Electroslag remelting method for high-temperature alloy return scrap containing hafnium and rhenium elements

Abstract

The invention provides an electroslag remelting method for high-temperature alloy return scraps containing hafnium and rhenium elements. The pre-melted slag material comprises the following components in percentage by mass: 60-70% of CaF2; 15 to 20 percent of Al2O3; 14 to 19 percent of CaO; and 0.1 to 0.5 percent of high-purity Al particles. Wherein after liquid pre-melting slag formed after the high-purity Al particles are melted is poured into a crystallizer, a liquid sealing layer can be formed between an arcing piece and an electrode ingot, and the phenomenon that active elements such as hafnium and rhenium in the high-temperature alloy return scrap react with oxygen during arcing melting, and consequently burning loss is caused is avoided. Tests show that in the finished product obtained by the method provided by the invention, the content of non-metallic inclusions can be reduced to ppm (10 <-6 >) level.

Description

Technical Field

[0001] This invention belongs to the technical field of recycling and reuse of high-temperature alloy return materials used in aerospace, gas turbine and other industries, and specifically relates to a method for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium elements. Background Technology

[0002] High-temperature alloys contain large amounts of strategic metallic elements such as nickel (Ni), cobalt (Co), chromium (Cr), tungsten (W), molybdenum (Mo), titanium (Ti), tantalum (Ta), hafnium (Hf), rhenium (Re), and rare earth elements. They possess excellent comprehensive properties and are widely used in aerospace engines and gas turbines as critical components such as discs, blades, and casings. Statistics show that the material utilization rate of high-temperature alloy parts is typically only 10-20% (weight percentage, wt), and for some complex parts, it is even lower. The remainder exists as scrap, gating systems, risers, machining chips, and test samples. Therefore, achieving the recycling and reuse of high-temperature alloy materials through technological advancements and process innovation is urgent and has significant practical implications and application prospects.

[0003] Currently, the production process of casting high-temperature alloy parts involves a high-temperature melting and casting process. The alloy melt comes into contact with refractory crucibles, ceramic cores, shells, and filters at high temperatures, resulting in physical, chemical, and even metallurgical reactions. This often leads to the return material containing more inclusions and impurities than the virgin material. Therefore, high-temperature alloy return material must undergo appropriate purification treatment before it can be recycled and reused with the same or similar grades.

[0004] Electroslag remelting, as a crucial step in the purification of high-temperature alloy return materials, is primarily used to remove impurities, improve purity, and enhance the alloy's microstructure. However, the remelting and recycling of high-temperature alloy return materials containing hafnium and rhenium is technically challenging. The key difficulties lie in controlling the high-temperature stability of hafnium, deeply removing harmful impurities, optimizing the melt-slag interface reaction, and matching process parameters. Metallic hafnium is highly chemically reactive and readily reacts with oxides in the slag (such as SiO2 and FeO) to form hafnium oxide (HfO2), leading to a decrease in the hafnium content of the alloy and affecting its high-temperature creep resistance and oxidation resistance. Furthermore, the product HfO2 has a high density, reaching 9.68 g / cm³. 3 During electroslag remelting, hafnium oxide can precipitate into the ingot through the slag pool, forming oxide inclusions. Unlike ordinary inclusions, these inclusions can be removed through physical adsorption or chemical metallurgical reaction with the molten slag. Furthermore, in high-temperature smelting environments, metallic hafnium can escape as vapor, therefore the molten pool temperature needs to be controlled below 1550°C.

[0005] In summary, the remelting and recycling of recycled materials from directional superalloys and single-crystal superalloys with higher content of rare and precious metals such as hafnium and rhenium presents significant technical challenges and complex processes. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a pre-melted slag material for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium, and a method for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium. The slag layer formed after the pre-melted slag material is melted can efficiently remove harmful impurities such as sulfur (S) and oxygen (O) from the alloy return material through chemical adsorption and physical capture, and can reduce the content of non-metallic inclusions to the ppm level.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a pre-melted slag material for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium elements, the composition of which, by mass fraction, includes: CaF2 60-70%; Al2O3 15-20%; CaO 14-20%; and high-purity Al particles 0.1-0.5%.

[0009] Preferably, the composition of the pre-melted slag material, by mass fraction, includes:

[0010] CaF2 65%; Al2O3 15%; CaO 19.8%; High-purity Al particles 0.2%;

[0011] or

[0012] CaF2 60%; Al2O3 20%; CaO 19.5%; High-purity Al particles 0.5%.

[0013] Secondly, the present invention provides a method for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium elements, comprising the following steps:

[0014] S1: The product obtained by welding electrode ingots and electrode rods of high-temperature alloy return materials containing hafnium and rhenium elements;

[0015] S2: Contact the molten pre-melted slag with the product obtained in step S1, and start the electroslag remelting process to obtain the product.

[0016] The pre-melted slag material is the pre-melted slag material mentioned above.

[0017] Preferably, the electroslag remelting includes an arc-starting stage, a smelting stage, and a hot capping stage;

[0018] Preferably, the melting rate during the arc initiation stage is 5–8 kg / min;

[0019] Preferably, the melting rate during the smelting stage is 4–6 kg / min;

[0020] Preferably, the melting rate during the hot capping stage is 3-4 kg / min.

[0021] Preferably, the melting rate during the arc initiation stage is 8 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min.

[0022] Preferably, the melting rate during the arc initiation stage is 5 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min.

[0023] Preferably, the electroslag remelting is carried out under a protective atmosphere;

[0024] Preferably, the protective atmosphere comprises argon gas with a purity ≥ 99.9 wt%.

[0025] Preferably, during the smelting process, the pressure of the protective atmosphere in the smelting area is maintained 10 to 50 Pa higher than atmospheric pressure.

[0026] Preferably, the liquid level of the molten pre-melted slag exceeds the bottom surface of the electrode ingot by 30-60 mm.

[0027] Preferably, the electrode ingot is prepared by vacuum induction melting of high-temperature alloy return material containing hafnium and rhenium elements.

[0028] Preferably, the vacuum degree of the vacuum induction melting is ≤0.5Pa.

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

[0030] This invention provides a CaF2-based pre-melted slag material, comprising, by mass fraction: 60-70% CaF2; 15-20% Al2O3; 14-19% CaO; and 0.1-0.5% high-purity Al particles. CaF2 serves as a basic solvent and reaction medium in the metallurgical process, reducing the melting point and viscosity of the slag, regulating its resistivity, and controlling the volatilization of sulfur (F). Adjusting the composition to control the slag viscosity helps adsorb high-density inclusions. Al2O3 stabilizes the slag structure, inhibits the burning loss of easily oxidized elements such as Al, and adsorbs high-melting-point inclusions. CaO is a strong deoxidizer, stabilizing the slag composition and adsorbing harmful elements such as Pb, Bi, and S, further improving alloy purity. The liquid pre-melted slag formed after the high-purity Al particles melt, when poured into the crystallizer, forms a liquid sealing layer between the arc-starting plate and the electrode ingot, preventing reactive elements such as hafnium and rhenium in the high-temperature alloy return material from reacting with oxygen during arc-starting melting, thus avoiding burning loss. By combining the above four components, this invention can both avoid the loss of volatile elements in the recycled material and improve the purity of the alloy.

[0031] Tests have shown that, according to the method provided by this invention, the content of non-metallic inclusions in the finished product can be reduced to ppm (10).-6 (Grade 1). Furthermore, the hafnium and rhenium content in the remelted hafnium-rhenium high-temperature alloy recycled material prepared by this invention fully meets the standard requirements, demonstrating significant engineering application value and promising prospects for widespread application. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] To address the challenges of recycling and reusing high-temperature alloys containing hafnium and rhenium used in aerospace, gas turbine, and other fields, which present significant material waste and difficulties, this invention provides a pre-melted slag material for electroslag remelting of hafnium and rhenium-containing high-temperature alloy recyclables. Its composition, by mass fraction, includes: CaF2 60-70%, such as 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%; Al2O3 15-20%, such as 15%, 16%, 17%, 18%, 19%, or 20%; CaO 14-20%, such as 14%, 15%, 16%, 17%, 18%, or 19%; and high-purity Al particles 0.1-0.5%, such as 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%.

[0034] In some embodiments of the present invention, the composition of the pre-melted slag material, by mass fraction, includes:

[0035] CaF2 65%; Al2O3 15%; CaO 19.8%; High-purity Al particles 0.2%;

[0036] or

[0037] CaF2 60%; Al2O3 20%; CaO 19.5%; High-purity Al particles 0.5%.

[0038] In this invention, during the subsequent electroslag remelting process, the molten slag layer of the aforementioned pre-melted slag material efficiently removes harmful impurities such as sulfur (S) and oxygen (O) from the alloy return material through chemical adsorption and physical capture, reducing the content of non-metallic inclusions to the ppm level. Furthermore, the liquid pre-melted slag containing high-purity Al particles, after being poured into the crystallizer, can form a liquid sealing layer between the arc-starting plate and the electrode ingot, preventing reactive elements such as hafnium and rhenium in the return material from reacting with oxygen during arc-starting melting and thus avoiding burn-off.

[0039] This invention also provides a method for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium elements, comprising the following steps:

[0040] S1: The product obtained by welding electrode ingots and electrode rods of high-temperature alloy return materials containing hafnium and rhenium elements;

[0041] S2: Contact the molten pre-melted slag with the product obtained in step S1, and start the electroslag remelting process to obtain the product.

[0042] The pre-melted slag material is the pre-melted slag material involved in the above technical solution.

[0043] According to the present invention, the electrode ingot and electrode rod of high-temperature alloy return material containing hafnium and rhenium elements are first provided as a product for subsequent electroslag remelting.

[0044] In some embodiments of the present invention, the product of welding electrode ingots and electrode rods of high-temperature alloy return materials containing hafnium and rhenium elements is prepared according to the following method:

[0045] (1) Classification of high-temperature alloy return materials containing hafnium and rhenium: Using a handheld composition analyzer, high-temperature alloy return materials containing hafnium, rhenium and other metal elements of different grades, such as risers, gatings, scrap parts and other blocky return materials, are accurately classified and distinguished to strictly avoid mixing of return materials of different alloy grades.

[0046] (2) Cleaning of high-temperature alloy return materials containing hafnium and rhenium: Grinding, tumbling, and cutting methods are used to remove visible inclusions and other impurities from the surface of the sorted high-temperature alloy return materials. The cleaned return materials are then loaded into a feeding bucket, ready for smelting.

[0047] (3) Preparation of electrode ingots by vacuum induction melting: The cleaned and appropriately cut high-temperature alloy return material is loaded into the crucible of the vacuum induction furnace through a feeding bucket. After turning on the cooling water system, the vacuum pump is started to draw a vacuum. The vacuum degree of the melting chamber is ≤0.5Pa. Power is supplied to melt the alloy return material. When the alloy molten pool begins to appear at the bottom of the crucible, the vacuum valve is closed and high-purity argon gas is introduced into the melting chamber. The argon gas pressure reaches 20,000-30,000Pa, such as 20,000Pa, 22,000Pa, 25,000Pa, 28,000Pa, or 30,000Pa. Depending on the crucible capacity, the remaining return material is added using a feeder. After the return material is completely melted, it is poured into an ingot mold for cooling to obtain a high-temperature alloy return material electrode ingot.

[0048] (4) Electrode ingot processing: Machining the head and tail of the high-temperature alloy return material electrode ingot, and cutting a test piece with a thickness of 10-15mm from the tail of the electrode ingot to be used as an arc-starting piece for electroslag remelting.

[0049] (5) Electrode welding: High-purity argon gas shielded welding is used to weld the high-temperature alloy return material electrode ingot and the electrode rod together, and check that the axis of the electrode ingot after welding is coaxial with the electrode rod.

[0050] Then, according to the present invention, the molten pre-melted slag is brought into contact with the product obtained by the above scheme, and the electroslag remelting process is started.

[0051] The present invention preferably uses high-speed electroslag remelting in a positive pressure protective atmosphere. High-purity argon is preferably used as the protective atmosphere for electroslag remelting of alloy return material. The purity of argon is ≥99.9wt%. During the melting process, the argon pressure in the melting area is preferably maintained 10-50 Pa higher than atmospheric pressure, such as 10 Pa, 20 Pa, 30 Pa, 40 Pa or 50 Pa, to ensure that the burn-off of elements such as hafnium and rhenium is reduced.

[0052] In some embodiments of the present invention, it is preferred to use an electric furnace to pre-melt and uniformly mix the remelting slag (the slag system composition is the pre-melted slag material mentioned above), and then pour the cleared slag into the crystallizer. Preferably, the slag liquid level is 30-60 mm higher than the bottom surface of the electrode ingot, such as 30 mm, 35 mm, 40 mm, 45 mm, 50 mm, 55 mm or 60 mm, etc. Then, the power supply is immediately started for electroslag remelting. The power control mode is adopted, and the melting rate is controlled at 5-8 kg / min during the arc initiation stage of electroslag remelting, 4-6 kg / min during the smelting stage, and 3-4 kg / min during the hot capping stage.

[0053] In some embodiments of the present invention, the melting rate during the arc initiation stage is 8 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min.

[0054] or

[0055] The melting rate during the arc initiation stage is 5 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min.

[0056] In this invention, the melting rate of the three stages of electroslag remelting is higher than that of ordinary electroslag remelting, and the melting rate of the three stages is distributed from high to low. This can avoid or reduce the burn-off of main elements and trace elements in the alloy return material, and reduce the melting rate of the hot capping stage, which helps to promote alloy feeding, eliminate porosity and voids in the head of the return material ingot, and improve the metallurgical quality of the ingot.

[0057] In some preferred embodiments of the present invention, after the electroslag remelting is completed, it is preferable to perform ingot casting and composition inspection, as follows:

[0058] Ingot processing: After the high-temperature alloy return ingots from electroslag remelting are cooled to room temperature, they are machined to remove oxide scale, slag, and other inclusions from the head, tail, and surface of the ingot. A sample of alloy powder for chemical analysis, weighing 30–40 g, is machined from both the head and tail of the ingot.

[0059] Composition inspection: In accordance with the requirements of the material specifications, chemical composition analysis is performed on the high-temperature alloy return materials after processing. After the composition of the return material ingots after electroslag remelting meets the composition range requirements of the relevant standards and specifications, the ingots are put into storage for use.

[0060] In summary, this invention employs a high-purity argon positive pressure protective atmosphere during the smelting process, combined with an innovative smelting technology. It also designs a novel slag system based on CaF2-CaO-Al2O3, characterized by high alkalinity and low oxygen potential, to inhibit HfO2 formation. Furthermore, CaO is added to the slag to react with the harmful element S in the alloy, achieving efficient adsorption and desaturation while avoiding the loss of Al, Ti, and other elements due to slag-alloy melt interface reactions. Experimental verification shows that using the method provided by this invention, nearly 10 batches of high-temperature alloy return materials containing hafnium and rhenium exhibited minimal loss of reactive hafnium and rhenium, high purity, no loss of hafnium and rhenium, precise control of alloy composition, and minimal fluctuations. This achieves the engineering-scale recycling and reuse of hafnium and rhenium-containing high-temperature alloy return materials, demonstrating significant engineering application value and promising prospects for widespread application.

[0061] To further illustrate the present invention, the following embodiments provide a detailed description. In the following embodiments of the present invention, the purity of the high-purity Al particles is not less than 99.5%.

[0062] Example 1

[0063] (1) Classification of DZ125 directional high temperature alloy return material: Use a handheld composition analyzer to re-inspect DZ125 alloy block return material, such as risers, gatings, scrap parts, etc., and strictly avoid mixing materials;

[0064] (2) Cleaning of returned material: Grinding, rolling, and cutting are used to remove visible inclusions from the surface of the DZ125 alloy returned material. The cleaned returned material is then loaded into a charging bucket for smelting.

[0065] (3) Preparation of electrode ingots by vacuum induction melting: DZ125 alloy return material is loaded into the crucible of the vacuum induction furnace through a feeding bucket. The cooling water system is turned on, and the vacuum pump is started to evacuate the furnace to a vacuum level of 0.2 Pa. Power is supplied to melt the alloy return material. When a molten alloy pool begins to appear at the bottom of the crucible, the vacuum valve is closed, and high-purity argon gas is introduced into the melting chamber at a pressure of 20,000 Pa. The remaining return material is added using a feeder, depending on the crucible capacity. After the return material is completely melted, it is poured into an ingot mold for cooling.

[0066] (4) Electrode ingot processing: The head and tail of the alloy return material electrode ingot are machined. A 10mm thick test piece is cut off from the tail of the electrode ingot to be used as an arc-starting piece for electroslag remelting.

[0067] (5) Electrode welding: High-purity argon gas shielded welding is used to weld the high-temperature alloy return material ingot together with the electrode rod, and the axis of the ingot after welding is checked to be coaxial with the electrode rod.

[0068] (6) High-speed electroslag remelting under positive pressure protective atmosphere: High-purity argon is used as the protective atmosphere for electroslag remelting of alloy return material. The argon purity is 99.9 wt%. During the melting process, the argon pressure in the melting area is maintained 50 Pa higher than atmospheric pressure. The designed electroslag remelting slag system composition is CaF2: 65%; Al2O3: 15%; CaO: 19.8%; high-purity Al particles: 0.2%. The remelting slag is pre-melted and mixed evenly in an electric furnace. Then, the cleared slag is poured into the crystallizer. The slag liquid level is 30 mm higher than the bottom surface of the electrode ingot. The power supply is immediately started for electroslag remelting. The power control mode is adopted. The melting rate is controlled at 5 kg / min during the arc initiation stage of electroslag remelting, 4 kg / min during the melting stage, and 3 kg / min during the hot capping stage.

[0069] (7) Ingot processing: After the high-temperature alloy return material ingots after electroslag remelting are cooled to room temperature, the head and tail of the ingots and the surface of the ingots are cleaned by machining to remove oxide scale, slag and other inclusions. One sample of alloy powder for chemical analysis is processed from the head and tail of the ingots, each weighing 30g.

[0070] (8) Composition inspection: In accordance with the requirements of DZ125 standard, chemical composition analysis is performed on the high-temperature alloy return material samples after processing. After the composition of the return material ingots after electroslag remelting meets the composition range requirements, the ingots are put into storage for use.

[0071] The effects of Example 1 and ordinary electroslag remelting (without inert protective atmosphere) are compared in Table 1 below.

[0072] Table 1 Comparison of the implementation effects of the embodiments and the comparative examples

[0073]

[0074] Example 2

[0075] (1) Classification of DD5 single crystal high temperature alloy return materials: A handheld composition analyzer is used to re-test the composition of return material blocks such as risers, gatings, and scrap parts, and strictly avoid mixing return materials of different alloy grades;

[0076] (2) Cleaning of returned material: Grinding, tumbling, and cutting are used to remove visible inclusions from the surface of the DD5 alloy returned material. The cleaned returned material is then loaded into a charging bucket, ready for smelting.

[0077] (3) Preparation of electrode ingots by vacuum induction melting: DD5 alloy return material is loaded into the crucible of the vacuum induction furnace through a feeding bucket. After turning on the cooling water system, the vacuum pump is started to draw a vacuum, and the vacuum degree of the melting chamber is 0.1 Pa. Power is supplied to melt the alloy return material. When the alloy molten pool begins to appear at the bottom of the crucible, the vacuum valve is closed, and high-purity argon gas is introduced into the melting chamber. The argon gas pressure reaches 30000 Pa. Based on the crucible capacity, the remaining return material is added using a feeder. After the return material is completely melted, it is poured into the ingot mold for cooling.

[0078] (4) Electrode ingot processing: The head and tail of the alloy return material electrode ingot are machined, and a 15mm thick test piece is cut off from the tail of the electrode ingot to be used as an arc-starting piece for electroslag remelting.

[0079] (5) Electrode welding: High-purity argon gas shielded welding is used to weld the high-temperature alloy return material ingot to the electrode rod together, and the axis of the ingot after welding is checked to be coaxial with the electrode rod.

[0080] (6) High-speed electroslag remelting under positive pressure protective atmosphere: High-purity argon is used as the protective atmosphere for electroslag remelting of alloy return material. The purity of argon is 99.9 wt%. During the melting process, the argon pressure in the melting area is kept 30 Pa higher than atmospheric pressure. The designed electroslag remelting slag system composition is CaF2: 60%; Al2O3: 20%; CaO: 19.5%; high-purity Al particles: 0.5%. The remelting slag is pre-melted and mixed evenly in an electric furnace. Then, the cleared slag is poured into the crystallizer. The slag liquid level is 60 mm higher than the bottom surface of the electrode ingot. The power supply is immediately started for electroslag remelting. The power control mode is adopted. The melting rate is controlled at 8 kg / min during the arc initiation stage of electroslag remelting, 4 kg / min during the melting stage, and 3 kg / min during the hot capping stage. After the high-temperature alloy return material ingot after electroslag remelting is cooled to room temperature, the oxide scale, slag and other inclusions on the ingot head, tail and surface are cleaned by machining. Two alloy sample powders, each weighing 30g, were machined from the head and tail of the ingot for chemical analysis; composition testing was then conducted. In accordance with the requirements of the DD5 single-crystal alloy material specification, the processed high-temperature alloy return sample powders were subjected to chemical composition analysis. After the composition of the return ingot after electroslag remelting met the composition range requirements of the DD5 standard, the ingot was stored for future use.

[0081] The performance comparison between Example 2 and the conventional electroslag remelting comparison is shown in Table 2 below.

[0082] Table 2 Comparison of Implementation Effects between the Examples and Comparative Examples

[0083]

[0084] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A pre-melted slag material for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium, characterized in that, Its composition, by mass fraction, includes: CaF2 60-70%; Al2O3 15-20%; CaO 14-20%; and high-purity Al particles 0.1-0.5%.

2. The premelted slag material according to claim 1, characterized in that, The composition of the pre-melted slag, by mass fraction, includes: CaF2 65%; Al2O3 15%; CaO 19.8%; High-purity Al particles 0.2%; or CaF2 60%; Al2O3 20%; CaO 19.5%; High-purity Al particles 0.5%.

3. A method for electroslag remelting of high-temperature alloy return materials containing hafnium and rhenium, characterized in that, Includes the following steps: S1: The product obtained by welding electrode ingots and electrode rods of high-temperature alloy return materials containing hafnium and rhenium elements; S2: Contact the molten pre-melted slag with the product obtained in step S1, and start the electroslag remelting process to obtain the product. The pre-melted slag material is the pre-melted slag material as described in claim 1 or 2.

4. The method according to claim 3, characterized in that, The electroslag remelting includes an arc initiation stage, a smelting stage, and a hot capping stage; The melting rate during the arc initiation stage is 5–8 kg / min; The melting rate during the smelting stage is 4–6 kg / min; The melting rate during the hot capping stage is 3-4 kg / min.

5. The method according to claim 4, characterized in that, The melting rate during the arc initiation stage is 8 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min. or The melting rate during the arc initiation stage is 5 kg / min, the melting rate during the smelting stage is 4 kg / min, and the melting rate during the hot capping stage is 3 kg / min.

6. The method according to claim 4 or 5, characterized in that, The electroslag remelting was carried out under a protective atmosphere; The protective atmosphere includes argon gas with a purity ≥ 99.9 wt%.

7. The method according to claim 6, characterized in that, During the electroslag remelting process, the pressure of the protective atmosphere in the smelting zone is maintained 10-50 Pa higher than atmospheric pressure.

8. The method according to any one of claims 3 to 7, characterized in that, The liquid level of the molten pre-melted slag exceeds the bottom surface of the electrode ingot by 30-60 mm.

9. The method according to any one of claims 3 to 8, characterized in that, The electrode ingot is prepared by vacuum induction melting of high-temperature alloy return material containing hafnium and rhenium elements.

10. The method according to claim 9, characterized in that, The vacuum degree of the vacuum induction melting is ≤0.5Pa.

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