WO2011138952A1 - Heat-resistant nickel-based superalloy containing annealing twins and heat-resistant superalloy member - Google Patents

Abstract

Disclosed is a heat-resistant nickel-based superalloy containing chromium, cobalt, titanium, aluminum, and nickel as main elements. This superalloy can contain additional component elements and inevitable impurity elements, and the total of the length for annealing twins is 500 µm or more per 104 µm² of cross-sectional area.

Description

Nickel-base heat-resistant superalloys and heat-resistant superalloy components containing annealing twins

The present invention relates to a heat-resistant member such as an aero engine and a power generation gas turbine, and more particularly to a nickel-based heat-resistant superalloy used for a turbine disk, a turbine blade, or the like.

Heat-resistant members such as aero engines and power generation gas turbines, for example, turbine discs, are components that hold moving blades and rotate at high speeds. These components can withstand extremely high centrifugal stress, and have fatigue strength and creep. A material having excellent strength and fracture toughness is required. On the other hand, with improvement in fuel efficiency and performance, improvement in engine gas temperature and weight reduction of the turbine disk are required, and higher heat resistance and strength are required for the material.

Generally, a nickel-based forged alloy is used for the turbine disk. For example, Inconel 718, which uses a γ ″ (gamma double prime) phase as a reinforcing phase, and Waspaloy, which precipitates about 25 vol% of a γ ′ (gamma prime) phase, which is more stable than the γ ″ phase, is used as a reinforcing phase. ing. Moreover, since 1986, Udimet 720 has been introduced from the viewpoint of increasing the temperature. Udimet 720 is excellent in heat resistance properties by precipitating about 45 vol% of the γ 'phase and adding tungsten for solid solution strengthening of the γ phase.

On the other hand, Udimet 720 is not necessarily sufficient in tissue stability, and because a harmful TCP (Topologically closed-packed) phase is formed during use, Udimit720Li (U720Li / U720LI) has been developed with improvements such as reducing the amount of chromium. It was done. However, even in the improved Udimit 720Li, the generation of the TCP phase is still unavoidable, and the use at a long time or at a high temperature is limited. It is also pointed out that Udimit 720 and Udimit 720Li have a narrow process window for hot working, heat treatment, and the like because the difference between the γ ′ solidus temperature (solvus) and the initial melting temperature is small. Due to these reasons, it is difficult to produce a homogeneous turbine disk by the casting forging process, which is a practical problem.

For high-pressure turbine disks that require high strength, powder metallurgical alloys such as AF115, N18, and Rene88DT may be used. The powder metallurgy alloy has an advantage that a homogeneous disk without segregation can be obtained despite containing a large amount of reinforcing elements. On the other hand, this powder metallurgical alloy requires advanced manufacturing process management such as high-vacuum melting and optimization of mesh size at the time of powder classification in order to suppress the inclusion inclusions, which greatly increases the manufacturing cost. There is a problem of going up.

In addition, many proposals for improving the chemical composition of conventional nickel-base heat-resistant superalloys have been made. All of them contain cobalt, chromium, molybdenum or molybdenum and tungsten, aluminum, and titanium as main constituent elements, and typically, either or both of niobium and tantalum are essential constituent elements. Yes. Such niobium or tantalum content is suitable for the above-mentioned powder metallurgy, but is a factor that makes casting forging difficult. Moreover, although the content rate of cobalt is comparatively high, content is restrained to about 20 mass% or less from balance with cost etc. except for the specific case.

Titanium is added because it functions to strengthen the γ 'phase and improve the tensile strength and crack propagation resistance. However, excessive addition of titanium is limited to about 5% by mass from the viewpoint that it is difficult to obtain a healthy γ ′ structure by generating a harmful phase in addition to increasing the γ ′ solidus temperature. ing.

In such a situation, the present inventors have studied the optimization of the chemical composition of the nickel-base heat-resistant superalloy and can suppress harmful TCP phases by positively adding cobalt to 55% by mass. I have found that. Further, the present inventors have found that it is possible to stabilize the two-phase structure of γ / γ ′ by increasing titanium at a predetermined ratio simultaneously with cobalt. Based on these findings, a nickel-based heat-resistant superalloy that can withstand a long time in a higher temperature range than conventional alloys and has good workability has been proposed (Patent Document 1).

On the other hand, in order to improve the performance of nickel-base heat-resistant superalloys, several proposals have been made focusing on the microstructure of nickel-base heat-resistant alloys. For example, a nickel-base heat-resistant alloy billet made of a powder alloy is subjected to forging and heat treatment steps, so that the average grain size is 20-40 μm, fine γ ′ of 30 nm is uniformly distributed throughout the grain, and the grain boundary Further, an alloy having a microstructure in which a coarse γ ′ of 0.3 to 0.4 μm is formed has been proposed (Patent Documents 2 and 3).

In addition, in the metal structure observed two-dimensionally with a transmission electron microscope, there are 700 or more precipitates having a major axis of 0.5 nm or more per 1 μm ² and an average diameter of 25 nm to 1 μm. An alloy containing large precipitates has been proposed (Patent Document 4).

However, the alloys described in Patent Documents 2 and 3 are powder alloys with complicated processes and high production costs. In this alloy, the optimum microstructure varies depending on the chemical composition, and some limited materials and It can be considered that it is applicable only to the manufacturing method. Patent Document 4 only proposes a preferable range of the metal structure, and no specific data regarding the correlation with the alloy characteristics is found.

Pamphlet of International Publication No. 2006/059805 Japanese Patent No. 2666911 Japanese Patent No. 2667929 JP 2003-89836 A

In order to improve energy efficiency in recent years, there is an urgent need to develop materials that can be used at higher temperatures for heat-resistant members such as aircraft engines and power generation gas turbines. For example, for a turbine disk, there is a strong demand for the development of a new alloy having further excellent mechanical properties such as fatigue strength, high temperature creep strength, fracture toughness, and high temperature fatigue crack resistance.
The present invention has been made in view of the circumstances as described above, and it is an object of the present invention to provide a nickel-base heat-resistant superalloy containing an annealing twin whose heat resistance characteristics are largely improved.

In order to solve the above problems, the present inventors have focused on the correlation between the mechanical properties such as fatigue strength, high temperature creep strength, fracture toughness, high temperature fatigue crack resistance, and the microstructure of the nickel-base heat resistant superalloy. It has been found that the mechanical characteristics, particularly the heat resistance characteristics can be greatly improved by optimizing the microstructure of the annealing stage of the nickel-base heat resistant alloy. The present invention has been completed based on such findings.

That is, the nickel-base heat-resistant superalloy containing the annealing twin of the present invention includes chromium, cobalt, titanium, aluminum and nickel as main elements, and allows the inclusion of additive component elements and inevitable impurity elements. In this case, the total length of the annealing twin is 500 μm or more per 104 μm ² in cross-sectional area.

In the nickel-base heat-resistant superalloy containing the annealing twin, the average crystal grain size of the microstructure is preferably 1 μm or more and less than 60 μm.

In the nickel-base heat-resistant superalloy containing the annealing twin, chromium is 1.0% to 30.0%, cobalt is 5.0% to 55.0%, and titanium is 2.% by mass. It is preferable to contain 5% or more and 15.0% or less and aluminum 0.2% or more and 7.0% or less.

Also, the nickel-base heat-resistant superalloy containing the annealing twin preferably contains 9.5% or more and 50.0% or less of cobalt by mass%.

Further, the nickel-base heat-resistant superalloy containing the annealing twin preferably contains 13.5% or more and 50.0% or less of cobalt by mass%.

Also, the nickel-base heat-resistant superalloy containing the annealing twin preferably contains 19.5% or more and 50.0% or less of cobalt by mass%.

In addition, the nickel-base heat-resistant superalloy containing the annealing twin preferably contains 5.1% or more and 15.0 or less of titanium by mass%.

Further, the nickel-base heat-resistant superalloy containing the annealing twin preferably contains 5.3% to 10.0% of titanium by mass.

In the nickel-base heat-resistant superalloy containing the annealing twin, at least one of 5.0% by mass or less of molybdenum, 7.0% by mass or less of tungsten, and 5.0% by mass or less of niobium is added as an additive element. Can be included as

In the nickel-base heat-resistant superalloy containing the annealing twin, 0.01 mass% or more and 0.2% or less zirconium, 0.01 mass% or more and 0.15% or less carbon, 0.005 mass % Or more and 0.1% by mass or less of boron can be included as an inevitable impurity element.

The heat-resistant superalloy member of the present invention is characterized in that it is manufactured from the above nickel-base heat-resistant superalloy containing the annealing twin by at least one method of casting, forging or powder metallurgy.

According to the nickel-base heat-resistant superalloy and heat-resistant superalloy member containing the annealing twin of the present invention, heat resistance characteristics are largely improved mainly.

1 (a) and 1 (b) and FIGS. 1 (c) and 1 (d) are TEM photographs of Alloy 1 and Alloy 4 before the creep test, respectively. 1 (a) and 1 (c) show a bright field image, and FIGS. 1 (b) and 1 (d) show a secondary γ ′ phase dark field image. 2 (a) and 2 (b) are photographs of an annealing twin observed using an Electron Back-Scatter Diffraction (EBSD) system. The phase indicated by the linear band in the crystal grains is the annealing twin. The relationship between the total length of annealing twins from Alloy 1 to Alloy 4 and the creep life is illustrated. The relationship between the total length of the annealing twins from Alloy 1 to Alloy 4 and the low cycle fatigue test (LCF) is illustrated. 6 is a TEM photograph of Alloy 1 (FIG. 5 (a), FIG. 5 (b)) and Alloy 2 (FIG. 5 (c)) after performing a creep test at 725 ° C. FIG.

The deformation strengthening mechanism during the creep test (Deformation Step) includes solid solution strengthening by dissolved atoms (Solid solution solution by strengthening by solute absolute atoms), grain boundary strengthening by chemical reaction (Grain by Boundary by strengthening by chemistry, reaction by particles by bounds), nano Strengthening of the scale with twin boundaries (Nanoscale twin boundary strengthening) has been discussed. These factors are balanced against resistance to tensile, high temperature creep, stress rupture and fatigue crack growth, although some correlation can be seen with the mechanical properties of each nickel-base heat-resistant superalloy. The desired material design factors for nickel-base heat-resistant superalloys have not yet been derived.

By observing the microstructure of the nickel-base heat-resistant superalloy, the inventors have found that annealing twins are formed in the crystal grains during the annealing process, and the total length per unit area of this annealing twin is the nickel-base heat-resistant superalloy. We found for the first time that it is an important factor for improving the heat resistance of alloys.

Annealing twins (annealed twins) are twins formed by annealing a metal.
The nickel-base heat-resistant superalloy containing the annealing twin of the present invention can be manufactured by applying various general methods. For example, high-quality various metal raw materials are melted by high-frequency vacuum so as to have a predetermined chemical composition, and vacuum casting is performed to produce an ingot. This ingot is repeatedly forged to produce an alloy having a uniform fine structure, and finally a die is forged into a predetermined shape to form a billet. Alternatively, the ingot is melted and atomized in an inert gas atmosphere to produce an alloy powder, and then the alloy powder is consolidated in a vacuum and forged to produce a billet. By annealing these billets under appropriate conditions, a nickel-base heat-resistant superalloy having a microstructure containing an annealing twin can be produced. The annealing treatment conditions vary depending on the chemical composition and the like, but generally, the annealing is performed at 600 to 800 ° C. for 10 to 30 hours. Further, the annealing process can be performed not only once but also in a multistage process of two or more times. Furthermore, prior to the annealing treatment, a solution treatment at 900 to 1200 ° C. for 1 to 10 hours can be performed to promote the formation of a microstructure having a sufficiently fine crystal grain size and a homogeneous structure.

Total annealing twin length, by controlling so that 104 .mu.m ² per 500μm or more is the cross-sectional area of the nickel-base heat-resistant superalloy, nickel-based heat-resistant superalloy, balanced and very good heat resistance It will have. In this way, by having a large number of annealing twins in the microstructure of the nickel-base heat-resistant superalloy, the annealing twin blocks the movement of the dislocation and the movement of the deformation twin, and the heat resistance characteristics at high temperatures. Improvement is expected to be achieved.

In the microstructure formed in the nickel-base heat-resistant superalloy, the size of the crystal grains is not particularly limited as long as the total annealing twin length is 500 μm or more per cross-sectional area of 104 μm ^2. The average grain size is preferably 1 μm or more and less than 60 μm, more preferably 5 μm or more and 50 μm or less.

The nickel-base heat-resistant superalloy containing the annealing twin of the present invention contains chromium, cobalt, titanium, aluminum, and nickel as main constituent elements and allows the inclusion of inevitable impurity elements.

Chrome is added to improve environmental resistance and fatigue crack propagation characteristics. In order to improve these characteristics, if the content is less than 1.0% by mass, desirable characteristics cannot be obtained. If the content exceeds 30.0% by mass, a harmful TCP phase tends to be generated. For this reason, the chromium content is 1.0% by mass or more and 30.0% by mass or less, preferably 5.0% by mass or more and 23.0% by mass or less, more preferably 9.0% by mass or more. It is 20.0 mass% or less.

Cobalt is a component useful for controlling the γ ′ phase solvus temperature. Increasing cobalt reduces the γ ′ solid phase temperature, widens the process window, and improves the forgeability. In particular, when a large amount of titanium is contained, cobalt can be added in a slightly larger amount in order to suppress the TCP phase and improve the high temperature strength. Usually, the cobalt content is 5.0 to 55.0 mass%, preferably 9.5 to 50.0 mass%, more preferably 13.5 to 50 mass%. It is 0.0 mass% or less, More preferably, it is 8 mass% or more and 35 mass% or less. Even in the composition region where the titanium content is 5.1% by mass or more, by adjusting the cobalt content to 19.5% by mass or more and 55.0% by mass or less, a balance between heat resistance and easy processability is achieved. Practical use of nickel-base heat-resistant superalloy is possible.

In the case of the cobalt-titanium composite addition proposed by the present inventors in Patent Document 1, for example, when a Co—Ti alloy is added, the content of cobalt and titanium is set according to the relational expression described later. be able to. The same effect can be obtained even when the cobalt content is 19.5% by mass or more, further 23.1% by mass or more, and up to 55.0% by mass.
However, as long as it is based on the high temperature compression test results, nickel-base heat-resistant superalloys containing cobalt in excess of 55.0% by mass tend to decrease in strength up to 750 ° C. The upper limit of the content of is 55.0% by mass. Further, the cobalt content may be 22.0% by mass or more and 35.0% by mass or less, or 23.1% by mass or more and 35.0% by mass or less.

Titanium is a desirable additive element for strengthening the γ ′ phase and leading to strength improvement, and the content of titanium is usually 2.5% by mass or more and 15.0% by mass or less. In the case of the composite addition of cobalt-titanium, a more excellent effect is recognized by addition of 5.1 mass% or more and 15.0 mass% or less of titanium. Titanium achieves a nickel-base heat-resistant superalloy with excellent phase stability and high strength by complex addition with cobalt. Basically, by selecting a heat-resistant superalloy having a γ + γ'2 phase structure and adding a Co + Co ₃ Ti alloy, a nickel-based heat-resistant superalloy having a stable structure up to a high alloy concentration and high strength can be obtained. Can be realized. In this case, the titanium content is preferably within a range represented by the following formula.
That is, 0.17 × (mass% of cobalt−23) +3 or more,
0.17 × (mass% of cobalt−20) +7 or less.
However, if the titanium content exceeds 15.0% by mass, the formation of η phase, which is a harmful phase, often becomes remarkable, so the upper limit of the titanium content is 15.0% by mass. Preferably, the titanium content is 5.1 mass% or more and 15.0 mass% or less, more preferably 5.3 mass% or more and 11.0 mass% or less, and further preferably 5.3 mass% or more and 10 or less. 0.0 mass% or less.

Aluminum is an element that forms a γ ′ phase, and the aluminum content is adjusted so as to have an appropriate amount of γ ′ phase. The content of aluminum is in the range of 0.2% by mass or more and 7.0% by mass or less. Further, the content ratio of titanium and aluminum is strongly related to the generation of η phase, and in order to suppress the generation of the TCP phase, which is a harmful phase, it is preferable to increase the aluminum content as much as possible. Furthermore, aluminum is directly involved in the formation of aluminum oxide on the surface of the nickel-base heat-resistant superalloy and contributes to oxidation resistance.

The nickel-base heat-resistant superalloy containing the annealing twin of the present invention contains nickel as a main constituent element in addition to the above chromium, cobalt, titanium and aluminum.
Further, the nickel-base heat-resistant superalloy containing the annealing twin of the present invention can also contain the following elements as additive components.
Molybdenum has the effect of mainly strengthening the γ phase and improving the creep characteristics. Molybdenum is an element with a high density, so if its content is too large, the density of the nickel-base heat-resistant superalloy will increase, which is not preferable in practice. Usually, the molybdenum content is 5.0% by mass or less, preferably 0.1% by mass or more and less than 4.0% by mass.

Tungsten is an element that dissolves in the γ phase and the γ ′ phase, strengthens both phases, and is effective in improving the high temperature strength. If the content of tungsten is small, the creep characteristics may be insufficient. If the content is large, it is an element having a high density like molybdenum, and thus the density of the nickel-base heat-resistant superalloy may be increased. Usually, the tungsten content is 7.0% by mass or less, preferably 0.1% by mass or more and 5.0% by mass or less.

Niobium is effective as a specific gravity control and strengthening element, but if the content is increased to some extent, there is a possibility that undesirable phases are formed or cracks occur at high temperatures. Usually, the niobium content is 5.0% by mass or less, preferably 0.1% by mass or more and 4.0% by mass or less.

On the other hand, zirconium is an element effective for improving ductility, fatigue characteristics, and the like. Usually, the zirconium content is 0.01 mass% or more and 0.2 mass% or less, preferably 0.01 mass% or more and 0.15 mass% or less, more preferably 0.01 mass% or more and 0.05 mass% or less. It is as follows.

Carbon is an element effective for improving ductility and creep properties at high temperatures. Usually, the carbon content is 0.01 to 0.15% by mass, preferably 0.01 to 0.10% by mass, more preferably 0.01 to 0.05% by mass. % Or less. Boron can improve creep characteristics and fatigue characteristics at high temperatures. Usually, the boron content is 0.005 to 0.1% by mass, preferably 0.005 to 0.05% by mass, more preferably 0.01 to 0.03% by mass. It is as follows. If the content of carbon and boron exceeds the above range, the creep strength may be reduced or the process window may be narrowed. Zirconium, carbon, and boron are allowed to be contained in the chemical composition as an inevitable impurity element in the nickel-base heat-resistant superalloy containing the annealing twin of the present invention.

The nickel-base heat-resistant superalloy containing the annealing twin of the present invention can also contain at least one element of rhenium, vanadium, hafnium, or magnesium as other elements, as long as the characteristics are not impaired. It is possible to add while appropriately controlling the content. Further, addition of ruthenium is allowed, and ruthenium is effective in improving heat resistance and workability.

The heat-resistant superalloy member of the present invention is manufactured from the nickel-base heat-resistant superalloy containing the annealing twin as described above by at least one method of casting, forging or powder or gold.

Hereinafter, the nickel base heat resistant superalloy and the heat resistant superalloy member containing the annealing twin of the present invention will be described in more detail with reference to examples. Of course, the present invention is not limited by the following examples.

Ingots were prepared with the four chemical compositions shown in Table 1 by vacuum induction heating, and these billets were further forged to produce billets. Mo (molybdenum) and W (tungsten) are additive component elements in the chemical composition of the alloy, and C (carbon), B (boron), and Zr (zirconium) are contained in the chemical composition as unavoidable impurity elements. Is.

Samples rolled from alloy 1 to alloy 4 with hot rolling rolls were subjected to solution treatment in air at 1,100 ° C. for 4 hours, and then annealed at 650 ° C. for 24 hours and further at 760 ° C. for 16 hours. went. About the sample which performed the annealing process, the compression yield pressure and creep rupture characteristic in room temperature and 750 degreeC were evaluated. The results are shown in Table 2. Both alloys had excellent compressive yield pressure and creep rupture properties both at room temperature and at elevated temperatures.

Further, the samples subjected to the annealing treatment were evaluated for 0.2% creep time and rupture time at 750 ° C., LCF (Low Creep Fatigue) and FCGR (Fatigue Crack Growth Rate) at 650 ° C. and 725 ° C. The results are shown in Table 3.

Various microstructure observations were performed on the above alloy 1 to alloy 4.
FIG. 1 shows TEM photographs of Alloys 1 and 4 before the creep test. 1 (a) and 1 (c) show a bright field image, and FIGS. 1 (b) and 1 (d) show a secondary γ ′ phase dark field image.
The particle sizes of Alloy 1 and Alloy 4 were both about 10 μm, and the concentration of the γ ′ phase was about 45%. In addition, the secondary γ ′ phase shown in FIGS. 1B and 1D was almost uniform and about 100 nm in size.
In the above structure observation, no significant difference was observed between the two alloys.

FIG. 2 is a photograph of an annealing twin observed using an Electron Back-Scatter Diffraction (EBSD) system. Phases indicated by linear bands in the crystal grains of FIGS. 2 (a) and 2 (b) are annealing twins formed in Alloy 1 and Alloy 4. FIG. The quantitative relationship between the strip-shaped annealing twins is different between the alloy 1 and the alloy 4, and when the total length of the annealing twins per unit cross-sectional area of the sample is compared, the alloy 1 has 2,944 μm / 104 μm ² , In Alloy 4, it was 1,419 μm / 104 μm ² . Similarly, alloy 2 was measured for length of annealing twin for alloy 3, respectively, 2,144μm / 104μm ^2, was 1,542μm / 104μm ^2.

The relationship between the total annealing twin length and creep strength is shown in FIG. There was a good correlation between the two factors, and it was revealed that the creep life improved as the total length of the annealing twins increased. In addition, there is also a correlation between the total length of the annealing twin and low cycle fatigue (LCF), and as shown in FIG. 4, in proportion to the increase in the total length of the annealing twin. It was found that LCF was improved.

Thus, the total value of the annealing twin length has a clear correlation with the creep strength and the low cycle fatigue, and the larger the total annealing twin length, the greater the effect of improving the mechanical properties.

5 (a) and 5 (b) are TEM photographs showing the microstructure of Alloy 1 after the creep test was performed at 725 ° C. FIG.5 (c) is the TEM photograph which showed the microstructure of the alloy 2 after implementing a creep test on the same conditions.
FIG. 5A shows a state in which the dislocation site (B) cannot penetrate the annealing twin (A) and the movement of the dislocation is blocked by the adjacent annealing twin. Moreover, both FIG.5 (b) and FIG.5 (c) have shown the state which has interrupted the movement of the annealing twin (A) and the deformation twin (C). In this way, by having many annealing twins in the microstructure of the nickel-base heat-resistant superalloy, the annealing twin blocks the movement of the dislocation and the movement of the deformation twin, and has excellent heat resistance at high temperatures. Suggests that is achieved.

“Resistance to fatigue crack growth”, which is a further requirement factor for nickel-base heat-resistant superalloys, means that the fatigue crack growth rate (FCGR) is reduced, and the rim part of the turbine disk It is a particularly important factor as a characteristic.
The shape and dimensions of the specimen used for the measurement of fatigue crack growth rate (FCGR) conformed to ASTM standard E647-81 (1981). The test conditions were a high-temperature atmosphere, a stress ratio (minimum stress / maximum stress) 0.05, a load waveform triangular wave, and a repetition frequency of 2 Hz.

As shown in Table 3, the FCGR value is almost constant regardless of the total length of the annealing twins, although some numerical variations are observed at any temperature of 650 ° C and 725 ° C. Met. Therefore, increasing the abundance of the annealing twin to improve creep strength and low cycle fatigue properties has little effect on the fatigue crack growth rate, and nickel with a well-balanced performance in practical terms. It became clear that a base heat-resistant superalloy was realized.

Further, the alloy 1 sample was separately subjected to solution treatment in air at 1,140 ° C., 1,150 ° C. and 1,160 ° C. for 4 hours, then at 650 ° C. for 24 hours, and further at 760 ° C. for 16 hours. Time annealing was performed. The total length of the annealing twin after the annealing treatment was 1,710 μm, 350 μm, and 80 μm per 104 μm ^{2 with} respect to the solution treatment temperature. In the sample subjected to the solution treatment at 1,140 ° C., the creep life at 750 ° C. was 100 hours or more. However, in the samples subjected to the solution treatment at 1,150 ° C. and 1,160 ° C., the annealing twin The length was short and the creep life at 750 ° C. was less than 5 hours. Moreover, when the crystal grain size was measured for each sample, the crystal grain size was 20 μm, 60 μm, and 250 μm with respect to the solution treatment temperature. In particular, in the sample subjected to the solution treatment at 1,160 ° C., since the total annealing twin length is small and the crystal grain size is large, any of creep strength, low cycle fatigue, and fatigue crack growth rate can be obtained. But it was not satisfactory.

Nickel-based heat-resistant superalloys are largely improved in heat-resistant characteristics, and are effective for heat-resistant components such as aircraft engines and power generation gas turbines, especially turbine disks and turbine blades.

Claims (11)

A nickel-base heat-resistant superalloy containing chromium, cobalt, titanium, aluminum and nickel as main elements and allowing the inclusion of additive component elements and unavoidable impurity elements, and the total length of the annealing twin is 104 μm ^{2 in} cross section. A nickel-base heat-resistant superalloy containing an annealing twin, characterized in that it is 500 μm or more per unit. The nickel-based heat-resistant superalloy containing an annealing twin according to claim 1, wherein the average crystal grain size of the microstructure is 1 µm or more and less than 60 µm. In mass%, chromium is 1.0% or more and 30.0% or less, cobalt is 5.0% or more and 55.0% or less, titanium is 2.5% or more and 15.0% or less, and aluminum is 0.2% or more. The nickel-base heat-resistant superalloy containing an annealing twin according to claim 1 or 2, characterized by containing 7% or less. The nickel-base heat-resistant superalloy containing an annealing twin according to claim 3, wherein cobalt is contained in an amount of 9.5% to 50.0% by mass. The nickel-base heat-resistant superalloy containing an annealing twin according to claim 4, wherein cobalt is contained in an amount of 13.5% to 50.0% by mass. The nickel-base heat-resistant superalloy containing an annealing twin according to claim 5, wherein cobalt is contained in an amount of 19.5% to 50.0% by mass%. The nickel-base heat-resistant superalloy containing an annealing twin according to any one of claims 3 to 6, characterized in that it contains 5.1% or more and 15.0 or less of titanium by mass%. The nickel-base heat-resistant superalloy containing an annealing twin according to claim 7, wherein the nickel-containing heat-resistant alloy contains 5.3% to 10.0% of titanium by mass. It contains at least one of 5.0 mass% or less of molybdenum, 7.0 mass% or less of tungsten, and 5.0 mass% or less of niobium as an additional component element. A nickel-base heat-resistant superalloy containing the annealing twin described in the paragraph. At least one of 0.01% by mass to 0.2% by mass of zirconium, 0.01% by mass to 0.15% by mass of carbon, and 0.005% by mass to 0.1% by mass of boron is unavoidable. The nickel-base heat-resistant superalloy containing an annealing twin according to any one of claims 1 to 9, wherein the nickel-base heat-resistant superalloy is contained as a general impurity element. A heat-resistant superstructure produced from the nickel-base heat-resistant superalloy containing the annealing twin according to any one of claims 1 to 10 by at least one method of casting, forging, or powder metallurgy. Alloy member.

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