An antioxidant nickel-based superalloy, its preparation method and application

Abstract

The present invention belongs to the field of alloys, and particularly relates to an oxidation-resistant nickel-based superalloy, its preparation method and application. The present invention provides an oxidation-resistant nickel-based superalloy, comprising C: 0.03 - 0.09%, Cr: 26.00 - 28.00%, Co: 5.10 - 6.90%, Mo: 7.00 - 9.50%, Al: 1.9 - 2.5%, Ti: 1.2 - 1.7%, Nb: 0.6 - 1.8%, B: 0.002 - 0.008%, Sc: 0.002 - 0.008%, Zr: 0 - 0.05%, W: 0 - 0.05%, and the balance being nickel and unavoidable impurities, by mass percentage. This alloy has excellent room-temperature tensile properties, good sensitivity to strain-age cracking resistance, outstanding oxidation resistance, and no cracks will appear after hot working, and it can meet the requirements for the design and use of advanced aero-engines and gas turbines.

Description

Technical Field

[0001] The present invention belongs to the field of alloys, and particularly relates to an oxidation-resistant nickel-based superalloy, a preparation method thereof, and an application thereof. Background Art

[0002] Nickel-based alloys are a type of alloy with the widest application and the highest high-temperature strength in superalloys. The main reasons are as follows: First, a relatively large number of alloying elements can be dissolved in nickel-based alloys, and good tissue stability can be maintained; second, a coherent and ordered A3B-type intermetallic compound can be formed, and the γ' [Ni3(Al, Ti)] phase, as a strengthening phase, effectively strengthens the alloy, enabling it to obtain a higher high-temperature strength than iron-based superalloys and cobalt-based superalloys; third, nickel-based alloys containing chromium have better oxidation resistance and resistance to gas corrosion than iron-based superalloys. Nickel-based alloys contain more than a dozen elements, among which Cr mainly plays an antioxidant and anti-corrosion role, and other elements mainly play a strengthening role. According to their strengthening methods, they can be divided into: solid solution strengthening elements, such as tungsten, molybdenum, cobalt, chromium, and vanadium; precipitation strengthening elements, such as aluminum, titanium, niobium, and tantalum; grain boundary strengthening elements, such as boron, zirconium, magnesium, and rare earth elements.

[0003] Nickel-based superalloys are known as the "heart of aeroengines" due to their excellent heat resistance and corrosion resistance, and have characteristics such as stable structure, high working temperature, and strong alloying ability. At present, they have become important metal materials necessary for aerospace, military, naval gas turbines, and rocket engines, and have also been widely used in fields such as high-temperature chemistry, atomic energy industry, and ground turbines. Summary of the Invention

[0004] The present invention is made based on the inventor's discovery and understanding of the following facts and problems:

[0005] With the development of China's industrialization drive, nickel-based superalloys are not only increasingly widely used in the aerospace field, but also gradually applied in energy power, transportation, petrochemical, metallurgical mining, and glass building materials in the civilian industry. With the emergence of aircraft engines that require materials to serve for a long time and industrial gas turbines that meet peak load power generation requirements, the materials used need to have anti-fatigue, anti-thermal fatigue, oxidation resistance, and tensile properties. Therefore, researching superalloys with higher temperature-bearing capacity and corrosion resistance is of great significance to the development of China's aviation industry.

[0006] 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 an oxidation-resistant nickel-based superalloy. The nickel-based alloy significantly increases the content of element Cr, reduces the content of Co, enables the alloy to have excellent room-temperature tensile properties, good sensitivity to strain-age cracking, outstanding oxidation resistance, and no cracks after hot working, and can meet the requirements of the design and use of advanced aeroengines and gas turbines.

[0007] An oxidation-resistant nickel-based superalloy according to an embodiment of the present invention comprises C: 0.03-0.09%, Cr: 26.00-28.00%, Co: 5.10-6.90%, Mo: 7.00-9.50%, Al: 1.9-2.5%, Ti: 1.2-1.7%, Nb: 0.6-1.8%, B: 0.002-0.008%, Sc: 0.002-0.008%, Zr: 0-0.05%, W: 0-0.05%, and the balance is nickel and inevitable impurities, by mass percentage.

[0008] The advantages and technical effects brought by the oxidation-resistant nickel-based superalloy according to an embodiment of the present invention are as follows: 1. In the embodiment of the present invention, the dosage of element Cr is significantly increased. The addition of Cr element enables the alloy to form a stable oxide film in an oxidation medium, improves the high-temperature oxidation resistance of the alloy, and can also improve the oxidation resistance of the nickel-based alloy in high-temperature sulfur-containing gases; 2. In the embodiment of the present invention, the content of Co element is reduced. The addition of Co can significantly improve the oxidation resistance of the alloy. Controlling Co within a lower content range can not only reduce the preparation cost of the alloy, but also maintain the comprehensive performance of the alloy at a relatively high level; 3. In the embodiment of the present invention, by adjusting the content ratio among the components, a nickel-based superalloy with excellent room-temperature tensile properties, good sensitivity to strain-age cracking, outstanding oxidation resistance and no hot-working cracks can be prepared, which can meet the requirements of the design and use of advanced aeroengines and gas turbines.

[0009] In some embodiments, the nickel-based alloy comprises C: 0.04-0.07%, Cr: 26.1-27.22%, Co: 5.24-6.65%, Mo: 7.66-9.02%, Al: 1.96-2.43%, Ti: 1.25-1.65%, Nb: 0.88-1.34%, B: 0.003-0.005%, Sc: 0.002-0.007%, Zr: 0.008-0.042%, W: 0.01-0.04%, and the balance is nickel and inevitable impurities, by mass percentage.

[0010] In some embodiments, the nickel-based superalloy further comprises Y with a mass percentage of 0.15-0.3%.

[0011] In some embodiments, the mass percentage contents of Cr, Co and Y satisfy the relational expression 1.95% < 0.35Cr - Co - 3.2Y < 3.43%.

[0012] In some embodiments, the mass percentage contents of Cr, Co and Y satisfy the relational expression 2.27% < 0.35Cr - Co - 3.2Y < 3.39%.

[0013] The embodiments of the present invention also provide an application of the oxidation-resistant nickel-based superalloy in an aeroengine or a gas turbine.

[0014] The embodiments of the present invention also provide an application of the oxidation-resistant nickel-based superalloy in an ultra-supercritical coal-fired power station.

[0015] The embodiments of the present invention also provide a preparation method of the oxidation-resistant nickel-based superalloy, comprising the following steps:

[0016] (1) In a vacuum induction melting furnace, heat up to 1500 - 1700 °C for high-temperature refining;

[0017] (2) Close the vacuum induction melting furnace and carry out casting at 1300 - 1400 °C to form an ingot;

[0018] (3) Heat-treat the ingot at 900 - 1000 °C.

[0019] The advantages and technical effects brought by the preparation method of the oxidation-resistant nickel-based superalloy according to the embodiments of the present invention are as follows: 1. In the embodiments of the present invention, the nickel-based superalloy prepared by this preparation method has excellent room-temperature tensile properties, good strain-age cracking sensitivity, oxidation resistance and no hot-working cracks, meeting the requirements for the design and use of advanced aeroengines and gas turbines; 2. In the embodiments of the present invention, the preparation method is simple, reducing energy consumption, shortening the production cycle and improving production efficiency.

[0020] In some embodiments, in step (1), the time for the high-temperature refining is 10 - 30 min.

[0021] In some embodiments, in step (3), the time for the heat treatment is 15 - 35 h. Detailed Embodiments

[0022] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

[0023] An oxidation-resistant nickel-based superalloy according to an embodiment of the present invention comprises C: 0.03-0.09%, Cr: 26.00-28.00%, Co: 5.10-6.90%, Mo: 7.00-9.50%, Al: 1.9-2.5%, Ti: 1.2-1.7%, Nb: 0.6-1.8%, B: 0.002-0.008%, Sc: 0.002-0.008%, Zr: 0-0.05%, W: 0-0.05%, with the balance being nickel and inevitable impurities, by mass percentage.

[0024] The oxidation-resistant nickel-based superalloy according to the embodiment of the present invention significantly increases the amount of element Cr used. The addition of Cr element enables the alloy to form a stable oxide film in an oxidation medium, improving the high-temperature oxidation resistance of the alloy and also enhancing the oxidation resistance of the nickel-based alloy in high-temperature sulfur-containing gases. The content of Co element is reduced. The addition of Co can significantly improve the oxidation resistance of the alloy. Controlling Co within a lower content range can not only reduce the preparation cost of the alloy but also maintain the comprehensive performance of the alloy at a relatively high level. By regulating the content ratio among various components, a nickel-based superalloy with excellent room-temperature tensile properties, good resistance to strain-age cracking sensitivity, outstanding oxidation resistance, and no hot-working cracks can be prepared, which can meet the requirements for the design and use of advanced aeroengines and gas turbines.

[0025] The functions of C, Cr, and Ti in the nickel-based superalloy according to the embodiment of the present invention are as follows:

[0026] Cr is an essential alloying element in superalloys. A part of the Cr element added to the superalloy dissolves into the γ' phase to play a strengthening role and forms a small amount of carbides to play a carbide strengthening role. Most of the remaining Cr dissolves in the γ matrix. The Cr element dissolved in the matrix causes lattice distortion and generates an elastic stress field to play a solid-solution strengthening role. At the same time, the Cr element also reduces the stacking fault energy of the solid solution and improves the high-temperature creep strength of the alloy. In addition, the most important role of the Cr element in superalloys is to form a Cr2O3-type oxide film to improve the oxidation and corrosion resistance of the alloy. And the higher the Cr element content, the better the oxidation resistance. However, in the alloy system of the embodiment of the present invention, too much Cr content will lead to a decrease in the plasticity of the alloy.

[0027] When Co is added as an alloying element to a nickel-based alloy, it can reduce the stacking fault energy of the matrix. With a low stacking fault energy, it is easier to form stacking faults, the probability of stacking faults occurring increases, and the stacking fault width increases. This hinders the movement of extended dislocations, that is, the reduction of the stacking fault energy makes cross-slip more difficult, thereby increasing the strength of the alloy. In addition, the reduction of the stacking fault energy can also reduce the creep rate, increasing the creep resistance. Moreover, the addition of Co element can also reduce the solubility of Al and Ti elements in the matrix of the nickel-based alloy, thereby increasing the quantity of γ' phase. At the same time, it promotes the transformation of the γ' phase from the original Ni3(Al,Ti) to (Ni,Co)3(Al,Ti), increasing the solution temperature of the γ' phase, so that the alloy can withstand a higher service temperature. However, in the alloy system of the embodiments of the present invention, too much addition of Co will lead to a decrease in the plasticity of the alloy. Therefore, the addition amount of Co is controlled within 5.10 - 6.90%.

[0028] In some embodiments, preferably, the nickel-based alloy comprises C: 0.04 - 0.07%, Cr: 26.1 - 27.22%, Co: 5.24 - 6.65%, Mo: 7.66 - 9.02%, Al: 1.96 - 2.43%, Ti: 1.25 - 1.65%, Nb: 0.88 - 1.34%, B: 0.003 - 0.005%, Sc: 0.002 - 0.007%, Zr: 0.008 - 0.042%, W: 0.01 - 0.04%, and the balance is nickel and inevitable impurities, by mass percentage.

[0029] In some embodiments, preferably, the nickel-based superalloy further comprises Y with a mass percentage of 0.15 - 0.3%.

[0030] In the embodiments of the present invention, rare earth element Y is added to the alloy. The formation free energy of Y with O, N, and S is very low, and it is extremely easy to form Y-containing oxides, nitrides, sulfides, and oxysulfides, which float up and are removed in the alloy liquid during smelting, thereby reducing the oxygen, nitrogen, and sulfur contents in the alloy and playing a role in purifying the grain boundaries. Secondly, Y element can segregate at the grain boundaries as a microalloying element, strengthening the grain boundaries, inhibiting the formation and propagation of cracks, and thus improving the creep rupture properties of the alloy. Thirdly, Y, as an active element, improves the oxidation resistance of the alloy. It reduces the oxidation activation energy in the later stage of oxidation, reduces the oxidation weight gain and oxidation rate of the alloy, and improves the compactness of the oxide film, thereby enhancing the surface stability of the alloy.

[0031] In some embodiments, preferably, the mass percentages of Cr, Co, and Y satisfy the relationship 1.95% < 0.35Cr - Co - 3.2Y < 3.43%. Further preferably, the mass percentages of Cr, Co, and Y satisfy the relationship 2.27% < 0.35Cr - Co - 3.2Y < 3.39%.

[0032] In the embodiments of the present invention, the relational expressions satisfied by the mass percentages of Cr, Co, and Y in the nickel-based superalloy are further optimized, enabling the synergistic effect among Cr, Co, and Y to be maximized. The alloy not only has excellent room-temperature tensile yield strength and room-temperature tensile ultimate strength, but also has outstanding oxidation resistance. The average oxidation rate can be controlled below 0.046 g / m 2 ·h, and the alloy reaches the best comprehensive performance level, meeting the requirements for the design and use of advanced aeroengines and gas turbines.

[0033] The embodiments of the present invention also provide an application of the oxidation-resistant nickel-based superalloy in an aeroengine or a gas turbine. The nickel-based superalloy in the embodiments of the present invention meets the requirements for the design and use of advanced aeroengines or gas turbines and can be applied to precision equipment of advanced aeroengines or gas turbines.

[0034] The embodiments of the present invention also provide an application of the oxidation-resistant nickel-based superalloy in an ultra-supercritical coal-fired power station. The nickel-based superalloy in the embodiments of the present invention has excellent comprehensive performance and can be applied to ultra-supercritical coal-fired power stations.

[0035] The embodiments of the present invention also provide a preparation method of an oxidation-resistant nickel-based superalloy, comprising the following steps:

[0036] (1) In a vacuum induction melting furnace, heat up to 1500 - 1700 °C for high-temperature refining;

[0037] (2) Cast at 1500 - 1620 °C to form an ingot;

[0038] (3) Heat-treat the ingot at 900 - 1000 °C.

[0039] The preparation method of the oxidation-resistant nickel-based superalloy in the embodiments of the present invention results in a nickel-based superalloy with excellent room-temperature tensile properties, good strain-age cracking sensitivity resistance, oxidation resistance, and no hot-working cracks, meeting the requirements for the design and use of advanced aeroengines and gas turbines; the preparation method is simple, reducing energy consumption, shortening the production cycle, and improving production efficiency.

[0040] In some embodiments, preferably, in step (1), the time for the high-temperature refining is 10 - 30 min. Further preferably, in step (3), the time for the heat treatment is 15 - 35 h.

[0041] In the embodiments of the present invention, the refining time is optimized to improve the refining effect and reduce the impurity content in the alloy. Heat treatment plays an important role in enhancing the comprehensive properties of the superalloy. Further, the heat treatment time is optimized to facilitate the preparation of a nickel-based superalloy with low impurity content, good high-temperature tissue stability, and excellent oxidation resistance.

[0042] The present invention will be described in detail below with reference to the embodiments.

[0043] Example 1

[0044] (1) In a vacuum induction melting furnace, the temperature is raised to 1600 °C for high-temperature refining, and the high-temperature refining time is 30 min.

[0045] (2) Pouring is carried out at 1580 °C to form an ingot.

[0046] (3) The ingot is heat-treated at 900 °C, and the heat treatment time is 35 h.

[0047] The alloy composition obtained in Example 1 is shown in Table 1, and the performance is shown in Table 2.

[0048] Example 2

[0049] (1) In a vacuum induction melting furnace, the temperature is raised to 1580 °C for high-temperature refining, and the high-temperature refining time is 10 min.

[0050] (2) Pouring is carried out at 1590 °C to form an ingot.

[0051] (3) The ingot is heat-treated at 1000 °C, and the heat treatment time is 15 h.

[0052] The alloy composition obtained in Example 2 is shown in Table 1, and the performance is shown in Table 2.

[0053] Examples 3-5 have the same preparation method as Example 1, except for the different alloy compositions. The alloy compositions obtained in Examples 3-5 are shown in Table 1, and the performance is shown in Table 2.

[0054] Example 6

[0055] Example 6 has the same preparation method as Example 1, with different alloy compositions. The value of 0.35Cr-Co-3.2Y is 1.69. The alloy composition obtained in Example 6 is shown in Table 1, and the performance is shown in Table 2.

[0056] Example 7

[0057] Example 7 has the same preparation method as Example 1, with different alloy compositions. The value of 0.35Cr-Co-3.2Y is 3.69. The alloy composition obtained in Example 7 is shown in Table 1, and the performance is shown in Table 2.

[0058] Example 8

[0059] Example 8 was prepared in the same manner as Example 1, but with different alloy compositions and without the rare earth element Y. The alloy composition of Example 8 is shown in Table 1, and the properties are shown in Table 2.

[0060] Comparative Example 1

[0061] Comparative Example 1 was prepared in the same manner as Example 1, except that in the alloy composition, the content of element Cr was 20.66%. The alloy composition of Comparative Example 1 is shown in Table 1, and the properties are shown in Table 2.

[0062] Comparative Example 2

[0063] Comparative Example 2 was prepared in the same manner as Example 1, except that in the alloy composition, the content of element Cr was 29.01%. The alloy composition of Comparative Example 2 is shown in Table 1, and the properties are shown in Table 2.

[0064] Comparative Example 3

[0065] Comparative Example 3 was prepared in the same manner as Example 1, except that in the alloy composition, the content of element Co was 4.88%. The alloy composition of Comparative Example 3 is shown in Table 1, and the properties are shown in Table 2.

[0066] Comparative Example 4

[0067] Comparative Example 4 was prepared in the same manner as Example 1, except that in the alloy composition, the content of element Co was 7.02%. The alloy composition of Comparative Example 4 is shown in Table 1, and the properties are shown in Table 2.

[0068] Comparative Example 5

[0069] Comparative Example 5 was prepared in the same manner as Example 1, except that in the alloy composition, the content of element Y was 0.35%. The alloy composition of Comparative Example 5 is shown in Table 1, and the properties are shown in Table 2.

[0070] Table 1 Alloy Compositions of Comparative Examples and Examples (wt.%)

[0071]

[0072] Note: The contents of Mn and Si are less than 0.50%.

[0073] Table 2 Alloy Properties of Examples and Comparative Examples

[0074]

[0075] Note: 1. R p0.2 is the room temperature tensile yield strength of the aged alloy, R m is the room temperature tensile ultimate strength of the aged alloy, and A is the elongation after fracture of the aged alloy at room temperature;

[0076] 2. Resistance to strain aging cracking sensitivity (CHRT value): For solution-treated sheets, the heating rate is 15 °C / min. When the temperature is raised to 816 °C, it is immediately stretched at a constant rate. The tensile plasticity at different temperatures is measured, and the minimum value is taken as the resistance to strain aging cracking sensitivity (CHRT value) of the alloy. The larger this value, the better the resistance to strain aging cracking, and the less likely it is to crack during welding.

[0077] 3. The average oxidation rate is the oxidation rate per unit area of the alloy at 900 °C. The smaller this value, the better the oxidation resistance.

[0078] 4. The detection condition for hot working cracks is: during hot working, the naked eye is used to observe whether macroscopic cracks occur.

[0079] From the data of each example and comparative example in Table 1 and Table 2, it can be seen that within a certain content range of each element in the alloy, the room temperature tensile yield strength can exceed 760 MPa, the room temperature tensile ultimate strength can reach above 1140 MPa, the elongation after fracture at room temperature can reach more than 29%, the resistance to strain aging cracking sensitivity is greater than 13.50%, and the average oxidation rate is less than 0.063 g / m 2 ·h. It can be seen that this nickel-based superalloy has excellent room temperature tensile properties, good resistance to strain aging cracking sensitivity, oxidation resistance, and no hot working cracks, meeting the requirements of the design and use of advanced aeroengines and gas turbines.

[0080] In Comparative Examples 1-2, the amount of element Cr was adjusted. The content of element Cr in Comparative Example 1 was 20.66%, and the strength and plasticity of the alloy were significantly reduced, and the oxidation rate was significantly increased; the content of element Cr in Comparative Example 2 was 29.01, the plasticity of the alloy decreased, and the room temperature tensile elongation A was unqualified.

[0081] In Comparative Examples 3-4, the amount of element Co was adjusted. The content of element Co in Comparative Example 3 was 4.88%, and the strength of the alloy was significantly reduced. The content of Co element in Comparative Example 4 was 7.02%, the plasticity of the alloy decreased slightly, the room temperature tensile elongation A was unqualified, and the resistance to strain aging cracking sensitivity was significantly reduced.

[0082] The content of element Y in Comparative Example 5 was 0.35%. Due to the excessive addition of Y, the plasticity of the alloy was significantly reduced, the room temperature tensile elongation A was unqualified, and cracking occurred during hot working.

[0083] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", 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 may be combined in any one or more embodiments or examples in a suitable manner. 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.

[0084] Although the above embodiments have been shown and described, it can 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. An antioxidant nickel-based superalloy, characterized in that, Comprising C: 0.03 - 0.09%, Cr: 26.00 - 28.00%, Co: 5.10 - 6.90%, Mo: 7.00 - 9.50%, Al: 1.9 - 2.5%, Ti: 1.2 - 1.7%, Nb: 0.6 - 1.8%, B: 0.002 - 0.008%, Sc: 0.002 - 0.008%, Zr: 0 - 0.05%, W: 0 - 0.05%, Y: 0.15 - 0.3%, the balance being nickel and unavoidable impurities, by mass percentage, wherein the mass percentages of Cr, Co and Y satisfy the relationship 1.95% < 0.35Cr - Co - 3.2Y < 3.43%.

2. The antioxidant nickel-based superalloy according to claim 1, characterized in that, The nickel-based alloy comprises C: 0.04 - 0.07%, Cr: 26.1 - 27.22%, Co: 5.24 - 6.65%, Mo: 7.66 - 9.02%, Al: 1.96 - 2.43%, Ti: 1.25 - 1.65%, Nb: 0.88 - 1.34%, B: 0.003 - 0.005%, Sc: 0.002 - 0.007%, Zr: 0.008 - 0.042%, W: 0.01 - 0.04%, Y: 0.15 - 0.3%, the balance being nickel and unavoidable impurities, by mass percentage.

3. The antioxidant nickel-based superalloy according to claim 1, characterized in that, The mass percentages of Cr, Co and Y satisfy the relationship 2.27% < 0.35Cr - Co - 3.2Y < 3.39%.

4. Application of the oxidation-resistant nickel-based superalloy according to any one of claims 1 to 3 in an aeroengine or a gas turbine.

5. Application of the oxidation-resistant nickel-based superalloy according to any one of claims 1 to 3 in an ultra-supercritical coal-fired power station.

6. A method for preparing an antioxidant nickel-based superalloy according to any one of claims 1 to 3, characterized in that, Comprising the following steps: (1) In a vacuum induction melting furnace, heating up to 1500 - 1700 °C for high-temperature refining; (2) Closing the vacuum induction melting furnace and pouring at 1500 - 1620 °C to form an ingot; (3) Heat-treating the ingot at 900 - 1000 °C.

7. The preparation method of the antioxidant nickel-based superalloy according to claim 6, characterized in that, In step (1), the time of the high-temperature refining is 10 - 30 min.

8. The preparation method of the antioxidant nickel-based superalloy according to claim 6 or 7, characterized in that, In step (3), the time of the heat treatment is 15 - 35 h.

Images