CN101538664A - Nickel-base high-temperature alloy with low density and high melting point and preparation process thereof - Google Patents

Abstract

The invention relates to superalloy technology, and in particular provides an equiaxed casting nickel-based superalloy with low density, high initial melting temperature and excellent casting performance and its preparation process, which can be used as a floating tile material for a combustion chamber. In terms of mass percentage, the alloy composition is as follows: C 0.03～0.06, Cr 5～12, Al 5.5～6.5, Co 3～8, W 3～7, Mo 2～4, Nb 1.6～3.2, B 0.01～0.03, Y 0.008～0.025, Ni balance. The master alloy is smelted in a vacuum induction furnace, and the smelting crucible is a CaO or MgO crucible. The operation process is as follows: put carbon, chromium, cobalt, tungsten, molybdenum, niobium alloy elements and nickel plates into the crucible according to the stated components; When it reaches 50Pa～0.1Pa, melt the alloy; after melting, refine at 1550℃～1600℃ for 30s～300s, add Al and Al-Y and Ni-B intermediate alloys for power failure, conjunctiva, and membrane rupture, stir evenly, and heat at 1450℃ ~1500℃ casting into master alloy ingot. The invention solves the problems of low initial melting temperature, poor plasticity and oxidation resistance of the nickel-based superalloy, and the like.

Description

A low-density high-melting-point nickel-based superalloy and its preparation process

technical field

The invention relates to superalloy technology, and in particular provides an equiaxed casting nickel-based superalloy with low density, high initial melting temperature and excellent casting performance and its preparation process, which can be used as a floating tile material for a combustion chamber.

Background technique

Superalloys refer to a class of metal materials based on iron, nickel, and cobalt that can work for a long time at high temperatures above 600°C and under certain stresses. For half a century, the temperature before the turbine of the aero-engine has increased from 730°C in the 1940s to 1677°C. The increase in service temperature puts forward more and more stringent requirements on the materials of aero-engines. Nickel-based superalloys are by far the most superior performance and the most widely used aero-engine materials. At present, the upper limit temperature of the alloy's service temperature has reached about 1200 ° C, which is close to the melting point of the alloy, but it is still the material of choice for the key components with the highest temperature and the largest stress load in advanced engines.

Nickel-based superalloys have excellent resistance to high-temperature oxidation and high-temperature corrosion. Compared with iron-based superalloys, nickel-based superalloys have good thermal conductivity, high structural stability, and can dissolve more elements without producing harmful phases; compared with cobalt-based superalloys, nickel-based superalloys have It has the characteristics of light specific gravity, low price, high strength and good oxidation resistance. In addition, nickel-based superalloys also have excellent castability and high-temperature durability.

What determines the excellent performance of nickel-based superalloys is the strengthening of the precipitated face-centered cubic intermetallic compound γ′ phase (Ni ₃ Al). Some alloys such as In718 are also strengthened by ordered body-centered tetragonal γ″ (Ni ₃ Nb). The general cobalt-based superalloys lack the strengthening effect of the γ′ phase and only rely on solid solution strengthening and carbide strengthening, so it is generally difficult to achieve nickel-based superalloys. The strength level of superalloys.

Nickel-based superalloys can not only have high-temperature strength that cannot be compared with cobalt-based alloys, but also have higher initial melting temperature, better cold and hot fatigue performance, higher plasticity and toughness, and higher plasticity and toughness by properly adjusting the alloy composition. High oxidation resistance and corrosion resistance, low density, it is of special significance to be used in many parts of aero-engine.

Although many nickel-based superalloys for aero-engines have been developed in China, such as K403, K405, K441 and K417G alloys, the biggest disadvantage of these alloys is that the initial melting temperature and plasticity are quite different from those of cobalt-based superalloys. application of these alloys. In addition, due to the complex shape of the floating tiles in the combustion chamber, it is not easy to prepare single crystal or adopt directional solidification process. Although intermetallic compounds have the characteristics of low specific gravity and high strength, their use is limited due to their poor plasticity and oxidation resistance. Therefore, it is necessary to develop an alloy that requires high initial melting temperature, low density, good casting performance, good thermal fatigue performance and high high temperature oxidation resistance.

Contents of the invention

The purpose of the present invention is to provide a high initial melting temperature, good high temperature strength, low specific gravity and low cost, good castability and excellent comprehensive performance equiaxed casting nickel-based superalloy and its preparation process, to solve the problem of nickel-based superalloy primary The melting temperature is low, and the plasticity and oxidation resistance are poor.

Technical scheme of the present invention is:

A low-density high-melting-point nickel-based superalloy, by mass percentage, the alloy composition is as follows:

C 0.03～0.06, Cr 5～12, Al 5.5～6.5, Co 3～8, W 3～7, Mo 2～4, Nb 1.6～3.2, B 0.01～0.03, Y 0.008～0.025, Ni balance.

The preparation process of the alloy is:

The master alloy is smelted in a vacuum induction furnace, and the smelting crucible is a CaO or MgO crucible. The operation process is as follows: put carbon, chromium, cobalt, tungsten, molybdenum, niobium alloy elements and nickel plates into the crucible according to the stated components; Heat on low power to get rid of gas. When the vacuum degree reaches 50Pa～0.1Pa, use high power to melt the alloy; after melting, refine at 1550℃～1600℃ for 30s～300s, the vacuum degree should reach 0.1Pa～0.001Pa, add Al and Al-Y and Ni-B master alloys are uniformly stirred and cast into master alloy ingots at 1450°C to 1500°C.

When casting test rods or castings of the nickel-based superalloy, use a vacuum induction furnace to remelt the master alloy ingot before casting, and the cast formwork is preheated at 850°C to 1100°C for 3 to 5 hours; the specific process is: the required Put the master alloy ingot into a CaO or MgO crucible, power on to remove gas; when the vacuum degree reaches 50Pa～0.01Pa level, increase the power to melt the alloy; refine at 1550℃～1600℃ for 30S～300S, and the vacuum degree should reach 0.1Pa～ 0.001Pa, cast at 1450℃～1500℃; after casting, cool in a vacuum chamber, and take it out after it is completely solidified.

The temperature measuring system of the present invention is a W-Re electric couple and a JH-5 type infrared photoconductive temperature/vacuum tester, and the temperature measuring protection sleeve is a Mo-Al ₂ O ₃ cermet tube.

Described superalloy, by mass percentage, preferred composition is as follows:

C 0.05, Cr 9, Al 6, Co 5.5, W 3.5, Mo 3, Nb 2.2, B 0.023, Y 0.013, Ni balance.

According to different requirements, different heat treatment systems can be adopted for the above-mentioned high-temperature alloys to obtain the required properties:

Heat treatment system one:

At 1090°C~1110°C, keep warm for 3h~5h, then air cool to room temperature.

This heat treatment system can obtain better plasticity, taking into account the strength.

Heat treatment system two:

At 1200℃～1220℃, keep warm for 3h～5h, and air cool to room temperature;

At 1040℃～1060℃, keep warm for 3h～5h, and air cool to room temperature;

At 850℃～890℃, keep warm for 20h～28h, and air cool to room temperature.

This heat treatment regime can obtain better tensile strength and creep properties.

The working principle of the present invention is as follows:

In superalloys, Al and Ti are the most important γ′ forming elements. The main purpose of the present invention is to add more aluminum to form a high volume fraction of γ' phase to increase its strength; because Ti sharply reduces the melting temperature of the alloy, Ti is completely limited in this alloy. By adding niobium to further increase the number of γ′ phases, improve the lattice mismatch of γ-γ′, enhance the strengthening effect of γ′ phases, and form stable MC with carbon; adding a small amount of carbon and boron, on the one hand, Strengthen the grain boundary, on the other hand, form carbides and borides with chromium, tungsten, molybdenum, and niobium to strengthen the alloy; alloying elements such as chromium, tungsten, and molybdenum solid-solution strengthen the alloy. The content of alloy carbon and boron is low, and it does not contain titanium, which ensures that the alloy has a high initial melting temperature and good cold and heat fatigue performance; chromium and yttrium can improve the oxidation resistance; yttrium can also improve the carbide form, improve its stability and Anti-cracking ability; the role of cobalt is solid solution strengthening, which can be replaced with Ni. The alloy sample of the invention is prepared by the common casting technology prevailing in the world, has good casting performance and is easy to process.

The alloy of the invention has the following advantages:

1. The initial melting temperature of the alloy is high. High-temperature DSC analysis shows that the initial melting temperature of the alloy of the present invention is as high as 1347°C, which is 90°C, 70°C, 50°C and 30°C higher than K419, K417G, K418 and K441 superalloys respectively, and slightly higher than DZ40M, K640 and other cobalt-based alloys .

2. Good casting performance. The melting temperature range of the alloy of the invention is 1347° C. to 1375° C., the solidification range is small, and components with complex shapes can be casted.

3. Alloy density is low. The density of the alloy of the present invention is only 8.1g/cm ³ , far lower than that of K441, K640 and other alloys.

4. The alloy has good oxidation resistance. The oxidation weight gain rate of the alloy of the invention at 1100°C is 0.067g/m ² h, and it reaches the complete anti-oxidation level in the temperature range of 900°C to 1100°C.

5. Good cold and heat fatigue performance. The crack growth rate of the alloy of the present invention is only far lower than that of K465, K417G, DZ40M and other alloys.

6. The phase stability of the alloy of the present invention is good, and harmful phases are not easily formed during long-term aging.

7. Low cost. The alloy of the invention does not contain precious elements such as tantalum and hafnium, and its price is far lower than that of DZ40M and K640 alloys.

8. High strength. At all temperatures, the tensile strength and durability of the alloy of the invention are much higher than those of DZ40M and K640 alloys with similar incipient melting temperatures.

Description of drawings

Fig. 1(a)-Fig. 1(c) are the microstructures of the alloy of the present invention. Among them, Fig. 1(a) typical as-cast alloy structure; Fig. 1(b) strengthening phase γ′ morphology of as-cast alloy; Fig. 1(c) γ′ morphology after heat treatment at 1100°C for 4 hours.

Figure 2 is the oxidation weight gain curve of the alloy.

Figure 3 is the thermal fatigue performance curve of the alloy.

Figure 4(a)-Figure 4(b) are the fatigue curves of the alloy at 700°C and 900°C. Among them, Figure 4(a) is the fatigue curve at 700°C, and Figure 4(b) is the fatigue curve at 900°C.

Detailed ways

The present invention is described in detail below by way of examples.

Example 1

The composition of this embodiment is shown in Table 1:

Table 1 Alloy composition table of the present invention (wt.%)

C Cr Co Al W Mo Nb Y B Ni Example 1 0.045 9.0 5.0 5.9 3.5 3.0 2.3 0.013 0.023 Remain

The preparation process of the alloy is as follows: the experimental master alloy is smelted by a vacuum induction furnace, the smelting crucible is a CaO crucible, the temperature measurement system is a W-Re galvanic couple and a JH-5 infrared photoconductive temperature/vacuum tester, and a temperature measurement protection sleeve It is a Mo-Al ₂ O ₃ cermet tube. Based on the smelting of 300kg master alloy, the operation process is as follows: put carbon, chromium, cobalt, tungsten, molybdenum, niobium alloy elements and nickel plate into the crucible; vacuumize the low-power 130kw furnace to remove the attached gas, when the vacuum reaches At 20Pa, increase the power to 200kw to melt the alloy; after melting, refine at 1580°C for 4min (vacuum degree is 0.06Pa, power is 90kw). Add Al and Al-Y and Ni-B master alloys for power failure, conjunctiva, and membrane rupture, and then stir at 130kw. After stirring, power off and cool down, 90kw impacts membrane rupture, and casts master alloy ingots at 1480°C.

After the master alloy was remelted in a 10kg vacuum induction furnace for the test, the alloy test rod was poured, using a CaO crucible, and the temperature measurement system was a W-Re galvanic couple. The casting process is as follows: the MgO or CaO formwork is embedded in a sand cylinder filled with _SiO2 , and the cast formwork is preheated in a muffle furnace at 900°C for 3 hours. Put the required master alloy ingot into the CaO crucible, put the sand cylinder just out of the muffle furnace into the vacuum induction furnace for casting. Vacuumize, use a small power of 10kw to remove gas, and when the vacuum reaches 5Pa, increase the power to 40kw to melt the alloy, and refine at 1550°C for 30S (vacuum to 0.05Pa, power 10kw). Turn off the power to cool down and wait for casting, increase the power to 20kw, heat up and stir, adjust the power to control the temperature, the casting temperature should be about 1470°C. After casting, cool in a vacuum chamber and take it out after it is completely solidified. The typical as-cast alloy structure of the alloy of the present invention is shown in Fig. 1(a), and the strengthening phase γ' morphology of the as-cast alloy is shown in Fig. 1(b).

The initial melting temperature of the alloy of the present invention is as high as 1352°C, which is higher than that of K419, K417G, K418 and K441 and other nickel-based superalloys of 90°C, 70°C, 50°C, and 30°C respectively, and is also higher than that of DZ40M and K640 alloys and other cobalt-based superalloys (See Table 2). The solidification interval is small, and the casting performance is superior. Alloy density is low, only 8.1g/cm ³ , much lower than DZ40M and K640 alloys (see Table 3). The invented alloy has good oxidation resistance, and the oxidation weight gain rate at 1100°C is 0.067g/m ² h, reaching the complete anti-oxidation level, as shown in Figure 2. The alloy (K495) of the present invention has good cold and heat fatigue performance, and the crack growth rate is much lower than that of alloys such as K465, K417G, and DZ40M, as shown in FIG. 3 . The strength is relatively high. At two typical temperatures of 20°C and 1000°C, the tensile strength of the alloy is in the middle of several typical cast superalloys in Table 4, while the plasticity is only lower than that of the DZ40M alloy. In Table 4, the alloys with higher strength than the inventive alloy have their incipient melting temperatures much lower than the inventive alloy. The alloy of the present invention is higher than DZ40M and K640 in terms of enduring strength and enduring life. In Table 5, the alloy of the present invention is also excellent. It shows that the alloy of the present invention is an ordinary cast superalloy with superior comprehensive properties.

Table 2 Melting temperature range of some cast superalloys

Alloy Melting temperature range (℃) The alloy of the present invention 1347～1375 K403 1260～1338 K419 1260～1340 K418 1295～1345 K417G 1281～1327 K441 1320～1410 K640 1340～1396 DZ40M 1345～1395

Table 3 Density of some cast superalloys

Alloy Density ρ(10 ³ kg/m ³ ) The alloy of the present invention 8.10 K403 8.10 K405 8.12 K417L 7.80 K441 8.8 K640 8.68 DZ40M 8.68

Table 4 Tensile properties of some cast superalloys

In the present invention, UTS is tensile strength, 0.2YS is yield strength, δ is elongation, and ψ is reduction of area.

Table 5 Durable life of some cast superalloys

serial number θ/℃ Enduring stress/MPa Durable life/h The alloy of the present invention 980 120 ＞100 K418B 980 150 ≥50 K417L 980 120 ≥18 K441 980 83 ≥18 K640 982 55 ≥100 DZ40M 980 83 71.4

Example 2

The difference from Example 1 is that the alloy composition of this example is shown in Table 6:

Table 6 Test alloy composition list (wt.%)

C Cr Co Al W Mo Nb Y B Ni Example 2 0.05 9.0 5.0 5.9 3.4 3.0 2.2 0.015 0.021 Remain

The preparation process of the alloy is as follows: the experimental master alloy is smelted by a vacuum induction furnace, the smelting crucible is a CaO crucible, the temperature measurement system is a W-Re galvanic couple and a JH-5 infrared photoconductive temperature/vacuum tester, and a temperature measurement protection sleeve It is a Mo-Al ₂ O ₃ cermet tube. The operation process of smelting 200kg master alloy meter is as follows: put carbon, chromium, cobalt, tungsten, molybdenum, niobium alloy elements and nickel plate into the crucible; vacuumize the furnace with a power of 120kw to remove the attached gas, when the vacuum degree reaches 1Pa When melting, increase the power to 180kw to melt the alloy; after melting, refine at 1550°C for 4 minutes (vacuum degree 0.08Pa, power 80kw), add Al and Al-Y and Ni-B intermediate alloys after power failure, conjunctiva, and membrane rupture, and then high-power 120kw stirring, power off to cool down after stirring, high power 120kw impact film rupture, temperature measurement, power adjustment, casting master alloy ingot at 1450°C.

After the master alloy was remelted in a 10kg vacuum induction furnace for the test, the alloy test rod was poured, using a CaO crucible, and the temperature measurement system was a W-Re galvanic couple. The casting process is as follows: the MgO or CaO formwork is embedded in a sand cylinder filled with _SiO2 , and the cast formwork is preheated in a muffle furnace at 1000°C for 4 hours. Put the required master alloy ingot into the CaO crucible, and then put the sand cylinder just out of the muffle furnace into the vacuum induction furnace for casting. Vacuumize, use 10kw power to remove gas, when the vacuum degree reaches 1Pa level, increase power 40kw to melt the alloy, and refine at 1550°C for 4min (vacuum degree is 3×10 ^-2 Pa, low power 10kw for heat preservation). Turn off the power to cool down and wait for casting, increase the power to 20kw, heat up and stir, adjust the power to control the temperature, and the casting temperature is 1450°C. After casting, cool in a vacuum chamber and take it out after it is completely solidified. The initial melting temperature of the alloy in this embodiment is as high as 1347°C.

The cast samples were compared with DZ40M, K418B, K441, K640 etc. after heat treatment.

The heat treatment system is: 1100 ° C, heat preservation for 4 hours, air cooling to room temperature, the γ′ morphology of the alloy after heat treatment is shown in Figure 1 (c).

Table 7 is a comparison of the results of the endurance strength test. Table 8 is a comparison of the notch durability performance of this example, which shows that the alloy has basically no notch sensitivity. Table 9 is the tensile properties of this example. Figure 4(a)-Figure 4(b) shows the low cycle fatigue performance at 700°C and 900°C, and the K495 alloy in the figure is the alloy of the present invention.

Table 7 Durable strength of some alloys around 100h (MPa)

Temperature/℃ The alloy of the present invention DZ40M K418B K441 K640 700 600 400 690 - 380 800 500 265 485 341 240 850 350 185 245 251 185 900 250 140 240 169 125 980 120 83 - 80 -

Table 8 Test alloy notch durability

Temperature/℃ Stress/MPa smooth sample Notched sample 700 680 100 1008 850 400 88 964 980 151 68 254 1040 80 63 313

Table 9 Tensile properties of test alloys

θ/℃ UTS(MPa) 0.2YS(MPa) δ(%) ψ(%) 20 852 758 10.2 17.2 1000 438 328 twenty three 31.5

Example 3

The alloy composition of embodiment is as follows:

Table 10 Test Alloy Composition Table (wt.%)

C Cr Co Al W Mo Nb Y B Ni Example 3 0.055 9.0 5.0 5.9 5.9 3.0 2.3 0.017 0.021 Remain

The preparation process of the alloy is as follows: the experimental master alloy is smelted by a vacuum induction furnace, the smelting crucible is a CaO crucible, the temperature measurement system is a W-Re galvanic couple and a JH-5 infrared photoconductive temperature/vacuum tester, and a temperature measurement protection sleeve It is a Mo-Al ₂ O ₃ cermet tube. The quantity of smelted master alloy is 20kg. The operation process is as follows: put carbon, chromium, cobalt, tungsten, molybdenum, niobium alloy elements and nickel plate into the crucible; vacuumize the low-power 30kw furnace to remove the attached gas, when the vacuum degree When it reaches 0.1Pa, increase the power to 60kw to melt the alloy; after melting, refine at 1600°C for 2min (vacuum degree 0.03Pa, power is 20kw), add Al and Al-Y and Ni-B master alloys in case of power failure, conjunctiva and membrane rupture , and then stirred with a high power of 70kw. After stirring, the power was cut off to cool down, and the high power of 70kw was impacted to rupture the membrane. The temperature was measured and the power was adjusted to 1500°C, and cast into a master alloy ingot.

After the master alloy was remelted in a 10kg vacuum induction furnace for the test, the alloy test rod was poured, using a CaO crucible, and the temperature measurement system was a W-Re galvanic couple. The casting process is as follows: the MgO or CaO formwork is embedded in a sand cylinder filled with _SiO2 , and the cast formwork is preheated in a muffle furnace at 900°C for 3 hours. Put the required master alloy ingot into the CaO crucible, and then put the sand cylinder just out of the muffle furnace into the vacuum induction furnace for casting. Give a small power of 10kw to remove gas, when the vacuum degree reaches 10Pa level, increase the power to 40kw to melt the alloy, and refine at 1550°C for 240s (vacuum degree 0.03Pa, power 10kw). Turn off the power to cool down and wait for casting, increase the power to 20kw, heat up and stir, adjust the power to control the temperature, and the casting temperature is 1470°C. After casting, cool in a vacuum chamber and take it out after it is completely solidified. The initial melting temperature of the alloy in this embodiment is as high as 1351°C.

The main difference between the alloy composition of this example and the previous example lies in the content of W and the heat treatment system. The content (mass percentage) of W is increased to 5.9%, and the heat treatment system selects the following three-level heat treatment system simultaneously:

At 1215°C, keep warm for 4 hours, then air cool to room temperature;

At 1050°C, keep warm for 4 hours, then air cool to room temperature;

At 870°C, keep warm for 24 hours, then air cool to room temperature.

Table 11 lists the tensile properties of the test and Table 12 the durability properties of the tested alloys. It shows that the high temperature strength of the alloy can be further improved according to the above composition and heat treatment system.

Table 11 Tensile properties of test alloys

θ/℃ UTS(MPa) 0.2YS(MPa) δ(%) ψ(%) 20 1013 848 11 15.8 900 745 542.5 11.8 34 1000 488 340 17 37 1100 260 180 18.5 34.5

Table 12 Durability properties of test alloys

Example 4-6

Difference with embodiment 1 is: the Cr and Nb content of embodiment 4 obviously improves, and the content of C and W some declines; Co and Mo of embodiment 5 improve, and Cr and Nb then have decline; Embodiment 6 The W content is somewhat increased, and other elements are basically unchanged (see Table 13).

Table 13 Alloy composition table of the present invention (wt.%)

C Cr co Al w Mo Nb Y B Ni Example 4 0.03 12.0 5.0 5.5 3.0 2.5 3.0 0.020 0.027 Remain Example 5 0.06 5.0 8.0 6.5 3.5 4.0 1.6 0.025 0.015 Remain Example 6 0.05 9.0 5.5 6.0 5 3.0 2.2 0.013 0.023 Remain

The melting temperature of the above alloy is in the range of 1347°C to 1375°C.

The heat treatment system of the above alloys is as follows:

Example 4: keep warm at 1110°C for 5 hours, and cool to room temperature in air.

Example 5: heat preservation at 1210°C for 4 hours, air cooling to room temperature; heat preservation at 1040°C for 4 hours, air cooling to room temperature; heat preservation at 850°C for 28 hours, air cooling to room temperature.

Example 6: heat preservation at 1220°C for 3 hours, air cooling to room temperature; heat preservation at 1060°C for 3 hours, air cooling to room temperature; heat preservation at 890°C for 20 hours, air cooling to room temperature.

Table 14 Tensile properties of the above alloys

Claims (6)

1. A nickel-based superalloy with low density and high melting point, characterized in that, by mass percentage, the alloy composition is as follows: C 0.03～0.06, Cr 5～12, Al 5.5～6.5, Co 3～8, W 3～7, Mo 2～4, Nb 1.6～3.2, B 0.01～0.03, Y 0.008～0.025, Ni balance. 2. The nickel-based superalloy according to claim 1, characterized in that, by mass percentage, the preferred components are as follows: C 0.05, Cr 9, Al 6, Co 5.5, W 3.5, Mo 3, Nb 2.2, B 0.023, Y 0.013, Ni balance. 3. The process for preparing nickel-based superalloys according to claim 1 is characterized in that the master alloy is smelted in a vacuum induction furnace, and the smelting crucible is a CaO or MgO crucible. The operation process is as follows: carbon, chromium , cobalt, tungsten, molybdenum, niobium alloy elements and nickel plate into the crucible; when the vacuum reaches 50Pa ~ 0.1Pa, melt the alloy; 0.1Pa～0.001Pa, add Al and Al-Y and Ni-B master alloy during power failure, conjunctiva and membrane rupture, stir evenly, and cast into master alloy ingot at 1450℃～1500℃. 4. According to the preparation process of nickel-based superalloy according to claim 3, it is characterized in that, when the nickel-based superalloy is cast into test rods or castings, the master alloy ingot is remelted in a vacuum induction furnace and then cast, and the cast formwork Preheat at 850°C-1100°C for 3-5 hours; the specific process is: put the required master alloy ingot into a CaO or MgO crucible, supply electricity to remove gas; when the vacuum degree reaches 50Pa-0.01Pa level, melt the alloy; Refining at 1550°C-1600°C for 30S-300S, vacuum degree should reach 0.1Pa-0.001Pa, casting at 1450°C-1500°C; after casting, cool in vacuum chamber, take out after complete solidification. 5. The preparation process of nickel-based superalloy according to claim 3 or 4, characterized in that the alloy heat treatment system is: 1090°C-1110°C, heat preservation for 3h-5h, air cooling to room temperature. 6. According to the preparation process of the nickel-based superalloy described in claim 3 or 4, it is characterized in that the alloy heat treatment system is: (1) At 1200℃～1220℃, keep warm for 3h～5h, and air cool to room temperature; (2) At 1040°C ~ 1060°C, keep warm for 3h ~ 5h, and air cool to room temperature; (3) Keep warm at 850℃～890℃ for 20h～28h, then air cool to room temperature.

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