High-thermal-stability nickel-based wrought superalloy and preparation method thereof

Abstract

The invention discloses a high-thermal-stability nickel-based wrought superalloy and a preparation method thereof, belongs to the technical field of superalloys, and aims to solve the problems of poor high-temperature structure stability, narrow thermal deformation process window and the like of the existing superalloy. The high-thermal-stability nickel-based wrought superalloy is prepared from the following components in percentage by mass: 9.0 to 12.0 percent of Cr, 12.0 to 16.0 percent of Co, 6.0 to 7.5 percent of W, 2.0 to 4.0 percent of Mo, 3.6 to 4.5 percent of Al, 1.4 to 2.0 percent of Ti, 1.2 to 1.8 percent of Nb, 0.2 to 0.8 percent of V, less than or equal to 1.0 percent of Fe, 0.03 to 0.10 percent of C, 0.01 to 0.03 percent of B, 0.02 to 0.08 percent of Zr, 0.01 to 0.02 percent of Ce and the balance of Ni and other inevitable impurities. Wherein the sum of the contents of W and Mo is 8.5-11.5%, and the mass ratio of W to Mo is 2.0-3.5. The high-thermal-stability nickel-based wrought superalloy has good high-temperature structure stability and excellent high-temperature performance.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy technology, and in particular to a high thermal stability nickel-based wrought high-temperature alloy and its preparation method. Background Technology

[0002] Advanced power plants such as aerospace engines and gas turbines operate under extreme environments of prolonged high temperatures and complex stresses, placing stringent demands on the high-temperature mechanical properties and long-term microstructural stability of nickel-based wrought superalloys. To improve the high-temperature tensile strength, creep strength, and fatigue strength of these alloys, strategies typically include increasing the content of alloying elements, enhancing the γ′ phase content, and reducing element diffusion. However, this also makes controlling the microstructural stability and hot-working properties of the alloy challenging.

[0003] Studies have found that the microstructure stability and hot working properties of nickel-based wrought superalloys fundamentally depend on their composition design. Therefore, how to optimize composition to ensure both high-temperature mechanical properties and good microstructure stability with a wide hot working window has become a pressing research topic. Developing nickel-based wrought superalloys with excellent comprehensive properties is of great significance for meeting the material selection requirements of advanced power plants. Summary of the Invention

[0004] In view of the above, the present invention aims to provide a high thermal stability nickel-based wrought superalloy and its preparation method, in order to solve the problems of poor high-temperature microstructure stability and narrow hot deformation process window of existing superalloys.

[0005] The objective of this invention is mainly achieved through the following technical solutions: On one hand, the present invention provides a high thermal stability nickel-based wrought superalloy, the composition of which, by mass percentage, includes: Cr 9.0-12.0%, Co 12.0-16.0%, W 6.0-7.5%, Mo 2.0-4.0%, Al 3.6-4.5%, Ti 1.4-2.0%, Nb 1.2-1.8%, V 0.2-0.8%, Fe ≤1.0%, C 0.03-0.10%, B 0.01-0.03%, Zr 0.02-0.08%, Ce 0.01-0.02%, with the balance being Ni and other unavoidable impurities; wherein the sum of the contents of W and Mo is 8.5-11.5%, and the mass ratio of W to Mo is 2.0-3.5.

[0006] Furthermore, the combined content of W and Mo is 9-9.9%.

[0007] Furthermore, the mass ratio of W to Mo is 2.0-3.1.

[0008] Furthermore, the combined content of Al, Ti, and Nb elements is 7.0-8.5%.

[0009] Furthermore, the ratio of (Ti+Nb) / Al is 0.7-1.0.

[0010] Furthermore, in high thermal stability nickel-based wrought superalloys, the mass percentage of the γ′ phase is controlled at 50-55%.

[0011] Furthermore, in high thermal stability nickel-based wrought superalloys, the complete dissolution temperature of the γ′ phase is 1120-1140℃.

[0012] This invention also provides a method for preparing the above-mentioned high thermal stability nickel-based wrought superalloy, comprising the following steps: Step 1: Weigh the raw materials according to the alloy composition ratio; Step 2: Perform vacuum induction melting and at least one remelting refining on the raw materials to obtain vacuum consumable remelted ingots; Step 3: Perform high-temperature diffusion homogenization treatment on the vacuum consumable remelted ingot, then perform free forging to obtain a billet, then perform a second homogenization treatment on the billet, then perform free forging again, and finally perform heat treatment to obtain a high thermal stability nickel-based wrought high-temperature alloy.

[0013] Furthermore, in step 2, the vacuum induction melting process includes the evacuation stage, the melting period, the refining period, and the tapping period.

[0014] Furthermore, in step 2, during the evacuation stage, the vacuum level is 10-100 Pa.

[0015] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: The high thermal stability nickel-based wrought superalloy of this invention, through rational composition design and optimized preparation methods, achieves a uniform and fine grain structure and dispersed precipitation of a high content (50-55 wt.%) of γ′ phase. It exhibits excellent high-temperature mechanical properties at 800-900℃ and maintains structural stability for 3000-5000 hours. Simultaneously, this alloy possesses a wide forging process window (80-100℃), enabling it to meet long-term service requirements under complex stress conditions at high temperatures, making it particularly suitable for manufacturing high-pressure compressors, turbine disks, blades, fasteners, and other high-temperature load-bearing components.

[0016] The high thermal stability nickel-based wrought superalloy of the present invention has the following tensile properties at 900℃: tensile strength of 665 MPa or more, for example 669-695 MPa, elongation of 19% or more, for example 19.2-32.5%, and creep strength at 900℃ / 100h of 317 MPa or more, for example 317-330 MPa.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Figure 1 The microstructure of the alloy of the present invention after long-term aging at 850℃ for 5000h; Figure 2 The microstructure of the alloy of this invention after long-term aging at 900℃ for 5000h is shown. Detailed Implementation

[0019] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0020] This invention provides a high thermal stability nickel-based wrought superalloy. The composition of the high thermal stability nickel-based wrought superalloy, by mass percentage, includes: Cr 9.0-12.0%, Co 12.0-16.0%, W 6.0-7.5%, Mo 2.0-4.0%, Al 3.6-4.5%, Ti 1.4-2.0%, Nb 1.2-1.8%, V 0.2-0.8%, Fe ≤1.0%, C 0.03-0.10%, B 0.001-0.01%, Zr 0.02-0.08%, Ce 0.01-0.02%, with the balance being Ni and other unavoidable impurities.

[0021] Specifically, the impurity elements of the aforementioned high thermal stability nickel-based wrought superalloys, by mass percentage, are: Mn ≤0.50%, Si ≤0.50%, P ≤0.010%, S ≤0.010%, Cu ≤0.07%, Bi ≤0.0001%, Sn ≤0.0012%, Sb ≤0.0025%, As ≤0.0025%, and Pb ≤0.001%.

[0022] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the sum of the contents of W and Mo is between 8.5% and 11.5%, and the mass ratio of W to Mo is between 2.0 and 3.5.

[0023] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the sum of the contents of Al, Ti, and Nb elements is between 7.0% and 8.5%.

[0024] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the ratio of (Ti+Nb) / Al is 0.7-1.0.

[0025] The following details the function and dosage selection of the components contained in this invention: The high-temperature strength and long-term microstructural stability of precipitation-strengthened nickel-based wrought superalloys are mainly influenced by the influence of alloying elements on the microstructure of the γ and γ′ phases. Based on the distribution of alloying elements in the γ and γ′ phases, Al, Ti, and Nb elements are segregated in the γ′ phase, Co and Mo elements are segregated in the γ phase, and W elements are almost evenly distributed in both phases. The composition adjustment of this invention can ensure that the alloy has high high-temperature strength. By replacing part of Ti with Nb to further dope and strengthen the γ′ phase, controlling the γ′ phase content to 50-55 wt.%, γ′-(Ni,Co)3(Al,Ti) becomes γ′-(Ni,Co)3(Al,Ti,Nb), improving the ordered strengthening effect and thermal stability of the γ′ phase, and helping to enhance the precipitation strengthening effect of the γ′ precipitate. Although the above composition system reduces the γ / γ′ mismatch amplitude and weakens the strengthening effect of the γ / γ′ coherent interface to a certain extent, it significantly improves the ordered strengthening degree of the γ′ phase, thereby enabling the alloy of this invention to have high high-temperature strength. The presence of grain boundary compounds can enhance the grain boundary strength of the alloy of this invention at high temperatures. The Nb and V elements also improve the thermal stability of MC-type carbides, promote their dispersed particle distribution, reduce the tendency of grain boundary slip and grain growth to a certain extent, and improve creep resistance at high temperatures.

[0026] The compositional system of this invention can improve the long-term microstructural stability of the alloys of this invention. For high-temperature alloys with a high content (>40%) of γ′ phase, adjusting the W / Mo atomic ratio to reduce the content of alloying elements and electron concentration in the γ matrix can delay the precipitation time of the harmful μ phase by 2000 h. More importantly, this allows more alloying elements to enter the γ′ phase, increasing the lattice constant of the γ′ phase. Considering that the lattice expansion of the γ phase with temperature is greater than that of the γ′ phase, this helps to reduce the γ / γ′ mismatch amplitude of the alloy at the service temperature. By controlling the element migration rate and the γ / γ′ mismatch amplitude, the high-temperature long-term microstructural stability of the γ / γ′ microstructure can be effectively improved. The improved thermal stability of MC-type carbonitrides helps to slow down the degradation reaction of grain boundary compounds.

[0027] The alloy of this invention exhibits excellent casting-forging process performance. Adding appropriate amounts of C and B elements helps improve the high-temperature melt fluidity of the alloy, reduces the number of casting voids, and improves the metallurgical quality of the remelted electrode in multi-stage processes.

[0028] The alloy of this invention improves grain boundary properties by adding Ce, thereby enhancing the hot workability of the alloy ingot. Partial Ti substitution with Nb slows the precipitation rate of the γ′ phase, which has a low diffusion rate in the Ni matrix; the precipitation of the γ′ phase often leads to localized strength increases and volume shrinkage. For nickel-based superalloys, appropriately increasing the V content can improve hot working plasticity and grain uniformity. These factors, to some extent, improve the hot workability of the alloy of this invention.

[0029] Al, Ti, and Nb are the most effective precipitation-strengthening γ' phase-forming elements in nickel-based superalloys. The γ' phase content in nickel-based superalloys is mainly determined by the total amount of Al, Ti, and Nb, as well as the (Ti+Nb) / Al content ratio. As the Al+Ti+Nb content increases, the volume fraction of the γ' phase in the alloy also increases, and the full melting temperature of the γ' phase also rises. An appropriate (Ti+Nb) / Al ratio can improve the order of the γ' phase, thereby further improving the high-temperature strength of the alloy and enhancing its high-temperature oxidation performance; the coupling effect of the elements will highlight this beneficial effect. However, an excessively high (Ti+Nb) / Al content ratio will promote the formation of η-Ni3Ti, Lavas, and δ-Ni3Nb phases, often exhibiting needle-like morphologies. This disrupts the continuity of the microstructure in nickel-based superalloys with high γ' phase content, easily inducing crack formation and propagation. In addition, Ti and Nb are both strong carbide-forming elements, which promote the precipitation of MC carbides in the alloy, which can refine the grains and pin the grain boundaries, thus improving the high-temperature strength of the alloy.

[0030] W and Mo are the most effective solid solution strengthening elements in nickel-based superalloys. W is basically uniformly distributed in the γ and γ' phases. W can also strengthen the γ' phase and increase its dissolution temperature. W can slow down the diffusion process. Although it has some solubility in the γ' phase, Mo is actually enriched in the γ phase and can produce a significant solid solution strengthening effect on the γ phase. Mo can increase the absolute value of γ / γ' mismatch, which is somewhat detrimental to the long-term stability of the γ-γ' microstructure. The addition of W and Mo must be moderate; excessive W and Mo will increase the tendency to precipitate harmful topologically close-packed (TCP) phases. In addition, controlling the W / Mo content ratio is also a means to control the tendency of harmful TCP phase precipitation. Increasing the W / Mo content ratio helps to reduce the content of alloying elements and electron concentration in the γ matrix, thereby effectively reducing the tendency of harmful TCP phases in the alloy.

[0031] Volatile metal (V) is a solid solution strengthening element in nickel-based wrought superalloys, primarily segregating in the γ matrix, secondarily distributed in the γ' phase, and sparingly in carbonitrides. V in the γ matrix causes lattice expansion, resulting in effective solid solution strengthening. A certain amount of nitrogen (N) inevitably remains in the smelted alloy steel ingot. N forms nitrides with Ti and Nb, which readily aggregate and form chains. These nitrides often become fatigue crack initiation sites, particularly detrimental to low-cycle fatigue performance. During smelting, V combines more readily with C and N to form thermodynamically stable M(CN)-type carbonitrides than Ti and Nb, and these compounds are distributed in a dispersed granular form, improving the alloy's high-temperature strength.

[0032] Fe is a constituent element of the γ matrix and can provide solid solution strengthening to the Ni matrix. Excessive Fe content promotes the precipitation of the σ phase, which appears as long needles, impairing the alloy's high-temperature performance. Conversely, excessively low Fe content is unfavorable for continuous industrial production. Metallurgical plants frequently smelt Fe-containing high-temperature alloys, and to control the Fe content, measures such as pure Ni smelting and furnace cleaning or furnace lining replacement must be taken, reducing production efficiency and increasing costs. To balance alloy microstructure stability with the requirements of actual industrial production, a small amount of Fe is permitted in the alloy, with a maximum limit of 1.0%.

[0033] Specifically, the composition of the aforementioned high thermal stability nickel-based wrought superalloy, by mass percentage, includes: Cr 9.5-11.0%, Co 14.0-15.5%, W 6.5-7.0%, Mo 2.3-3.5%, Al 4.0-4.5%, Ti 1.5-2.0%, Nb 1.3-1.7%, V 0.25-0.75%, Fe 0.1-0.8%, C 0.05-0.09%, B 0.003-0.01%, Zr 0.035-0.05%, Ce 0.01-0.02%, with the balance being Ni and other unavoidable impurities.

[0034] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the sum of the contents of W and Mo is 9-9.9%, and the mass ratio of W to Mo is between 2.0 and 3.1.

[0035] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the sum of the contents of Al, Ti, and Nb elements is between 7.1% and 7.7%.

[0036] Specifically, in the aforementioned high thermal stability nickel-based wrought superalloys, the (Ti+Nb) / Al ratio is 0.7-0.82.

[0037] Specifically, in the above-mentioned high thermal stability nickel-based wrought superalloy, the content of the reinforcing γ′ phase is controlled at 50-55 wt.%, and the total melting temperature of the γ′ phase is between 1120-1140℃.

[0038] Specifically, the content (area fraction) of harmful TCP phase precipitated in the above-mentioned high thermal stability nickel-based wrought superalloys after long-term aging in the temperature range of 800-900℃ for 3000-5000h does not exceed 1%.

[0039] Specifically, the aforementioned high thermal stability nickel-based wrought superalloys, while maintaining a high quality fraction of γ′ phase, also possess excellent high-temperature structural stability and a wide hot working window.

[0040] This invention also provides a method for preparing the above-mentioned high thermal stability nickel-based wrought superalloy, comprising the following steps: Step 1: Weigh the raw materials according to the alloy composition ratio; Step 2: Perform vacuum induction melting and at least one remelting refining on the raw materials to obtain vacuum consumable remelted ingots; Step 3: Perform high-temperature diffusion homogenization treatment on the vacuum consumable remelted ingot, then perform free forging to obtain a billet, then perform a second homogenization treatment on the billet, then perform free forging again, and finally perform heat treatment to obtain a high thermal stability nickel-based wrought high-temperature alloy.

[0041] Specifically, in order to improve the purity, density and homogeneity of the ingot, in step 2 above, the vacuum induction melting ingot is refined by electroslag remelting to remove inclusions and sulfur elements and improve the metallurgical quality of the alloy ingot, and then further refined by vacuum arc remelting to remove gases and improve crystal quality, so as to obtain a vacuum arc remelted ingot with certain thermoplasticity.

[0042] Specifically, in step 2 above, Nb in the alloy raw materials is added in the form of Ni-Nb master alloy to reduce solidification segregation of Nb element.

[0043] Specifically, in step 2 above, the vacuum induction melting process includes a vacuuming stage, a melting period, a refining period, and a tapping period. During the vacuuming stage, the vacuum degree is 10-100 Pa. During the melting period, the temperature is controlled at 1300-1650℃. During the refining period, the temperature is controlled at 1400-1600℃, and the vacuum degree is 1-20 Pa. During the tapping period, the temperature is controlled at 1400-1580℃, and argon gas is used for protection at 10000-50000 Pa. After casting, the ingot is demolded after cooling for 0.5-3 hours to obtain a vacuum induction melted ingot.

[0044] Specifically, in step 2 above, after the vacuum induction melting ingot is machined to prepare the electrode, it is then subjected to vacuum self-consumption remelting. The vacuum self-consumption remelting process adopts a stepless speed control process for melting rate, in which water and helium are used for dual cooling to improve the solidification effect of the steel ingot and thus effectively suppress the formation of metallurgical defects such as black spots and white spots.

[0045] Specifically, in step 3 above, the heat preservation temperature for diffusion homogenization treatment is 1160~1220℃ (e.g., 1160℃, 1170℃, 1180℃, 1190℃, 1200℃, 1210℃, 1220℃), and the heat preservation time is 23~25h (e.g., 23h, 24h, 25h).

[0046] Specifically, in step 3 above, after free forging and blanking, a secondary homogenization process is performed after the forging ratio reaches 1-2 (e.g., 1, 2).

[0047] Specifically, in step 3 above, the heat preservation temperature for the secondary homogenization treatment is 1140~1200℃ (e.g., 1140℃, 1150℃, 1160℃, 1170℃, 1180℃, 1190℃, 1200℃), and the heat preservation time is 3~5h (e.g., 3h, 4h, 5h).

[0048] Specifically, in step 3 above, the forging ratio of the final forging billet is 4-6 (e.g., 4, 5, 6).

[0049] Specifically, in step 3 above, the heat treatment includes solution treatment and aging treatment. The solution treatment regime is to hold at 1150~1220℃ for 2-3 hours, and the aging treatment regime is to hold at 1000~1100℃ for 4-5 hours and then at 800~900℃ for 8-9 hours.

[0050] The high thermal stability nickel-based wrought superalloy of this invention, through rational composition design and optimized preparation methods, achieves a uniform and fine grain structure and dispersed precipitation of a high content (50-55 wt.%) of γ′ phase. It exhibits excellent high-temperature mechanical properties at 800-900℃ and maintains structural stability for 3000-5000 hours. Simultaneously, this alloy possesses a wide forging process window (80-100℃), enabling it to meet long-term service requirements under complex stress conditions at high temperatures, making it particularly suitable for manufacturing high-pressure compressors, turbine disks, blades, fasteners, and other high-temperature load-bearing components.

[0051] The high thermal stability nickel-based wrought superalloy of the present invention has the following tensile properties at 900℃: tensile strength of 665 MPa or more, for example 669-695 MPa, elongation of 19% or more, for example 19.2-32.5%, and creep strength at 900℃ / 100h of 317 MPa or more, for example 317-330 MPa.

[0052] Examples 1-5 The embodiments provide a high thermal stability nickel-based wrought superalloy and its preparation method. The components of the embodiments are shown in Table 1, and the process and physicochemical test results are shown in Table 2.

[0053] The preparation method of Example 1 includes: The smelting process employs a dual-stage process, including vacuum induction melting and vacuum consumable remelting. The vacuum induction melting ingot is machined to prepare a consumable remelting electrode. The filling ratio of the consumable remelting electrode to the crystallizer is 0.8, the melting rate is (1.0~5.0) kg / min, and the cooling time after the remelting electrode completes melting is (1~10) h. Then, it is demolded and cooled to obtain the vacuum consumable remelting ingot.

[0054] After the alloy ingot is subjected to high-temperature diffusion homogenization treatment at 1210℃ for 24 hours, it is then free forged by upsetting and drawing. After the forging ratio reaches 1.0, it is subjected to a second homogenization treatment at 1180℃ for 4 hours, and then free forging is carried out by upsetting and drawing again. After the forging ratio reaches 5.0, the alloy forging billet is obtained.

[0055] The alloy forging billet undergoes heat treatment, including solution treatment and aging treatment. The solution treatment regime is 1220℃ for 2 hours, and the aging treatment regime is 1100℃ for 4 hours and 900℃ for 8 hours.

[0056] The preparation method of Example 2 includes: The smelting process employs a dual-process: vacuum induction melting and vacuum consumable remelting. The vacuum induction melting ingot is machined to prepare a consumable remelting electrode. The filling ratio of the consumable remelting electrode to the crystallizer is 0.8, the melting rate is (1.0~5.0) kg / min, and the cooling time after the remelting electrode completes melting is (1~10) h. Then, it is demolded and cooled to obtain the vacuum consumable remelting ingot.

[0057] After the alloy ingot is subjected to high-temperature diffusion homogenization treatment at 1160℃ for 25 hours, it is then free forged by upsetting and drawing to achieve a forging ratio of 1.0. After that, it is subjected to a second homogenization treatment at 1140℃ for 5 hours, and then free forging is carried out by upsetting and drawing to achieve a forging ratio of 6.0, thus obtaining the alloy forging billet.

[0058] The alloy forging billet undergoes heat treatment, including solution treatment and aging treatment. The solution treatment regime is 1130℃ for 2.5 hours, and the aging treatment regime is 1050℃ for 4.5 hours and 900℃ for 8 hours.

[0059] The preparation method of Example 3 includes: The smelting process employs a dual-process: vacuum induction melting and vacuum consumable remelting. The vacuum induction melting ingot is machined to prepare a consumable remelting electrode. The filling ratio of the consumable remelting electrode to the crystallizer is 0.8, the melting rate is (1.0~5.0) kg / min, and the cooling time after the remelting electrode completes melting is (1~10) h. Then, it is demolded and cooled to obtain the vacuum consumable remelting ingot.

[0060] After the alloy ingot is subjected to high-temperature diffusion homogenization treatment at 1180℃ for 24 hours, it is then free forged by upsetting and drawing to achieve a forging ratio of 2.0. After that, it is subjected to a second homogenization treatment at 1170℃ for 4 hours, and then free forging is carried out by upsetting and drawing to achieve a forging ratio of 4.0, thus obtaining the alloy forging billet.

[0061] The alloy forging billet undergoes heat treatment, including solution treatment and aging treatment. The solution treatment regime is 1160℃ for 2 hours, and the aging treatment regime is 1060℃ for 4 hours and 800℃ for 9 hours.

[0062] The preparation method of Example 4 includes: The smelting process employs a three-stage process: vacuum induction melting, protective atmosphere electroslag remelting, and vacuum consumable remelting. Vacuum induction melting ingots are machined to prepare electroslag remelting electrodes. The electrode-to-crystallizer filling ratio is 0.7–0.8, and the electroslag ratio is CaF2: CaO: MgO: Al2O3: Ti2O = (60–70)%: (10–20)%: (1–10)%: (10–20)%: (1–10)%. The steady-state melting rate is (5.0–10.0) kg / min. The cooling time after secondary alloy ingot melting is (1–10) h, followed by demolding and cooling. The secondary alloy ingot is machined to prepare a consumable remelting electrode. The filling ratio of the consumable remelting electrode to the crystallizer is 0.8, the melting rate is (1.0~5.0) kg / min, and the cooling time after the remelting electrode is completed is (1~10) h. Then it is demolded and cooled to obtain a vacuum consumable remelting ingot.

[0063] After the alloy ingot is subjected to high-temperature diffusion homogenization treatment at 1200℃ for 24 hours, it is then free forged by upsetting and drawing to achieve a forging ratio of 1.0. After that, it is subjected to a second homogenization treatment at 1160℃ for 4.5 hours, and then free forging is carried out by upsetting and drawing to achieve a forging ratio of 6.0, thus obtaining the alloy forging billet.

[0064] The alloy forging billet undergoes heat treatment, including solution treatment and aging treatment. The solution treatment regime is 1150℃ for 3 hours, and the aging treatment regime is 1080℃ for 4 hours and 850℃ for 8.5 hours.

[0065] The preparation method of Example 5 includes: The smelting process employs a three-stage process: vacuum induction melting, protective atmosphere electroslag remelting, and vacuum consumable remelting. Vacuum induction melting ingots are machined to prepare electroslag remelting electrodes. The electrode-to-crystallizer filling ratio is 0.7–0.8, and the electroslag ratio is CaF2: CaO: MgO: Al2O3: Ti2O = (60–70)%: (10–20)%: (1–10)%: (10–20)%: (1–10)%. The steady-state melting rate is (5.0–10.0) kg / min. The cooling time after secondary alloy ingot melting is (1–10) h, followed by demolding and cooling. The secondary alloy ingot is machined to prepare a consumable remelting electrode. The filling ratio of the consumable remelting electrode to the crystallizer is 0.8, the melting rate is (1.0~5.0) kg / min, and the cooling time after the remelting electrode is completed is (1~10) h. Then it is demolded and cooled to obtain a vacuum consumable remelting ingot.

[0066] After the alloy ingot is subjected to high-temperature diffusion homogenization treatment at 1190℃ for 24.5h, it is then free forged by upsetting and drawing to achieve a forging ratio of 1.0. After that, it is subjected to a second homogenization treatment at 1170℃ for 4.8h, and then free forging is carried out by upsetting and drawing to achieve a forging ratio of 6.0, thus obtaining the alloy forging billet.

[0067] The alloy forging billet undergoes heat treatment, including solution treatment and aging treatment. The solution treatment regime is 1150℃ for 2.5 hours, and the aging treatment regime is 1000℃ for 5 hours and 810℃ for 9 hours.

[0068] In the high thermal stability nickel-based wrought superalloys of Examples 1-5, the content of the strengthening γ′ phase is controlled at 50-55 wt.%, and the total melting temperature of the γ′ phase is between 1120-1140℃.

[0069] Comparative Example 1: This comparative example provides a nickel-based wrought superalloy and its preparation method.

[0070] The alloy composition in this comparative example does not contain Nb but contains a relatively large amount of Mo. The specific composition is shown in Table 1.

[0071] The preparation method of this comparative example is the same as that of Example 5, and will not be repeated here.

[0072] Comparative Example 2: A high thermal stability nickel-based wrought superalloy and its preparation method The alloy composition in this example does not contain Nb, but contains a relatively large amount of Mo, Al and Ti. The specific composition is shown in Table 1.

[0073] The preparation method of this comparative example is the same as that of Example 5, and will not be repeated here.

[0074] Table 1. Main components (mass percentage, wt.%) of the Examples and Comparative Examples

[0075] Table 2 Comparison of process and physicochemical test results between the examples and comparative examples

[0076] The alloy of this invention exhibits good high-temperature, long-term structural stability, such as... Figure 1 The image shows the microstructure of the alloy of the present invention after long-term aging at 850℃ for 5000 hours. Figure 2 The microstructure of the alloy of this invention after long-term aging at 900℃ for 5000h is such that it can meet the material selection requirements for long-term service at 900℃ in advanced aerospace engines and gas turbines.

[0077] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high thermal stability nickel-based wrought superalloy, characterized in that, The high thermal stability nickel-based wrought superalloy comprises, by mass percentage: Cr 9.0-12.0%, Co 12.0-16.0%, W 6.0-7.5%, Mo 2.0-4.0%, Al 3.6-4.5%, Ti 1.4-2.0%, Nb 1.2-1.8%, V 0.2-0.8%, Fe ≤1.0%, C 0.03-0.10%, B 0.01-0.03%, Zr 0.02-0.08%, Ce 0.01-0.02%, with the balance being Ni and other unavoidable impurities; wherein the sum of W and Mo content is 8.5-11.5%, and the mass ratio of W to Mo is 2.0-3.

5.

2. The high thermal stability nickel-based wrought superalloy according to claim 1, characterized in that, The combined content of W and Mo is 9-9.9%.

3. The high thermal stability nickel-based wrought superalloy according to claim 1, characterized in that, The mass ratio of W to Mo is 2.0-3.

1.

4. The high thermal stability nickel-based wrought superalloy according to claim 1, characterized in that, The combined content of Al, Ti, and Nb elements is 7.0-8.5%.

5. The high thermal stability nickel-based wrought superalloy according to claim 1, characterized in that, The ratio of (Ti+Nb) / Al is 0.7-1.

0.

6. The high thermal stability nickel-based wrought superalloy according to any one of claims 1 to 5, characterized in that, In the high thermal stability nickel-based wrought superalloy, the mass percentage of the γ′ phase is controlled at 50-55%.

7. The high thermal stability nickel-based wrought superalloy according to any one of claims 1 to 5, characterized in that, In the aforementioned high thermal stability nickel-based wrought superalloy, the complete melting temperature of the γ′ phase is 1120-1140℃.

8. A method for preparing a high thermal stability nickel-based wrought superalloy according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Weigh the raw materials according to the alloy composition ratio; Step 2: Perform vacuum induction melting and at least one remelting refining on the raw materials to obtain vacuum consumable remelted ingots; Step 3: Perform high-temperature diffusion homogenization treatment on the vacuum consumable remelted ingot, then perform free forging to obtain a billet, then perform a second homogenization treatment on the billet, then perform free forging again, and finally perform heat treatment to obtain a high thermal stability nickel-based wrought high-temperature alloy.

9. The preparation method according to claim 8, characterized in that, In step 2, the vacuum induction melting process includes the evacuation stage, the melting period, the refining period, and the tapping period.

10. The preparation method according to claim 9, characterized in that, In step 2, during the evacuation stage, the vacuum level is 10-100 Pa.

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