Low-cobalt nickel-based alloy and preparation method and application thereof

Abstract

The invention discloses a low-cobalt nickel-based alloy which comprises the following components in percentage by mass: 10-14% of Co; 10%-14% of Cr; 3.5%-5% of Mo; 1%-2.8% of W; 2%-5% of Al; 2%-4% of Ti; 0.5%-2.5% of Nb; 4%-7% of Ta; 0.02% to 0.1% of C; 0.02% to 0.1% of B; 0.02% to 0.1% of Zr; and the balance of Ni and impurities. The invention further provides a preparation method and application of the low-cobalt nickel-based alloy. According to the low-cobalt nickel-based alloy provided by the invention, the creep resistance of the alloy is improved by reducing the consumption of cobalt and increasing the consumption of tantalum. The problem that an existing nickel-based high-temperature alloy material is difficult to improve in the aspects of solidus temperature, heat treatment windows and the like is solved.

Description

Technical Field

[0001] This application relates to the field of alloy materials technology, and in particular to a low cobalt-nickel based alloy, its preparation method and application. Background Technology

[0002] To meet the demands of civil aviation for reduced procurement and lifecycle costs, achieving higher fuel economy, reduced NOx emissions and noise, and lower module weight, higher pressure ratios, as well as higher compressor emissions and turbine inlet temperatures, are inevitably required. Therefore, as the most critical high-temperature rotating component in aero engines, the turbine disk must withstand higher temperatures and stresses, placing greater demands on the high-strength nickel alloys used in these critical components.

[0003] The composition of nickel-based superalloys used in turbine disks is complex, containing more than 10 common elements, including Co, Cr, W, Mo, Al, Ti, Nb, Ta, Hf, C, B, and Zr, in addition to Ni. The research and application of nickel-based superalloys for turbine disks require excellent high-temperature mechanical properties, superior oxidation and corrosion resistance, good thermal and microstructural stability, and good fabrication and processing performance. Taking the ME (ME501~ME511) series alloys from General Electric as an example, their high-temperature mechanical properties are significantly improved compared to second-generation alloys. The solidus temperature of this alloy is between 1232.6 and 1259.2℃, and the heat treatment window is 60.7 to 99.9℃. The low solidus temperature poses a risk of initial melting, posing difficulties and risks to the heat treatment and fabrication of turbine disks. Further optimization and improvement of alloy performance requires resolving the contradiction between improving high-temperature mechanical properties and reducing fabrication and processing risks. Summary of the Invention

[0004] To address the aforementioned technical problems, the first objective of this invention is to provide a low-cobalt nickel-based alloy; the second objective is to provide a method for preparing the aforementioned low-cobalt nickel-based alloy; and the third objective is to provide applications of the aforementioned low-cobalt nickel-based alloy. The low-cobalt nickel-based alloy provided in this application improves the alloy's creep resistance by reducing cobalt and increasing the amount of tantalum, thereby solving the problem that existing nickel-based high-temperature alloys have difficulty improving solidus temperature and heat treatment window.

[0005] The technical solution provided by this invention is as follows: A low-cobalt nickel-based alloy, comprising the following components by mass fraction: Co 10%~14%; Cr 10%~14%; Mo 3.5%~5%; W 1%~2.8%; Al 2%~5%; Ti 2%~4%; Nb 0.5%~2.5%; Ta 4%~7%; C 0.02%~0.1%; B 0.02%~0.1%; Zr 0.02%~0.1%; The balance consists of Ni and impurities.

[0006] Preferably, by mass fraction, it comprises the following components: Co 11%~13%; Cr 11%~13% Mo 4%~5%; W 1.5%~2.5%; Al 2%~4%; Ti 2%~4%; Nb 0.5%~2.5%; Ta 4%~6%; C 0.03%~0.05%; B 0.02%~0.04%; Zr 0.04%~0.06%; The balance consists of Ni and impurities.

[0007] Preferably, by mass fraction, it comprises the following components: Co 12%; Cr 12%; Mo 4%; W 2%; Al 3%; Ti 3%; Nb 1.5%; Ta 5%; C 0.04%; B 0.03%; Zr 0.05%; The balance consists of Ni and impurities.

[0008] The preparation method of the above-mentioned low-cobalt nickel-based alloy includes the following steps: S1. Prepare the master alloy by using the above components in a vacuum induction melting process; S2. The master alloy is made into powder using a gas atomization process; S3. The powder is densified using a hot isostatic pressing process. S4. The alloy after hot isostatic pressing is subjected to hot deformation treatment, which includes at least one of hot extrusion treatment and hot forging treatment. S5. The alloy after hot deformation is subjected to heat treatment, which includes at least one of solution heat treatment and aging heat treatment.

[0009] Preferably, in step S1, the pouring temperature is 1400-1550℃; and / or, In step S2, before hot isostatic pressing, the powder pretreatment includes: cladding preparation, cladding welding, powder loading, degassing, and sealing welding, and then hot isostatic pressing is performed. The hot isostatic pressing temperature is 1050-1200℃, the pressure is 100-180MPa, and the time is 3-8 hours.

[0010] Preferably, in step S4, the hot isostatically pressed alloy is machined to remove the outer sheath of the alloy. The straight sheath is completely removed, and then a stainless steel sheath is used to wrap the hot isostatically pressed alloy ingot, followed by hot deformation treatment.

[0011] Preferably, in step S4, the hot extrusion temperature is 1050-1150℃ and the extrusion ratio is 4-8; The hot forging temperature range is 1050-1150℃, and the rate is less than 0.01 / s; In step S5, the solution heat treatment specifically involves heating to 1130-1200℃, holding at that temperature for 1-4 hours, and then rapidly cooling to room temperature. The aging heat treatment is as follows: heat to 750-800 ℃, hold for 6-12 hours, and then air cool to room temperature.

[0012] The above-mentioned low-cobalt nickel-based alloys, or the low-cobalt nickel-based alloys prepared by the above-mentioned methods, are used in the preparation of hot-end components for equipment in the fields of aerospace, marine, power generation, and oil and gas.

[0013] This application provides a low-cobalt nickel-based alloy, comprising the following components by mass fraction: Co 10%–14%; Cr 10%–14%; Mo 3.5%–5%; W 1%–2.8%; Al 2%–5%; Ti 2%–4%; Nb 0.5%–2.5%; Ta 4%–7%; C 0.02%–0.1%; B 0.02%–0.1%; Zr 0.02%–0.1%; with the balance being Ni and impurities. The low-cobalt nickel-based alloy provided in this application improves the alloy's creep resistance by reducing cobalt and increasing the amount of tantalum. This addresses the problem that existing nickel-based high-temperature alloys struggle to improve solidus temperature and heat treatment window.

[0014] The solidus temperature of the low-cobalt nickel-based alloy provided in this application is between 1253-1271℃, while that of the ME series alloys is between 1232.6-1259.2℃, achieving comparable performance and reducing the risk of initial melting during heat treatment. Meanwhile, the heat treatment window of this application is between 62.6-102.9℃, while that of the ME series alloys is between 60.7-99.9℃. This application is comparable to the ME series, ensuring the implementation of heat treatment, and the alloy formulations of some embodiments are significantly improved compared to the ME series. Furthermore, the alloy of this application exhibits a 0.2% plastic strain time of greater than or equal to 140 hours at 815℃ / 345MPa, an improvement of approximately 70 hours compared to the ME series alloys, resulting in a significant improvement in the alloy's resistance to creep deformation. It also ensures the alloy's elongation, with an elongation of greater than or equal to 10% at 815℃, thereby better ensuring the stability and reliability of alloy components at high temperatures and providing more room for performance optimization of nickel-based alloys.

[0015] Applying the low-cobalt nickel-based alloy of this application to turbine disks can significantly improve high-temperature stability and upper limit of operating temperature, extend high-temperature service life, maintain high strength even when close to melting point, shorten the liquid phase range with high solidus temperature, reduce segregation tendency during solidification, reduce casting defects, avoid brittle phase formation at high temperatures, suppress harmful phase transformation, and have stronger adaptability to extreme environments.

[0016] This application also provides a method for preparing the above-mentioned low-cobalt nickel-based alloy.

[0017] This application also provides the application of the above-mentioned low-cobalt nickel-based alloy, or the low-cobalt nickel-based alloy prepared by the above method, in the manufacture of hot-end components for equipment in the aerospace, marine, power generation, and oil and gas fields. It is particularly suitable for the manufacture of turbine disks for aerospace engines.

[0018] As is known in the art, alloy formulations may contain unavoidable impurities in addition to the selected metallic elements, and the formulation provided in this application is no exception. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is the solidification equilibrium phase diagram of the alloy in Example 1 of the present invention; Figure 2 This is the solidification equilibrium phase diagram of the alloy in Example 2 of the present invention; Figure 3This is the solidification equilibrium phase diagram of the alloy in Example 3 of the present invention; Figure 4 The solidification equilibrium phase diagram of the alloy in Example 4 of this invention; Figure 5 The solidification equilibrium phase diagram of the alloy in Example 5 of this invention; Figure 6 The solidification equilibrium phase diagram of the alloy in Example 6 of this invention; Figure 7 The solidification equilibrium phase diagram of the alloy in Example 7 of this invention; Figure 8 This is the solidification equilibrium phase diagram of the alloy in Comparative Example 1 of the present invention; Figure 9 This is the solidification equilibrium phase diagram of the alloy in Comparative Example 2 of the present invention; Figure 10 This is the solidification equilibrium phase diagram of the alloy in Comparative Example 3 of the present invention; Figure 11 This is a comparison of the tensile strength of Example 1 of the present invention with that of ME501 alloy; Figure 12 This is a comparison of the yield strength of Example 1 of the present invention and ME501 alloy; Figure 13 This is a comparison of the tensile elongation of Example 1 of the present invention with that of ME501 alloy; Figure 14 This is a comparison of the creep performance (time to reach 0.2% creep strain) between Example 1 of the present invention and ME501 alloy. Figure 15 This is a grain structure diagram of the alloy in Example 1 of the present invention after solution treatment and aging heat treatment; Figure 16 The image shows the microstructure of the γ' precipitate phase and carbides in the alloy of Example 1 of this invention after solution treatment and aging heat treatment. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Table 1 provides seven specific examples, four comparative examples, and formulations for the ME series alloys: Table 1. Chemical composition (wt.%) of the examples, comparative examples, and ME 501-511 alloys.

[0023] As can be seen from Table 1, the contents of Co and W in the alloys in the embodiments of this application are significantly different from those of the comparative alloys ME501-511, and the contents of other elements have also been adjusted to some extent.

[0024] Prepare the experimental alloys according to the proportions in Table 1 and the following methods: S1. Prepare the master alloy by vacuum induction melting process using the above components, with a casting temperature of 1450℃. S2. The master alloy is made into powder by gas atomization process, and the powder particle size is selected in the range of +270 mesh to -800 mesh after sieving. S3. Powder pretreatment includes: encapsulation preparation, encapsulation welding, powder loading, degassing, and sealing welding. Then, hot isostatic pressing is used to densify the powder. The hot isostatic pressing temperature is 1100℃, the pressure is 150MPa, and the time is 4 hours. S4. The hot isostatic pressed alloy is machined to remove the outer casing of the alloy until the casing is completely removed. Then, the hot isostatic pressed alloy ingot is wrapped with a stainless steel casing. Then, the grain structure is refined by hot extrusion at a temperature of 1080℃ and an extrusion ratio of 6:1. S5. The hot-extruded alloy is subjected to solution heat treatment and aging heat treatment successively; among which... Solution heat treatment process: 1190℃, hold for 2 hours, then rapidly cool to room temperature; Aging heat treatment process: 760 ℃, hold for 8 hours, then air cool to room temperature.

[0025] The phase diagram data of the prepared nickel-based alloys are shown in Table 2: Table 2 Comparison of phase diagram data of the examples, comparative examples, and ME 501-511 alloys

[0026] As can be seen from Table 2, in terms of alloy performance, the solidus temperatures of the seven embodiments are between 1253 and 1271 °C, while the solidus temperatures of the ME series alloys are between 1232.6 and 1259.2 °C, achieving comparable performance. At the same time, the heat treatment window of the seven embodiments is between 62.6 and 102.9 °C, while the heat treatment window of the ME series alloys is only 60.7 to 99.9 °C, which is comparable to the ME series. Moreover, the alloy formulations of some embodiments are significantly improved compared to the ME series.

[0027] The tensile strength and other properties of Example 1 and ME501 alloy were tested, as shown in Tables 3 and 4: Table 3 Comparison of tensile properties between Example 1 and ME501 alloy

[0028] Table 4 Comparison of creep properties between Example 1 and ME501 alloy

[0029] As shown in Table 3, the tensile strength and yield strength of the alloy in Example 1 are not significantly different from those of ME501, a representative advanced alloy in the field, and its performance at high temperatures is slightly higher than that of ME501. This indicates that even without the addition of hafnium and with a low cobalt content, the alloy still possesses performance comparable to the internationally advanced powder metallurgy high-temperature alloy ME501, but the price of raw materials will decrease significantly. Furthermore, due to the absence of hafnium, the process control difficulty in the master alloy smelting and gas atomization remelting processes will be greatly reduced. The main reason is that hafnium, as a highly reactive element, easily reacts with the crucible at high temperatures to form non-metallic inclusions, affecting the alloy's performance, especially its fatigue performance.

[0030] As can be seen from Table 4, under creep conditions of 815℃ / 345MPa, the alloy of Example 1 has a 0.2% plastic strain time that is 72.5 hours longer than that of the ME501 alloy. Under high temperature conditions, the alloy’s resistance to creep deformation is significantly improved.

[0031] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A low cobalt nickel-based alloy characterized in that, by mass, comprising: Co 10%~14%; Cr 10%～14%； Mo 3.5%~5%; W 1%～2.8%； Al 2%～5%； Ti 2%~4%; Nb 0.5%~2.5%; Ta 4%~7%; C 0.02%～0.1%； B 0.02%～0.1%； Zr 0.02%～0.1%； the balance being Ni and impurities.

2. The low cobalt nickel-based alloy of claim 1, wherein, by mass, comprising: Co 11%~13%; Cr 11%～13% Mo 4%~5%; W 1.5%～2.5%； Al 2%～4%； Ti 2%~4%; Nb 0.5%~2.5%; Ta 4%~6%; C 0.03%～0.05%； B 0.02%～0.04%； Zr 0.04%～0.06%； the balance being Ni and impurities.

3. The low cobalt nickel-based alloy of claim 2, wherein, by mass, comprising: Co 12%; Cr 12%； Mo 4%; W 2%； Al 3%； Ti 3%; Nb 1.5%; Ta 5%; C 0.04%； B 0.03%； Zr 0.05%； the balance being Ni and impurities.

4. The method of producing a low-cobalt nickel-based alloy according to any one of claims 1 to 3, characterized in that, comprising the following steps: S1, the above components are prepared into an alloy master alloy using a vacuum induction melting process; S2, the alloy master alloy is made into a powder using a gas atomization process; S3, the powder is densified using a hot isostatic pressing process; S4, the alloy after hot isostatic pressing is subjected to hot deformation treatment, which includes at least one of hot extrusion treatment and hot forging treatment; S5, the alloy after hot deformation treatment is subjected to heat treatment, which includes at least one of solid solution heat treatment and aging heat treatment.

5. The method of producing a low cobalt nickel-based alloy according to claim 4, characterized by, In step S1, the pouring temperature is 1400-1550℃; and / or, In step S2, before hot isostatic pressing, the powder pretreatment includes: can preparation, can welding, powder loading, degassing, sealing, and then hot isostatic pressing at a temperature of 1050-1200℃, a pressure of 100-180MPa, and a time of 3-8 hours.

6. The method of producing a low cobalt nickel-based alloy according to claim 4, characterized by, In step S4, the alloy after hot isostatic pressing is subjected to machining treatment to remove the outer can of the alloy, and the outer can is completely removed, and then a stainless steel can is used to wrap the hot isostatic pressing alloy ingot, and then subjected to hot deformation treatment.

7. The preparation method of the low-cobalt nickel-based alloy according to claim 4, characterized in that, In step S4, the hot extrusion treatment temperature is 1050-1150℃, and the extrusion ratio is 4-8; The hot forging treatment degree ranges from 1050 to 1150℃, and the rate is less than 0.01 / s; In step S5, the solid solution heat treatment is specifically: heating to 1130-1200℃, holding for 1-4 hours, and then rapidly cooling to room temperature; The aging heat treatment is specifically: heating to 750-800℃, holding for 6-12 hours, and then air cooling to room temperature.

8. The low-cobalt nickel-based alloy of any one of claims 1-4, or the low-cobalt nickel-based alloy prepared by the preparation method of any one of claims 5-7, for use in preparing hot end components of equipment in the fields of aerospace, marine, power generation, and oil and gas.

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