdenum oxide. The specific effects are as follows: If the particle size of the molybdenum oxide is increased, the reduction rate of the molybdenum oxide will be reduced; if the particle size of the aluminum particles is further reduced, since there is a dense aluminum oxide film on the outside of the aluminum particle raw material, the reaction rate in the initial stage of the redox reaction is relatively low; as the reaction proceeds and the heat increases, the subsequent reaction will be relatively violent, which is not conducive to the smoothness of the reaction of aluminum with molybdenum oxide, and the temperature fluctuates violently, which is not conducive to the smoothness during the electroslag remelting process. Therefore, by limiting the proportion of the chip-shaped superalloy return material, the conductivity of the outer layer of the consumable electrode is regulated. However, the higher the conductivity of the outer layer is not necessarily better. When the conductivity of the outer layer is higher and its resistivity is lower, the heat generation of the outer layer is lower at this time, which is not conducive to the progress of the molybdenum oxide reduction reaction. Therefore, the dosage of the molybdenum-containing chip-shaped return material in the outer layer should not be too high either.

[0013] Further, the outer layer of the consumable electrode is also wrapped with a steel cover. Since the consumable electrode is wrapped with a steel cover on the outside, the volatilization of molybdenum oxide is avoided, thereby improving the molybdenum recovery rate and further reducing the cost.

[0014] Further, the length of the molybdenum-containing chip-shaped return 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 chip-shaped return material used in the inner layer of the consumable electrode is 2 - 6 mm, and the thickness is 1 - 2 mm. By selecting a molybdenum-containing chip-shaped return material with a smaller length in the outer layer of the consumable electrode, its resistance value is relatively large, and a molybdenum-containing chip-shaped return material with a larger length is selected in the inner layer, and its resistance value is relatively small, so as to adjust the difference in resistivity between the outer layer and the inner layer, and further control the heat generation of the outer layer to be greater than that of the inner layer. During the smelting process, the current is generally kept relatively constant by adjusting the voltage, but there will inevitably be fluctuations in the smelting current within a certain range, and the variation range of the current parameters characterizes whether the smelting process is stable.

[0015] Further, the mass ratio of the outer layer to the inner layer of the consumable electrode is 5-15:100. The setting of this ratio is comprehensively considered based on the stability of the molybdenum addition and remelting processes, 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 generated alumina is also relatively small, which has little significance for replenishing the slag pool. On the contrary, if the ratio is too high, more alumina will enter the slag pool; a certain amount of alumina in the slag pool is beneficial to the stability of the remelting process, but when the alumina exceeds a certain range, it will cause severe fluctuations in smelting parameters, especially the current, and even interrupt the smelting process.

[0016] Further, the electroslag remelting specifically includes the following steps: S1, arc starting and slag melting: Press the arc starting electrode and the arc starting material tightly, apply electricity, and then add the slag material to start melting the slag; S2, remelting stage: As the slag material melts, the double-layer consumable electrode gradually inserts into the slag pool and melts, and remelting begins; S3, refining stage: After the metal consumable electrode is completely remelted, change the double-layer consumable electrode to a graphite electrode and continue heating and refining; S4, casting and forming: After refining is completed, cast it into an alloy ingot of a specified size.

[0017] Further, the arc starting electrode used in S1 is prepared from molybdenum-containing chip-shaped return materials, and its diameter is 1 / 3 - 1 / 2 of the diameter of the double-layer consumable electrode; the height is 5 mm - 10 mm; and / or the arc starting material used in the electroslag remelting includes molybdenum-containing chip-shaped return materials and calcium fluoride, and the mass ratio of the two is 3 - 5:1.

[0018] The arc starting electrode is prepared from molybdenum-containing chip-shaped return materials, which further increases the usage amount of the return materials and improves the utilization rate of the return materials. The diameter of the arc starting electrode is smaller than that of the double-layer consumable electrode, so the current density here is small, which is more conducive to arc starting.

[0019] Further, the power supply used for arc starting and slag melting in S1 is an industrial frequency alternating current power supply; and / or the electroslag remelting is carried out in a crucible, and the power supply used in the refining stage described in step S3 is a low-frequency power supply with a frequency of 0.1 - 0.5 Hz.

[0020] Among them, the power supply used in the refining stage is a low-frequency power supply with a frequency of 0.1 - 0.5 Hz. The electroslag remelting is carried out in a crucible, and the consumable electrode is heated and melted to form a high-temperature metal liquid in the crucible. In the refining stage, a low-frequency power supply is used, and the molten steel in the crucible will be subjected to a large electromagnetic force, which promotes the convection of the alloy liquid, expands the slag-metal contact area, and removes the inclusions in the return materials as much as possible, further improving the purity of the product obtained by smelting with the return materials.

[0021] Furthermore, in the second aspect of the present invention, there is provided an apparatus for the above smelting method, including a graphite electrode, a bottom electrode, a crucible, and a double-layer consumable electrode used in any of the above smelting methods. Inside the crucible, a bottom electrode, starting arc material, starting arc electrode, and double-layer consumable electrode are sequentially arranged from bottom to top and connected. The graphite electrode is used to replace the double-layer consumable electrode in the refining stage, and a steel pipe is provided inside it. There is a gap between the inner wall of the graphite electrode and the outer wall of the steel pipe, and this gap forms a second air inlet channel. The steel pipe is a hollow pipe, and a first air inlet channel is formed inside it. The side wall of the steel pipe is provided with a plurality of air holes distributed at intervals, and the air holes are used to connect the first air inlet channel and the second air inlet channel.

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

[0023] Among them, considering the resistance of the atmosphere and the slag pool, the gas pressure in the first gas channel is selected to be 0.11 - 0.13 MPa, so that methane can smoothly enter the slag pool. Moreover, the CH4 introduced through the first air inlet channel decomposes into carbon and hydrogen at high temperature, diffusively deoxidizes the molten slag, and further purifies the superalloy return material. However, the generated carbon is likely to accumulate on the inner wall of the steel pipe. Therefore, argon with a slightly higher pressure is introduced into the second air inlet channel, and the argon purges the carbon powder attached to the inner wall of the steel pipe through the air holes, thus avoiding the blockage of the air holes and ensuring the smooth progress of blowing.

[0024] Furthermore, the air holes are arranged to incline upward from the inner wall of the steel pipe to its outer wall, and the angle between the axis of a single air hole and the vertical direction is 10 - 20°.

[0025] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects:

[0026] (1) By designing a double-layer consumable electrode in the present invention, specifically, the molybdenum-containing chip-shaped return material is made into the inner layer of the consumable electrode, and the outer layer of the consumable electrode is wrapped outside it. The purity of the return material is improved by electroslag remelting. Further, the outer layer of the consumable electrode is made by pressing a mixed material including aluminum particles, molybdenum oxide powder, and molybdenum-containing chip-shaped return material. The conductivity of the outer layer is changed by adding the molybdenum-containing chip-shaped return material, and the particle size selection of the aluminum particles and molybdenum oxide powder is beneficial to promoting the comprehensive performance of the reduction of molybdenum oxide powder by the aluminum particles. At the same time, the by-product alumina from the reaction of the aluminum particles and molybdenum oxide powder can supplement the effect of alumina in the slag pool, and has less influence on the stability of electroslag remelting compared with the externally added alumina. Further, the amount of molybdenum single substance generated can be adjusted by controlling the amount of aluminum particles and molybdenum oxide powder in the outer layer, so as to realize the adjustment of the molybdenum content in the remelted superalloy ingot.

[0027] (2) The present invention further optimizes the specific process of electroslag remelting. The electroslag remelting is carried out in a crucible, and a subsequent refining stage is added to further improve the purity of the product obtained by smelting with return materials. Further, the interior of the graphite electrode used in the refining stage is optimized, and a first air inlet channel and a second air inlet channel are provided. 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 holes in the steel pipe, thereby avoiding the accumulation of carbon powder and ensuring the smooth progress of air blowing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the arc starting stage of the melting device according to an embodiment of the present invention.

[0029] Figure 2 It is a schematic structural diagram of the remelting stage of the melting device according to an embodiment of the present invention.

[0030] Figure 3 It is a schematic structural diagram of the refining stage of the melting device according to an embodiment of the present invention.

[0031] Reference Signs Description:

[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 starting electrode;

[0037] 6. Bottom water tank;

[0038] 7. Bottom electrode;

[0039] 8. Superalloy liquid;

[0040] 9. Slag pool;

[0041] 10. Low frequency power supply;

[0042] 11. Graphite electrode;

[0043] 12. Steel pipe;

[0044] 13. First air inlet channel;

[0045] 14. Second air inlet channel. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] To further understand the content of the present invention, the present invention will be described in detail in combination with embodiments.

[0047] Embodiment 1

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

[0049] (1) Preparation of consumable electrode: Use the turning molybdenum-containing scrap returns to press into the inner layer 2-2 of the consumable electrode. The length of the turning molybdenum-containing scrap returns used is 4-6 mm, and the thickness is 1-2 mm. Calculated based on the mass of the inner layer 2-2 of the consumable electrode being 100%. Among them, the inner layer 2-2 of the consumable electrode can also be formed by casting, and the specific forming process is not limited to pressing. Use the mixed material of aluminum particles, molybdenum oxide, and turning molybdenum-containing scrap returns to press into the outer layer 2-1 of the consumable electrode outside the inner layer 2-2 of the consumable electrode. The more detailed process parameters of the outer layer 2-1 of the consumable electrode are as follows: The mass of the turning molybdenum-containing scrap returns used is 7.5%, its length is 2-3 mm, and the thickness is 1-2 mm; the mass of molybdenum oxide powder is 5.36%, its particle size is 1000 mesh, and it is ground from molybdenum oxide clinker. The content of molybdenum element in it is 56%, that is, the mass of molybdenum element contained in it is 3.00%; the dosage of aluminum powder is 2.14%, and its particle size is 0.5 mm; that is, the mass ratio of molybdenum element contained in molybdenum oxide powder to the mass of aluminum particles is 1.40, that is, the ratio of the total mass of aluminum particles and molybdenum oxide powder in the outer layer to the dosage of turning molybdenum-containing scrap returns is 1. 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 15:100.

[0050] A steel cover is also wrapped outside the double-layer consumable electrode, preferably made of stainless steel, and the thickness of the steel cover is 0.5 mm.

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

[0052] (2) Electro-slag remelting

[0053] The device used for electro-slag remelting in this embodiment includes a power supply, a graphite electrode 11, an arc-starting 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, an arc-starting material 4, an arc-starting electrode 5, and a double-layer consumable electrode are sequentially arranged from bottom to top and connected. Among them, the double-layer consumable electrode, the arc-starting electrode 5, the arc-starting material 4, and the bottom electrode 7 are coaxially arranged in sequence along the height direction. The connection relationship between each component refers to Figures 1 - 3 as shown.

[0054] Referring to the figure, after assembling the device used for electro-slag remelting, the steps of electro-slag remelting specifically include the following:

[0055] S1, Arc starting and slag melting: Press the arc starting electrode 5 against the arc starting material 4, energize, then add the slag material to start slag melting;

[0056] S2, Remelting stage: As the slag material melts, the double-layer consumable electrode gradually inserts into the slag pool 9 and melts, and remelting starts;

[0057] S3, Refining stage: After the metal consumable electrode is completely remelted, change the double-layer consumable electrode to the graphite electrode 11 and continue heating and refining;

[0058] S4, Pouring and forming: After refining, pour it into an alloy ingot of specified size.

[0059] And after S4, the obtained alloy ingot is forged, cut into raw materials, and polished, then added to a vacuum induction furnace and start smelting according to the superalloy smelting process.

[0060] Among them, the arc starting material 4 is a mixture of turned molybdenum-containing chip return material and calcium fluoride, and the mass ratio of the two is 4:1.

[0061] Among them, the diameter of the arc starting electrode 5 is smaller than the outer diameter of the double-layer consumable electrode, and its outer diameter is preferably 1 / 3 - 1 / 2 of the outer diameter of the double-layer consumable electrode, and the preferred height range is 5 mm - 10 mm.

[0062] Among them, the power supply used in the arc starting and slag melting and remelting stages is preferably the industrial frequency AC power supply 1.

[0063] Among them, the power supply used in the refining stage is preferably the low-frequency power supply 10, and its frequency is preferably 0.1 - 0.5 Hz. The structure of the graphite electrode 11 used in the refining stage refers to Figure 3 As shown, the graphite electrode 11 is a hollow graphite electrode, and a steel pipe 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 pipe 12, and this gap forms the second air inlet channel 14; the steel pipe 12 is a hollow pipe, and its internal forms the first air inlet channel 13 for passing through; and multiple evenly distributed air holes are provided on the side wall of the steel pipe, and the air holes are used to connect the first air inlet channel 13 and the second air inlet channel 14. Its more specific parameters are as follows:

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

[0065] Among them, the distance that the bottom of the steel pipe 12 is higher than the bottom of the graphite electrode 11 is preferably 20 - 40 mm, 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] Among them, the distance between the outer wall of the steel pipe 12 and the inner wall of the graphite electrode 11 is preferably 2 - 5 mm, that is, the size of the second gas channel 14 is preferably 2 - 5 mm.

[0067] Among them, the first gas passage 13 is used to introduce methane at 0.12 MPa, and the second gas passage 14 is used to introduce argon at 0.14 MPa.

[0068] Among them, argon with a slightly higher pressure is introduced into the second intake passage 14 and blown obliquely downward along the pore wall of the pore into the first gas passage 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 pores are arranged obliquely upward from the inner wall to the outer wall of the steel pipe 12. The included angle between the axis of a single pore and the vertical direction is preferably in the range of 10-20°, and its diameter can be selected in the range of 2-4 mm.

[0070] A plurality of pores are distributed at intervals along the axial direction of the steel pipe 12 to form a single row of pores. The number of the single row of pores arranged in a circular array along the circumferential direction of the steel pipe 12 can be 4-6; the adjacent two pores in the single row of pores are arranged at intervals of 30-50 mm in the height direction. Methane entering the first gas passage 13 will decompose into carbon only at high temperatures, but the temperature at the part of the steel pipe above 500-600 mm is relatively low and not enough to decompose methane. Therefore, the single row of pores can extend upward from the bottom end of the side wall of the steel pipe 12 to 500-600 mm.

[0071] The molybdenum content of the superalloy ingot obtained by smelting in this embodiment is 3.10%, and the recovery rate is 96.90%, which is significantly higher than that of the molybdenum content of the turned chip-shaped superalloy return material; moreover, compared with the composition of the superalloy obtained by the original electroslag remelting, the content of inclusions in the superalloy ingot obtained by smelting is grade A0.5, grade B1.0, grade C0., grade D1.0. In addition, the current parameter variation during the smelting process is ≤±4%, which further shows that the smelting process is stable and conducive to ensuring the smooth progress of the remelting process.

[0072] Comparative Example 1

[0073] This comparative example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is that a mixed material containing aluminum particles, molybdenum oxide and turned molybdenum-containing chip-shaped return materials is pressed into a single-layer consumable electrode, and the mass ratio of the aluminum particles, molybdenum oxide powder and turned molybdenum-containing chip-shaped return materials 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, and the other operation steps are basically the same.

[0074] The molybdenum content of the superalloy ingot obtained by smelting in this comparative example is 2.65%, and the recovery rate is 82.9%. In addition, the current parameter variation during the smelting process is ≤±6%, which further shows that the smelting process is relatively stable.

[0075] Comparative Example 2

[0076] This comparative example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is as follows: Calculated based on the mass of the inner layer of the consumable electrode being 100%, no turned molybdenum-containing chip-shaped return materials are added to the outer layer of the consumable electrode. The mass ratio of aluminum particles, molybdenum oxide powder, and turned molybdenum-containing chip-shaped return materials in the double-layer consumable electrode is 2.14:5.36:100; the remaining operations are basically the same.

[0077] For the superalloy ingot obtained by smelting in this comparative example, the obtained molybdenum content is 2.4%, and the yield is 70.6%. In addition, the current parameters during the smelting process change by ≥10%, further indicating that the stability of the smelting process is poor.

[0078] Comparative Example 3

[0079] This comparative example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is as follows: Calculated 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 that of the chip-shaped superalloy return materials, that is, the mass ratio of the total mass of molybdenum oxide powder and aluminum particles, chip-shaped superalloy return materials in the outer layer of the consumable electrode is 5.36:2.14:15, and the remaining operations are basically the same.

[0080] For the superalloy ingot obtained by smelting in this comparative example, the obtained molybdenum content is 2.17%, and the yield is 72.3%. In addition, the current parameters during the smelting process change by ≥±10%, further indicating that the stability of the smelting process is poor.

[0081] Comparative Example 4

[0082] This comparative example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is as follows: Calculated 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 that of the chip-shaped superalloy return materials, that is, the mass ratio of the total mass of molybdenum oxide powder and aluminum particles, chip-shaped superalloy return materials in the outer layer of the consumable electrode is 5.36:2.14:3, and the remaining operations are basically the same.

[0083] For the superalloy ingot obtained by smelting in this comparative example, the obtained molybdenum content is 2.12%, and the yield is 64.0%. In addition, the current parameters during the smelting process change by approximately ≥±12%, further indicating that the stability of the smelting process is even worse.

[0084] Comparative Example 5

[0085] This comparative example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is as follows: The particle size of the molybdenum oxide powder used is 1000 mesh, and the particle size of the aluminum particles is 1000 mesh, and the remaining operations are basically the same.

[0086] The superalloy ingot obtained by smelting in this comparative example has a molybdenum content of 2.43% and a recovery rate of 76%. In addition, the current parameter variation during the smelting process is ≤ ±8%, further indicating that the smelting process is relatively stable.

[0087] Comparative Example 6

[0088] This comparative example provides a method for smelting molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. 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, and the remaining operations are basically the same.

[0089] The superalloy ingot obtained by smelting in this comparative example has a molybdenum content of 2.25% and a recovery rate of 70.3%. In addition, the current parameter variation during the smelting process is ≥ ±10%, further indicating that the stability of the smelting process is poor.

[0090] Comparative Example 7

[0091] This comparative example provides a method for smelting molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The difference from Example 1 is that the outer layer of the consumable electrode is not coated with a steel cover, and the remaining operations are basically the same.

[0092] The superalloy ingot obtained by smelting in this comparative example has a molybdenum content of 2.66% and a recovery rate of 83.1%. In addition, the current parameter variation during the smelting process is ≤ ±6%, further indicating that the smelting process is relatively stable.

[0093] Example 2

[0094] This example provides a method for smelting molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The molybdenum content in the turned molybdenum-containing chip-shaped return materials used is 2.5%, and the specific steps are as follows:

[0095] (I) Preparation of consumable electrode

[0096] The turned molybdenum-containing chip-shaped return materials are pressed into the inner layer 2-2 of the consumable electrode, where the length of the turned molybdenum-containing chip-shaped return materials used is 4 - 6 mm, and the thickness is 1 - 2 mm; calculated based on the mass of the inner layer of the consumable electrode being 100%.

[0097] The homogeneous mixture of aluminum particles, molybdenum oxide, and turned molybdenum-containing chip-shaped return materials is pressed into the outer layer 2-1 of the consumable electrode on the outside of the inner layer of the consumable electrode. The more detailed process parameters of the outer layer 2-1 of the consumable electrode are as follows: The mass of the used turned molybdenum-containing chip-shaped return material is 3.33%, its length is 2 - 4 mm, and its thickness is 1 - 2 mm; the mass of molybdenum oxide powder is 4.82%, which is ground from molybdenum oxide clinker, its particle size is 800 mesh, and the content of molybdenum element in it is 56%, that is, the mass of molybdenum element contained in it is 2.70%; the dosage of aluminum powder is 1.85%, and its particle size is 1 mm; that is, the mass ratio of the molybdenum element contained in molybdenum oxide powder to the mass of aluminum particles is 1.46; that is, the ratio of the total mass of aluminum particles and molybdenum oxide powder in the outer layer to the mass of the turned molybdenum-containing chip-shaped return material is 2.

[0098] From the above mass ratios, it can be seen that 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 is wrapped around the outside of the double-layer consumable electrode, preferably made of stainless steel, and the thickness of the steel cover is 1.0 mm.

[0100] The diameter of the consumable electrode prepared in this example is 400 mm, the height is 2 m, and the mass is about 1890 kg, of which the mass of the inner layer is about 1718 kg.

[0101] (II) Electroslag remelting

[0102] The device used for electroslag remelting in this example is basically the same as that in Example 1. The difference in the specific steps of electroslag remelting from Example 1 is that the starting arc material 4 is a homogeneous mixture of turned molybdenum-containing chip-shaped return material and calcium fluoride, and the mass ratio of the two is 3:1; the first gas channel 13 is used to introduce methane at 0.11 MPa; the second gas channel 14 is used to introduce argon at 0.13 MPa; the remaining steps are basically the same.

[0103] For the superalloy ingot obtained by smelting in this example, the obtained molybdenum content is 4.65%, and the recovery rate is 93.0%, which is significantly increased compared with the molybdenum content of the turned chip-shaped superalloy return material; and for the components of the other alloys in the smelted superalloy ingot compared with the components of the superalloy ingot obtained by the original electroslag remelting, the inclusion content is grade A0.5, grade B1.0, grade C0., and grade D1.0. In addition, the current parameter variation during the smelting process is ≤ ±4%, further indicating that the process during the smelting process is stable.

[0104] Example 3

[0105] This example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return materials. The molybdenum content in the used turned molybdenum-containing chip-shaped 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 pressed using the turned molybdenum-containing chip-shaped return material, where the length of the used turned molybdenum-containing chip-shaped return material is 4 - 6 mm and the thickness is 1 - 2 mm; calculated based on the mass of the inner layer 2-2 of the consumable electrode being 100%.

[0108] The outer layer 2-1 of the consumable electrode is pressed using a mixture of aluminum particles, molybdenum oxide, and the turned molybdenum-containing chip-shaped return material outside the inner layer 2-2 of the consumable electrode. The more detailed process parameters of the outer layer 2-1 of the consumable electrode are as follows: the mass of the used turned molybdenum-containing chip-shaped return material is 1.66%, its length is 2 - 3 mm, and the thickness is 1 - 2 mm; the mass of molybdenum oxide powder is 2.41%, which is ground from molybdenum oxide clinker, its particle size is 1000 mesh, and the content of molybdenum element is 56%, that is, the mass of the contained molybdenum element is 1.35%; the dosage of aluminum powder is 0.93%, and its particle size is 0.5 mm; that is, the mass ratio of the molybdenum element contained in the molybdenum oxide powder to the mass of the aluminum particles is 1.45, that is, the ratio of the total mass of the aluminum particles and molybdenum oxide powder in the outer layer to the dosage of the turned molybdenum-containing chip-shaped return material is 2.

[0109] From the above mass ratios, it can be seen that 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 is wrapped outside the double-layer consumable electrode, preferably made of stainless steel, and the thickness of the steel cover is 1.0 mm.

[0111] The diameter of the consumable electrode prepared in this example is 400 mm, the height is 2 m, and the mass is about 1890 kg, of which the mass of the inner layer is about 1794 kg.

[0112] (2) Electro-slag remelting

[0113] The device and specific steps used for electro-slag remelting in this example are basically the same as those in Example 2.

[0114] For the superalloy ingot obtained by smelting in this example, the obtained molybdenum content is 3.58% and the recovery rate is 94.7%, which is significantly increased compared with the molybdenum content of the turned chip-shaped superalloy return material; and for the components of the other alloys in the smelted superalloy ingot compared with the components of the superalloy ingot obtained by the original electro-slag remelting, the inclusion content is grade A 0.5, grade B 1.0, grade C 0., grade D 1.0. In addition, the current parameter variation during the smelting process is ≤ ±4%, further indicating that the process during the smelting process is stable.

[0115] Example 4

[0116] This example provides a method for smelting a molybdenum-containing superalloy using molybdenum-containing chip-shaped return material, where the molybdenum content in the used turned molybdenum-containing chip-shaped return material is 1.0%, and the specific steps are as follows:

[0117] (1) Preparation of consumable electrode

[0118] The inner layer 2-2 of the consumable electrode is pressed from the turned molybdenum-containing chip return material. The length of the turned molybdenum-containing chip return material used is 4-6 mm, and the thickness is 1-2 mm. Calculated based on the mass of the inner layer 2-2 of the consumable electrode being 100%.

[0119] The outer layer 2-1 of the consumable electrode is pressed from the mixed material of aluminum particles, molybdenum oxide and the turned molybdenum-containing chip return material on the outside of the inner layer 2-2 of the consumable electrode. The more detailed process parameters of the outer layer 2-1 of the consumable electrode are as follows: the mass of the turned molybdenum-containing chip return material used is 6%, its length is 2-3 mm, and the thickness is 1-2 mm; the mass of molybdenum oxide powder is 6.43%, which is ground from molybdenum oxide clinker, its particle size is 800 mesh, and the content of molybdenum element is 56%, that is, the mass of molybdenum element contained therein is 3.60%; the dosage of aluminum powder is 2.57%, and its particle size is 0.8 mm; that is, the mass ratio of molybdenum element contained in molybdenum oxide powder to the mass of aluminum particles is 1.40, that is, the ratio of the total mass of aluminum particles and molybdenum oxide powder in the outer layer to the dosage of the turned molybdenum-containing chip return material is 1.5.

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

[0121] The outer of the double-layer consumable electrode is wrapped with a steel cover, preferably made of stainless steel, and the thickness of the steel cover is 0.8 mm. The diameter of the consumable electrode prepared in this example is 500 mm, the height is 2 m, and the mass is about 3000 kg, of which the inner layer mass is about 2608 kg.

[0122] (2) Electroslag remelting

[0123] The device used for electroslag remelting in this example is basically the same as that in Example 1, and the specific steps of electroslag remelting are basically the same as those in Example 1. The differences are as follows: the starting arc material 4 is a mixed material of the turned molybdenum-containing chip return material and calcium fluoride, and the mass ratio of the two is 5:1; the first gas channel 13 is used to introduce methane at 0.13 MPa; the second gas channel 14 is used to introduce argon at 0.15 MPa; the remaining steps are basically the same.

[0124] For the superalloy ingot obtained by smelting in this example, the obtained molybdenum content is 4.06%, and the yield is 95.5%, which is significantly higher than the molybdenum content of the turned chip superalloy return material; and the components of the remaining alloys in the smelted superalloy ingot are compared with the components of the superalloy obtained by the original electroslag remelting, and the inclusion content is A0.5 level, B1.0 level, C0. level, D1.0 level. In addition, the current parameter variation during the smelting process is ≤±4%, which further indicates that the process during the smelting process is stable.

Claims

1. A method for smelting molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material, characterized in that: include: The molybdenum-containing shavings-like return material is made into a consumable electrode inner layer (2-2), and the consumable electrode outer layer (2-1) is wrapped outside the consumable electrode to form a double-layer consumable electrode; The obtained double-layer consumable electrode is subjected to electroslag remelting to prepare a molybdenum-containing high-temperature alloy ingot; wherein the outer layer (2-1) of the consumable electrode is formed by pressing a mixed material containing aluminum particles, molybdenum oxide powder and molybdenum-containing chip-shaped return material, and the mass ratio of the molybdenum element in the molybdenum oxide powder to the mass ratio of the aluminum particles is 1.4 to 1.5:

1.

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

1.

3. The method for smelting molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to claim 1, characterized in that: The consumable electrode outer layer (2-1) is also wrapped with a steel cover.

4. The method for smelting a molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to any one of claims 1 to 3, characterized in that: The molybdenum-containing chip-like return material used in the consumable electrode outer layer (2-1) has a length of 2-4 mm and a thickness of 1-2 mm; the molybdenum-containing chip-like return material used in the consumable electrode inner layer (2-2) has a length of 2-6 mm and a thickness of 1-2 mm.

5. The method for smelting a molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to any one of claims 1 to 3, characterized in that: The mass ratio of the consumable electrode outer layer (2-1) to the consumable electrode inner layer (2-2) is 5 to 15:

100.

6. The method for smelting a molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to any one of claims 1 to 3, characterized in that: The electroslag remelting specifically comprises the following steps: S1, arcing and slag removal: the arcing electrode (5) and the arc-starting material (4) are pressed tightly, and then energized, and then slag material is added 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 further heated and refined; S4, casting and molding: after refining, cast into alloy ingots of specified size.

7. The method for smelting a molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to claim 6, characterized in that: The arc-starting electrode (5) used in S1 is prepared from molybdenum-containing shavings and has a diameter of 1 / 3 to 1 / 2 of the diameter of the double-layer consumable electrode and a height of 5 mm to 10 mm; And / or the arc starting material (4) used in S1 comprises molybdenum-containing shavings return material and calcium fluoride, and the mass ratio of the two is 3 to 5:

1.

8. The method for smelting a molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to claim 6, characterized in that: The power source used for arcing and slag formation in S1 is an industrial frequency AC power source (1); And / or the electroslag remelting is carried out in a crucible (3), and the power source used in the refining stage of step S3 is a low-frequency power source (10) with a frequency of 0.1 to 0.5 Hz.

9. A device for smelting molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material, characterized in that: The invention comprises a graphite electrode (11), a bottom electrode (7), a crucible (3) and a double-layer consumable electrode used in a smelting method according to any one of claims 1 to 8, wherein the bottom electrode (7), arc starting material (4), arc starting electrode (5) and the double-layer consumable electrode are arranged in sequence from bottom to top in the crucible (3), wherein the graphite electrode (11) is used to replace the double-layer consumable electrode in the refining stage, and a steel pipe (12) is arranged inside the graphite electrode (11), and there is a gap between the inner wall of the graphite electrode (11) and the outer wall of the steel pipe (12), and the gap forms a second air inlet channel (14); the steel pipe (12) is a hollow pipe, and a first air inlet channel (13) is formed inside the steel pipe (12); and a plurality of air holes distributed at intervals are arranged on the side wall of the steel pipe (12), and the air holes are used to connect the first air inlet channel (13) and the second air inlet channel (14).

10. The device for smelting molybdenum-containing high-temperature alloy using molybdenum-containing chip-shaped return material according to claim 9, characterized in that: The first gas channel (13) is used to introduce methane at a pressure of 0.11 to 0.13 MPa; the second gas channel (14) is used to introduce argon at a pressure of 0.13 to 0.15 MPa, and the pressure of the gas introduced into the first gas channel (13) is lower than the pressure of the gas introduced into the second gas channel (14); And / or the pores are arranged obliquely upward along the direction from the inner wall of the steel pipe (12) to the outer wall, and the angle between the axial direction and the vertical direction of a single pore is 10 to 20 degrees.

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