A nickel-based superalloy with fatigue resistance and high plasticity, and its preparation method and application

Abstract

The present invention discloses a nickel-based superalloy with fatigue resistance and high plasticity, comprising: C: 0.05-0.08%; Cr: 7.5-10.0%; Co: 9.5-11.0%; W: 9.2-10.8%; Al: 4.5-6.5%; Ta: 2.0-3.8%; Mo: 0.1-1.2%; Hf: 0.5-2.5%; Ti: 0.4-2.5%; B: 0.012-0.018%; Nd: 0.02-0.1%; Mg: 0.004-0.1%; Mn≤0.05%; Si≤0.15%, and the balance is Ni and inevitable impurities, calculated by mass percentage. In the relational expression, the Nd, Mg and Al satisfy the relational expression: 4.6 < Nd / (1.2Mg) - Al < 5.4. The nickel-based alloy of the present invention has excellent properties and can be applied to aeroengines and gas turbines.

Description

Technical Field

[0001] The present invention belongs to the technical field of superalloys, and particularly relates to a nickel-based superalloy with fatigue resistance and high strength and plasticity, and a preparation method and application thereof. Background Art

[0002] Nickel-based superalloys were first applied in the United States as key components in the hot section of aeroengines. This alloy is a type of superalloy with nickel as the matrix and other alloying elements added, and has high strength, good oxidation resistance and corrosion resistance. At present, advanced aeroengines, aerospace advanced engines and gas turbines not only have extremely high requirements for the machining accuracy and assembly accuracy of high-end hot-section components, but also require no failure fracture during long-term service at 800-950 °C, that is, the alloy is required to have excellent high-temperature long-term stability to avoid component failure before the overhaul period arrives. In addition, it is required that the hot-section components have a cyclic life time of not less than 100,000 hours under high alternating stress at 800-950 °C. However, there is currently no nickel-based superalloy that can meet all these properties at the same time. Therefore, further research and improvement of nickel-based alloys are needed. Summary of the Invention

[0003] The present invention is made based on the inventor's discovery and recognition of the following facts and problems:

[0004] With the development of aeroengines and gas turbines, higher requirements are put forward for the properties of nickel-based superalloys. At present, there are almost no alloys among the existing superalloys at home and abroad that can fully meet the use requirements. Generally, alloys that can meet the mechanical property requirements have poor long-term stability, low high-cycle fatigue fracture life, and TCP phases precipitate after 2000h of treatment, resulting in performance degradation.

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an embodiment of the present invention provides a nickel-based superalloy with fatigue resistance and high strength and plasticity. This alloy has excellent tensile properties and creep life, no TCP phase precipitates after being treated at 950 °C for 3000h, and has excellent fatigue resistance at both 800 °C and 950 °C, and can meet the design and use requirements of advanced aeroengines, aerospace engines and gas turbines.

[0006] The fatigue-resistant and high-plasticity nickel-based superalloy according to the embodiments of the present invention comprises: C: 0.05 to 0.08%; Cr: 7.5 to 10.0%; Co: 9.5 to 11.0%; W: 9.2 to 10.8%; Al: 4.5 to 6.5%; Ta: 2.0 to 3.8%; Mo: 0.1 to 1.2%; Hf: 0.5 to 2.5%; Ti: 0.4 to 2.5%; B: 0.012 to 0.018%; Nd: 0.02 to 0.1%; Mg: 0.004 to 0.1%; Mn ≤ 0.05%; Si ≤ 0.15%, and the balance is Ni and inevitable impurities, by mass percentage;

[0007] Wherein, Nd, Mg and Al satisfy the relational expression: 4.6 < Nd / (1.2Mg) - Al < 5.4, and in the relational expression, Nd, Mg and Al are the values obtained by removing the percentage sign from the mass percentages of elements Nd, Mg and Al in the nickel-based superalloy.

[0008] The advantages and technical effects brought by the fatigue-resistant and high-plasticity nickel-based superalloy according to the embodiments of the present invention are as follows: 1. In the embodiments of the present invention, adding element Nd to the nickel-based alloy can refine the alloy grains, pin the grains at high temperatures, and improve the stability of the alloy; 2. In the embodiments of the present invention, controlling Nd, Mg and Al to satisfy the relational expression 4.6 < Nd / (1.2Mg) - Al < 5.4 can exert the synergistic effect among Nd, Mg and Al, so that while the alloy has excellent tensile properties and creep life, it can effectively improve the fatigue resistance of the alloy; 3. In the embodiments of the present invention, the density of the nickel-based superalloy does not exceed 8.25 g / cm 3 , and the self-weight is relatively light, which is beneficial to reducing the fuel consumption of aeroengines and gas turbines and improving the maneuverability, and at the same time can meet the requirement that the vibration during the operation of high-end devices is as small as possible, preventing the formation of vibration damage; 4. In the embodiments of the present invention, by controlling the amounts of various elements within a suitable range, the alloy not only has excellent tensile properties and creep life, but also no TCP phase precipitates after being treated at 950 °C for 3000 h, and has excellent long-term service stability. In addition, it has excellent fatigue resistance at 800 °C and 950 °C, and can meet the requirements for the design and use of advanced aero and space engines and gas turbines.

[0009] In some embodiments, Nd, Mg and Al satisfy the relational expression: 4.62 ≤ Nd / (1.2Mg) - Al ≤ 5.36.

[0010] In some embodiments, C, B and Mg satisfy the relational expression: 0.02 < 0.2Mg / B - C < 0.03, wherein C, B and Mg are the values obtained by removing the percentage sign from the mass percentages of elements C, B and Mg in the nickel-based superalloy.

[0011] In some embodiments, C, B, and Mg satisfy the relational expression: 0.022 ≤ 0.2Mg / B - C ≤ 0.027.

[0012] In some embodiments, the fatigue-resistant and high-strength-plastic nickel-based superalloy comprises: C: 0.052 - 0.075%; Cr: 8.98 - 9.32%; Co: 10.31 - 10.52%; W: 10.04 - 10.21%; Al: 5.12 - 5.56%; Ta: 2.93 - 3.12%; Mo: 0.78 - 0.94%; Hf: 1.76 - 1.84%; Ti: 1.56 - 1.82%; B: 0.013 - 0.017%; Nd: 0.065 - 0.092%; Mg: 0.005 - 0.0077%; Mn ≤ 0.013%; Si ≤ 0.013%, and the balance is Ni and inevitable impurities, by mass percentage.

[0013] The embodiment of the present invention also provides an application of the fatigue-resistant and high-strength-plastic nickel-based superalloy in an aeroengine.

[0014] The embodiment of the present invention also provides an application of the fatigue-resistant and high-strength-plastic nickel-based superalloy in a gas turbine.

[0015] The embodiment of the present invention also provides a preparation method of a fatigue-resistant and high-strength-plastic nickel-based superalloy, comprising the following steps:

[0016] (1) According to the alloy design ratio, add raw materials of Cr, Co, W, Mo, Ta, B, Hf, Nd, Mg, Si, Mn, and part of C into a crucible, heat and melt under vacuum, and then perform heat preservation treatment;

[0017] (2) After the heat preservation treatment in step (1) is completed, add Al, Ti, and the remaining C raw materials into the crucible, introduce argon, heat and melt under vacuum, and cast to obtain a nickel-based superalloy.

[0018] The advantages and technical effects brought by the preparation method of the fatigue-resistant and high-strength-plastic nickel-based superalloy in the embodiment of the present invention are as follows: 1. In the method of the embodiment of the present invention, the easily burned C element is added step by step, which is beneficial to removing gases in the alloy and improving the mechanical properties of the alloy; 2. In the method of the embodiment of the present invention, raw materials with a specific element ratio are used, and the obtained alloy not only has excellent tensile properties, creep life, and fatigue properties, but also does not precipitate TCP phase after being treated at 950 °C for 3000 h, has excellent long-term service stability, and can meet the requirements of the design and use of advanced aeroengines and gas turbines.

[0019] In some embodiments, in step (1), the part of the C raw material is 10 - 20% of the designed dosage of the C raw material.

[0020] In some embodiments, in the step (2), the amount of argon introduced is such that the air pressure in the crucible is -0.02 to -0.1 MPa; the vacuum degree of the vacuum condition is <0.1 Pa, and the casting temperature is >1550 °C. Detailed implementation manners

[0021] The embodiments of the present invention will be described in detail below. The embodiments are exemplary and are intended to explain the present invention and should not be construed as a limitation to the present invention.

[0022] The fatigue-resistant and high-plasticity nickel-based superalloy of the embodiment of the present invention includes: C: 0.05 to 0.08%; Cr: 7.5 to 10.0%; Co: 9.5 to 11.0%; W: 9.2 to 10.8%; Al: 4.5 to 6.5%; Ta: 2.0 to 3.8%; Mo: 0.1 to 1.2%; Hf: 0.5 to 2.5%; Ti: 0.4 to 2.5%; B: 0.012 to 0.018%; Nd: 0.02 to 0.1%; Mg: 0.004 to 0.1%; Mn ≤ 0.05%; Si ≤ 0.15%, and the balance is Ni and inevitable impurities, by mass percentage;

[0023] Among them, the Nd, Mg and Al satisfy the relationship: 4.6 < Nd / (1.2Mg) - Al < 5.4, preferably: 4.62 ≤ Nd / (1.2Mg) - Al ≤ 5.36; in the relationship, Nd, Mg and Al are the values after removing the percentage sign of the mass percentages of the elements Nd, Mg and Al in the nickel-based superalloy.

[0024] The fatigue-resistant and high-plasticity nickel-based superalloy of the embodiment of the present invention adds the element Nd, which can refine the alloy grains, pin the grains at high temperatures, and improve the stability of the alloy; controlling Nd, Mg and Al to satisfy the relationship 4.6 < Nd / (1.2Mg) - Al < 5.4 can exert the synergistic effect between Nd, Mg and Al, so that the alloy has excellent tensile properties and creep life while effectively improving the fatigue resistance of the alloy; the density of the nickel-based superalloy does not exceed 8.25 g / cm 3 , has a relatively high self-weight, which is beneficial to reducing the fuel consumption of aeroengines and gas turbines and improving the maneuverability, and at the same time can meet the requirement that the vibration during the operation of high-end devices is as small as possible, preventing the formation of vibration damage; by controlling the amounts of each element within a suitable range, the alloy not only has excellent tensile properties and creep life, but also has no TCP phase precipitation after being treated at 950 °C for 3000 h, and has excellent long-term service stability. In addition, it has excellent fatigue resistance at 800 °C and 950 °C, and can meet the requirements for the design and use of advanced aero-engines, aerospace engines and gas turbines.

[0025] Among them, the functions of the main elements in the alloy of the embodiments of the present invention are as follows:

[0026] Chromium (Cr): When Cr is added to nickel-based superalloys, about one-tenth of the added Cr content usually enters the γ' phase, and a small amount forms carbides, and most of the rest dissolves in γ. Cr in the γ matrix of the superalloy causes lattice distortion, generates elastic stress field strengthening, and thus increases the strength of the γ solid solution, playing a role in solid solution strengthening. At the same time, Cr also reduces the stacking fault energy of the solid solution, significantly improving the high-temperature creep resistance. At the same time, Cr can also form M23C6 or M6C carbides distributed along the grain boundaries with C, playing a role in strengthening the grain boundaries. In addition, a very important role of Cr in superalloys is to form a Cr2O3-type oxide film, making the superalloy have good oxidation and corrosion resistance. However, when the Cr content is too high, it is easy to form the TCP phase, reducing the long-term tissue performance stability and fatigue life of the alloy. Therefore, its content generally does not exceed 25%. In the embodiments of the present invention, considering both corrosion resistance and fatigue resistance, the Cr content is controlled at 7.5-10.0%.

[0027] Cobalt (Co): Co is an important solid solution strengthening element and precipitation strengthening element. The Co element can be dissolved in the matrix to provide good solid solution strengthening effect for the alloy, can significantly reduce the stacking fault energy of the matrix, widen the width of the extended dislocation, making it difficult for dislocations to bunch and cross-slip, thereby improving the creep resistance and creep life of the alloy. Co can also partially replace the elements in the Ni3Al-type precipitation strengthening phase, improving the stability of the phase during long-term service; Co can also reduce the solid solubility of Al and Ti elements in the matrix, promoting the precipitation of the γ' strengthening phase and increasing its precipitation quantity and solid solution temperature. In the embodiments of the present invention, the Co content is controlled at 9.5-11.0%.

[0028] Tungsten (W) and Molybdenum (Mo): W and Mo are one of the main solid solution strengthening elements. They can be dissolved not only in the alloy matrix but also in the γ′ strengthening phase. At the same time, they can increase the interatomic binding force, raise the diffusion activation energy and the recrystallization temperature, thus effectively improving the high-temperature strength. In nickel-based superalloys, W is dissolved in the γ matrix and the γ′ phase in equal amounts. The atomic radius of W is relatively large, more than a dozen percent larger than that of nickel atoms, which can cause obvious lattice expansion, form a large long-range stress field, prevent dislocation movement, and play an obvious solid solution strengthening role. At the same time, W significantly reduces the stacking fault energy of the γ matrix and effectively improves the creep properties of the superalloy. However, W is an element that accelerates high-temperature corrosion, and a harmful δ phase will form during long-term service, reducing the strength and toughness of the alloy. Therefore, the W content is controlled at 9.2 - 10.8%. Mo has the same effect as W. The difference is that most Mo atoms are dissolved in the γ matrix, accounting for about 1 / 4 in the γ′ phase, and the solid solution strengthening effect is obvious. However, when Mo is too high, the μ phase is easily formed during long-term high-temperature aging, reducing the toughness of the alloy. Therefore, the Mo content is controlled at 0.1 - 1.2%.

[0029] Aluminum (Al), Titanium (Ti), and Tantalum (Ta): These three are the elements that form the strengthening phase γ' in nickel-based alloys. Generally, it is considered that as the content of these three elements increases, the number of γ' increases, and the high-temperature creep, creep rupture, and fatigue properties are improved. However, too much γ' will deteriorate the processing performance. When Al is added to nickel-based superalloys, about 20% of it enters the γ matrix, playing a role in solid solution strengthening, and 80% of Al forms Ni3(Al) for precipitation strengthening. Secondly, the addition of Al changes the solubility of each element in the γ' phase. As the Al content increases, the amounts of elements such as Al, Ni, Ti, and W entering the γ' phase increase, thus further increasing the number of γ' phases and enhancing the strengthening effect. When Ti is added to nickel-based superalloys, about 10% of it enters the γ matrix, playing a certain role in solid solution strengthening, and 90% of Ti enters the γ' phase, where it can replace the Al atoms in Ni3(Al) to form Ni3(Al, Ti). Under the condition of a certain Al content, as the Ti content increases, the number of γ' phases increases, and at the same time, the anti-phase domain boundary energy is significantly increased, which can strengthen the cutting mechanism to cause a strengthening effect. However, if the Ti content is too high, the lattice constants of the γ' phase and γ are not very different, which will accelerate the growth of the γ' phase, making the γ' phase thermodynamically unstable and having a tendency to transform into η-Ni3Ti. Ta is also the main alloying element that strengthens the γ' phase. More than 90% of the Ta added to the alloy enters the γ' phase (Ni3(Al, Ti, Ta)), thus increasing the number of γ' phases and the anti-phase domain boundary energy, and correspondingly improving the strength, creep resistance, and fatigue life of the alloy. In addition, Ti and Ta will also combine with C to form MC-type carbides, which hinder the growth and sliding of grain boundaries at high temperatures, playing a role in improving the high-temperature mechanical properties. However, too much Ti and Ta will form large particle MC-type carbides, which is instead unfavorable to the mechanical properties of the alloy. Therefore, considering all three comprehensively, the specific control ranges are as follows: Al: 4.5 - 6.5%, Ti: 0.4 - 2.5%, Ta: 2.0 - 3.8%.

[0030] Magnesium (Mg): Mg segregates at grain boundaries to improve the grain boundary bonding force and increase the grain boundary strength. Mg atoms not only segregate at grain boundaries but also at the boundaries of carbides, borides, and γ' phases, thereby reducing the eutectic structure between borides and the γ matrix. Mg atoms also enter the γ', borides, and carbides, which is beneficial to improving the mechanical properties of the alloy. Trace amounts of Mg segregating at grain boundaries reduce the grain boundary energy and phase boundary energy, improving and refining the morphology of grain boundary carbides and other grain boundary precipitates. Mg forms high-melting-point compounds such as MgS with harmful impurities such as sulfur, purifying the grain boundaries and significantly reducing the concentrations of impurity elements such as S, O, and P at the grain boundaries, reducing the harmful effects of S, O, and P and other impurities. In the examples of the present invention, the Mg content is controlled at 0.004 - 0.01%.

[0031] Neodymium (Nd): When the rare earth element Nd is added to the nickel-based superalloy, due to the high activity of Nd, it easily reacts with oxygen, nitrogen, and sulfur to form oxides, nitrides, and sulfides of rare earth elements, which float up and are removed from the alloy liquid, playing a role in reducing the harmful effects of oxygen, nitrogen, and sulfur at the grain boundaries. In addition, Nd can also interact with harmful elements such as Pb, As, Sb, Sn, and Bi, which are low-melting-point impurity elements in the alloy liquid, to form compounds with higher melting points and be removed, achieving the purpose of purifying the alloy and being beneficial to the improvement of the mechanical properties of the alloy. At the same time, Nd segregates at the grain boundaries, strengthening the grain boundaries, inhibiting the formation and propagation of cracks, and improving the high-temperature creep and fatigue properties of the alloy. In the embodiments of the present invention, the content of Nd is controlled at 0.02 - 0.1%.

[0032] Through research, the present invention finds that the best strengthening effect can be obtained by optimizing the ratios of Al, Mg, and Nd; when the ratios of Al, Mg, and Nd in the alloy of the embodiments of the present invention satisfy 4.6 < Nd / (1.2Mg) - Al < 5.4, the superalloy has higher tensile properties, creep life, and fatigue properties.

[0033] Carbon (C), boron (B), and magnesium (Mg): As a grain boundary strengthening element, C is added to the nickel-based superalloy to mainly form carbides. The carbides precipitated during the solidification process of the liquid metal are primary carbides, which are in the shape of blocks or Chinese cursive script, and are mainly distributed at the grain boundaries or between dendrites. Large primary carbides often become fatigue crack sources and propagation channels. Secondary carbides are precipitated during the aging process or during use, and can be carbides such as MC, M 23 C6 and M6C. The C in the superalloy improves the mechanical properties by forming carbides. The discontinuous carbide particles precipitated at the grain boundaries prevent grain boundary sliding and crack propagation, improve the creep life, and improve the creep plasticity. When the C content is less than 0.05%, it is not sufficient to form a sufficient amount of MC and M 23C6. When the C content is too high, the formed carbides are relatively large in size and will consume excessive amounts of W, Mo, Cr, Ti, and Ta in the alloy. On the one hand, it not only reduces the solution strengthening effect of W, Mo, Cr, Ti, and Ta, and on the other hand, the Ti and Ta used to form the Ni3(Al,Ti) and Ni3(Al,Ti,Ta) composite strengthening phases will be reduced, which has an adverse impact on the high-temperature properties, creep properties, and fatigue properties of the alloy. Therefore, C should be controlled within the range of 0.05 - 0.07%. B is the most widely used microalloying element in superalloys. B has a significant impact on the creep and fatigue properties of superalloys and usually has an optimal content range. The beneficial effect of B is that the atomic radius of B is very small, only about 85 picometers, while the atomic radius of Ni is about 135 picometers. Therefore, B atoms are easily enriched at the grain boundaries, preventing harmful low-melting-point elements from segregating at the grain boundaries. This improves the grain boundary bonding force. Borides are distributed in the form of particles or blocks at the grain boundaries, preventing grain boundary slip and inhibiting the connection and expansion of grain boundary cavities, eliminating the precipitation of harmful phases at the grain boundaries, reducing the content of harmful elements at the grain boundaries, and improving the precipitation morphology of carbides. In addition, boron atoms segregate at the grain boundaries and are prone to eutectic reactions at high temperatures to form the eutectic structure of boride M3B2 and the γ matrix. With the increase in the B content, the temperature at which borides are generated gradually decreases, and the amount of boride eutectics increases, thereby reducing the strength and plasticity of the alloy. Therefore, the alloy in the embodiment of the present invention selects an appropriate B content of 0.012 - 0.018%. Although Zr helps to purify the grain boundaries and enhance the grain boundary bonding force, the combined addition of Zr and B helps to maintain the high-temperature strength and creep life of the alloy, but the addition of Zr will promote severe segregation of eutectic-forming elements in the alloy during the late stage of solidification, increasing the eutectic content. At the same time, during the solidification process of the alloy, a Zr-rich film is formed on the solid / liquid interface, reducing the solidification rate of the alloy and causing the growth of the γ' phase in the alloy, thus affecting the mechanical properties of the alloy. Therefore, Zr elements are not added in this invention patent. Superalloys are microalloyed with Mg. Mg atoms segregate at the grain boundaries, and this segregation is an equilibrium segregation. The segregation of Mg at the grain boundaries improves the grain boundary bonding force and increases the grain boundary strength. Trace amounts of Mg increase the creep time and plasticity, improve the creep properties and high-temperature tensile plasticity, increase the impact toughness and fatigue strength, and for some alloys, it can also improve the hot working properties and increase the yield.

[0034] It is found through research in the present invention that the high-temperature mechanical properties of the alloy not only depend on the amount of γ' phase, but also on the precipitated phases and characteristics at the grain boundaries. By optimizing the ratios of C, B, and Mg, the best strengthening effect can be obtained. In some embodiments, the ratios of C, B, and Mg in the alloy of the embodiments of the present invention satisfy 0.02 < 0.2Mg / B - C < 0.03, where C, B, and Mg are the values obtained by removing the percentage signs from the mass percentages of elements C, B, and Mg in the nickel-based superalloy. Further preferably, C, B, and Mg satisfy the relational expression: 0.022 ≤ 0.2Mg / B - C ≤ 0.027.

[0035] In the embodiments of the present invention, controlling C, B, and Mg to satisfy the relational expression 0.02 < 0.2Mg / B - C < 0.03 can exert the synergistic effect among C, B, and Mg, enabling the alloy to have higher tensile properties, creep life, and fatigue resistance.

[0036] In some embodiments, preferably, the fatigue-resistant and high-strength nickel-based superalloy includes: C: 0.052 - 0.075%; Cr: 8.98 - 9.32%; Co: 10.31 - 10.52%; W: 10.04 - 10.21%; Al: 5.12 - 5.56%; Ta: 2.93 - 3.12%; Mo: 0.78 - 0.94%; Hf: 1.76 - 1.84%; Ti: 1.56 - 1.82%; B: 0.013 - 0.017%; Mg: 0.005 - 0.0077%; Mn ≤ 0.013%; Si ≤ 0.013%; Nd: 0.065 - 0.092%, and the balance is Ni and inevitable impurities, by mass percentage.

[0037] The embodiments of the present invention also provide an application of the fatigue-resistant and high-strength nickel-based superalloy in an aeroengine. The fatigue-resistant and high-strength nickel-based superalloy of the embodiments of the present invention has excellent tensile properties, creep life, and fatigue resistance, and can be applied to an aeroengine.

[0038] The embodiments of the present invention also provide an application of the fatigue-resistant and high-strength nickel-based superalloy in a gas turbine. The fatigue-resistant and high-strength nickel-based superalloy of the embodiments of the present invention has excellent tensile properties, creep life, and fatigue resistance, and can be applied to a gas turbine.

[0039] The embodiments of the present invention also provide a preparation method for a fatigue-resistant and high-strength nickel-based superalloy, comprising the following steps:

[0040] (1) According to the alloy design ratio, add raw materials of Cr, Co, W, Mo, Ta, B, Hf, Nd, Mg, Si, Mn, and part of C into a crucible, heat and melt under vacuum, and then perform heat preservation treatment;

[0041] (2) After the heat preservation treatment in step (1) is completed, Al, Ti and the remaining C raw materials are added to the crucible, argon is introduced, and vacuum heating and melting are carried out, and then casting is carried out to obtain a nickel-based superalloy.

[0042] The preparation method of the fatigue-resistant and high-strength-plastic nickel-based superalloy according to the embodiment of the present invention adds the easily burned C element step by step, which is beneficial to removing the gas in the alloy and improving the mechanical properties of the alloy; using raw materials with a specific element ratio, the obtained alloy not only has excellent tensile properties, creep life and fatigue properties, but also does not precipitate TCP phase after being treated at 950 °C for 3000 h, and has excellent long-term service stability, and can meet the requirements of the design and use of advanced aeroengines and gas turbines.

[0043] In some embodiments, preferably, in step (1), the partial C raw material is 10-20% of the designed dosage of the C raw material. Further preferably, in step (1), the heat preservation temperature is 1600 °C - 1650 °C, and the heat preservation time is 10-30 min.

[0044] In some embodiments, preferably, in step (2), the amount of argon introduced is such that the air pressure in the crucible is -0.02 to -0.1 MPa; the vacuum degree of the vacuum condition is <0.1 Pa, and the casting temperature >1550 °C.

[0045] Example 1

[0046] (1) Cr, Co, W, Mo, Ta, B, Hf, Nd, Mg, Si, Mn and 15% of the C raw materials are added into the crucible, and vacuum heating is carried out until complete melting. Subsequently, the temperature is controlled at 1610 °C, the vacuum degree is controlled to be less than 0.1 Pa, heat preservation is carried out for 10 min, and then heating is stopped and kept for 5 min;

[0047] (2) Al, Ti and the remaining C raw materials are added to the crucible; at the same time, argon is filled into the furnace until the pressure is -0.02 MPa, heating and melting are carried out under a vacuum degree less than 0.1 Pa, tapping is carried out at 1560 °C for casting, and after cooling to room temperature, demoulding is carried out and surface sandblasting is carried out to remove the oxide scale, and a nickel-based superalloy is obtained.

[0048] Examples 2-5

[0049] The preparation methods of Examples 2-5 are the same as those of Example 1, except that the alloy compositions are different.

[0050] The alloy compositions prepared in Examples 1-5 are shown in Table 1, and the properties are shown in Table 2.

[0051] Comparative Example 1

[0052] The preparation method of Comparative Example 1 was the same as that of Example 4, except that the alloy composition was different: the alloy did not contain the element Nd. The performance data of the alloy obtained in Comparative Example 1 are shown in Table 2.

[0053] Comparative Example 2

[0054] The preparation method of Comparative Example 2 was the same as that of Example 4, except that the alloy composition was different: the content of the element Nd in the alloy was 0.13%. The performance data of the alloy obtained in Comparative Example 2 are shown in Table 2.

[0055] Comparative Example 3

[0056] The preparation method of Comparative Example 3 was the same as that of Example 4, except that the alloy composition was different: the contents of the elements Al, Mg, and Nd in the superalloy were Al: 5.45%; Mg: 0.006%; Nd: 0.08%; Nd / 1.2Mg - Al = 5.66, which did not meet the requirement of 4.6 < Nd / 1.2Mg - Al < 5.4.

[0057] Comparative Example 4

[0058] The preparation method of Comparative Example 4 was the same as that of Example 4, except that the alloy composition was different: the contents of the elements Al, Mg, and Nd in the superalloy were Al: 4.54%; Mg: 0.009%; Nd: 0.092%; Nd / 1.2Mg - Al = 3.97, which did not meet the requirement of 4.6 < Nd / 1.2Mg - Al < 5.4.

[0059] Comparative Example 5

[0060] The preparation method of Comparative Example 5 was the same as that of Example 4, except that the alloy composition was different: Zr with a content of 0.03% was added to the alloy. The performance data of the alloy obtained in Comparative Example 5 are shown in Table 2.

[0061] Comparative Example 6

[0062] The preparation method of Comparative Example 6 was the same as that of Example 4, except that the alloy composition was different: the content of the element Mg in the alloy was 0.15%. The performance data of the alloy obtained in Comparative Example 6 are shown in Table 2.

[0063] Table 1

[0064]

[0065]

[0066] Table 2

[0067]

[0068]

[0069] Note: 1. Endurance life test: The life of a smooth specimen when it fractures under a stress of 200 MPa at 980 °C on an endurance testing machine.

[0070] 2. TCP phase test: Observe the microstructure of the specimen after being treated at 950 °C for 3000 h using a scanning electron microscope.

[0071] 3. High-cycle fatigue: On a high-frequency tensile-compressive testing machine, for a smooth specimen at 800 °C and 950 °C, applying a sinusoidal wave load, stress ratio R = 0.1, and the fatigue strength with a cycle > 10 7 cycles.

[0072] From the data in the above table, it can be seen that the nickel-based superalloys prepared in Examples 1 - 5 have very good tensile properties at room temperature and 900 °C. At room temperature, the tensile properties are Rm ≥ 1100 MPa, Rp0.2 ≥ 900 MPa, A ≥ 15.0%; at 900 °C, the high-temperature tensile properties are Rm ≥ 950 MPa, Rp0.2 ≥ 650 MPa, A ≥ 12.0%. In addition, the nickel-based superalloys of the embodiments of the present invention also have excellent endurance life, long-term service stability, and fatigue resistance. The endurance time at 980 °C and 200 MPa is greater than 150 h, and no TCP phase precipitates after 3000 h at 950 °C. At the same time, at 800 °C and 950 °C, the fatigue strength can reach above 200 MPa and 150 MPa respectively. In particular, when further satisfying the relationship 0.02 < 0.2Mg / B - C < 0.03, such as in Examples 3 - 5, the prepared nickel-based superalloys have more excellent properties.

[0073] In Comparative Example 1, no Nd element was added. Although the tensile strength at room temperature could still be maintained at a certain level, the elongation at room temperature and the tensile strength and elongation at 900 °C were all significantly reduced; the high-temperature strength at 900 °C decreased by 212 MPa, and the elongation decreased by about 50%; the endurance life at 980 °C and 200 MPa decreased to 62 h, a decrease of about 68%, and the fatigue resistance was also significantly reduced; in Comparative Example 2, the content of element Nd was too high, and the tensile strength and elongation of the nickel-based superalloy at room temperature and 900 °C were both significantly reduced. The high-temperature strength at 900 °C decreased by 310 MPa, and the elongation decreased by about 50%; the endurance life at 980 °C and 200 MPa decreased to 45 h, a decrease of about 77%, and the fatigue resistance was also significantly reduced, failing to meet the usage requirements.

[0074] In Comparative Example 3 and Comparative Example 4, the controlled proportions of the three elements Al, Nd, and Mg are not within the ranges to be controlled in the embodiments of the present invention. Although the tensile strength and elongation of the alloy at room temperature can basically meet the usage requirements, the tensile strength and elongation at 900°C, the creep life at 980°C and 200 MPa, and the fatigue resistance all decrease significantly. For the alloy in Comparative Example 3, the high-temperature strength at 900°C decreases by 100 MPa, and the elongation decreases by approximately 50%; the creep life at 980°C / 200 MPa decreases by approximately 50%. The fatigue strength at 800°C and 900°C decreases; for the alloy in Comparative Example 4, the high-temperature strength at 900°C decreases by 282 MPa, and the elongation decreases by approximately 50%; the creep life at 980°C / 200 MPa decreases by approximately 53%. The fatigue strength at 800°C and 900°C decreases.

[0075] In Comparative Example 5, 0.03% of the element Zr is added to the alloy. Since the addition of the Zr element will promote the severe segregation of eutectic-forming elements in the alloy during the late stage of solidification, increasing the eutectic content. At the same time, during the solidification process of the alloy, a Zr-rich film is formed on the solid / liquid interface, reducing the solidification rate of the alloy, resulting in the growth of γ' phase in the alloy, thus affecting the mechanical properties of the alloy, especially the significant reduction of the tensile strength at 900°C. At the same time, the creep life at 980°C and 200 MPa decreases by approximately 36%, and the fatigue resistance also decreases.

[0076] In Comparative Example 6, an excessive amount of Mg element is added to the alloy, resulting in a significant reduction in the tensile properties of the nickel-based superalloy at room temperature and 900°C. The high-temperature strength at 900°C decreases by 354 MPa, the elongation decreases by approximately 50%, the creep life at 980°C and 200 MPa decreases to 49 h, a decrease of approximately 75%. At the same time, the fatigue resistance also decreases significantly, and the fatigue strength at 800°C and 900°C decreases, unable to meet the usage requirements.

[0077] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0078] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above embodiments are within the scope of protection of the present invention.

Claims

1. A nickel-based superalloy with fatigue resistance and high plasticity, characterized in that, Comprising: C: 0.05 - 0.08%; Cr: 7.5 - 10.0%; Co: 9.5 - 11.0%; W: 9.2 - 10.8%; Al: 4.5 - 6.5%; Ta: 2.0 - 3.8%; Mo: 0.1 - 1.2%; Hf: 0.5 - 2.5%; Ti: 0.4 - 2.5%; B: 0.012 - 0.018%; Nd: 0.02 - 0.1%; Mg: 0.004 - 0.1%; Mn ≤ 0.05%; Si ≤ 0.15%, the balance being Ni and unavoidable impurities, by mass percentage; Wherein, the Nd, Mg and Al satisfy the relationship: 4.6 < Nd / (1.2Mg) - Al < 5.4, where Nd, Mg and Al in the relationship are the values after removing the percentage sign of the mass percentages of the elements Nd, Mg and Al in the nickel-based superalloy; The C, B and Mg satisfy the relationship: 0.02 < 0.2Mg / B - C < 0.03, where C, B and Mg are the values after removing the percentage sign of the mass percentages of the elements C, B and Mg in the nickel-based superalloy.

2. The fatigue-resistant and high-plasticity nickel-based superalloy according to claim 1, characterized in that, The Nd, Mg and Al satisfy the relationship: 4.62 ≤ Nd / (1.2Mg) - Al ≤ 5.

36.

3. The fatigue-resistant and high-plasticity nickel-based superalloy according to claim 1, characterized in that, The C, B and Mg satisfy the relationship: 0.022 ≤ 0.2Mg / B - C ≤ 0.

027.

4. The fatigue-resistant and high-plasticity nickel-based superalloy according to claim 1, characterized in that, Comprising: C: 0.052 - 0.075%; Cr: 8.98 - 9.32%; Co: 10.31 - 10.52%; W: 10.04 - 10.21%; Al: 5.12 - 5.56%; Ta: 2.93 - 3.12%; Mo: 0.78 - 0.94%; Hf: 1.76 - 1.84%; Ti: 1.56 - 1.82%; B: 0.013 - 0.017%; Nd: 0.065 - 0.092%; Mg: 0.005 - 0.0077%; Mn ≤ 0.013%; Si ≤ 0.013%, the balance being Ni and unavoidable impurities, by mass percentage.

5. Application of the fatigue-resistant and high-plasticity nickel-based superalloy according to any one of claims 1 - 4 in hot-end components of an aeroengine.

6. Application of the fatigue-resistant and high-plasticity nickel-based superalloy according to any one of claims 1 - 4 in hot-end components of a gas turbine.

7. A method for preparing a nickel-based superalloy with fatigue resistance and high plasticity according to any one of claims 1 to 4, characterized in that, Comprising the following steps: (1) According to the alloy design ratio, add raw materials of Cr, Co, W, Mo, Ta, B, Hf, Nd, Mg, Si, Mn and part of C into a crucible, heat and melt under vacuum, and then carry out heat preservation treatment; (2) After the heat preservation treatment in step (1) ends, add Al, Ti and the remaining C raw materials into the crucible, introduce argon, heat and melt under vacuum, and cast to obtain a nickel-based superalloy.

8. The preparation method of the fatigue-resistant and high-plasticity nickel-based superalloy according to claim 7, characterized in that, In step (1), the part of C raw materials is 10 - 20% of the designed dosage of C raw materials.

9. The preparation method of the fatigue-resistant and high-plasticity nickel-based superalloy according to claim 7, characterized in that, In the step (2), the amount of argon introduced is such that the air pressure in the crucible is -0.02 to -0.1 MPa; the degree of vacuum for the vacuum heating is <0.1 Pa, and the temperature for casting is >1550 °C.

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