A preparation method of a nickel-based high-temperature alloy with precisely controlled carbon content

Abstract

The application discloses a preparation method of a nickel-based high-temperature alloy with precisely controlled carbon content. The preparation method of the nickel-based high-temperature alloy comprises the following steps: when vacuum induction melting the nickel-based high-temperature alloy, after pure Ni and pure Cr are melted and purified, a nickel-carbon rod is directly put into a charging chamber at the top of an induction furnace, and then twice melting and condensing are carried out. Finally, all the Al and Ti are added into the furnace, and the Ni80Mg20 alloy is placed in the charging chamber at the top of the vacuum induction furnace for standby use. After all the alloy materials are melted and purified, the Ni80Mg20 alloy in the charging chamber at the top of the vacuum induction furnace is put into the induction furnace by operating a charging rod. The power is increased to 30 kW, and then directly increased to 50 kW after 3 minutes. After maintaining for 2 minutes, the power is reduced to 30 kW and maintained for 1 minute. The power is reduced to 10 kW for casting and forming, and the nickel-based high-temperature alloy material is prepared. The method can precisely control the carbon content of the nickel-based high-temperature alloy, is simple and easy to operate, and is worthy of promotion and application.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature alloy preparation technology, specifically relating to a method for preparing nickel-based high-temperature alloys with precisely controllable carbon content. Background Technology

[0002] High-temperature alloys possess excellent high-temperature strength, oxidation and corrosion resistance, and good structural stability, making them irreplaceable key materials in the energy industry. Traditional 9-12% Cr ferritic heat-resistant steels and existing Ni-Cr austenitic heat-resistant steels cannot achieve a minimum stress of 100 MPa after 100,000 hours of creep rupture at temperatures above 700°C. To improve power plant thermal efficiency, reduce greenhouse gas emissions, and build a resource-saving and environmentally friendly society, large-capacity, high-parameter ultra-supercritical units represent the direction of power plant development in my country. Therefore, with the increasing pressure and temperature of ultra-supercritical units, higher demands are placed on the research and development of alloy materials for key components. Key components of 700°C ultra-supercritical units must use nickel-based high-temperature alloys, but the challenge of precisely controlling the composition of high-temperature alloy materials in my country severely restricts the preparation of high-performance alloy materials, thus affecting the rapid development of ultra-supercritical units.

[0003] Since nickel-based superalloys primarily enhance their high-temperature performance by adding reactive elements such as Al and Ti to precipitate a second phase, vacuum induction melting technology must be employed to prepare nickel-based superalloy materials for ultra-supercritical turbine blades. During vacuum induction melting, the induction furnace is under a high vacuum negative pressure. Due to carbon's strong deoxidizing ability, its products, such as CO, are extracted by the vacuum control system, easily leading to a reduction in the effective carbon content of the alloy. Furthermore, the traditional method of directly adding carbon rods cannot effectively and accurately control the carbon content in the finished superalloy because carbon rods have a high melting point, requiring a long refining time for them to gradually melt into the alloy. However, excessively long refining times can lead to energy waste and the volatilization of other alloying elements and trace elements. Moreover, due to carbon's strong deoxidizing effect, carbon itself also volatilizes. Therefore, it is difficult to accurately control the content of various elements in the superalloy. Currently, various methods exist for adding carbon, such as: in vacuum induction melting of nickel-based superalloys, carbon rods are directly added from the top charging chamber of the induction furnace after the alloying elements have been purified; another method involves using a vacuum arc furnace to melt nickel blocks, encasing carbon blocks in molten nickel to produce button-shaped ingots of pure nickel encased in carbon, which are then placed in the induction furnace along with other alloy materials before vacuum induction smelting. However, both of these methods, used alone or in combination, struggle to accurately control the carbon content, with compositional testing showing actual carbon content far below the designed level. Therefore, researching a method for preparing nickel-based superalloys that can precisely control carbon content is crucial. Summary of the Invention

[0004] To address the above problems, the purpose of this invention is to provide a method for preparing nickel-based superalloys with precisely controllable carbon content.

[0005] This invention discloses a method for preparing a nickel-based superalloy with precisely controllable carbon content, which is implemented according to the following steps:

[0006] 1) According to the target nickel-based superalloy composition content, pure Ni and pure Cr, excluding nickel in nickel-carbon rods and nickel in Ni80Mg20 alloy, are smelted in a vacuum induction furnace.

[0007] 2) After all the pure Ni and pure Cr have melted, adjust the power of the vacuum induction furnace to 0kW and let it solidify for 15-20 minutes to allow the alloy surface in the induction furnace to form a film. Then, add the nickel-carbon rod from the top charging chamber of the induction furnace, and slowly increase the power of the vacuum induction furnace to 30kW to melt the nickel-carbon rod. After melting, solidify for 10 minutes and increase the power to 10kW after the surface film has formed. Then, increase the power by 10kW every minute until it reaches 50kW and hold for 2 minutes. Then, reduce the power to 0kW and solidify for 30 minutes.

[0008] 3) Add the required pure Al and pure Ti to the furnace to form the target nickel-based superalloy. Place the Ni80Mg20 alloy in the top charging chamber of the vacuum induction furnace for later use. Re-evacuate to 1-2 Pa. After cleaning all the alloy material at 50 kW, slowly reduce the power to 0 kW within 1 minute. Cool for 10 minutes. Use the charging rod to add the Ni80Mg20 alloy from the top charging chamber of the vacuum induction furnace into the induction furnace. Increase the power to 30 kW. After 3 minutes, increase it directly to 50 kW. Maintain this power for 2 minutes. Then reduce the power to 30 kW and maintain this power for 1 minute. Finally, reduce the power to 10 kW and cast the alloy to obtain the nickel-based superalloy material.

[0009] The principle behind the precise control of carbon content in this invention's preparation method is as follows: During vacuum induction melting, the induction furnace is under high vacuum. After adding the nickel-carbon rod, a very small amount of carbon participates in the deoxidation reaction. The high vacuum environment effectively reduces carbon loss and allows harmful impurities to volatilize and be discharged, ensuring that more carbon will subsequently diffuse into the nickel-based high-temperature alloy material. After adding the nickel-carbon rod, there are two melting and cooling processes: The first process uses 30kW to melt the nickel-carbon rod and combines it with 10 minutes of cooling. The low power combined with the short cooling time allows the carbon to be mixed into the surface liquid alloy material in a very short time, as the nickel and carbon have been powdered. The second process uses a rapid increase in power to 50kW to melt the alloy material, which can accelerate the breaking of the molten pool film. During the melting process, the alloy liquid tumbles up and down, ensuring a rapid and uniform distribution of carbon throughout the molten pool. The powdered carbon diffuses very easily into the surrounding alloy material, and the shorter refining time also reduces the volatilization of the carbon itself. At the same time, the subsequent 30-minute cooling process also provides more time for carbon to diffuse into the alloy matrix.

[0010] The method for preparing nickel-based superalloys of this invention can precisely control the carbon content of nickel-based superalloys, is simple and easy to operate, and is worthy of widespread application. Detailed Implementation

[0011] The present invention will be further described below with reference to embodiments, but this is not intended to limit the present invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the protection scope of the present invention.

[0012] This invention discloses a method for preparing a nickel-based superalloy with precisely controllable carbon content, which is implemented according to the following steps:

[0013] ①Preparing the toner: First, fix the spectral carbon rod on a clean bench vise. Place a clean container under the vise to hold the spectral carbon powder. Use a regular file to slowly file the spectral carbon rod into carbon powder.

[0014] ② Batching Calculation: Based on the carbon content of the nickel-based superalloy, the carbon yield ε1 during vacuum induction melting of the nickel-based superalloy material is calculated as 75%, and the carbon yield ε2 during high-temperature sintering is calculated as 88%. Then, the required mass of carbon is calculated. For example: when the required melting mass is W... 合金 And the carbon content is W 碳％ When making nickel-based superalloys, the required carbon content is: Considering the high-temperature sintering yield ε2, the required carbon content before sintering is:

[0015] ③ Mixing powder: Based on the required amount of carbon before sintering, calculate the amount of nickel powder required by mixing 200-mesh nickel powder and carbon powder that has been filed with a file at a mass ratio of 8.05-8.15:1. Then mix the two together and stir the mixture of nickel powder and carbon powder continuously with a stainless steel spoon until the color is uniform.

[0016] ④ Powder compaction: The nickel-carbon mixed powder is pressed into cylindrical nickel-carbon rods using a molding process. To avoid damaging the pressed nickel-carbon rods during sampling, they can be placed in a ceramic boat.

[0017] ⑤ Sintering of nickel-carbon rods: Sinter in a box furnace at 1200±5℃ for 14-16 minutes under atmospheric conditions, then remove and set aside for use;

[0018] ⑥ Addition of nickel-carbon rods: During the vacuum induction melting of nickel-based superalloy materials, pure Ni and pure Cr, excluding nickel in the nickel-carbon rods and nickel in the Ni80Mg20 alloy, are melted in a vacuum induction furnace according to the target nickel-based superalloy composition. After the alloy is completely melted, the power of the vacuum induction furnace is adjusted to 0kW. The furnace is cooled for 15-20 minutes to allow the alloy surface in the induction furnace to form a film. Then, the nickel-carbon rods are added from the top charging chamber of the induction furnace. The power of the vacuum induction furnace is then slowly increased to 30kW to melt the nickel-carbon rods. After melting, the furnace is cooled for 10 minutes. After the surface film forms, the power is increased to 10kW. Then, the power is rapidly increased by 10kW every minute until it reaches 50kW. The furnace is held at 50kW for 2 minutes, and then the power is reduced to 0kW. After 30 minutes of cooling, the furnace is opened and the required pure Al and pure Ti for the target nickel-based superalloy composition are added. Simultaneously, 2.375 grams of Ni80Mg20 alloy is placed in the top charging chamber of the vacuum induction furnace for later use. The vacuum is then re-evacuated to 1-2 Pa. After melting all the alloy material at 50 kW, the power is slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy in the top charging chamber is added to the induction furnace by manipulating the charging rod. The power is increased to 30 kW, and after 3 minutes, it is directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power is reduced to 10 kW for casting. To avoid splashing of the molten alloy during melting, the nickel-carbon rod must be dried before being placed in the top charging chamber of the vacuum induction furnace.

[0019] Example 1

[0020] In this embodiment, the design and measured composition mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 1 (wt.%):

[0021] Table 1. Design and measured composition (mass percentage) of nickel-based superalloy material in Example 1

[0022] Design Components 0.01 19.5 1.80 2.25 0.008 ≤0.015 ≤0.015 margin Actual components 0.0103 19.5 1.81 2.25 0.0051 0.011 0.0011 margin

[0023] In this embodiment, the total weight of the nickel-based superalloy is designed to be 9.5 kg.

[0024] 1. Preparation of toner: First, fix the spectral carbon rod on a clean bench vise. Place a clean container under the vise to hold the spectral carbon powder. Use a regular file to slowly file the spectral carbon rod into carbon powder.

[0025] 2. Batching calculation: Based on the carbon content of the nickel-based superalloy, the carbon yield ε1 in the vacuum induction melting of the nickel-based superalloy material is calculated as 75%, and the carbon yield ε2 in the high-temperature sintering process is calculated as 88%. Then, the required carbon mass is calculated to be 1.44g.

[0026] 3. Mixing powder: Based on the required amount of carbon before sintering, the amount of nickel powder required is 11.66g, calculated by mass ratio of 200-mesh nickel powder to carbon powder that has been filed with a file at a ratio of 8.10:1. Then, mix the two together and stir the mixture of nickel powder and carbon powder continuously with a stainless steel spoon until the color is uniform.

[0027] 4. Powder Compacting: The nickel-carbon mixed powder is pressed into cylindrical nickel-carbon rods using a molding process. To avoid damaging the pressed nickel-carbon rods during sampling, they can be placed in a ceramic boat.

[0028] 5. Weigh the raw materials according to the target nickel-based superalloy composition. First, melt 7.25 kg of pure Ni and 1.95 kg of pure Cr in a vacuum induction furnace. After complete melting, adjust the power of the vacuum induction furnace to 0 kW and allow it to solidify for 15-20 minutes to form a film on the alloy surface. Then, add 13.1 g of nickel-carbon rods from the top charging chamber of the induction furnace. Slowly increase the power of the vacuum induction furnace to 30 kW to melt the nickel-carbon rods. After melting, allow it to solidify for 10 minutes. After the surface film forms, increase the power to 10 kW. Then, rapidly increase the power by 10 kW every minute until reaching 50 kW and hold for 2 minutes. Then, reduce the power to 0 kW and allow it to solidify for 30 minutes. Open the furnace and release the target alloy. The required composition for the nickel-based superalloy was achieved using 173.9 grams of pure Al and 221.9 grams of pure Ti. Simultaneously, 2.375 grams of Ni80Mg20 alloy was placed in the top charging chamber of a vacuum induction furnace for later use. The furnace was re-vacuumed to 1-2 Pa. After melting all the alloy material at 50 kW, the power was slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, resulting in the nickel-based superalloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0029] Example 2

[0030] In this embodiment, the design and measured composition mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 2 (wt.%):

[0031] Table 2. Design and measured composition (mass percentage) of nickel-based superalloy materials in Example 2

[0032] Design Components 0.06 19.5 1.40 2.25 0.008 ≤0.015 ≤0.015 margin Actual components 0.065 19.4 1.41 2.20 0.0057 0.010 0.0009 margin

[0033] In this embodiment, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials are weighed according to the target nickel-based superalloy composition. First, 7.22 kg of pure Ni and 1.95 kg of pure Cr are melted in a vacuum induction furnace. After complete melting, the power of the vacuum induction furnace is adjusted to 0 kW, and the alloy is allowed to solidify for 15-20 minutes to form a film on the surface. Then, 78.6 g of nickel-carbon rods are added from the top charging chamber of the induction furnace. The power of the vacuum induction furnace is then slowly increased to 30 kW to melt the nickel-carbon rods. After melting, the alloy is allowed to solidify for 10 minutes. After surface film formation, the power is increased to 10 kW, and then the power is rapidly increased by 10 kW every minute until it reaches 50 kW. The temperature is held for 2 minutes, then the power is reduced to 0 kW, and the alloy is allowed to solidify for 30 minutes. Finally, the furnace is opened and the target nickel alloy is released. The required composition of the nickel-based superalloy was achieved using 133.9 grams of pure Al and 221.9 grams of pure Ti. Simultaneously, 2.375 grams of Ni80Mg20 alloy was placed in the top charging chamber of the vacuum induction furnace for later use. The vacuum was re-evacuated to 1-2 Pa. After melting all the alloy material at 50 kW, the power was slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, it was directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, resulting in the nickel-based superalloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0034] Example 3

[0035] In this embodiment, the design and measured composition mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 3 (wt.%):

[0036] Table 3. Design and measured composition (mass percentage) of nickel-based superalloy material in Example 3

[0037] Design Components 0.1 19.5 1.40 2.25 0.008 ≤0.015 ≤0.015 margin Actual components 0.11 19.8 1.38 2.22 0.0045 0.008 0.0008 margin

[0038] In this embodiment, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials are weighed according to the target nickel-based superalloy composition. First, 7.17 kg of pure Ni and 1.95 kg of pure Cr are melted in a vacuum induction furnace. After complete melting, the power of the vacuum induction furnace is adjusted to 0 kW, and the alloy is allowed to solidify for 15-20 minutes to form a film on the surface. Then, 131 g of nickel-carbon rods are added from the top charging chamber of the induction furnace. The power of the vacuum induction furnace is then slowly increased to 30 kW to melt the nickel-carbon rods. After melting, the alloy is allowed to solidify for 10 minutes. After surface film formation, the power is increased to 10 kW, and then the power is rapidly increased by 10 kW every minute until it reaches 50 kW. The temperature is held for 2 minutes, then the power is reduced to 0 kW, and the alloy is allowed to solidify for 30 minutes. Finally, the furnace is opened and the target nickel-based superalloy is released. The required high-temperature alloy composition consisted of 133.9 grams of pure Al and 221.9 grams of pure Ti. Simultaneously, 2.375 grams of Ni80Mg20 alloy was placed in the top charging chamber of the vacuum induction furnace for later use. The vacuum was re-evacuated to 1-2 Pa. After all the alloy material was melted at 50 kW, the power was slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, it was directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, resulting in the nickel-based high-temperature alloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0039] Example 4

[0040] In this embodiment, the design and measured composition mass percentage of the nickel-based high-temperature alloy material used for ultra-supercritical steam turbine blades are shown in Table 4 (wt.%):

[0041] Table 4. Design and measured composition (mass percentage) of nickel-based superalloy material in Example 4

[0042] Design Components 0.06 19.5 1.80 2.25 1.5 0.008 ≤0.015 ≤0.015 margin Actual components 0.058 19.1 1.84 2.26 1.45 0.0047 0.009 0.0011 margin

[0043] In this embodiment, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials were weighed according to the target nickel-based superalloy composition. First, 7.04 kg of pure Ni, 1.95 kg of pure Cr, and 142.5 g of pure Nb were melted in a vacuum induction furnace. After complete melting, the vacuum induction furnace power was adjusted to 0 kW, and the furnace was allowed to solidify for 15-20 minutes to allow a film to form on the alloy surface. Then, 78.6 g of nickel-carbon rods were added from the top charging chamber of the induction furnace. The vacuum induction furnace power was then slowly increased to 30 kW to melt the nickel-carbon rods. After melting, the furnace was allowed to solidify for 10 minutes. After a surface film formed, the power was increased to 10 kW, and then the power was rapidly increased by 10 kW every minute until reaching 50 kW. The furnace was held at 50 kW for 2 minutes, then the power was reduced to 0 kW, and the furnace was allowed to solidify for 30 minutes. The furnace was filled with 173.9 grams of pure Al and 221.9 grams of pure Ti, required for the target nickel-based superalloy composition. Simultaneously, 2.375 grams of Ni80Mg20 alloy was placed in the top charging chamber of the vacuum induction furnace for later use. The vacuum was re-evacuated to 1-2 Pa. After melting all the alloy material at 50 kW, the power was slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, it was directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, yielding the nickel-based superalloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0044] Example 5

[0045] In this embodiment, the design and measured composition mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 5 (wt.%):

[0046] Table 5. Design and measured composition (mass percentage) of nickel-based superalloy material in Example 5

[0047] Design Components 0.06 19.5 1.80 1.80 2.0 0.008 ≤0.015 ≤0.015 margin Actual components 0.057 19.2 1.78 1.76 1.98 0.0049 0.008 0.0008 margin

[0048] In this embodiment, the total weight of the nickel-based superalloy is designed to be 9.5 kg. Raw materials are weighed according to the target nickel-based superalloy composition. First, 7.03 kg of pure Ni, 1.95 kg of pure Cr, and 190 g of pure Co are melted in a vacuum induction furnace. After complete melting, the power of the vacuum induction furnace is adjusted to 0 kW, and the alloy is allowed to solidify for 15-20 minutes to form a film on the surface. Then, 78.6 g of nickel-carbon rods are added from the top charging chamber of the induction furnace. The power of the vacuum induction furnace is then slowly increased to 30 kW to melt the nickel-carbon rods. After melting, the alloy is allowed to solidify for 10 minutes. After surface film formation, the power is increased to 10 kW, and then the power is rapidly increased by 10 kW every minute until it reaches 50 kW. The furnace is held at 50 kW for 2 minutes, then the power is reduced to 0 kW, and the alloy is allowed to solidify for 30 minutes before the furnace is opened. 173.9 grams of pure Al and 177.5 grams of pure Ti, required for the target nickel-based superalloy composition, were added. Simultaneously, 2.375 grams of Ni80Mg20 alloy was placed in the top charging chamber of the vacuum induction furnace for later use. The vacuum was re-evacuated to 1-2 Pa. After melting all the alloy material at 50 kW, the power was slowly reduced to 0 kW over 1 minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, it was directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, thus obtaining the nickel-based superalloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0049] Comparative Example 1

[0050] Pure carbon rods are fed directly into the charging chamber at the top of the vacuum induction furnace. The carbon yield is calculated to be 75% during vacuum induction melting of nickel-based superalloys.

[0051] In this comparative example, the design and measured compositional mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 6 (wt.%):

[0052] Table 6 Comparative Example 1: Design and Measured Composition (Mass Percentage) of Nickel-Based Superalloy Materials

[0053] Design Components 0.06 19.5 1.40 2.25 0.008 ≤0.015 ≤0.015 margin Actual components 0.0103 19.6 1.43 2.24 0.0039 0.007 0.0015 margin

[0054] In this comparative example, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials were weighed according to the target nickel-based superalloy composition. First, 7.29 kg of pure Ni and 1.95 kg of pure Cr were melted in a vacuum induction furnace. After complete melting, the furnace power was adjusted to 0 kW, and the alloy was allowed to solidify for 15-20 minutes to form a film on the surface. Then, 7.6 g of pure carbon rods were added from the top charging chamber of the furnace. The furnace power was then slowly increased to 30 kW. After melting, the alloy was allowed to solidify for 10 minutes. After surface film formation, the power was increased to 10 kW, and then rapidly increased by 10 kW every minute until reaching 50 kW. The power was held for 2 minutes, then reduced to 0 kW, and solidified for 30 minutes. The furnace was then opened to release the target nickel-based superalloy. The required alloy composition consists of 133.9 grams of pure Al and 221.9 grams of pure Ti. Simultaneously, 2.375 grams of Ni80Mg20 alloy is placed in the top feeding chamber of the vacuum induction furnace for later use. The vacuum is then re-evacuated to 1-2 Pa. After all the alloy material is melted at 50 kW, the power is slowly reduced to 0 kW within 1 minute. After cooling for 10 minutes, the Ni80Mg20 alloy in the top feeding chamber of the vacuum induction furnace is fed into the induction furnace by manipulating the feeding rod. The power is increased to 30 kW, and after 3 minutes, it is directly increased to 50 kW. After maintaining this power for 2 minutes, it is reduced to 30 kW and maintained for 1 minute. Finally, the power is reduced to 10 kW for casting, thus obtaining the nickel-based high-temperature alloy material.

[0055] Compositional testing revealed a significant difference between the measured and designed carbon (C) mass fraction. While this method allows for the direct weighing of the required carbon blocks after batching calculations, the solid carbon blocks are difficult to disperse during actual smelting. The density of carbon blocks is much lower than that of nickel-based superalloys, causing them to float on the surface of the molten metal and hindering their diffusion into the alloy material within a short time. Consequently, the measured C mass fraction in the nickel-based superalloy rarely reaches the designed content.

[0056] Comparative Example 2

[0057] Pure carbon rods are fed directly into the charging chamber at the top of the vacuum induction furnace. The carbon yield is calculated to be 75% during vacuum induction melting of nickel-based superalloys.

[0058] In this comparative example, the design and measured compositional mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 7 (wt.%):

[0059] Table 7 Comparative Example 2: Design and Measured Composition (Mass Percentage) of Nickel-Based Superalloy Materials

[0060] Design Components 0.06 19.5 1.80 2.7 0.008 ≤0.015 ≤0.015 margin Actual components 0.026 19.3 1.75 2.65 0.0047 0.009 0.0012 margin

[0061] In this comparative example, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials were weighed according to the target nickel-based superalloy composition. First, 7.21 kg of pure Ni and 1.95 kg of pure Cr were melted in a vacuum induction furnace. After complete melting, the furnace power was adjusted to 0 kW, and the alloy was allowed to solidify for 15-20 minutes to form a film on the surface. Then, 7.6 g of pure carbon rods were added from the top charging chamber of the furnace. The furnace power was then slowly increased to 30 kW. After melting, the alloy was allowed to solidify for 10 minutes. After surface film formation, the power was increased to 10 kW, and then rapidly increased by 10 kW every minute until reaching 50 kW. The power was held for 2 minutes, then reduced to 0 kW, and solidified for 30 minutes. The furnace was then opened to release the target nickel-based superalloy. The required alloy composition consists of 173.9 grams of pure Al and 266.3 grams of pure Ti. Simultaneously, 2.375 grams of Ni80Mg20 alloy is placed in the top feeding chamber of the vacuum induction furnace for later use. The vacuum is then re-evacuated to 1-2 Pa. After all the alloy material is melted at 50 kW, the power is slowly reduced to 0 kW within 1 minute. After cooling for 10 minutes, the Ni80Mg20 alloy in the top feeding chamber of the vacuum induction furnace is fed into the induction furnace by manipulating the feeding rod. The power is increased to 30 kW, and after 3 minutes, it is directly increased to 50 kW. After maintaining this power for 2 minutes, it is reduced to 30 kW and maintained for 1 minute. Finally, the power is reduced to 10 kW for casting, thus obtaining the nickel-based high-temperature alloy material.

[0062] Compositional testing revealed a significant difference between the measured and designed carbon (C) mass fraction. While this method allows for the direct weighing of the required carbon blocks after batching calculations, the solid carbon blocks are difficult to disperse during actual smelting. The density of carbon blocks is much lower than that of nickel-based superalloys, causing them to float on the surface of the molten metal and hindering their diffusion into the alloy material within a short time. Consequently, the measured C mass fraction in the nickel-based superalloy rarely reaches the designed content.

[0063] Comparative Example 3

[0064] A button ingot consisting of 50 grams of pure nickel encasing a 7.6-gram pure carbon rod was pre-prepared using a vacuum arc furnace. During the induction melting process, the prepared nickel-carbon button ingot was placed at the bottom of the furnace along with other raw materials. Based on the designed mass percentage of carbon in the nickel-based superalloy, the carbon yield was calculated as 75%.

[0065] In this comparative example, the design and measured compositional mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 8 (wt.%):

[0066] Table 8. Comparative Example 3: Design and Measured Composition (Mass Percentage) of Nickel-Based Superalloy Materials

[0067] Design Components 0.06 19.5 1.0 2.7 0.008 ≤0.015 ≤0.015 margin Actual components 0.024 19.2 0.98 2.67 0.0061 0.007 0.0009 margin

[0068] In this comparative example, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials were weighed according to the target nickel-based superalloy composition. First, 7.24 kg of pure Ni, 1.95 kg of pure Cr, and 57.6 g of nickel-carbon button ingots (including 7.6 g of carbon rods) were melted in a vacuum induction furnace. After complete melting, the furnace power was adjusted to 0 kW, and the furnace was allowed to solidify for 15-20 minutes to allow a film to form on the alloy surface. After the film formed, the power was increased to 10 kW, and then rapidly increased by 10 kW every minute until reaching 50 kW, which was held for 2 minutes. The power was then reduced to 0 kW, and the furnace was allowed to solidify for 30 minutes. Finally, the furnace was opened, and 93.9 g of pure Ni, Cr, and Cr were added to achieve the target nickel-based superalloy composition. Al and 266.3 grams of pure Ti were mixed, and 2.375 grams of Ni80Mg20 alloy were placed in the top feeding chamber of the vacuum induction furnace for later use. The vacuum was evacuated to 1-2 Pa. After all the alloy material was melted at 50 kW, the power was slowly reduced to 0 kW within 1 minute. After cooling for 10 minutes, the Ni80Mg20 alloy in the top feeding chamber of the vacuum induction furnace was fed into the induction furnace by manipulating the feeding rod. The power was increased to 30 kW, and after 3 minutes it was directly increased to 50 kW. After maintaining this power for 2 minutes, it was reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW and the alloy was cast to obtain the nickel-based high-temperature alloy material.

[0069] Compositional testing revealed a significant discrepancy between the measured carbon (C) content and the designed carbon content. Adding carbon in this manner requires melting pure nickel in a vacuum arc furnace, encasing the carbon rod to be added, and obtaining a button ingot. Although the nickel-carbon button ingot is placed at the bottom of the crucible, the solid carbon rod makes it difficult for it to diffuse rapidly into the alloy material during the entire melting process. Furthermore, because carbon is added before melting begins, volatilization losses occur during the melting process, ultimately making it difficult to achieve the designed carbon content.

[0070] Comparative Example 4

[0071] A button ingot consisting of 50 grams of pure nickel encasing a 7.6-gram pure carbon rod was pre-prepared using a vacuum arc furnace. During the induction melting process, the prepared nickel-carbon button ingot was placed at the bottom of the furnace along with other raw materials. Based on the designed mass percentage of carbon in the nickel-based superalloy, the carbon yield was calculated as 75%.

[0072] In this comparative example, the design and measured compositional mass percentage of the nickel-based superalloy material used for ultra-supercritical steam turbine blades are shown in Table 9 (wt.%):

[0073] Table 9 Comparative Example 1: Design and Measured Composition (Mass Percentage) of Nickel-Based Superalloy Materials

[0074] Design Components 0.06 19.5 1.80 1.80 1.8 0.008 ≤0.015 ≤0.015 margin Actual components 0.035 19.4 1.74 1.73 1.76 0.0079 0.008 0.0015 margin

[0075] In this comparative example, the total weight of the designed nickel-based superalloy is 9.5 kg. Raw materials were weighed according to the target nickel-based superalloy composition. First, 7.08 kg of pure Ni, 1.95 kg of pure Cr, 171 g of pure Co, and 57.6 g of nickel-carbon button ingots (including 7.6 g of carbon rods) were melted in a vacuum induction furnace. After complete melting, the induction furnace power was adjusted to 0 kW, and the furnace was allowed to solidify for 15-20 minutes to allow a film to form on the alloy surface. After the film formed, the power was increased to 10 kW, and then rapidly increased by 10 kW every minute until reaching 50 kW, which was held for 2 minutes. The power was then reduced to 0 kW, and the furnace was allowed to solidify for 30 minutes. Finally, the furnace was opened, and 173 g of the desired nickel-based superalloy composition was added. 0.9 grams of pure Al and 177.5 grams of pure Ti were mixed with 2.375 grams of Ni80Mg20 alloy, which were placed in the top charging chamber of a vacuum induction furnace. The furnace was then re-vacuumed to 1-2 Pa. After melting all the alloy material at 50 kW, the power was slowly reduced to 0 kW over one minute. After cooling for 10 minutes, the Ni80Mg20 alloy from the top charging chamber was added into the induction furnace by manipulating the charging rod. The power was increased to 30 kW, and after 3 minutes, it was directly increased to 50 kW, maintained for 2 minutes, then reduced to 30 kW and maintained for 1 minute. Finally, the power was reduced to 10 kW for casting, yielding a nickel-based superalloy material. Composition testing showed that the C mass fraction met the design requirements and was accurate.

[0076] Compositional analysis revealed a significant discrepancy between the measured carbon (C) content and the designed carbon content. Adding carbon in this manner requires melting pure nickel in a vacuum arc furnace, encasing the carbon rod to be added, and obtaining a button-shaped ingot. Although the nickel-carbon button ingot is placed at the bottom of the crucible, the solid carbon rod makes it difficult for it to diffuse rapidly into the alloy material during the entire melting process. Furthermore, because carbon is added before melting begins, volatilization losses occur during the melting process, ultimately making it difficult to achieve the designed carbon content.

Claims

1. A method for preparing a nickel-based superalloy with precisely controllable carbon content, characterized in that, Follow these steps to achieve the following: 1) According to the target nickel-based superalloy composition, pure Ni and pure Cr, excluding nickel in the nickel-carbon rod and nickel in the Ni80Mg20 alloy, are smelted in a vacuum induction furnace; the preparation method of the nickel-carbon rod is as follows: a. Preparation of carbon powder: The spectral carbon rod is filed into carbon powder using a conventional file; b. Mixing powder: Mix nickel powder and carbon powder evenly at a mass ratio of 8.05~8.15:1; Toner usage = , among which, according to W 合金 The target is the quality of the nickel-based superalloy; W 碳% The target is the carbon content of the nickel-based superalloy. ε 1 represents the carbon yield during vacuum induction melting of nickel-based superalloy materials, and ε2 represents the carbon yield during high-temperature sintering. c. Powder compaction: Nickel-carbon mixed powder is pressed into cylindrical nickel-carbon rods using a molding process; d. Sintering of nickel-carbon rods: After sintering in a box furnace at 1200±5°C for 14~16 minutes under atmospheric conditions, the rods are removed. 2) After all the pure Ni and pure Cr have melted, adjust the power of the vacuum induction furnace to 0kW and let it solidify for 15-20 minutes to allow the alloy surface in the induction furnace to form a film. Then, add the nickel-carbon rod from the top charging chamber of the induction furnace and slowly increase the power of the vacuum induction furnace to 30kW to melt the nickel-carbon rod. After melting, solidify for 10 minutes and increase the power to 10kW after the surface film has formed. Then, increase the power by 10kW every minute until it reaches 50kW and hold for 2 minutes. Then, reduce the power to 0kW and solidify for 30 minutes. 3) Add the required pure Al and pure Ti to the furnace to form the target nickel-based superalloy. Place the Ni80Mg20 alloy in the top charging chamber of the vacuum induction furnace for later use. Re-evacuate to 1~2 Pa. After cleaning all the alloy material at 50kW, slowly reduce the power to 0kW within 1 minute. Cool for 10 minutes. Use the charging rod to add the Ni80Mg20 alloy from the top charging chamber of the vacuum induction furnace into the induction furnace. Increase the power to 30kW. After 3 minutes, directly increase it to 50kW. Maintain this power for 2 minutes, then reduce it to 30kW and maintain this power for 1 minute. Reduce the power to 10kW and cast to obtain the nickel-based superalloy material.

2. The preparation method according to claim 1, characterized in that, In step b, ε 1 = 75%, ε 2 = 88%.

3. The preparation method according to claim 1, characterized in that, In step b, the nickel powder has a particle size of 80 mesh.

4. The preparation method according to claim 1, characterized in that, In step 1), the nickel-carbon rods must be dried before being placed into the feeding chamber at the top of the vacuum induction furnace.