Nickel-based deformed high-temperature alloy and preparation method thereof

Abstract

The present invention relates to a nickel-based deformable high-temperature alloy and a preparation method thereof, and relates to the technical field of high-temperature alloy design and preparation. The main technical solution adopted is: a nickel-based deformable high-temperature alloy, wherein the chemical composition of the nickel-based deformable high-temperature alloy is as follows, in weight percentage: Co: 15.6-23.4wt%; Cr: 11-15wt%; Ti: 4.75-6.25wt%; Al: 2.25-3.00wt%; W: 0.0-1.2wt%; Mo: 2.0-3.0wt%; C: 0.01-0.02wt%; Zr: 0.025-0.05wt%; B: 0.01-0.05wt%; rare earth element RE: 0.2-0.5wt%; Nb: greater than 0 and less than or equal to 0.2wt%; Mg: greater than 0 and less than or equal to 0.02wt%; the balance is Ni. The nickel-based deformable high-temperature alloy of the present invention has more excellent hot working performance than the currently commercial GH4720Li alloy with the highest temperature bearing capacity, as well as higher tensile strength and long life in the service temperature range.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature alloy design and preparation, and in particular to a nickel-based deformable high-temperature alloy and a preparation method thereof. Background Art

[0002] With the development of the aviation industry, the performance of aircraft engines continues to improve. As the core hot-end component of the engine, high-temperature alloy turbine disks must have excellent heat-bearing capacity. The heat-bearing capacity of the deformable high-temperature alloys used in turbine disks has increased by an average of 2°C per year. The alloy types have evolved from the GH4169 alloy with a temperature resistance of 650°C to the GH4720Li alloy with a temperature resistance of 725°C. GH4720Li is currently the highest heat-bearing deformable high-temperature alloy commercially available.

[0003] Deformed high-temperature alloys are usually strengthened by solid solution strengthening, precipitation strengthening and grain refinement to achieve higher temperature resistance. Among them, precipitation strengthening is the most significant strengthening method. For example, the GH4720Li alloy contains about 45wt% of the γ′ ordered phase. Although the high mass fraction of the γ′ phase can enable the alloy to obtain excellent strength in the service temperature range, it also significantly deteriorates the high-temperature hot working performance of the alloy. This is because the γ′ phase is located inside the matrix grains, and the coarse grain boundary bonding strength is lower than the internal strength of the grains, which makes the alloy prone to intergranular cracking during hot working and cannot be processed in engineering. Therefore, based on the GH4720Li alloy, if the precipitate phase content is increased, it is difficult to design and prepare a turbine disk alloy that can withstand 750°C.

[0004] Currently, the addition and application of rare earth elements (REs) such as Ce, Y, and La in superalloys has been widely studied, but these reports focus on single crystal or cast superalloys. The addition of REs purifies the alloy by reacting with impurities such as O, N, and S in the alloy melt. REs also concentrate at grain boundaries, strengthening them. Furthermore, REs enhance the adhesion between the oxide film and the alloy matrix, improving the alloy's oxidation resistance. While the service performance of RE single crystal and cast superalloys has been significantly improved, the use of REs to improve the forging properties of high-temperature-resistant, difficult-to-deform superalloys remains rare.

[0005] Because rare earth elements are highly active and yields are low during smelting, existing technologies have addressed the problem of rare earth superalloy ingot smelting. Existing technologies have also developed superalloys with high oxygen contents, which exhibit excellent service performance. Although these superalloys are ultimately subjected to thermal deformation, the rare earths are primarily added through mechanical alloying powders, resulting in low production efficiency and high costs. Existing technologies have also proposed rare earth nickel-cobalt-based superalloys, but these technologies still only utilize rare earths to enhance the alloy's tensile properties at or below service temperatures.

[0006] In summary, the inventors of the present invention believe that: for the current rare earth modified nickel-based deformable high-temperature alloys, how to coordinate the grain boundary and intragranular strength of the alloy so that the temperature resistance of the nickel-based deformable high-temperature alloy can not only reach 750°C, but also have excellent hot workability, improve the yield rate of the alloy, and promote the purpose of multi-purpose alloy, is of great significance for nickel-based deformable high-temperature alloys. Summary of the Invention

[0007] In view of this, the present invention provides a nickel-based deformable high-temperature alloy and a preparation method thereof, the main purpose of which is to make the nickel-based deformable high-temperature alloy have excellent temperature bearing capacity and hot workability.

[0008] To achieve the above objectives, the present invention mainly provides the following technical solutions:

[0009] In one aspect, an embodiment of the present invention provides a nickel-based deformed high-temperature alloy, wherein the chemical composition of the nickel-based deformed high-temperature alloy is as follows, calculated by weight percentage:

[0010] Co: 15.6-23.4wt%;

[0011] Cr: 11-15wt%;

[0012] Ti: 4.75-6.25wt%;

[0013] Al: 2.25-3.00 wt%;

[0014] W: 0.0~1.2wt%;

[0015] Mo: 2.0-3.0 wt%;

[0016] C: 0.01-0.02 wt%;

[0017] Zr: 0.025-0.05wt%;

[0018] B: 0.01~0.05wt%;

[0019] Rare earth element RE: 0.2-0.5wt%;

[0020] Nb: greater than 0 and less than or equal to 0.2wt%;

[0021] Mg is greater than 0 and less than or equal to 0.02wt%;

[0022] The remainder is Ni.

[0023] Preferably, in the nickel-based deformable high-temperature alloy: the percentage ratio of the Ti element to the Al element is 1.5-2.5; and / or the sum of the percentage contents of the W element and the Mo element is ≤3.25%.

[0024] Preferably, the grain size of the nickel-based deformable high-temperature alloy is above level 8. Preferably, the difference between the maximum grain size and the minimum grain size of the nickel-based deformable high-temperature alloy is within level 3.

[0025] Preferably, the microstructure of the nickel-based wrought high-temperature alloy comprises a dispersed distribution of a small, stable γ′ phase of 100-400 nm within the grains; a micron-sized γ′ phase is distributed at the grain boundaries, and discontinuous granular carbides and granular borides (wherein the granular carbides include rare earth carbides) precipitate at the grain boundaries. Preferably, the mass fraction of the micron-sized γ′ phase in the microstructure of the nickel-based wrought high-temperature alloy is 20-30 wt %. Preferably, the size of the granular carbides is 1-15 μm; preferably, the size of the granular boride is ≤5 μm; further preferably, the combined area percentage of the discontinuous granular carbides and granular boride is 3-10%.

[0026] Preferably, the nickel-based deformed high-temperature alloy has a yield strength of ≥1050 MPa and a tensile strength of ≥1200 MPa at a temperature of 730°C; and / or the nickel-based deformed high-temperature alloy has a yield strength of ≥1000 MPa and a tensile strength of ≥1150 MPa at 750°C; and / or the nickel-based deformed high-temperature alloy has a durability of ≥200 h at 730°C / 530 MPa; and / or the nickel-based deformed high-temperature alloy has a durability of ≥150 h at 750°C / 430 MPa; and / or the nickel-based deformed high-temperature alloy has no TCP phase precipitation at 750°C / 1000 h and reaches a full oxidation resistance level at a temperature of 750°C.

[0027] Preferably, the nickel-based deformable high-temperature alloy is used to be processed into turbine disks or blades of aircraft engines.

[0028] On the other hand, the method for preparing any of the above-mentioned nickel-based deformed high-temperature alloys comprises the following steps:

[0029] Step 1) preparing an alloy ingot;

[0030] Step 2) homogenizing the high-temperature alloy ingot at a temperature of 1150-1200° C. for 10-18 hours; then subjecting the ingot to a further holding treatment at a temperature of 1100-1150° C. for 15-30 hours to generate rare earth precipitates and strengthen grain boundaries; then, directly removing the ingot from the furnace for heat treatment to obtain a deformed high-temperature alloy;

[0031] Step 3) heat-treating the deformed high-temperature alloy to obtain a nickel-based deformed high-temperature alloy.

[0032] Preferably, in the step 1), a nickel-based deformed high-temperature alloy ingot is prepared by vacuum induction melting, protective atmosphere electroslag remelting and vacuum consumable melting; preferably, in vacuum induction melting, raw materials of elements other than C, rare earth and Mg are added to a melting crucible, and after the vacuum degree is ≤0.1Pa, the electrochemical material is subjected to high-temperature refining at 1500-1650°C for 10-20min, and electromagnetic stirring is performed, and then cooled to 1350-1450°C, filled with argon, and carbon, rare earth and magnesium elements are added. After melting for 10-15min, the electroslag electrode rod is cast; preferably, in the electroslag remelting process, in order to improve the rare earth yield, 10-20wt% of rare earth oxides are added to the electroslag slag; preferably, during the vacuum induction melting step, the rare earth element RE is added in the form of one or more of the intermediate alloys Al-Ce, Ni-Ce, Al-Y, Ni-Y, Al-La, and Ni-La; and the rare earth element RE is added at the beginning of low-temperature refining; further preferably, the low-temperature refining temperature is 1400-1500°C; preferably, the Mg element is added at the beginning of low-temperature refining; preferably, the Mg element is added in the form of a Ni-Mg intermediate alloy; further preferably, the rare earth element RE is added after the Ni-Mg element is added.

[0033] Preferably, in step 2), the temperature of the heat treatment is 1050-1140°C.

[0034] Preferably, the alloy after homogenization and heat preservation treatment and before heat treatment has an elongation of ≥10% at 1080° C. and an elongation of ≥20% at 1150° C.

[0035] Preferably, in step 3), the heat treatment includes: solution treatment, first aging treatment, and second aging treatment performed in sequence; preferably, in the solution treatment step, the solution treatment temperature is 1100-1200° C., and the solution treatment time is 2-6 hours; further preferably, oil cooling to room temperature is required after the solution treatment is completed; preferably, in the first aging treatment step, the first aging treatment temperature is 600-700° C., and the first aging treatment time is 20-30 hours; preferably, in the second aging treatment step, the second aging treatment temperature is 760-800° C., and the second aging treatment time is 10-20 hours.

[0036] Compared with the prior art, the nickel-based deformed high-temperature alloy and its preparation method of the present invention have at least the following beneficial effects:

[0037] In one aspect, an embodiment of the present invention provides a nickel-based deformable high-temperature alloy having the following chemical composition, by weight percentage: Co: 15.6-23.4 wt%; Cr: 11-15 wt%; Ti: 4.75-6.25 wt%; Al: 2.25-3.00 wt%; W: 0.0-1.2 wt%; Mo: 2.0-3.0 wt%; C: 0.01-0.02 wt%; Zr: 0.025-0.05 wt%; B: 0.01-0.05 wt%; rare earth element (RE): 0.2-0.5 wt%; Nb: greater than 0 and less than or equal to 0.2 wt%; Mg: greater than 0 and less than or equal to 0.02 wt%; the balance being Ni. Furthermore, in addition to the other elements and their contents, the present invention further includes Nb, rare earth (RE), and Mg. Here, the three elements of Nb, rare earth RE, and Mg work synergistically to coordinate the grain boundary and intragranular strength, so that the temperature resistance of the nickel-based deformable high-temperature alloy can not only reach 750°C, but also have excellent hot workability. Rare earth RE can segregate at the grain boundaries and purify the grain boundaries, improving the grain boundary bonding strength. The addition of Mg is to purify the grain boundaries, reduce the burn-off of rare earth elements, and increase the rare earth element acquisition rate in the alloy. In order to coordinate the grain boundary and intragranular strength, Nb is added to increase the γ′ phase content in the grain boundaries. Nb is not easy to diffuse, making the γ′ phase more stable, thereby improving the intragranular strength. By adding three elements with set compositions, the grain boundary and intragranular strength are synergistically adjusted, so that the deformable alloy has excellent hot workability and high temperature resistance.

[0038] On the other hand, embodiments of the present invention also provide a method for preparing a nickel-based deformable superalloy. Due to the compositional design of the aforementioned nickel-based deformable superalloy, the homogenization annealing process is simplified and shortened. Specifically, the conventional homogenization system for GH4720Li alloy is a two-step annealing process: the first step is 1160±10°C for 15-20 hours, the second step is 1190±10°C for 20-30 hours, followed by furnace cooling to room temperature; then, the alloy is reheated to 1140±20°C for forging. However, the present invention, by adding rare earth elements RE, Mg, and Nb, refines dendrites and reduces or even eliminates eutectic structure, eliminating the need for the first hold at 1160±10°C. Furthermore, because the addition of RE improves the alloy's oxidation resistance, the homogenization annealing temperature can be raised to above 1190°C (preferably in the range of 1150-1200°C), shortening the hold time. The temperature is then lowered to below 1150°C in order to generate rare earth precipitation phase and strengthen the grain boundaries. At this temperature, the steel can be directly taken out of the furnace for hot forging, simplifying the hot working process.

[0039] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is the microstructure diagram of the deformed high-temperature alloy prepared in Example 1;

[0041] Figure 2 This is the microstructure diagram of the deformed high-temperature alloy prepared in Comparative Example 1;

[0042] Figure 3 This is a physical picture of the alloy disc prepared in Example 1;

[0043] Figure 4 This is a physical picture of the alloy disc prepared in Comparative Example 1. DETAILED DESCRIPTION

[0044] To further illustrate the technical means and effects employed by the present invention to achieve its intended objectives, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments. In the following description, different references to "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0045] On the one hand, an embodiment of the present invention provides a nickel-based deformable high-temperature alloy. The chemical composition of the nickel-based deformable high-temperature alloy is as follows, calculated by weight percentage: Co: 15.6~23.4wt%; Cr: 11~15wt%; Ti: 4.75~6.25wt%; Al: 2.25~3.00wt%; W: 0.0~1.2wt%; Mo: 2.0~3.0wt%; C: 0.01~0.02wt%; Zr: 0.025~0.05wt%; B: 0.01~0.05wt%; rare earth element RE: 0.2-0.5wt%; Nb: greater than 0 and less than or equal to 0.2wt%; Mg greater than 0 and less than or equal to 0.02wt%; and the balance is Ni.

[0046] Regarding the above-mentioned component design, the following explanations are required:

[0047] (1) Compared with conventional nickel-based deformable high-temperature alloys, the present invention adds Nb, rare earth RE, and Mg elements. The addition of these three elements in the present invention allows them to work synergistically to coordinate the strength between the grain boundaries and within the grains (increasing the nanoscale γ′ phase within the grains and increasing the rare earth carbides and borides at the grain boundaries), thereby enabling the nickel-based deformable high-temperature alloy to not only have a temperature resistance of 750°C but also excellent hot workability.

[0048] Rare earth elements (RE) can segregate at grain boundaries and purify them, increasing their bond strength. Mg is added to purify the grain boundaries, reduce rare earth element burnout, and increase the rare earth element yield in the alloy. To balance grain boundary and intragranular strength, Nb is added to increase the γ′ phase content at the grain boundaries. Nb also resists diffusion, making the γ′ phase more stable and thus improving intragranular strength. By adding these three elements with a defined composition, the grain boundary and intragranular strengths are synergistically adjusted, resulting in the deformed alloy possessing excellent hot workability and high temperature resistance.

[0049] (2) In order to ensure that the rare earth RE elements play their role, the content of Co and B elements in the alloy is increased to promote the formation of rare earth precipitation phase, refine the cast grains, pin the grain boundaries, and improve the thermoplasticity of the ingot. At the same time, since rare earths also have the effect of improving the oxidation resistance of the alloy, the Cr content in the alloy is reduced to improve the thermal stability of the alloy. Since the increase in Al and Ti content deteriorates the hot working properties of the alloy, the hot working properties are improved in the present invention due to the addition of RE elements, so the upper limit of the Al and Ti content in the alloy is increased. Rare earth RE elements can also play a role in solid solution strengthening. In order not to significantly increase the density of the alloy, the content of solid solution elements such as W and Mo is reduced.

[0050] (3) The alloy of the present invention adds rare earth elements RE to the nickel-based deformable high-temperature alloy and combines it with a heat treatment process to make the rare earth elements RE segregate to the grain boundaries of the coarse cast grains, thereby improving the bonding force of the grain boundaries and making the modified alloy have more excellent hot working properties.

[0051] In addition, the contents of γ' phase-forming elements Al and Ti in the alloy of the present invention are increased by a certain amount compared to GH4720Li, but the Ti / Al ratio is controlled within the range of 1.5 to 2.5 to prevent the formation of η phase, which is detrimental to performance. The W and Mo elements in the alloy play a solid solution strengthening role, but as the W and Mo contents increase, the density of the alloy also increases, so the W+Mo content in the alloy of the present invention is ≤3.25%. At the same time, in the service temperature range, a large number of surface defects such as microtwins and stacking faults will be generated in the alloy. The rare earth element RE will be concentrated around these surface defects, inhibiting defect movement and improving the medium-temperature strength and long-term service life of the alloy.

[0052] (4) In the microstructure of the nickel-based deformed high-temperature alloy of the present invention: in the microstructure of the nickel-based deformed high-temperature alloy, a small and stable γ′ phase of 100-400 nm is dispersed inside the grains; a micron-sized γ′ phase is distributed at the grain boundaries, and discontinuous granular carbides and granular borides precipitate at the grain boundaries; wherein the mass fraction of the micron-sized γ′ phase in the microstructure of the nickel-based deformed high-temperature alloy is 20-30wt%. Here, the γ′ phase inside the grain plays a role in strengthening the grain. If the grain boundaries lack the strengthening phase, it will lead to poor coordinated deformation ability between the grain and the grain boundary, making the alloy prone to intergranular cracking at high temperatures. The micron-sized γ′ phase, discontinuous carbides and borides at the grain boundaries play the role of strengthening the grain boundaries, so that the alloy has excellent high-temperature performance. It can be seen that the alloy of the present invention is strengthened both inside the grain and at the grain boundaries, so that the deformed alloy has excellent hot workability and high temperature bearing capacity.

[0053] In another aspect, embodiments of the present invention further provide a method for preparing the aforementioned nickel-based deformable high-temperature alloy, specifically as follows: vacuum induction melting, electroslag remelting, and vacuum induction melting are performed to produce a pure ingot. Since elemental rare earth RE is an active metal and easily self-ignites, rare earth RE elements are added in the form of intermediate alloys such as Al-Ce, Ni-Ce, Al-Y, Ni-Y, Al-La, and Ni-La during the low-temperature refining stage (1400-1500°C) of vacuum induction melting to improve the yield of rare earth RE elements. Mg is added via a Ni-Mg intermediate alloy; rare earth elements are added after the Ni-Mg elements are added to improve the yield of rare earth elements (Mg is substantially burned off during melting, and its content in the final ingot is ≤0.005wt%). To obtain the alloy ingot, a homogenization annealing treatment is performed at 1150-1200°C for 10-18 hours to eliminate component segregation. The ingot is then subjected to a holding treatment at 1100-1150°C for 15-30 hours to segregate the rare earth elements (RE) at the grain boundaries and enhance their bonding strength. The ingot is then removed from the furnace and hot-worked at 1050-1140°C to produce the component. The deformed alloy component undergoes a solution treatment at 1100-1120°C for 2-6 hours, followed by oil cooling to room temperature. The component then undergoes a first aging treatment at 600-700°C for 20-30 hours, followed by air cooling to room temperature. The component then undergoes a second aging treatment at 760-800°C for 10-20 hours, followed by air cooling to room temperature. The alloy has a yield strength of ≥1050MPa and a tensile strength of ≥1200MPa at 730℃, and a yield strength of ≥1000MPa and a tensile strength of ≥1150MPa at 750℃. The alloy has a lifespan of ≥200h at 730℃ / 530MPa and a lifespan of ≥150h at 750℃ / 430MPa. After long-term aging treatment at 750℃ / 1000h, no TCP phase precipitates, and the alloy reaches a fully resistant oxidation level at 750℃ (average oxidation rate <0.1g / m 2·h).

[0054] Furthermore, it should be noted that the compositional design of the nickel-based superalloy of the present invention simplifies and shortens the homogenization annealing process. Specifically, the conventional homogenization system for GH4720Li alloy involves a two-step annealing process: a first step at 1160±10°C for 15-20 hours, a second step at 1190±10°C for 20-30 hours, followed by furnace cooling to room temperature; the alloy is then reheated to 1140±20°C for forging. However, the present invention, by adding rare earth elements (RE), Mg, and Nb, refines dendrites and reduces or even eliminates eutectic structure, eliminating the need for the first hold at 1160±10°C. Furthermore, since the addition of RE improves the alloy's oxidation resistance, the homogenization annealing temperature can be raised to above 1190°C, shortening the hold time. The temperature is then lowered to below 1150°C to generate rare earth precipitation phases and strengthen grain boundaries. At this temperature, the alloy can be directly removed from the furnace for hot forging, simplifying the hot working process.

[0055] The present invention is further described below by means of specific examples:

[0056] In the following embodiments, the chemical composition of the nickel-based deformable high-temperature alloy is as follows, calculated by weight percentage: Co: 15.6-23.4wt%; Cr: 11-15wt%; Ti: 4.75-6.25wt%; Al: 2.25-3.00wt%; W: 0.0-1.2wt%; Mo: 2.0-3.0wt%; C: 0.01-0.02wt%; Zr: 0.025-0.05wt%; B: 0.01-0.05wt%; rare earth element RE: 0.2-0.5wt%; Nb: greater than 0 and less than or equal to 0.2wt%; Mg greater than 0 and less than or equal to 0.02wt%; and the balance is Ni.

[0057] The alloy compositions and contents of the embodiments of the present invention and the comparative examples are shown in Table 1:

[0058] Table 1

[0059] C Al B Cr Mo Ti W Zr Co RE Nb Mg Ni Example 1 0.02 2.5 0.025 13 2.00 6.25 1.0 0.034 20 0.2 0.05 0.02 Remain Example 2 0.02 2.5 0.03 12 2.50 5.75 0.75 0.034 18 0.35 0.10 0.015 Remain Example 3 0.02 2.5 0.04 11 3.00 5.55 0.25 0.034 15 0.5 0.20 0.01 Remain Comparative Example 1 0.02 2.5 0.025 16 3.00 5.00 1.5 0.034 14.5 -- -- -- Remain Comparative Example 2 0.02 2.5 0.025 13 2.00 6.25 1.0 0.034 20 0.2 -- -- Remain Comparative Example 3 0.02 2.5 0.025 13 2.00 6.25 1.0 0.034 20 0.2 0.05 -- Remain Comparative Example 4 0.02 2.5 0.025 13 2.00 6.25 1.0 0.034 20 0.2 -- 0.02 Remain

[0060] Example 1

[0061] This embodiment prepares a nickel-based deformed high-temperature alloy, wherein the composition of the nickel-based deformed high-temperature alloy is shown in Table 1, and mainly includes the following steps:

[0062] Step 1) preparing an alloy ingot by vacuum induction melting, protective atmosphere electroslag remelting and vacuum induction melting.

[0063] Among them, in vacuum induction melting, raw materials of elements other than C, rare earth and Mg are added to the melting crucible. After the vacuum degree is ≤0.1Pa, the electrochemical material is subjected to high-temperature refining at 1500℃ for 15 minutes and electromagnetic stirring. Then, it is cooled to 1350℃, filled with argon, and carbon, rare earth and magnesium elements are added. After melting for 15 minutes, it is cast into electroslag electrode rods.

[0064] During vacuum induction melting, Al-Ce is added to the melt wrapped in aluminum foil during low-temperature refining at 1400°C. Mg is added via a Ni-Mg master alloy.

[0065] In addition, the rare earth elements are added after the Ni-Mg elements are added.

[0066] Step 2) The alloy ingot is subjected to homogenization annealing treatment at 1150°C for 18 hours to eliminate the segregation of the ingot components; then the ingot is subjected to a heat treatment at 1100°C for 30 hours to segregate the rare earth element Ce at the grain boundaries and improve the grain boundary bonding strength. The ingot is then taken out of the furnace for hot working. The initial forging temperature is 1140°C and the final forging temperature is 1050°C. After the bars are forged, they are forged into cakes. The cakes are forged into round cakes such as Figure 3 shown.

[0067] The obtained round cake in step 3) was subjected to solution treatment at 1100℃ for 4h and then oil-cooled to room temperature, and then subjected to the first aging treatment at 650℃ for 24h and then air-cooled to room temperature, and then subjected to the second aging treatment at 760℃ for 16h and then air-cooled to room temperature to obtain a nickel-based deformed high-temperature alloy. Figure 1 shown.

[0068] from Figure 1 The grain size is uniform and fine, with the alloy containing 20 wt% of micron-sized γ′ phase (primarily distributed at grain boundaries). The average grain size is 8, with γ′ phase 100-300 nm within the grains. Discontinuous granular carbides and borides precipitate at the grain boundaries. The carbide particles are 1-15 μm in size; the boride particles are ≤5 μm. The combined area percentage of the discontinuous granular carbides and borides is 3-10%.

[0069] The nickel-based deformed high-temperature alloy prepared in this embodiment was subjected to performance tests, and the test results are shown in Table 2. The nickel-based deformed high-temperature alloy prepared in this embodiment has a yield strength of 1105MPa and a tensile strength of 1278MPa at a temperature of 730°C; a yield strength of 1048MPa and a tensile strength of 1245MPa at a temperature of 750°C. The endurance life in a 730°C / 530MPa environment is 210h, and the endurance life in a 750°C / 430MPa environment is 185h. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates in the alloy, and it reaches a fully anti-oxidation level at 750°C (average oxidation rate 0.05g / m 2 ·h).

[0070] Example 2

[0071] This embodiment prepares a nickel-based deformed high-temperature alloy, wherein the composition of the nickel-based deformed high-temperature alloy is shown in Table 1, and mainly includes the following steps:

[0072] Step 1) preparing an alloy ingot by vacuum induction melting, protective atmosphere electroslag remelting and vacuum induction melting.

[0073] In vacuum induction melting, raw materials other than carbon, rare earth elements, and magnesium are added to a crucible. After the vacuum reaches ≤0.1 Pa, the material is subjected to high-temperature refining at 1650°C for 15 minutes with electromagnetic stirring. The material is then cooled to 1450°C, filled with argon, and carbon, rare earth elements, and magnesium are added. After melting for 10 minutes, it is cast into electroslag electrode rods. During the electroslag remelting process, 15wt% of rare earth oxides are added to the slag to improve the rare earth recovery rate.

[0074] During vacuum induction melting, Al-Y is added to the melt wrapped in aluminum foil during low-temperature refining at 1450°C. Mg is added via a Ni-Mg master alloy.

[0075] In addition, the rare earth elements are added after the Ni-Mg elements are added.

[0076] Step 2) The alloy ingot is subjected to homogenization annealing treatment at 1180°C for 15 hours to eliminate ingot component segregation; then, the ingot is subjected to a holding treatment at 1130°C for 25 hours to segregate the rare earth element RE at the grain boundaries and improve the grain boundary bonding strength. The ingot is then removed from the furnace for hot working, with the initial forging temperature of 1140°C and the final forging temperature of 1050°C. After the bar is forged, it is subjected to upsetting.

[0077] The round cake obtained in step 3) was solution treated at 1110°C for 6 hours and then oil-cooled to room temperature, further subjected to a first aging treatment at 600°C for 30 hours and then air-cooled to room temperature, and then subjected to a second aging treatment at 780°C for 10 hours and then air-cooled to room temperature to obtain a nickel-based deformed high-temperature alloy.

[0078] The alloy prepared in this example has uniform and fine grains, with an average grain size of 9. The alloy contains 25 wt% of micron-sized γ′ phase (primarily distributed at grain boundaries). Furthermore, the grains contain 100-300 nm of γ′ phase within them, and discontinuous granular carbides and borides precipitate at the grain boundaries.

[0079] The nickel-based deformed high-temperature alloy prepared in this embodiment was subjected to performance tests, and the test results are shown in Table 2. The nickel-based deformed high-temperature alloy prepared in this embodiment has a yield strength of 1125MPa and a tensile strength of 1345MPa at a temperature of 730°C; a yield strength of 1080MPa and a tensile strength of 1293MPa at a temperature of 750°C. The alloy has a long-term lifespan of 240h in a 730°C / 530MPa environment and a long-term lifespan of 198h in a 750°C / 430MPa environment. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates in the alloy, and it reaches a fully anti-oxidation level at 750°C (average oxidation rate 0.03g / m 2 ·h).

[0080] Example 3

[0081] This embodiment prepares a nickel-based deformed high-temperature alloy, wherein the composition of the nickel-based deformed high-temperature alloy is shown in Table 1, and mainly includes the following steps:

[0082] Step 1) preparing an alloy ingot by vacuum induction melting, electroslag remelting and vacuum induction melting.

[0083] A nickel-based deformed high-temperature alloy ingot is prepared by vacuum induction melting, protective atmosphere electroslag remelting and vacuum consumable melting; preferably, in vacuum induction melting, raw materials of elements other than C, rare earth and Mg are added to a melting crucible, and after the vacuum degree is ≤0.1Pa, the electrochemical material is subjected to high-temperature refining at 1600°C for 15 minutes and electromagnetic stirring, and then cooled to 1400°C, filled with argon, and carbon, rare earth and magnesium elements are added. After melting for 13 minutes, it is cast into an electroslag electrode rod.

[0084] During vacuum induction melting, Al-La is added to the melt wrapped in aluminum foil during low-temperature refining at 1500°C. Mg is added via a Ni-Mg master alloy.

[0085] In addition, the rare earth elements are added after the Ni-Mg elements are added.

[0086] Step 2) The alloy ingot is subjected to homogenization annealing treatment at a temperature of 1200° C. for 10 hours to eliminate ingot component segregation; then, the ingot is subjected to a holding treatment at a temperature of 1150° C. for 15 hours to cause the rare earth element RE to segregate at the grain boundaries and improve the grain boundary bonding strength. The ingot is then removed from the furnace for hot working, with the initial forging temperature of 1140° C. and the final forging temperature of 1050° C. After the bar is forged, it is subjected to upsetting.

[0087] The round cake obtained in step 3) was solution treated at 1120°C for 2 hours and then oil-cooled to room temperature. It was further subjected to a first aging treatment at 700°C for 30 hours and then air-cooled to room temperature. It was then subjected to a second aging treatment at 800°C for 20 hours and then air-cooled to room temperature to obtain a nickel-based deformed high-temperature alloy.

[0088] The alloy prepared in this example has uniform and fine grains, with an average grain size of 9.5 Å. The alloy contains 30 wt% of micron-sized γ′ phase (primarily distributed at grain boundaries). Furthermore, the grains contain 100-300 nm of γ′ phase within them, and discontinuous granular carbides and borides precipitate at the grain boundaries.

[0089] The nickel-based deformed high-temperature alloy prepared in this embodiment was subjected to performance tests, and the test results are shown in Table 2. The nickel-based deformed high-temperature alloy prepared in this embodiment has a yield strength of 1135MPa and a tensile strength of 1420MPa at a temperature of 730°C; a yield strength of 1100MPa and a tensile strength of 1310MPa at a temperature of 750°C. The alloy has a long-term lifespan of 256h in a 730°C / 530MPa environment and a long-term lifespan of 201h in a 750°C / 430MPa environment. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates in the alloy, and it reaches a fully anti-oxidation level at 750°C (average oxidation rate 0.01g / m 2 ·h).

[0090] Comparative Example 1

[0091] Comparative Example 1: A pure GH4720Li alloy ingot was prepared in the following main steps:

[0092] Pure GH4720Li alloy ingots were prepared by vacuum induction melting, electroslag remelting and vacuum induction melting. The alloy ingots obtained by triple smelting were kept at 1160℃ for 20h, then heated to 1190℃ and kept at this temperature for 30h for homogenization annealing to eliminate the segregation of ingot components; cooled to room temperature with the furnace; then reheated to 1140±20℃ for hot working, with the initial forging temperature of 1140℃ and the final forging temperature of 1100℃. After forging the bars, they were forged into cakes, and the round cakes were forged into round cakes. Figure 4 shown.

[0093] The obtained round cake was subjected to solution treatment at 1100℃ / 4h and then oil-cooled to room temperature, further subjected to the first step aging treatment at 650℃ / 24h and then air-cooled to room temperature, and then subjected to the second step aging treatment at 760℃ / 16h and then air-cooled to room temperature to obtain GH4720Li deformed high-temperature alloy. Among them, the microstructure of GH4720Li deformed high-temperature alloy is as follows Figure 2 As shown. Figure 2 As shown, the alloy prepared in Comparative Example 1 contains about 15 wt% of micron-sized γ′ phase, and the grain size of the alloy is level 7. The boride and carbide precipitation sizes of the alloy prepared in Comparative Example 1 are 1-2 μm, and the sum of the area percentage contents is ≤2%.

[0094] The performance test results of the GH4720Li deformable high-temperature alloy are shown in Table 2. Among them, the yield strength of the alloy at 730°C is 980MPa and the tensile strength is 1100MPa; the yield strength at 750°C is 946MPa and the tensile strength is 1001MPa. The alloy has a long-term durability of 166h at 730°C / 530MPa and a long-term durability of 90h at 750°C / 430MPa. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates, and the alloy reaches the oxidation resistance level at 750°C (average oxidation rate 0.12g / m 2 ·h).

[0095] Here, the main reason for the poor performance of the alloy prepared in Comparative Example 1 is that no rare earth or Mg elements are added, resulting in the intragranular strength being higher than the grain boundary strength at high temperatures (service temperature and processing temperature), so that the overall strength of the alloy is reduced and the service life is shortened.

[0096] Comparative Example 2

[0097] Comparative Example 2: A nickel-based deformed high-temperature alloy was prepared. The composition of the nickel-based deformed high-temperature alloy is shown in Table 1. The method mainly includes the following steps:

[0098] Pure alloy ingots were produced using vacuum induction melting, electroslag remelting, and vacuum induction melting. The resulting ingots were held at 1160°C for 18 hours, then heated to 1190°C for 25 hours for homogenization annealing to eliminate component segregation. They were then removed from the furnace for hot working, with initial forging temperatures of 1140°C and final forging temperatures of 1100°C. After forging, the bars were forged and then formed into cakes.

[0099] The resulting round cake was solution treated at 1100°C for 4 hours and then oil-cooled to room temperature. It then underwent a first aging treatment at 650°C for 24 hours and then air-cooled to room temperature. It then underwent a second aging treatment at 760°C for 16 hours and then air-cooled to room temperature to produce a deformed high-temperature alloy. The alloy prepared in Comparative Example 2 contained approximately 10% by weight of micron-sized γ′ phase and had an average grain size of 6.

[0100] The performance test results of the deformed high-temperature alloy are shown in Table 2. Among them, the yield strength of the alloy at 730°C is 1015MPa and the tensile strength is 1120MPa; the yield strength at 750°C is 970MPa and the tensile strength is 1050MPa. The alloy has a long-term durability of 170h at 730°C / 530MPa and a long-term durability of 100h at 750°C / 430MPa. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates, and the alloy reaches the oxidation resistance level at 750°C (average oxidation rate 0.18g / m 2 ·h).

[0101] Comparative Example 3

[0102] Comparative Example 3: A nickel-based deformed high-temperature alloy was prepared. The composition of the nickel-based deformed high-temperature alloy is shown in Table 1. The method mainly includes the following steps:

[0103] Pure alloy ingots were produced using vacuum induction melting, electroslag remelting, and vacuum induction melting. The resulting alloy ingots were held at 1160°C for 20 hours, then heated to 1190°C for 30 hours for homogenization annealing to eliminate component segregation. They were then removed from the furnace for hot working, with initial forging temperatures of 1140°C and final forging temperatures of 1100°C. After forging, the bars were forged and then formed into cakes.

[0104] The resulting round cake was solution treated at 1100°C for 4 hours and then oil-cooled to room temperature. It then underwent a first aging treatment at 650°C for 24 hours and then air-cooled to room temperature. It then underwent a second aging treatment at 760°C for 16 hours and then air-cooled to room temperature to produce a deformed high-temperature alloy. The alloy prepared in Comparative Example 3 contained approximately 17% by weight of micron-sized γ′ phase and had an average grain size of 7.

[0105] The performance test results of the deformed high-temperature alloy are shown in Table 2. Among them, the yield strength of the alloy at 730°C is 1020MPa and the tensile strength is 1135MPa; the yield strength at 750°C is 980MPa and the tensile strength is 1074MPa. The alloy has a long-term durability of 185h at 730°C / 530MPa and a long-term durability of 134h at 750°C / 430MPa. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates, and the alloy reaches the oxidation resistance level at 750°C (average oxidation rate 0.16g / m 2 ·h).

[0106] Comparative Example 4

[0107] Comparative Example 4: A nickel-based deformed high-temperature alloy was prepared. The composition of the nickel-based deformed high-temperature alloy is shown in Table 1. The method mainly includes the following steps:

[0108] Pure alloy ingots were produced using vacuum induction melting, electroslag remelting, and vacuum induction melting. The resulting alloy ingots were held at 1160°C for 15 hours, then heated to 1190°C for 30 hours for homogenization annealing to eliminate component segregation. They were then removed from the furnace for hot working, with initial forging temperatures of 1140°C and final forging temperatures of 1100°C. After forging, the bars were forged and then formed into cakes.

[0109] The resulting round cake was solution treated at 1100°C for 4 hours and then oil-cooled to room temperature. It then underwent a first aging treatment at 650°C for 24 hours and then air-cooled to room temperature. It then underwent a second aging treatment at 760°C for 16 hours and then air-cooled to room temperature to produce a deformed high-temperature alloy. The alloy prepared in Comparative Example 4 contained approximately 10% by weight of micron-sized γ′ phase and had an average grain size of 6.

[0110] The performance test results of the deformed high-temperature alloy are shown in Table 2. Among them, the yield strength of the alloy at 730°C is 1017MPa and the tensile strength is 1119MPa; the yield strength at 750°C is 973MPa and the tensile strength is 1055MPa. The alloy has a long-term durability of 179h at 730°C / 530MPa and a long-term durability of 122h at 750°C / 430MPa. After long-term aging treatment at 750°C / 1000h, no TCP phase precipitates, and the alloy reaches the oxidation resistance level at 750°C (average oxidation rate 0.15g / m 2 ·h).

[0111] Table 2 shows the performance test data of the nickel-based deformed high-temperature alloys prepared in Examples 1-3 and Comparative Examples 1-4.

[0112] Table 2

[0113]

[0114] It can be seen from Table 2 that the performance of the nickel-based deformed high-temperature alloy prepared in this embodiment is significantly better than that of the deformed high-temperature alloys prepared in Comparative Example 1 (conventional GH4720Li deformed high-temperature alloy) and Comparative Examples 2-4.

[0115] In summary, the nickel-based deformable superalloy designed in this invention incorporates Nb, rare earth elements RE, and Mg, and adjusts the contents of other elements accordingly. This allows these three elements to work synergistically, coordinating grain boundary and intragranular strength, improving the alloy's hot working properties, promoting dynamic recrystallization, and inhibiting grain growth. This results in a hot working temperature window wider than that of GH4720Li alloy, and produces intact disks free of surface cracks. Furthermore, the alloy exhibits significantly higher strength at 750°C than GH4720Li alloy, and the addition of rare earth elements further enhances its oxidation resistance.

[0116] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiment based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A nickel-based deformed high-temperature alloy, characterized in that: The nickel-based deformable high-temperature alloy is composed of the following chemical components by weight percentage: Co: 15.6-23.4wt%; Cr: 11-15wt%; Ti: 5.55-6.25wt%; Al: greater than or equal to 2.25 and less than 3.00 wt%; W: 0.25~1.2wt%; Mo: 2.0-3.0 wt%; C: 0.01-0.02 wt%; Zr: 0.025-0.05wt%; B: 0.01~0.05wt%; Rare earth element RE: 0.2-0.5wt%; Nb: greater than 0 and less than or equal to 0.2wt%; Mg: 0.01-0.02wt%; The remainder is Ni; Wherein, in the nickel-based deformable high-temperature alloy: the percentage ratio of the Ti element to the Al element is 1.5 to 2.5; the sum of the percentage contents of the W element and the Mo element is ≤3.25%; In the microstructure of the nickel-based deformed high-temperature alloy, a fine and stable γ′ phase of 100-400 nm is dispersed inside the grains; a micron-sized phase is distributed at the grain boundaries, and discontinuous particulate carbides and particulate borides precipitate at the grain boundaries; the mass fraction of the micron-sized γ′ phase in the microstructure of the nickel-based deformed high-temperature alloy is 20-30 wt%; the size of the particulate carbides is 1-15 μm; and the size of the particulate boride is ≤5 μm.

2. The nickel-based deformable high-temperature alloy according to claim 1, characterized in that: The grain size of the nickel-based deformable high-temperature alloy is above level 8.

3. The nickel-based deformable high-temperature alloy according to claim 2, characterized in that: The difference between the maximum grain size and the minimum grain size of the nickel-based deformable high-temperature alloy is within 3 levels.

4. The nickel-based deformable high-temperature alloy according to claim 1, characterized in that: The sum of the area percentages of the discontinuous particulate carbides and particulate borides is 3-10%.

5. The nickel-based deformable high-temperature alloy according to claim 1, characterized in that: The nickel-based deformable high-temperature alloy has a yield strength of ≥1050 MPa and a tensile strength of ≥1200 MPa at 730°C; and / or The nickel-based deformable high-temperature alloy has a yield strength of ≥1000 MPa and a tensile strength of ≥1150 MPa at 750°C; and / or The nickel-based deformable high-temperature alloy has a durability of ≥200 h at 730° C. / 530 MPa; and / or; The nickel-based deformable high-temperature alloy has a lifespan of ≥150h at 750°C / 430MPa; and / or The nickel-based deformable high-temperature alloy has no TCP phase precipitation under the condition of 750° C. / 1000 h, and reaches a complete oxidation resistance level at a temperature of 750° C.

6. The nickel-based deformable high-temperature alloy according to any one of claims 1 to 5, characterized in that: The nickel-based deformable high-temperature alloy is a turbine disk or blade of an aero-engine.

7. The method for preparing the nickel-based deformed high-temperature alloy according to any one of claims 1 to 6, characterized in that: It includes the following steps: Step 1) preparing an alloy ingot; Step 2) homogenizing the high-temperature alloy ingot at a temperature of 1150-1200° C. for 10-18 hours; then subjecting the ingot to a further holding treatment at a temperature of 1100-1150° C. for 15-30 hours to generate rare earth precipitates and strengthen grain boundaries; then, directly removing the ingot from the furnace for heat treatment to obtain a deformed high-temperature alloy; Step 3) heat-treating the deformed high-temperature alloy to obtain a nickel-based deformed high-temperature alloy.

8. The method for preparing the nickel-based deformed high-temperature alloy according to claim 7, characterized in that: In said step 1): Nickel-based deformed high-temperature alloy ingots were prepared by vacuum induction melting, protective atmosphere electroslag remelting and vacuum consumable melting.

9. The method for preparing the nickel-based deformed high-temperature alloy according to claim 8, characterized in that: In said step 1): In vacuum induction melting, raw materials of elements other than C, rare earth and Mg are added to the melting crucible. After the vacuum degree is ≤0.1Pa, the electrochemical material is subjected to high-temperature refining at 1500-1650℃ for 10-20min and electromagnetic stirring. Then, it is cooled to 1350-1450℃, filled with argon, and carbon, rare earth and magnesium elements are added. After melting for 10-15min, it is cast into electroslag electrode rods.

10. The method for preparing the nickel-based deformed high-temperature alloy according to claim 8, characterized in that: In said step 1): During the electroslag remelting process, in order to improve the rare earth recovery rate, 10-20wt% of rare earth oxides need to be added to the electroslag slag.

11. The method for preparing a nickel-based deformed high-temperature alloy according to claim 8, characterized in that: In said step 1): During the vacuum induction melting step, the rare earth element RE is added in the form of one or more of the intermediate alloys Al-Ce, Ni-Ce, Al-Y, Ni-Y, Al-La, and Ni-La; and the rare earth element RE is added at the beginning of low-temperature refining.

12. The method for preparing a nickel-based deformed high-temperature alloy according to claim 11, characterized in that: In the step 1), the temperature of low-temperature refining is 1400-1500°C.

13. The method for preparing the nickel-based deformed high-temperature alloy according to claim 8, characterized in that: In said step 1): Mg element is added at the beginning of low temperature refining.

14. The method for preparing a nickel-based deformed high-temperature alloy according to claim 13, wherein: In the step 1), the Mg element is added in the form of a Ni-Mg master alloy.

15. The method for preparing a nickel-based deformed high-temperature alloy according to claim 14, wherein: In the step 1), the rare earth element RE is added after the Ni-Mg element is added.

16. The method for preparing the nickel-based deformed high-temperature alloy according to claim 7, characterized in that: In the step 2): The heat treatment temperature is 1050-1140°C; and / or The elongation of the alloy after homogenization and holding treatment and before heat treatment at 1080°C is ≥10%, and the elongation at 1150°C is ≥20%.

17. The method for preparing the nickel-based deformed high-temperature alloy according to claim 7, characterized in that: In the step 3), the heat treatment includes: solution treatment, first aging treatment, and second aging treatment performed in sequence.

18. The method for preparing a nickel-based deformed high-temperature alloy according to claim 17, wherein: In the solution treatment step: the solution treatment temperature is 1100-1200° C., and the solution treatment time is 2-6 hours; further preferably, oil cooling to room temperature is required after the solution treatment is completed.

19. The method for preparing a nickel-based deformed high-temperature alloy according to claim 17, wherein: In the first aging treatment step, the temperature of the first aging treatment is 600-700° C., and the time of the first aging treatment is 20-30 hours.

20. The method for preparing a nickel-based deformed high-temperature alloy according to claim 17, wherein: In the second aging treatment step: the temperature of the second aging treatment is 760-800° C., and the time of the second aging treatment is 10-20 hours.

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