A cobalt-based high-temperature alloy containing silicon and manganese elements and a preparation method thereof

Abstract

This invention relates to a cobalt-based superalloy containing silicon and manganese and its preparation method. The preparation method includes the following steps: preparing raw materials according to the chemical composition of the cobalt-based superalloy containing silicon and manganese; the raw materials include a first raw material and a second raw material; the first raw material provides elements including C, Cr, Ni, W, B, and Co; the second raw material is a manganese-silicon-nickel master alloy used to provide Si, Mn, and Ni; firstly, the first raw material is melted and alloyed for refining; then, the temperature of the melt is lowered to the homogenization temperature, and the manganese-silicon-nickel master alloy is added to the melt for homogenization treatment to obtain a homogenized alloy liquid; the homogenized alloy liquid is then cast to obtain the cobalt-based superalloy containing silicon and manganese. This invention improves the accuracy and purity of composition control in cobalt-based superalloys containing silicon and manganese, and the preparation process is simple, easy to operate, and highly practical.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy technology, and in particular to a cobalt-based high-temperature alloy containing silicon and manganese elements and its preparation method. Background Technology

[0002] High-temperature alloys possess excellent high-temperature strength and structural stability, while also exhibiting resistance to oxidation and corrosion, as well as fatigue and creep. They are widely used in petrochemical, energy, and aerospace industries, and have become indispensable key structural materials for national economic development and modern defense industry construction. Among them, high-temperature alloys containing silicon and manganese possess excellent high-temperature strength, casting fluidity, resistance to high-temperature oxidation, and corrosion resistance, making them suitable for manufacturing components such as guide vanes and nozzle guide vanes for aero-jet engines and industrial gas turbines.

[0003] In the high-temperature alloy smelting process, Si and Mn not only enhance melt deoxidation but also increase the fluidity of the alloy melt through alloying, improving casting performance and facilitating the filling of complex structural castings. Currently, high-temperature alloys are typically prepared using vacuum melting. Due to the significant differences in the saturated vapor pressures of each element, understanding the burn-off patterns of different elements during melting is crucial for precise control of alloy composition. In high-temperature alloys containing Si and Mn, the saturated vapor pressures of each element at the same temperature are ranked as follows: Mn > Al > Cr > Co > Ni > Si > Ti > V > Hf > Zr > Mo > W > Ta. Among them, Mn has a high saturated vapor pressure, which easily leads to severe volatilization during vacuum melting, making it difficult to control the composition accurately; Si has a high affinity for O, which easily forms granular SiO2 inclusions, affecting the purity of the alloy. Furthermore, when Si and Mn are added to the high-temperature alloy melt in elemental form, the gases and slag formed by the interfacial reaction with the molten metal may form harmful inclusions distributed between dendrites or at grain boundaries during the casting process, causing grain boundary embrittlement. Under long-term high temperature and stress conditions, these inclusions are very likely to generate crack initiation sites or become channels for crack propagation, which is detrimental to the quality control of castings.

[0004] Therefore, accurately controlling the composition and uniformity of Si and Mn, and ensuring the purity of the alloy, is the key to guaranteeing the performance and structural stability of cobalt-based superalloys containing silicon and manganese. Summary of the Invention

[0005] In view of this, the present invention provides a cobalt-based superalloy containing silicon and manganese and a method for preparing the same, the main purpose of which is to ensure the accuracy and purity of the composition of the cobalt-based superalloy containing silicon and manganese.

[0006] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0007] On one hand, embodiments of the present invention provide a method for preparing a cobalt-based superalloy containing silicon and manganese, wherein the preparation method includes the following steps:

[0008] Raw material preparation steps: Prepare raw materials according to the chemical composition of the cobalt-based high-temperature alloy containing silicon and manganese; wherein, the raw materials include a first raw material and a second raw material; wherein, the first raw material is used to provide elements including C, Cr, Ni, W, B, and Co; the second raw material is selected from a manganese-silicon-nickel master alloy to provide Si, Mn, and Ni elements;

[0009] Vacuum melting steps: First, the first raw material is melted and alloyed for refining; then, the temperature of the melt is lowered to the homogenization temperature, and the manganese-silicon-nickel master alloy is added to the melt for homogenization to obtain a homogenized alloy liquid.

[0010] Casting step: The homogenized alloy liquid is cast to obtain a cobalt-based high-temperature alloy containing silicon and manganese.

[0011] Preferably, in the manganese-silicon-nickel master alloy: the mass fraction of Si is 15-25 wt%, the mass fraction of Mn is 15-25 wt%, and Ni is the balance (here, the mass fraction of each element in the manganese-silicon-nickel master alloy is determined based on the absence of single-element precipitation in the phase diagram and the Si / Mn ratio of the target alloy); preferably, the manganese-silicon-nickel master alloy includes Mn 15 Ni 50 Si 35 , MnNiSi, Mn3Ni3Si2, Mn2Ni3Si2, Mn3Ni2Si, Mn 52 Ni 29 Si 19 and Mn 45 Ni 28 Si 27 One or more of them.

[0012] Preferably, the preparation method of the manganese-silicon-nickel master alloy includes the following steps:

[0013] 1) Determine the chemical composition of the manganese-silicon-nickel master alloy based on the mass fractions of manganese, silicon, and nickel in the cobalt-based superalloy containing silicon and manganese elements;

[0014] 2) Based on the chemical composition of the manganese-silicon-nickel master alloy, weigh out the raw materials elemental silicon, elemental manganese, and elemental nickel; preferably, the weighed elemental silicon and elemental manganese are wrapped in nickel foil respectively.

[0015] 3) First, melt and clean the elemental nickel, then add elemental silicon to the melt and alloy it at 1480-1500℃; then, turn off the power and cool down, introduce inert gas into the alloyed melt, add elemental manganese, and homogenize it; after homogenization, heat up and cast to obtain a manganese-silicon-nickel master alloy; preferably, turn off the power and cool down until solidification appears on the surface of the melt; preferably, the homogenization temperature is 1230-1250℃; preferably, after homogenization, heat the melt to 30-60℃ above the liquidus line and cast it (the liquidus line can be determined by turning off the power and cooling down until solidification appears on the surface, which can be approximated as the liquidus line temperature); preferably, crush the obtained manganese-silicon-nickel master alloy and use it as the second raw material; preferably, in step 3), elemental nickel is added to a silicon-based crucible for melting and cleaning. Preferably, when the smelting mass is less than 5 kg, the alloying time is 2-5 min and the homogenization time is 3-7 min; preferably, when the smelting mass is greater than or equal to 5 kg and less than 10 kg, the alloying time is 5-7 min and the homogenization time is 7-10 min; preferably, when the smelting mass is greater than or equal to 10 kg and less than 25 kg, the alloying time is 10-15 min and the homogenization time is 15-20 min; preferably, when the smelting mass is greater than or equal to 25 kg, the alloying time is 20-30 min and the homogenization time is 30-40 min.

[0016] Preferably, the chemical composition of the cobalt-based superalloy containing silicon and manganese, by weight percentage, is as follows: C: 0.40-0.60 wt%, Cr: 24.0-26.0 wt%, Ni: 10.0-11.0 wt%, W: 7.2-8.2 wt%, Si: 0.6-0.9 wt%, Mn: 0.6-1.0 wt%, B: 0.001-0.008 wt%, Ca: 0-0.005 wt%, Zr: 0-0.01 wt%, Co balance.

[0017] Preferably, in cobalt-based superalloys containing silicon and manganese: when the weight percentage ratio of Si to Mn is 0.7-1.3: the sum of the weight percentages of Si and Mn is greater than or equal to 1.3 wt% and less than or equal to 1.8 wt%.

[0018] Preferably, the first raw material includes elemental Co, elemental C, elemental Cr, elemental W, elemental Ni, and elemental B; wherein, in the vacuum melting step, the first raw material is first loaded into the crucible in the order of Co, C, Cr, W, Ni, and B, and then subjected to melting, alloying, and refining treatment.

[0019] Preferably, when the raw materials also include elemental Ca and Zr, after the first raw material is melted, alloyed and refined, and before the homogenization treatment: elemental Ca and Zr are added to the melt, and the temperature of the melt at the time of addition is approximately 1450-1500°C.

[0020] Preferably, in the vacuum melting step: the first raw material is placed in a crucible and vacuum melted; when the vacuum degree is less than 5 Pa, electric melting is started; alloying refining is performed at 1550-1600℃; then, the temperature of the melt is reduced to 1400-1450℃, and the manganese-silicon-nickel master alloy is added for homogenization treatment; preferably, when the raw material mass is less than 5 kg, the alloying refining treatment time is 2-5 min and the homogenization treatment time is 3-7 min; preferably, when the raw material mass... When the raw material weight is greater than or equal to 5 kg and less than 10 kg, the alloying refining treatment time is 5-7 min and the homogenization treatment time is 7-10 min; preferably, when the raw material weight is greater than or equal to 10 kg and less than 25 kg, the alloying refining treatment time is 10-15 min and the homogenization treatment time is 15-20 min; preferably, when the raw material weight is greater than or equal to 25 kg, the alloying refining treatment time is 20-30 min and the homogenization treatment time is 30-40 min.

[0021] Preferably, in the vacuum melting step: when adding a manganese-silicon-nickel master alloy to the melt for homogenization, electromagnetic stirring is required to ensure that the manganese-silicon-nickel master alloy is completely melted into the melt and uniformly alloyed, thereby significantly reducing slag during melting and ensuring the purity of the melt; preferably, during homogenization, the power of the electromagnetic stirring is 0.4-0.5 (preferably 1 / 2) of the power of the alloy refining process; preferably, when the raw material mass is less than 10 kg, the electromagnetic stirring time is 1-3 min; when the raw material mass is 10-25 kg, the electromagnetic stirring time is 5-7 min; when the raw material mass is greater than 25 kg, the electromagnetic stirring time is 10-15 min.

[0022] Preferably, in the casting step: the homogenized alloy liquid is heated to 30-60°C above the liquidus line and then cast to obtain a cobalt-based high-temperature alloy containing silicon and manganese.

[0023] On the other hand, embodiments of the present invention provide a cobalt-based superalloy containing silicon and manganese, wherein the cobalt-based superalloy containing silicon and manganese is prepared by any of the above-described methods for preparing cobalt-based superalloys containing silicon and manganese.

[0024] Compared with the prior art, the cobalt-based superalloy containing silicon and manganese and its preparation method of the present invention have at least the following beneficial effects:

[0025] On one hand, the present invention provides a method for preparing a cobalt-based superalloy containing silicon and manganese. By using a Ni-Si-Mn master alloy as the raw material for providing silicon and manganese, and pre-alloying Si and Mn with Ni to form a Ni-Si-Mn master alloy before preparing the cobalt-based superalloy containing silicon and manganese, inclusions and slag formed during Si and Mn smelting can be removed in advance (Si and Mn have a strong affinity for oxygen, which forms slag during smelting. Pre-alloying Si and Mn with Ni during the preparation of the Ni-Si-Mn master alloy avoids the rapid oxidation and slag formation caused by adding elemental Si and Mn). In the specific preparation of the cobalt-based superalloy containing silicon and manganese, adding a low-melting-point Ni-Si-Mn master alloy to the alloyed melt facilitates precise control of the alloy composition. Therefore, the process of the present invention can improve the accuracy and purity of the composition control of cobalt-based superalloys containing silicon and manganese, and the preparation process is simple, easy to operate, and highly practical. The method of this invention has significant scientific and social implications for improving the smelting quality, overall performance, and production cost of alloys.

[0026] On the other hand, embodiments of the present invention provide a cobalt-based superalloy containing silicon and manganese, wherein the cobalt-based superalloy containing silicon and manganese is prepared by the above-mentioned preparation method of cobalt-based superalloy containing silicon and manganese. Therefore, the chemical composition of the cobalt-based superalloy containing silicon and manganese has excellent control precision and excellent performance.

[0027] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0028] Figure 1 This is the isothermal phase diagram of the Ni-Si-Mn system at 1000℃. Detailed Implementation

[0029] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0030] To ensure the accuracy and purity of the composition of cobalt-based superalloys containing silicon and manganese, this invention proposes a preparation method suitable for such alloys. By designing and preparing a Ni-Si-Mn master alloy, Si, Mn and Ni are pre-alloyed, and inclusion particles and slag formed during Si and Mn smelting are removed in advance. Then, they are added to the target alloy through low-temperature alloying. This achieves precise control of the composition and purity of Si and Mn-containing superalloys, which has important scientific and social significance for improving the smelting quality, comprehensive performance and production cost of the alloy.

[0031] For cobalt-based superalloys containing silicon and manganese, existing processes involve adding elemental silicon and manganese after low-temperature refining to ensure the alloy's composition. However, at high temperatures, element volatilization and the slag generated by their reaction with the molten metal make precise control of the alloy composition difficult. Unlike existing technologies, this invention controls the composition by adding a low-melting-point manganese-silicon-nickel master alloy (the master alloy's melting point is lower than that of the elemental components) to the alloyed melt. Adding silicon and manganese in the form of the master alloy effectively reduces their volatilization rate and burn-off. Preferably, combined with electromagnetic stirring and homogenization for a certain period, slag is filtered and floated to achieve purified smelting, ensuring the uniformity and stability of the melt structure and improving the suitability of this type of alloy for more complex operating conditions.

[0032] According to thermodynamic principles, the general conditions for a system to reach equilibrium at isothermal and isobaric conditions are:

[0033] (1) The total Gibbs free energy G of the system reaches its minimum value Gmin.

[0034] (2) The chemical potential of component i is equal in all phases, that is,

[0035]

[0036] In formula (1), G m Expressed as the molar Gibbs free energy of each phase, Represented as the sum of Gibbs free energies of pure components, RT∑ i X i lnX i The increase in free energy caused by the ideal mixing entropy, ∑ i ∑ j X i X j ∑ ν Ω ν (X i -X j ) v This refers to the excess free energy caused by deviation from an ideal solution.

[0037] The isothermal phase diagram of the Ni-Si-Mn master alloy system at 1000℃ is calculated as follows: Figure 1 As shown, from Figure 1 From this, we can see that the Mn-Ni-Si system contains several ternary phases: Mn 15 Ni 50 Si 35 (Φ), MnNiSi(E), Mn3Ni3Si2(τ1), Mn2Ni3Si2(τ2), Mn3Ni2Si(Ω), Mn 52 Ni 29 Si 19 (I) and Mn 45 Ni 28 Si 27 (W). Here, the composition ratio of Ni-Si-Mn master alloy is designed based on the chemical composition of the target alloy, and the selection of master alloy materials for this type of high-temperature alloy is determined.

[0038] According to the composition requirements, the raw materials and master alloy are calculated and weighed for later use. The preparation process includes: base melting, alloying, homogenization, and casting. The Ni-Si-Mn master alloy is added during the low-temperature homogenization process, combined with electromagnetic stirring, to ensure that the master alloy is completely melted into the melt and uniformly alloyed. This significantly reduces slag during smelting and ensures the purity of the melt. Furthermore, compared with traditional processes, it reduces the loss of silicon and manganese elements, which is beneficial for composition control. The casting temperature of the alloy ingot should be controlled within the range of 30-60℃ above the liquidus line to facilitate rapid solidification of the alloy ingot and avoid macroscopic segregation.

[0039] Specifically, this invention provides a method for preparing a cobalt-based superalloy containing silicon and manganese, the main steps of which are as follows:

[0040] 1) Raw material preparation steps: Prepare raw materials according to the chemical composition of the cobalt-based high-temperature alloy containing silicon and manganese; wherein, the raw materials include a first raw material and a second raw material; wherein, the elements provided by the first raw material include C, Cr, Ni, W, B, and Co; the second raw material is a manganese-silicon-nickel master alloy, which is used to provide Si, Mn, and Ni.

[0041] The chemical composition of the cobalt-based superalloy containing silicon and manganese described in this application is as follows: C: 0.40-0.60 wt%, Cr: 24.0-26.0 wt%, Ni: 10.0-11.0 wt%, W: 7.2-8.2 wt%, Si: 0.6-0.9 wt%, Mn: 0.6-1.0 wt%, B: 0.001-0.008 wt%, Ca: 0-0.005 wt%, Zr: 0-0.01 wt%, and Co as the balance. To ensure the casting fluidity and smelting deoxidation rate of the alloy, it is preferable that when the weight percentage of Si / Mn is 0.7-1.3, the total weight percentage of Si ≤ 1.3 wt% + the total weight percentage of Mn ≤ 1.8 wt%.

[0042] In the manganese-silicon-nickel master alloy: the mass fraction of Si is 15-25 wt%, the mass fraction of Mn is 15-25 wt%, and Ni is the balance; preferably, the manganese-silicon-nickel master alloy includes Mn. 15 Ni 50 Si 35 , MnNiSi, Mn3Ni3Si2, Mn2Ni3Si2, Mn3Ni2Si, Mn 52 Ni 29 Si 19 and Mn 45 Ni 28 Si 27 One or more of them.

[0043] Preferably, the design of the manganese-silicon-nickel master alloy is as follows:

[0044] a) Composition design of manganese-silicon-nickel master alloy

[0045] The design of manganese-silicon-nickel master alloys must meet the principles of low melting point and easy alloying. When the nickel content is >60% (according to the phase diagram, the percentage of Ni atoms is >60% when fully alloyed to form γ. Converted to mass percentage: 60% × 58.69 / (60% × 58.69 + 40% × 54.94) × 100% = 61.57%), complete alloying of silicon and manganese can be ensured. Based on the phase diagram of the Ni-Si-Mn master alloy system, Mn can be selected as the master alloy. 15 Ni 50 Si 35 , MnNiSi, Mn3Ni3Si2, Mn2Ni3Si2, Mn3Ni2Si, Mn 52 Ni 29 Si 19 Mn 45 Ni 28 Si 27This type of nickel-based metal solid solution. The chemical composition of the master alloy is determined based on the mass fractions of manganese, silicon, and nickel required for chemical composition control (the mass percentages of Si and Mn in the master alloy are consistent with those in the target alloy, with the remainder being Ni). Furthermore, the composition ratio of the Ni-Si-Mn master alloy is designed based on the chemical composition of the target alloy, determining the master alloy composition for this type of high-temperature alloy to be Ni-(15%-25%)Si-(15%-25%)Mn. At high temperatures, this master alloy can melt relatively quickly into the high-temperature alloy melt without forming harmful phases in the final alloy.

[0046] b) Preparation and post-processing of manganese-silicon-nickel master alloy

[0047] Based on the chemical composition of the manganese-silicon-nickel master alloy, a certain amount of pure silicon, pure manganese, and pure nickel are calculated and weighed. Si and Mn are wrapped in nickel foil respectively. A silica crucible is used to avoid the reaction between elemental Si and aluminum or magnesium crucibles. Ni is first placed in the crucible for melting. After clearing, Si is added (the term "clearing" means that the raw materials are completely melted until no bubbles overflow from the surface of the melt). After alloying at around 1500℃ for a period of time, the power is turned off and the temperature is lowered. High-purity Ar gas is introduced and Mn is added. After homogenization treatment for a period of time, the temperature is raised and poured. After natural cooling, the master alloy ingot is obtained. The alloy block is crushed and dried using a crusher before use.

[0048] It is important to note that the purpose of preparing the manganese-silicon-nickel master alloy is primarily to precisely control the addition amounts of Mn and Si in the target alloy. When Si and Mn are added to the high-temperature alloy melt in elemental form, the resulting interfacial reaction with the molten metal produces gases and slag, causing Si and Mn to burn off, making accurate control of their addition amounts impossible. In the preparation of the master alloy, the reaction of Si and Mn with the melt to generate slag is followed by slag removal and filtration, resulting in a definite Si and Mn content in the final master alloy. During the preparation of the target alloy, precisely controlling the Si and Mn composition can be achieved by weighing an appropriate amount of the master alloy according to the mass percentage of Si and Mn in the target alloy.

[0049] 2) Vacuum melting step: First, the first raw material is melted and alloyed for refining; then, the temperature of the melt is reduced to the homogenization temperature, and the manganese-silicon-nickel master alloy is added to the melt for homogenization to obtain a homogenized alloy liquid.

[0050] Here, the relationship between the alloying refining time, the homogenization time and the furnace charge (raw material) is shown in Table 1.

[0051] Table 1. Insulation and stirring times corresponding to different furnace charge weights.

[0052]

[0053] When melting the alloy base material (first raw material), the order of addition is Co, C, Cr, W, Ni. This is to ensure good melting of the alloy and prevent localized element enrichment during melting, which could lead to the formation of high-melting-point phases such as α-W, α-Cr, and β-Cr. Therefore, the order of addition is as follows: the matrix elements with relatively lower melting points are placed at the bottom of the crucible to melt first and form a molten pool. The elements with relatively higher melting points above are then placed in the molten pool for easier melting and to avoid agglomeration and the formation of harmful phases.

[0054] The Ni-Si-Mn master alloy is added during the low-temperature homogenization process, and in conjunction with electromagnetic stirring, ensures that the master alloy is completely melted into the melt and uniformly alloyed. This significantly reduces slag during smelting and ensures the purity of the melt. The low-temperature melting temperature of the master alloy is 1200-1400℃. During melting, a power supply with a strength between that used for low-temperature homogenization and electromagnetic stirring is employed to control the melt temperature. The electromagnetic stirring power can be half that of the alloying refining process.

[0055] 3) Casting step: The homogenized alloy liquid is cast to obtain a cobalt-based high-temperature alloy containing silicon and manganese.

[0056] Here, the casting temperature of the alloy ingot should be controlled within the range of 30-60℃ above the liquidus line, which is conducive to the rapid solidification of the alloy ingot and avoids macroscopic segregation.

[0057] In summary, regarding the above-mentioned solution of the present invention, it should be noted that: the process method, by adding a low-melting-point Ni-Si-Mn master alloy to the alloyed melt, facilitates precise control of the alloy composition. Furthermore, during the preparation of the master alloy, most inclusions and slag generated during the smelting of elemental Si and Mn can be filtered out, which is beneficial for the purification control of the target alloy and for improving the product quality, yield, and performance of such alloy castings. The preparation process of the present invention is simple, easy to operate, and highly practical.

[0058] The present invention will be further illustrated below with specific embodiments:

[0059] Example 1

[0060] This embodiment prepares a cobalt-based superalloy containing silicon and manganese, wherein the smelting mass is 50 kg. Based on the target alloy's chemical composition, a Ni-Si-Mn master alloy is first prepared; here, according to... Figure 1Based on the chemical composition requirements of the prepared cobalt-based superalloy containing silicon and manganese, the chemical composition of the Ni-Si-Mn master alloy was designed, and then it was prepared (the prepared Ni-Si-Mn master alloy is mainly composed of MnNiSi and Mn3Ni3Si2 nickel solid solutions; nickel solid solutions refer to Ni as the matrix, with various alloying elements doped in the middle, arranged in the form of γ phase, and the atoms are randomly arranged). The calculated batching points are shown in Table 2.

[0061] Table 2 shows the alloy ingredient list.

[0062] raw materials Content, wt% Amount added, kg Remark C 0.50 0.25 Cr 25.50 12.75 Ni 7.3 2.53 When calculating the amount added, remove Ni from the intermediate alloy. W 7.5 3.75 B 0.005 0.003 Ni-Si-Mn 4.0 1.95 Si:20%, Mn:20%, Ni:60% Co margin 28.77

[0063] Regarding Ni in Table 2, it refers to the mass fraction of added Ni element. The Ni-Si-Mn master alloy also contains a portion of Ni, and the sum of the two falls within the range selected for cobalt-based superalloys.

[0064] The preparation method of the cobalt-based superalloy containing silicon and manganese in this embodiment mainly includes the following steps:

[0065] 1) First, prepare the Ni-Si-Mn master alloy. Considering the loss of raw materials, the raw materials of the master alloy can be proportioned as follows: 20.5wt% silicon, 22.0wt% manganese, and the balance nickel. Weigh the required preparation weight and wrap Si and Mn separately with nickel foil for later use.

[0066] 2) A silicon-based crucible was used for melting the Ni-Si-Mn master alloy. Ni was placed in the crucible for melting, and after clearing, Si was added. Alloying was then performed at 1500℃ for 3 minutes. The power was turned off and the temperature was lowered. When solidification was observed at the edge of the melt, high-purity Ar gas was introduced until the vacuum gauge read 0.06 kPa. At this point, the minimum heating power (1 / 4 to 1 / 2 of the homogenization power) was input, and Mn was added to the melt. Homogenization (alloying and homogenization) was performed at 1250℃ for 5 minutes. After completion, the temperature was raised to 1270℃ for casting to obtain the master alloy ingot.

[0067] 3) Weigh the raw materials according to the target alloy composition and cut the corresponding weight of intermediate alloy ingots. The principle for using intermediate alloy is that the calculated Ni, Si and Mn contents do not exceed the upper limit of the target alloy.

[0068] 4) Load the other raw materials into the crucible in the order of Co, C, Cr, W, Ni, and B, and perform vacuum melting. When the vacuum degree is <5 Pa, start electric melting (electric melting involves energizing the vacuum induction furnace to melt the raw materials in the crucible). Perform alloying refining treatment at 1580℃ for 20 minutes, then lower the temperature to 1400℃, add the prepared Ni-Si-Mn master alloy to the melt, perform homogenization treatment (i.e., secondary alloying), and hold for 30 minutes (i.e., homogenization treatment for 30 minutes) to obtain a homogenized alloy liquid.

[0069] 5) The homogenized alloy liquid is heated to 1480℃ and poured to obtain a cobalt-based high-temperature alloy ingot containing silicon and manganese.

[0070] Chemical composition analysis was performed on the upper, middle, and lower parts of the cobalt-based superalloy ingot prepared in this embodiment (i.e., samples were taken from the beginning, end, and near the middle section of the rod-shaped alloy ingot in this embodiment) to examine the uniformity of the alloy composition. The test results are shown in Table 3. It can be seen from Table 3 that the chemical composition control accuracy reached ±0.05%, and the uniformity and purity of the master alloy composition were good.

[0071] Table 3 shows the actual chemical composition of the alloy ingot prepared in this embodiment.

[0072]

[0073] Meanwhile, the cobalt-based superalloy ingot containing silicon and manganese prepared in this embodiment was remelted to prepare equiaxed crystal test bars, and mechanical properties were tested. The mechanical properties of the alloy under different conditions are shown in Table 4.

[0074] Table 4 shows the mechanical properties of the alloy.

[0075]

[0076] As can be seen from Table 4, the cobalt-based superalloy ingot containing silicon and manganese prepared in Example 1 exhibits excellent performance.

[0077] Example 2

[0078] This embodiment prepares a cobalt-based superalloy containing silicon and manganese, wherein the smelting mass is 80 kg. Based on the target alloy's chemical composition, a Ni-Si-Mn master alloy is first prepared; here, according to... Figure 1Based on the chemical composition requirements of the prepared cobalt-based superalloy containing silicon and manganese, the chemical composition of the Ni-Si-Mn master alloy was designed, and then it was prepared (the prepared Ni-Si-Mn master alloy is mainly composed of MnNiSi, Mn3Ni3Si2, and nickel solid solution; nickel solid solution refers to a Ni-based matrix with various alloying elements doped in the middle, arranged in the form of γ phase, with disordered atomic arrangement). The calculated batching points are shown in Table 5.

[0079] Table 5 shows the alloy ingredient list.

[0080] raw materials Content, wt% Amount added, kg Remark C 0.50 0.40 Cr 25.50 20.40 Ni 7.3 4.05 When calculating the amount added, remove Ni from the intermediate alloy. W 7.5 6.00 B 0.005 0.005 Ni-Si-Mn 4.0 3.12 Si:20%, Mn:20%, Ni:60% Co margin 46.03

[0081] Regarding Ni in Table 5, it refers to the mass fraction of added Ni element. The Ni-Si-Mn master alloy also contains a portion of Ni, and the sum of the two falls within the range selected for cobalt-based superalloys.

[0082] The specific steps of this embodiment are as follows:

[0083] 1) First, prepare the Ni-Si-Mn master alloy. Considering the loss of raw materials, the raw materials of the master alloy can be proportioned as follows: 20.5wt% silicon, 22.0wt% manganese, and the balance nickel. Weigh the required preparation weight and wrap Si and Mn separately with nickel foil for later use.

[0084] 2) A silicon-based crucible was used for melting the Ni-Si-Mn master alloy. Ni was placed in the crucible for melting, and after clearing, Si was added. Alloying was then performed at 1500℃ for 3 minutes. The power was turned off and the temperature was lowered. When solidification was observed at the edge of the melt, high-purity Ar gas was introduced until the vacuum gauge reading was 0.08 kPa. At this point, the heating power was adjusted to approximately 30 kW, and Mn was added to the melt. Homogenization (alloying and homogenization) was performed at 1250℃ for 5 minutes. After the homogenization was completed, the temperature was raised to 1270℃ for casting to obtain the master alloy ingot.

[0085] 3) Weigh the raw materials according to the target alloy composition and cut the corresponding weight of intermediate alloy ingots. The principle for using intermediate alloy is that the calculated Ni, Si and Mn contents do not exceed the upper limit of the target alloy.

[0086] 4) Load the other raw materials into the crucible in the order of Co, C, Cr, W, Ni, and B, and perform vacuum melting. When the vacuum degree is <5 Pa, start electric melting (electric melting involves supplying power to the vacuum induction furnace to melt the raw materials in the crucible). Perform alloying refining at 1580℃ for 20 minutes, then lower the temperature to 1400℃, add the prepared Ni-Si-Mn master alloy, perform homogenization treatment (i.e., secondary alloying), and hold at that temperature for 30 minutes (i.e., homogenization treatment for 30 minutes).

[0087] 5) The homogenized alloy liquid is heated to 1480℃ to complete the casting, and a cobalt-based high-temperature alloy ingot containing silicon and manganese is obtained.

[0088] Chemical composition analysis was performed on the upper, middle, and lower parts of the cobalt-based superalloy ingot prepared in this embodiment (i.e., samples were taken from the beginning, end, and near the middle section of the rod-shaped alloy ingot in this embodiment) to examine the uniformity of the alloy composition. The test results are shown in Table 6. It can be seen from Table 6 that the chemical composition control accuracy reached ±0.1%, and the uniformity and purity of the master alloy composition were good.

[0089] Table 6 shows the actual chemical composition of the alloy ingot.

[0090]

[0091] Meanwhile, the cobalt-based superalloy ingot containing silicon and manganese prepared in Example 2 was remelted to prepare equiaxed crystal test bars and its mechanical properties were tested. The mechanical properties of the alloy under different conditions are shown in Table 7.

[0092] Table 7 shows the mechanical properties of the alloy.

[0093]

[0094] As can be seen from Table 7, the cobalt-based superalloy ingot containing silicon and manganese prepared in Example 2 has excellent performance.

[0095] Comparative Example 1

[0096] The comparative example uses a conventional process to prepare a cobalt-based superalloy ingot containing silicon and manganese. Specifically, 50 kg of alloy was smelted using a conventional process, and the amounts of each element added are shown in Table 8.

[0097] Table 8 is the alloy ingredient list.

[0098] raw materials Content, wt% Amount added, kg C 0.50 0.25 Cr 25.50 12.75 Ni 10.9 5.45 W 7.5 3.75 B 0.005 0.003 Si 0.8 0.40 Mn 0.85 0.43 Co margin 26.97

[0099] The specific implementation steps are as follows:

[0100] 1) Load the main elements into the crucible, and the order of the elements (from bottom to top) is: Co, C, W, Cr, Ni. At the same time, wrap Si, Mn, and B with nickel foil for later use.

[0101] 2) Close the furnace lid, evacuate to below 10Pa, turn on the power to heat, with a power of about 50kW until the metal material in the crucible is completely melted, adjust the heating power to the surface temperature of the melt to about 1500℃ and keep it at that temperature for 25 minutes.

[0102] 3) When the power is off and the temperature is reduced to about 1450℃, add Si, Mn and B wrapped in nickel foil, close the vacuum pump group and the gate valve, and fill with high-purity Ar gas until the vacuum gauge reading is about 0.04MPa. Adjust the heating power to 20kW and heat and stir for about 10 minutes.

[0103] 4) Adjust the liquid temperature to about 1400℃ and hold for 30 minutes. After holding, raise the temperature to 1420℃ and pour to obtain the target alloy master alloy.

[0104] Chemical composition analysis was performed on the upper, middle, and lower parts of the cobalt-based superalloy ingot prepared in this comparative example (i.e., samples were taken from the beginning, end, and near the middle section of the rod-shaped alloy ingot in this comparative example) to examine the uniformity of alloy composition. The test results are shown in Table 9. As can be seen from Table 9, the alloy ingot prepared using the conventional process in the comparative example has poor uniformity of chemical composition of Si, Mn, and Cr. Furthermore, in order to reduce the splashing of Si and Mn elements, a certain amount of Ar gas needs to be introduced during the melting process, which reduces the removal effect of gaseous elements such as O and N, resulting in a higher O and N content in the alloy.

[0105] Table 9. Alloy chemical composition of Comparative Example 1

[0106]

[0107] Meanwhile, the alloy ingot prepared in Comparative Example 1 was remelted to prepare equiaxed crystal test bars and its mechanical properties were tested. The mechanical properties of the alloy under different conditions are shown in Table 10. It can be seen that the mechanical properties of the comparative alloy prepared by conventional process are poor and its stability is low.

[0108] Table 10 shows the mechanical properties of the alloy prepared in Comparative Example 1.

[0109]

[0110] By comparing the preparation process and performance test data of Examples 1-2 and Comparative Example 1, it is clear that the cobalt-based high-temperature alloy containing silicon and manganese prepared in the embodiments of the present invention has high precision in controlling the chemical composition, good uniformity and purity of the master alloy composition, and excellent mechanical properties.

[0111] In summary, the method for preparing a cobalt-based superalloy containing silicon and manganese provided by this invention designs the required content of manganese-silicon-nickel master alloy according to the desired composition control points. By adding a low-melting-point master alloy to the alloyed melt, the volatilization and burn-off of silicon and manganese components are reduced, facilitating precise control of the alloy composition. Combined with a homogenization process, the purification and homogenization of the silicon-manganese superalloy are achieved, ensuring the performance and microstructure stability of this type of alloy. Compared with traditional smelting techniques, this invention improves the accuracy and purity of composition control for cobalt-based superalloys containing silicon and manganese. The preparation process is simple, easy to operate, and highly practical.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a cobalt-based superalloy containing silicon and manganese, characterized in that, The preparation method includes the following steps: Raw material preparation steps: Prepare raw materials according to the chemical composition of the cobalt-based high-temperature alloy containing silicon and manganese; wherein, the raw materials include a first raw material and a second raw material; wherein, the first raw material is used to provide elements including C, Cr, Ni, W, B, and Co; the second raw material is selected from a manganese-silicon-nickel master alloy to provide Si, Mn, and Ni elements; wherein, in the manganese-silicon-nickel master alloy: the mass fraction of Si is 15-25wt%, the mass fraction of Mn is 15-25wt%, and Ni is the balance; Vacuum melting steps: First, the first raw material is melted and alloyed for refining; then, the temperature of the melt is lowered to the homogenization temperature, and the manganese-silicon-nickel master alloy is added to the melt for homogenization to obtain a homogenized alloy liquid. Casting step: The homogenized alloy liquid is cast to obtain a cobalt-based high-temperature alloy containing silicon and manganese. When adding a manganese-silicon-nickel master alloy to the melt for homogenization, electromagnetic stirring is required to ensure that the manganese-silicon-nickel master alloy is completely melted into the melt and uniformly alloyed, thereby significantly reducing slag during smelting and ensuring the purity of the melt.

2. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 1, characterized in that, The preparation method of the manganese-silicon-nickel master alloy includes the following steps: 1) Determine the chemical composition of the manganese-silicon-nickel master alloy based on the mass fractions of manganese, silicon, and nickel in the cobalt-based superalloy containing silicon and manganese elements; 2) Based on the chemical composition of the manganese-silicon-nickel master alloy, weigh out the raw materials: elemental silicon, elemental manganese, and elemental nickel; wherein, the weighed elemental silicon and elemental manganese are respectively wrapped in nickel foil; 3) First, melt and clean the elemental nickel, then add elemental silicon to the melt and alloy it at 1480-1500℃; then, turn off the power and cool down, introduce inert gas into the alloyed melt, add elemental manganese, and homogenize it; after homogenization, heat up and cast it to obtain a manganese-silicon-nickel master alloy.

3. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 2, characterized in that, In step 3) of the method for preparing the manganese-silicon-nickel master alloy: Power outage and cooling until signs of solidification appear on the surface of the melt; and / or The homogenization treatment temperature is 1230-1250℃; and / or After homogenization, the melt temperature is raised to 30-60°C above the liquidus for casting; and / or The obtained manganese-silicon-nickel master alloy is crushed and used as the second raw material; and / or Elemental nickel is added to a silicon-based crucible and then smelted and purified.

4. The method for preparing a cobalt-based superalloy containing silicon and manganese elements according to claim 1, characterized in that, The chemical composition of the cobalt-based superalloy containing silicon and manganese, by weight percentage, is as follows: C: 0.40-0.60wt%, Cr: 24.0-26.0 wt%, Ni: 10.0-11.0 wt%, W: 7.2-8.2 wt%, Si: 0.6-0.9wt%, Mn: 0.6-1.0 wt%, B: 0.001-0.008 wt%, Ca: 0-0.005 wt%, Zr: 0-0.01wt%, Co balance.

5. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 4, characterized in that, In cobalt-based superalloys containing silicon and manganese: When the weight percentage ratio of Si to Mn is 0.7-1.3, the sum of the weight percentages of Si and Mn is greater than or equal to 1.3 wt% and less than or equal to 1.8 wt%.

6. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 1, characterized in that, The first raw material includes elemental Co, elemental C, elemental Cr, elemental W, elemental Ni, and elemental B; wherein, in the vacuum melting step, the first raw material is first loaded into the crucible in the order of Co, C, Cr, W, Ni, and B, and then subjected to melting, alloying, and refining treatments; and / or When the raw materials also include elemental Ca and Zr, after the first raw material is melted, alloyed and refined, and before the homogenization treatment: elemental Ca and Zr are added to the melt, and the temperature of the melt is in the range of 1450-1500℃ when they are added.

7. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 1, characterized in that, In the vacuum melting step: The first raw material is placed in a crucible and vacuum melted. When the vacuum degree is less than 5 Pa, electric melting is started. Alloying and refining are carried out at 1550-1600℃. Then, the temperature of the melt is reduced to 1400-1450℃, and the manganese-silicon-nickel master alloy is added to it for homogenization treatment.

8. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 7, characterized in that, In the vacuum melting step: When the raw material mass is less than 5 kg, the alloying refining treatment time is 2-5 min and the homogenization treatment time is 3-7 min; When the raw material mass is greater than or equal to 5Kg and less than 10Kg, the alloying refining treatment time is 5-7min and the homogenization treatment time is 7-10min. When the raw material mass is greater than or equal to 10Kg and less than 25Kg, the alloying refining treatment time is 10-15min and the homogenization treatment time is 15-20min; When the raw material mass is greater than or equal to 25 kg, the alloying refining treatment time is 20-30 min and the homogenization treatment time is 30-40 min.

9. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 1, characterized in that, During the homogenization process, the power of the electromagnetic stirring process is 0.4-0.6 times that of the alloying refining process. Specifically, when the raw material mass is less than 10 kg, the electromagnetic stirring time is 1-3 min; when the raw material mass is 10-25 kg, the electromagnetic stirring time is 5-7 min; and when the raw material mass is greater than 25 kg, the electromagnetic stirring time is 10-15 min.

10. The method for preparing a cobalt-based superalloy containing silicon and manganese according to claim 1, characterized in that, In the pouring step: After the homogenized alloy liquid is heated to 30-60°C above the liquidus line, it is cast to obtain a cobalt-based high-temperature alloy containing silicon and manganese.

11. A cobalt-based superalloy containing silicon and manganese, characterized in that, The cobalt-based superalloy containing silicon and manganese is prepared by the method for preparing cobalt-based superalloys containing silicon and manganese as described in any one of claims 1-10.

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