A cobalt-based deformed high-temperature alloy and a preparation method thereof

Abstract

The invention relates to a cobalt-based deformable high-temperature alloy and a preparation method thereof. The main technical scheme adopted is: a cobalt-based deformable high-temperature alloy, which comprises the following chemical components, by weight percentage: C 0.02-0.1%, Al 2-5%, B 0.005-0.05%, Cr 12-18%, Mo 3-6%, Ti 5-7%, W 1.5-5%, Zr 0.005-0.05%, Ta 1-2%, Ni 25-40%, Mn≤0.1%, Fe≤0.3%, and the balance is Co and unavoidable impurity elements. The preparation method of the cobalt-based deformed high-temperature alloy comprises the following steps: subjecting the alloy raw materials to vacuum induction melting, electroslag remelting, and vacuum consumable melting in sequence to obtain an alloy ingot; subjecting the alloy ingot to blank forging to obtain an alloy bar; subjecting the alloy bar to plastic forming treatment to form an alloy of a set shape; subjecting the alloy of the set shape to solid solution and aging treatment to obtain a cobalt-based deformed high-temperature alloy. The cobalt-based deformed high-temperature alloy proposed by the present invention has excellent performance and can be used as the preferred material for aircraft engine and gas turbine disks.

Description

Technical Field

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

[0002] With the development and progress of science and technology, the outlet temperature of power systems (engines and gas turbines) is getting higher and higher, so the structural materials they require are also required to have higher temperature bearing capacity. Deformed high-temperature alloys are the main preparation materials for aircraft engines and gas turbines. Among them, the service environment of deformed high-temperature alloys used to prepare turbine disks is the most demanding. At present, the deformed high-temperature alloys used for aircraft engine turbine disks are mainly nickel-based high-temperature alloys, and the alloy grades have gradually developed from GH4169 alloy to GH4720Li alloy. However, it is difficult for deformed high-temperature alloys used for turbine disks to serve for a long time at temperatures above 750°C.

[0003] Cobalt-based high-temperature alloys have higher melting points, better thermal corrosion resistance and better welding performance than nickel-based high-temperature alloys. At present, there are many related technologies for cobalt-based high-temperature alloys. For example, Patent Publication No. CN103045910B discloses a high-temperature stable γ′ phase-strengthened cobalt-based high-temperature alloy and its preparation method, wherein the cobalt-based high-temperature alloy contains a γ′ phase volume fraction greater than 65%, but it is a cast cobalt-based high-temperature alloy (non-deformed high-temperature alloy); Patent Publication No. CN108315600B discloses a γ′ phase-strengthened cobalt-based high-temperature alloy and its preparation method, wherein the volume fraction of the γ′ phase in the disclosed cobalt-based alloy is greater than 65%. The alloy under this composition is a cast alloy, so it is even more difficult to perform plastic deformation processing, and it is impossible to use this alloy to prepare turbine disks. At the same time, the W content in the alloy is high, so the density of the alloy reaches 9g / cm 3 Patent publication number CN108385010B discloses a low-density, high-organization stability cobalt-based high-temperature alloy and its preparation method, which reduces the alloy density by 0.2-0.5g / cm by reducing the W content. 3 However, the cobalt-based alloy in this invention still utilizes the heat treatment of the cast structure, and its mechanical performance index is only measured by hardness, while the turbine disk alloy requires comprehensive high-strength properties (strength, endurance life, creep resistance and fatigue life, etc.).

[0004] In addition, there are many related technologies for cobalt-based deformable high-temperature alloys. For example, patent publication number CN110592432B discloses a cobalt-based deformable high-temperature alloy and a preparation method thereof, which makes the cobalt-based deformable high-temperature alloy have excellent hot working properties by reducing the degree of alloying, but the performance of the cobalt-based deformable high-temperature alloy obtained by this technology is not as good as that of the GH4720Li alloy; patent publication number CN109321786B discloses a cobalt-based high-temperature alloy and a preparation method thereof, which reduces the alloy density by reducing the W content. At the same time, compared with the cast cobalt-based high-temperature alloy, the volume fraction of the γ′ phase in the alloy is reduced, but the alloy contains Nb elements, which is easy to produce casting segregation that cannot be eliminated. At the same time, the W+Ta content in the alloy is still high and it is not easy to reduce the density of the alloy. The γ′ phase in the alloy is evenly dispersed and not easy to be plastically processed.

[0005] In summary, cobalt-based deformed high-temperature alloys have great application potential in the field of aircraft engine turbine disk preparation. At present, it is urgent to design a cobalt-based deformed high-temperature alloy that can produce high-strength cobalt-based deformed high-temperature alloys under the premise of plastic processing, so as to serve as the first material for aircraft engine and gas turbine disks (such as turbine disks). Summary of the invention

[0006] In view of this, the present invention provides a cobalt-based deformed high-temperature alloy and a preparation method thereof. The main purpose is to provide or prepare a cobalt-based deformed high-temperature alloy, which has excellent properties and can be used as a potential material for aircraft engine and gas turbine disks (such as turbine disks).

[0007] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0008] In one aspect, an embodiment of the present invention provides a cobalt-based deformed high-temperature alloy, wherein the cobalt-based deformed high-temperature alloy comprises the following chemical components in terms of weight percentage:

[0009] C 0.02-0.1%, Al 2-5%, B 0.005-0.05%, Cr 12-18%, Mo 3-6%, Ti 5-7%, W1.5-5%, Zr 0.005-0.05%, Ta 1-2%, Ni 25-40%, Mn≤0.1%, Fe≤0.3%, the balance is Co and unavoidable impurity elements.

[0010] Preferably, the weight percentage ratio of Ti to Al is 1.5-2.2.

[0011] Preferably, the sum of the weight percentages of Al, Ti and Ta is 9-12%.

[0012] Preferably, the sum of the weight percentages of W+Mo is 4.5-8%.

[0013] Preferably, in the cobalt-based deformable high-temperature alloy, γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 50-60%.

[0014] Preferably, the cobalt-based deformable high-temperature alloy has a yield strength of ≥1000 MPa and a tensile strength of ≥1050 MPa at a temperature of 750°C; preferably, the cobalt-based deformable high-temperature alloy has a yield strength of ≥850 MPa and a tensile strength of ≥950 MPa at a temperature of 850°C.

[0015] Preferably, the cobalt-based deformable high-temperature alloy has a durability life of ≥100 h in an environment of 750°C and 630 MPa, and the creep residual strain of the cobalt-based deformable high-temperature alloy in this environment at 100 h is ≤0.2%; preferably, the cobalt-based deformable high-temperature alloy has a durability life of ≥20 h in an environment of 850°C and 400 MPa.

[0016] Preferably, the cobalt-based deformable high-temperature alloy has no TCP phase precipitation after long-term aging treatment at 750° C. for 2000 h; and the cobalt-based deformable high-temperature alloy has no TCP phase precipitation after long-term aging treatment at 850° C. for 1000 h.

[0017] Preferably, the room temperature density of the cobalt-based deformable high-temperature alloy is ≤8.55 g / cm 3 .

[0018] On the other hand, the method for preparing the cobalt-based deformable high-temperature alloy described in any one of the above items comprises the following steps:

[0019] Melting step: the alloy raw material is subjected to the first step of vacuum induction melting, the second step of electroslag remelting, and the third step of vacuum consumable melting to obtain an alloy ingot;

[0020] Deformation step: performing blank forging on the alloy ingot to obtain alloy bars; performing plastic forming treatment on the alloy bars to form an alloy of a set shape;

[0021] Solution treatment and aging step: performing solution treatment and aging treatment on the alloy of the set shape to obtain the cobalt-based deformable high-temperature alloy.

[0022] Preferably, in the smelting step: the alloy ingots obtained after each smelting step of the first step of vacuum induction melting, the second step of electroslag remelting, and the third step of vacuum consumable melting are all subjected to annealing treatment; preferably, the temperature of the annealing treatment is 1100-1250°C; preferably, the heating rate during the annealing treatment is ≤60°C / h; preferably, the alloy ingot after annealing treatment is cooled with the furnace to no more than 200°C and then taken out of the furnace.

[0023] Preferably, in the deformation step:

[0024] The temperature of the blank forging is 1120-1200° C.; and / or

[0025] The open forging is open forging of 5-12 fires; preferably, the open forging of the first 1-7 fires is forging at a temperature of 1150-1200°C, preferably rush forging (regarding the term "rush forging", it is a professional term on the forging site, which means completing the forging in the shortest time (30min) to prevent serious temperature loss and ensure that the forging is near isothermal deformation), and the temperature of the open forging of the last 1-5 fires is 1120-1150°C. Preferably, in the open forging of the last 1-5 fires, the initial forging temperature is reduced by 5-10°C every 1-3 fires. (It should be noted here that the temperature at the beginning of each fire forging is called the initial forging temperature, and each fire has an initial forging temperature). By controlling the initial temperature to decrease by 5-10°C every 1-3 fires, the alloy is fully recrystallized while preventing grain growth, and ultimately a fine-grained structure is obtained; and / or

[0026] The average grain size of the alloy rod is 10-50 μm; and / or

[0027] The elongation of the alloy rod at a temperature of 1080° C. is ≥60%, and the elongation at a temperature of 1150° C. is ≥30%.

[0028] Preferably, in the deformation step: the temperature of the plastic forming treatment is 1080-1150° C.; and / or the plastic forming method includes one or more of rolling, forging and extrusion.

[0029] Preferably, the solution treatment and aging steps include:

[0030] Solution treatment: The alloy of the set shape is subjected to solution treatment at a temperature of 1120-1180°C for 4-8 hours, and then air-cooled to room temperature to obtain the alloy after solution treatment;

[0031] The first step of aging treatment: the alloy after the solution treatment is subjected to the first step of aging treatment at a temperature of 650-850°C for 4-28h, and then air-cooled to room temperature to obtain the alloy after the first step of aging treatment;

[0032] Second step aging treatment: the alloy after the first step aging treatment is subjected to the second step aging treatment at a temperature of 760-850°C for 10-20h, and air-cooled to room temperature to obtain a cobalt-based deformed high-temperature alloy.

[0033] Compared with the prior art, the cobalt-based deformed high-temperature alloy and the preparation method thereof of the present invention have at least the following beneficial effects:

[0034] On the one hand, the embodiment of the present invention provides a cobalt-based deformable high-temperature alloy. Regarding its chemical composition, a set content of Ni element is added to the Co matrix, which can react with the set content of Al, Ti and Ta elements to generate a mixed precipitate phase γ′-(Co, Ni) 3 (Ti,Al,Ta); while the mixed precipitate phase γ′-(Co,Ni) 3 (Ti,Al,Ta) ratio to γ′-Ni in nickel-based superalloys 3 The Al phase has better hot working properties than the γ′-Co in the Co-based high temperature alloy. 3 The Al phase has higher thermal stability; further, on the basis of the above, by setting the weight percentage ratio of Ti to Al to 1.5-2.2 and making the sum of the weight percentages of Al, Ti and Ta to 9-12%, the alloy has a sufficiently high γ′ phase while still having low density and thermal stability, and is not easy to form TCP harmful phase; in addition, due to the reduction of W element in the alloy, the alloy has low density, but in order to ensure a good solid solution strengthening effect, a Mo element with a weight percentage of 3-6% is added; on the basis of the above, in order to improve the antioxidant effect of the alloy and prevent the formation of TCP phase, a Cr element with a weight percentage of 12-18% is also added to the alloy.

[0035] On the other hand, an embodiment of the present invention also proposes a preparation method of a cobalt-based deformable high-temperature alloy, which is mainly prepared by triple smelting (vacuum induction melting, electroslag remelting, and vacuum consumable melting), and annealing is performed after each smelting step to melt a pure alloy ingot; the alloy ingot is then deformed, specifically, firstly performing open forging (through the corresponding open forging process, a rod with uniform structure and fine grains can be obtained, and further plastic forming can be performed at a temperature of 1080-1150°C), and then plastic forming into a set shape; finally, the alloy of the set shape is subjected to solid solution and aging treatment to obtain a cobalt-based deformable high-temperature alloy.

[0036] In summary, the cobalt-based deformed high-temperature alloy proposed and prepared by the present invention has high organizational stability, can maintain organizational stability for a long time at 750-850°C, and will not have TCP phase; at the same time, the cobalt-based deformed high-temperature alloy has a lower density than the traditional cobalt-based high-temperature alloy, and has machinability, is suitable for processing and forming to prepare high-temperature structural parts, and has excellent creep resistance and strong high-temperature mechanical properties; the high-strength cobalt-based deformed high-temperature alloy with comprehensive mechanical properties proposed by the present invention is the preferred material for aircraft engines and gas turbine disks resistant to temperatures above 750°C, and can especially be used as a potential turbine disk material resistant to 850°C.

[0037] 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 in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The γ′ phase morphology of the cobalt-based deformed high-temperature alloy prepared in Example 1;

[0039] Figure 2 The grain morphology of the cobalt-based deformed high-temperature alloy prepared in Example 1;

[0040] Figure 3 The microstructure of the as-cast alloy (alloy ingot) prepared in Example 1 after aging treatment at 750°C / 2000h;

[0041] Figure 4 The microstructure of the cast alloy (alloy ingot) prepared in Example 1 after aging treatment at 850°C / 1000h. DETAILED DESCRIPTION

[0042] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0043] Since cobalt-based high-temperature alloys contain dozens of alloying elements, the role of each element is not a single superposition. Therefore, the present invention considers the comprehensive properties of the alloy such as high-temperature strength, creep resistance, endurance, hot corrosion resistance, fatigue life and high-temperature structural stability, and prepares a high volume fraction of γ′-(Co,Ni) under the premise of plastic processing. 3 (Ti, Al, Ta) phase strengthened cobalt-based deformed high temperature alloy, the alloy is a potential 850°C resistant turbine disk material. The specific scheme of the present invention is as follows:

[0044] On the one hand, the embodiment of the present invention provides a cobalt-based deformable high-temperature alloy, which includes the following chemical components by weight percentage: C 0.02-0.1%, Al 2-5%, B 0.005-0.05%, Cr 12-18%, Mo 3-6%, Ti 5-7%, W 1.5-5%, Zr 0.005-0.05%, Ta 1-2%, Ni 25-40%, Mn≤0.1%, Fe≤0.3%, and the balance is Co and unavoidable impurity elements. Preferably, the weight percentage ratio of Ti to Al is 1.5-2.2; the sum of the weight percentages of Al, Ti, and Ta is 9-12%; and the sum of the weight percentages of W+Mo is 4.5-8%.

[0045] Here, the cobalt-based deformable high-temperature alloy proposed in the embodiment of the present invention is formed by adding Ni element to the Co matrix, and the Ni element reacts with Al, Ti and Ta elements to form a mixed precipitate phase γ′-(Co, Ni) 3 (Ti,Al,Ta), while the mixed precipitate phase γ′-(Co,Ni) 3 (Ti,Al,Ta) ratio to γ′-Ni in nickel-based superalloys 3 The Al phase has better hot working properties than the γ′-Co in the Co-based high temperature alloy. 3 The Al phase has higher thermal stability. Preferably, the embodiment of the present invention sets the weight percentage ratio of Ti and Al to 1.5-2.2, and the sum of the weight percentages of Al, Ti, and Ta to 9-12%. This is to ensure that the alloy has a sufficiently high γ′ phase, while still having low density and thermal stability, and is not prone to forming TCP harmful phases. On the basis of the above, the reduction of the W element in the alloy makes the alloy have a low density, but in order to ensure a good solid solution strengthening effect, a Mo element with a weight percentage of 3-6% is added; on the basis of the above, in order to improve the antioxidant effect of the alloy and prevent the formation of TCP phase, a Cr element with a weight percentage of 12-18% is also added to the alloy.

[0046] Here, regarding the mixed precipitate phase γ′-(Co,Ni) 3 (Ti, Al, Ta): The precipitate phase in the existing deformed high-temperature alloy is γ′-Ni 3 The present invention adjusts the element composition in the alloy, replaces part of the Ni atoms with Co atoms, and replaces the Al atoms with Ti and Ta atoms to form γ′-(Co, Ni) 3 (Ti,Al,Ta) phase, with γ′-Ni 3 The crystal structure of the Al precipitated phase remains the same. However, the γ′-(Co,Ni) 3The lattice constant of the (Ti, Al, Ta) precipitate phase increases, resulting in an increase in the mismatch between the precipitate phase and the matrix, thereby increasing the strengthening effect of the precipitate phase; at the same time, these elements cause the precipitate phase itself to produce solid solution strengthening, which makes the precipitate phase hinder the enhancement of dislocation movement, thereby improving the strength of the alloy.

[0047] In addition, the composition of elements in high-temperature alloys is not only affected by the content of a single element, but the interaction between each element is also crucial. Here, the present invention is different from the alloy technology of a cobalt-based high-temperature alloy and its preparation method disclosed in CN109321786B mentioned in the background technology: in order to reduce the serious segregation during the smelting process, the present invention does not contain Nb elements in the alloy design, and Nb is also a γ' phase forming element, while the present invention forms the γ' phase through Al, Ti and Ta, and in order to prevent the formation of η phase, the present invention also limits the Al / Ti ratio. At the same time, the present invention also considers the control of alloy density, so the content of solid solution elements such as W and Mo is limited. In summary, the alloy composition range and the content relationship between the above elements have a common synergistic effect, so that the present invention finally obtains high strength, excellent creep resistance, good oxidation resistance and other comprehensive properties while ensuring that the alloy can be hot-plastic processed. However, the design of alloy elements in CN109321786B only considers the expansion of the processing window, and the service performance only considers oxidation resistance. The service performance of the alloy prepared by this method obviously does not meet the requirements of the present invention.

[0048] On the other hand, the embodiment of the present invention provides a method for preparing the above-mentioned cobalt-based deformable high-temperature alloy, which mainly includes the following steps:

[0049] 1) Melting step: The alloy raw materials are subjected to a first step of vacuum induction melting, a second step of electroslag remelting, and a third step of vacuum consumable melting to obtain an alloy ingot.

[0050] From the chemical composition of the above cobalt-based deformed high-temperature alloy, it can be known that the alloying degree of the cobalt-based deformed high-temperature alloy is high, so it is necessary to carry out the first step of vacuum induction melting, the second step of electroslag remelting and the third step of vacuum consumable melting in sequence to prepare a pure ingot; and the high alloying will inevitably cause serious component segregation in the ingot, so the residual stress of the ingot obtained by each step of melting is large, so the ingot obtained by each step of melting needs to be annealed at a temperature of 1100-1250°C, and during the annealing treatment, the heating rate is ≤60°C / h to prevent the ingot from being directly cracked and failed due to excessive stress, and after annealing, it is cooled to ≤200°C with the furnace and taken out of the furnace. Preferably, the ingot obtained after the first step of vacuum induction melting can be subjected to one-step annealing treatment, the ingot obtained after the second step of electroslag remelting can be subjected to one-step annealing treatment, and the ingot obtained after the third step of vacuum consumable melting needs to be subjected to two-step annealing homogenization treatment.

[0051] 2) Deformation step: the alloy ingot is forged to obtain alloy rods; the alloy rods are plastically formed to form an alloy of a set shape (the set shape here is a desired shape).

[0052] In this step: the temperature of the blank forging is 1120-1200℃; the blank forging is 5-12 fires (all can be forged by a fast forging machine, and can also include forging by extrusion); wherein, the first 1-7 fires of blank forging are rush forging at a temperature of 1150-1200℃, in order to break the cast structure; the blank forging temperature of the last 1-5 fires is 1120-1150℃, and the volume fraction of the equilibrium γ′ phase in the alloy in this temperature range is 25-25%, which can inhibit grain growth and promote recrystallization; every 2-3 fires, the initial forging temperature is reduced by 5-10℃ to obtain a rod with uniform structure and fine grains; the average grain size of the alloy rod after blanking is 10-50μm. After blanking forging, the alloy rod has excellent thermoplasticity, and its elongation is ≥60% at a temperature of 1080℃ and ≥30% at a temperature of 1150℃. The alloy bar after blanking is suitable for further plastic forming at 1080-1150℃.

[0053] 3) Solution treatment and aging step: performing solution treatment and aging treatment on the alloy of the set shape to obtain the cobalt-based deformable high-temperature alloy.

[0054] The alloy of the set shape needs to undergo a solution treatment (solution treatment of the alloy of the set shape is performed for 4-8 hours at a temperature of 1120-1180°C, and air cooling to room temperature), a first-step aging treatment (at a temperature of 650-850°C, the alloy after the solution treatment is subjected to a first-step aging treatment for 4-28 hours, and air cooling to room temperature), and a second-step aging treatment (at a temperature of 760-850°C, the alloy after the first-step aging treatment is subjected to a second-step aging treatment for 10-20 hours, and air cooling to room temperature) to obtain a cobalt-based deformed high-temperature alloy.

[0055] The cobalt-based deformed high-temperature alloy obtained after solution aging treatment contains 50-60% volume fraction of γ′-(Co,Ni) 3(Ti, Al, Ta) phase, and exists stably. Moreover, the cobalt-based deformed high-temperature alloy has a yield strength of ≥1000MPa and a tensile strength of ≥1050MPa at a temperature of 750°C; the cobalt-based deformed high-temperature alloy has a yield strength of ≥850MPa and a tensile strength of ≥950MPa at a temperature of 850°C. The cobalt-based deformed high-temperature alloy has a long-lasting life of ≥100h in an environment of 750°C and 630Mpa, and the residual creep strain of the cobalt-based deformed high-temperature alloy in this environment at 100h is ≤0.2%. The cobalt-based deformed high-temperature alloy has a long-lasting life of ≥20h in an environment of 850°C and 400MPa. After long-term aging treatment at 750°C and 2000h, no TCP phase precipitates in the cobalt-based deformed high-temperature alloy; after long-term aging treatment at 850°C and 1000h, no TCP phase precipitates in the cobalt-based deformed high-temperature alloy. The density of the cobalt-based deformed high-temperature alloy is ≤8.5g / cm 3 .

[0056] The present invention is further described below through specific implementations, and the embodiments are intended to explain the present invention rather than to limit it.

[0057] The chemical compositions of the cobalt-based deformed high-temperature alloys prepared in the following examples of the present invention and the alloy GH4720Li prepared in the comparative example are shown in Table 1, in terms of weight percentage.

[0058] Table 1 (Weight percentage of elements in alloy)

[0059] alloy C Al B Cr Mo Ti W Zr Ta Ni Co Example 1 0.02 3.20 0.02 13 3.05 6.22 1.98 0.034 1.53 40 Remain Example 2 0.04 3.55 0.02 17 3.05 5.98 1.50 0.034 1.53 40 Remain Example 3 0.04 2.92 0.02 14 3.05 5.25 1.50 0.034 2.00 40 Remain Example 4 0.06 2.56 0.02 16 4.50 5.60 1.50 0.034 2.00 40 Remain Example 5 0.06 3.89 0.02 15 4.50 5.90 2.58 0.034 1.53 35 Remain Example 6 0.08 4.00 0.02 13 4.50 6.20 2.58 0.034 1.03 30 Remain Example 7 0.1 4.2 0.02 18 3.90 6.36 3.78 0.034 1.03 25 Remain GH4720Li 0.02 2.5 0.02 16 3.00 5.00 1.25 0.034 - Remain 15

[0060] Example 1

[0061] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy is shown in Table 1; the preparation method mainly includes the following steps:

[0062] Melting steps: Alloy ingots are prepared by vacuum induction melting in the first step, electroslag remelting in the second step, and vacuum consumable melting in the third step. Among them, the electrode ingots obtained by vacuum induction melting in the first step and the electrode ingots obtained by electroslag remelting in the second step are subjected to one-step annealing treatment (i.e., the electrode ingots are heated to 1150°C at a rate of 60°C / h for annealing, and then cooled to ≤200°C with the furnace after annealing) to ensure that the electrode ingots will not break due to stress. The alloy ingots obtained by triple smelting (i.e., after vacuum consumable melting in the third step) are subjected to two-step homogenization annealing treatments at 1160°C and 1190°C respectively (wherein the first step annealing treatment is 24h and the second step annealing treatment is 16h).

[0063] The alloy ingot prepared in this step is subjected to a long-term aging treatment test (later deformation processing and solution aging will not affect the long-term aging property): after a long-term aging treatment at 750°C for 2000h (for specific microstructure morphology, see Figure 3 As shown in the figure), there is no TCP phase precipitation, and after long-term aging treatment at 850℃ and 1000h (for specific organizational morphology, see Figure 4 No TCP phase was precipitated.

[0064] Deformation steps: Use a fast forging machine to forge the alloy ingot to obtain an alloy bar; then cut the alloy bar with a height of 370 mm, and then upset (forge) it at 1120°C to obtain a disc blank; wherein the height of the disc blank is 150 mm.

[0065] Among them, in the blank forging process: the temperature of the blank forging in the first 5 fires is 1150-1180℃ to ensure the crushing of the cast structure; the forging temperature in the last 4 fires is 1120-1150℃, and the initial forging temperature is reduced by 10℃ every 2 fires to obtain a rod with uniform structure and fine grains to obtain an alloy rod.

[0066] The average grain size of the alloy rod is 15 μm. After forging, the alloy has excellent thermoplasticity, with an elongation of 85% at 1080°C and an elongation of 50% at 1150°C.

[0067] Solution treatment and aging steps: The disc blank is solution treated at 1150°C for 6 hours, and then air-cooled to room temperature to obtain a solution treated disc blank. Then, the disc blank after solution treatment is subjected to the first step aging treatment at 650°C for 28 hours, and then air-cooled to room temperature to obtain a disc blank after the first step aging treatment; finally, the disc blank after the first step aging treatment is subjected to the second step aging treatment at 760°C for 20 hours, and air-cooled to room temperature to obtain a cobalt-based deformed high-temperature alloy (turbine disc blank).

[0068] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.17% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.42g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 54%.

[0069] In addition, the γ′ phase morphology of the cobalt-based deformed high-temperature alloy prepared in this embodiment is as follows: Figure 1 The grain morphology is shown in Figure 2 shown.

[0070] Example 2

[0071] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy in this embodiment is shown in Table 1. The preparation steps (melting step, deformation step, solution and aging step) and parameters of this embodiment are consistent with those of Example 1.

[0072] Long-term aging treatment tests were carried out on the alloy ingots prepared in the smelting step; wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0073] For the deformation step, the average grain size of the alloy rod obtained by billet forging is 15 μm, the elongation is 90% at a temperature of 1080°C, and the elongation is 58% at a temperature of 1150°C.

[0074] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 16% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.39g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 55%.

[0075] Example 3

[0076] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy is shown in Table 1, and the preparation method mainly includes the following steps:

[0077] Melting steps: Alloy ingots are prepared by vacuum induction melting in the first step, electroslag remelting in the second step, and vacuum consumable melting in the third step. Among them, the electrode ingots obtained by vacuum induction melting in the first step and the electrode ingots obtained by electroslag remelting in the second step are subjected to one-step annealing treatment (i.e., the electrode ingots are heated to 1100°C at a rate of 60°C / h for annealing, and then cooled to ≤200°C with the furnace after annealing) to ensure that the electrode ingots will not break due to stress. The alloy ingots obtained by triple smelting (i.e., after vacuum consumable melting in the third step) are subjected to two-step homogenization annealing treatments at 1140°C and 1180°C respectively (wherein the first step annealing treatment is 24h and the second step annealing treatment is 16h).

[0078] The alloy ingot prepared in this step was subjected to a long-term aging treatment test (later deformation processing and solution aging will not affect the long-term aging properties); wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0079] Deformation steps: the alloy ingot is forged by a fast forging machine to obtain an alloy bar; then the alloy bar with a height of 370 mm is cut, and then it is upset at 1110° C. to obtain a disc with a height of 150 mm.

[0080] Among them, in the blank forging process: the temperature of the first 4 fires of blank forging is 1150-1170℃ to ensure the crushing of the cast structure; the temperature of the last 2 fires is 1100-1140℃, and the initial forging temperature is reduced by 10℃ every 1 fire to obtain a rod with uniform structure and fine grains to obtain an alloy rod. Among them, the average grain size of the alloy rod is 10μm. The alloy after blank forging has excellent thermoplasticity, with an elongation of 90% at a temperature of 1080℃ and an elongation of 60% at a temperature of 1150℃.

[0081] Solution treatment and aging steps: The alloy of the disc blank is solution treated at a temperature of 1120°C for 8 hours, and then air-cooled to room temperature to obtain a disc blank after solution treatment. Then, the disc blank after solution treatment is subjected to the first step aging treatment at a temperature of 680°C for 20 hours, and then air-cooled to room temperature to obtain a disc blank after the first step aging treatment; finally, the disc blank after the first step aging treatment is subjected to the second step aging treatment at a temperature of 800°C for 16 hours and then air-cooled to room temperature to obtain a cobalt-based deformed high-temperature alloy (turbine disc blank).

[0082] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.19% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.40g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 52%.

[0083] Example 4

[0084] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy in this embodiment is shown in Table 1. The preparation steps (melting step, deformation step, solid solution and aging step) and parameters of this embodiment are consistent with those of Example 3.

[0085] Long-term aging treatment tests were carried out on the alloy ingots prepared in the smelting step; wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0086] In the deformation step, the average grain size of the alloy rod obtained by forging was 10 μm, the elongation at 1080°C was 84%, and the elongation at 1150°C was 45%.

[0087] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.19% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.50g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 52%.

[0088] Example 5

[0089] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy is shown in Table 1, and the preparation method mainly includes the following steps:

[0090] Melting steps: Alloy ingots are prepared by vacuum induction melting in the first step, electroslag remelting in the second step, and vacuum consumable melting in the third step. Among them, the electrode ingots obtained by vacuum induction melting in the first step and the electrode ingots obtained by electroslag remelting in the second step are subjected to one-step annealing treatment (i.e., the electrode ingots are heated to 1190°C at a rate of 60°C / h for annealing, and then cooled to ≤200°C with the furnace after annealing) to ensure that the electrode ingots will not break due to stress. The alloy ingots obtained by triple smelting (i.e., after vacuum consumable melting in the third step) are subjected to two-step homogenization annealing treatments at 1170°C and 1200°C respectively (wherein the first step annealing treatment is 24h and the second step annealing treatment is 16h).

[0091] The alloy ingot prepared in this step was subjected to a long-term aging treatment test (later deformation processing and solution aging will not affect the long-term aging properties); wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0092] Deformation steps: the alloy ingot is forged by a fast forging machine to obtain an alloy bar; then the alloy bar with a height of 370 mm is cut, and then it is upset at 1130° C. to obtain a disc with a height of 150 mm.

[0093] Among them, in the blank forging process: the temperature of the blank forging in the first 6 fires is 1150-1180℃ to ensure the crushing of the cast structure; the forging temperature in the last 4 fires is 1120-1150℃, and the initial forging temperature is reduced by 5℃ every 2 fires to obtain a rod with uniform structure and fine grains to obtain an alloy rod.

[0094] The average grain size of the alloy rod is 30 μm. After forging, the alloy has excellent hot plasticity, with an elongation of 75% at a temperature of 1080°C and an elongation of 43% at a temperature of 1150°C.

[0095] Solution treatment and aging steps: The alloy of the disc blank is solution treated at a temperature of 1180°C for 4 hours, and then air-cooled to room temperature to obtain a disc blank after solution treatment. Then, the disc blank after solution treatment is subjected to the first step aging treatment at 700°C for 10 hours, and then air-cooled to room temperature to obtain the alloy after the first step aging treatment; finally, the disc blank after the first step aging treatment is subjected to the second step aging treatment at 850°C for 14 hours and then air-cooled to room temperature to obtain a cobalt-based deformed high-temperature alloy (turbine disc blank).

[0096] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.15% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.50g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 55%.

[0097] Example 6

[0098] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy is shown in Table 1. The preparation steps (melting step, deformation step, solution and aging step) and parameters of this embodiment are consistent with those of Example 5.

[0099] Long-term aging treatment tests were carried out on the alloy ingots prepared in the smelting step; wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0100] For the deformation step, the average grain size of the alloy rod obtained by forging is 30 μm, the elongation at a temperature of 1080°C is 70%, and the elongation at a temperature of 1150°C is 40%.

[0101] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.14% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.52g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 55%.

[0102] Example 7

[0103] In this embodiment, a cobalt-based deformed high-temperature alloy (turbine disk blank) is prepared, wherein the chemical composition of the cobalt-based deformed high-temperature alloy is shown in Table 1. The preparation steps (melting step, deformation step, solution and aging step) and parameters of this embodiment are consistent with those of Example 7.

[0104] Long-term aging treatment tests were carried out on the alloy ingots prepared in the smelting step; wherein, no TCP phase was precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0105] For the deformation step, the average grain size of the alloy rod obtained by forging is 40μm, the elongation at a temperature of 1080℃ is 70%, and the elongation at a temperature of 1150℃ is 35%.

[0106] The cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment has a creep residual strain of 0.12% at 750°C and 630MPa for 100h. The room temperature density of the cobalt-based deformed high-temperature alloy (turbine disk blank) prepared in this embodiment is 8.55g / cm 3 , and the γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 58%.

[0107] Comparative Example

[0108] A GH4720Li alloy was prepared in a comparative example, and its chemical composition is shown in Table 1. The specific preparation steps are as follows:

[0109] Melting steps: Pure GH4720Li alloy ingots are prepared by vacuum induction melting, electroslag remelting and vacuum consumable melting. Among them, the electrode ingots obtained by the first step of vacuum induction melting and the electrode ingots obtained by the second step of electroslag remelting are subjected to one-step annealing treatment (that is, the electrode ingots are heated to 1120°C at a rate of 60°C / h for annealing, and then cooled to ≤200°C with the furnace after annealing) to ensure that the electrode ingots will not break due to stress. The alloy ingots obtained by triple smelting (three-step smelting) are subjected to two-step homogenization annealing treatments at temperatures of 1140°C and 1180°C respectively (wherein the first step annealing treatment is 24h and the second step annealing treatment is 16h).

[0110] The GH4720Li alloy ingot prepared in the smelting step was subjected to a long-term aging treatment test; TCP phase precipitated after long-term aging treatment at 750°C for 2000 h and after long-term aging treatment at 850°C for 1000 h.

[0111] Deformation steps: The GH4720Li alloy ingot is prepared by a fast forging machine to obtain an alloy rod; then the alloy rod with a height of 370 mm is cut, and then it is upset at 1080°C to obtain a disc with a height of 150 mm.

[0112] Among them, the temperature of the first four fires of forging is 1140-1160℃ to ensure the crushing of the cast structure; the temperature of the last two fires is 1080-1120℃, and the initial forging temperature is reduced by 10℃ every other fire to obtain a rod with uniform structure and fine grains, and obtain an alloy rod. Among them, the average grain size of the alloy rod is 15μm. The alloy after forging has excellent thermoplasticity, with an elongation of 60% at a temperature of 1080℃ and an elongation of 20% at a temperature of 1150℃.

[0113] Solution treatment and aging steps: The alloy of the disc blank is solution treated at a temperature of 1100°C for 4 hours, and then air-cooled to room temperature to obtain a disc blank after solution treatment. Then, the disc blank after solution treatment is subjected to the first step aging treatment at 650°C for 24 hours, and then air-cooled to room temperature to obtain a disc blank after the first step aging treatment; finally, the disc blank after the first step aging treatment is subjected to the second step aging treatment at 760°C for 16 hours and then air-cooled to room temperature to obtain the GH4720Li deformed high-temperature alloy (turbine disc blank).

[0114] The room temperature density of the GH4720Li deformed high-temperature alloy (turbine disk blank) prepared in the comparative example is 8.20 g / cm 3 , and the volume fraction of γ′ phase in the alloy is 42%.

[0115] The mechanical properties of the cobalt-based deformed high-temperature alloys (turbine disk blanks) prepared in Examples 1 to 7 and the GH4720Li deformed high-temperature alloy (turbine disk blank) prepared in the comparative example were tested. The results are shown in Table 2.

[0116] Table 2

[0117]

[0118] It can be seen from the above examples and the data in Tables 1 and 2 that the performance of the cobalt-based deformable high-temperature alloy prepared in the examples of the present invention is far superior to that of the GH4720Li alloy.

[0119] In summary, the cobalt-based deformed high-temperature alloy proposed and prepared by the present invention has high organizational stability, can maintain organizational stability for a long time at 750-850°C, and will not have TCP phase; at the same time, the cobalt-based deformed high-temperature alloy has a lower density than the traditional cobalt-based high-temperature alloy, and has machinability, is suitable for processing and forming to prepare high-temperature structural parts, and has excellent creep resistance and strong high-temperature mechanical properties; the high-strength cobalt-based deformed high-temperature alloy with comprehensive mechanical properties proposed by the present invention is the preferred material for aircraft engines and gas turbine disks resistant to temperatures above 750°C, and can especially be used as a potential 850°C resistant turbine disk material.

[0120] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A cobalt-based deformable high-temperature alloy, It is characterized in that The cobalt-based deformable high-temperature alloy comprises the following chemical components in weight percentage: C 0.02-0.1%, Al 2-5%, B 0.005-0.05%, Cr 12-18%, Mo 3-6%, Ti 5-7%, W 1.5-5%, Zr 0.005-0.05%, Ta 1-2%, Ni 25-40%, Mn≤0.1%, Fe≤0.3%, the balance is Co and unavoidable impurity elements; Wherein, the cobalt-based deformed high-temperature alloy has a yield strength of ≥1000MPa and a tensile strength of ≥1050MPa at a temperature of 750°C; the cobalt-based deformed high-temperature alloy has a yield strength of ≥850MPa and a tensile strength of ≥950MPa at a temperature of 850°C; The cobalt-based deformed high-temperature alloy has a rupture life of ≥100 h in an environment of 750° C. and 630 MPa, and a creep residual strain of ≤0.2% in the environment for 100 h. The cobalt-based deformed high-temperature alloy has no TCP phase precipitation after long-term aging treatment at 750°C for 2000 hours; the cobalt-based deformed high-temperature alloy has no TCP phase precipitation after long-term aging treatment at 850°C for 1000 hours; The cobalt-based deformable high-temperature alloy has a durability of ≥20 hours in an environment of 850° C. and 400 MPa.

2. The cobalt-based deformable high-temperature alloy according to claim 1, It is characterized in that The weight percentage ratio of Ti to Al is 1.5-2.2; and / or The sum of the weight percentages of Al, Ti and Ta is 9-12%; The sum of the weight percentages of W+Mo is 4.5-8%.

3. The cobalt-based deformable high-temperature alloy according to claim 1, It is characterized in that In the cobalt-based deformable high-temperature alloy, γ′-(Co,Ni) 3 The volume fraction of the (Ti, Al, Ta) phase is 50-60%.

4. The cobalt-based deformable high-temperature alloy according to claim 1, It is characterized in that The room temperature density of the cobalt-based deformable high-temperature alloy is ≤8.55 g / cm 3 .

5. A method for preparing the cobalt-based deformable high-temperature alloy according to any one of claims 1 to 4, It is characterized in that It includes the following steps: Melting step: the alloy raw material is subjected to the first step of vacuum induction melting, the second step of electroslag remelting, and the third step of vacuum consumable melting to obtain an alloy ingot; Deformation step: performing blank forging on the alloy ingot to obtain alloy bars; performing plastic forming treatment on the alloy bars to form an alloy of a set shape; Solution treatment and aging step: performing solution treatment and aging treatment on the alloy of the set shape to obtain the cobalt-based deformable high-temperature alloy.

6. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 5, It is characterized in that In the smelting step: The alloy ingots obtained after each of the first step of vacuum induction melting, the second step of electroslag remelting and the third step of vacuum consumable melting are all subjected to annealing treatment.

7. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 6, It is characterized in that The annealing temperature is 1100-1250°C; and / or The heating rate during annealing is ≤60℃ / h; and / or The alloy ingot after annealing is cooled to a temperature not exceeding 200°C and then taken out of the furnace.

8. The method for preparing the cobalt-based deformed high-temperature alloy according to claim 5, It is characterized in that In the deformation step: The temperature of the blank forging is 1120-1200° C.; and / or The average grain size of the alloy rod is 10-50 μm; and / or The elongation of the alloy rod at a temperature of 1080° C. is ≥60%, and the elongation at a temperature of 1150° C. is ≥30%.

9. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 5, It is characterized in that In the deformation step: the blank forging is blank forging of 5-12 fires.

10. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 9, It is characterized in that The first 1-7 fires of the billet forging are performed at a temperature of 1150-1200°C; the temperature of the last 1-5 fires of the billet forging is 1120-1150°C.

11. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 10, It is characterized in that The first 1-7 fires of forging are called rush forging.

12. The method for preparing the cobalt-based deformable high-temperature alloy according to claim 10, It is characterized in that During the last 1-5 rounds of billet forging, the initial forging temperature is reduced by 5-10°C every 1-3 rounds.

13. The method for preparing the cobalt-based deformable high-temperature alloy according to any one of claims 5 to 12, It is characterized in that In the deformation step: The temperature of the plastic forming process is 1080-1150°C; and / or The plastic forming method includes one or more of rolling, forging and extrusion.

14. A method for preparing a cobalt-based deformable high-temperature alloy according to any one of claims 5 to 12, It is characterized in that The solution treatment and aging steps include: Solution treatment: performing solution treatment on the alloy of the set shape at a temperature of 1120-1180° C. for 4-8 hours, and air cooling to room temperature to obtain a solution treated alloy; The first step of aging treatment: the alloy after the solution treatment is subjected to the first step of aging treatment at a temperature of 650-850°C for 4-28h, and then air-cooled to room temperature to obtain the alloy after the first step of aging treatment; Second step aging treatment: the alloy after the first step aging treatment is subjected to the second step aging treatment at a temperature of 760-850°C for 10-20h, and air-cooled to room temperature to obtain a cobalt-based deformed high-temperature alloy.

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