JP2007211273A - Unidirectional solidification nickel-base superalloy excellent in strength, corrosion resistance and oxidation resistance and method for producing unidirectional solidification nickel-base superalloy - Google Patents

Abstract

A nickel-based superalloy for unidirectional solidification that has a creep rupture strength at high temperatures almost equal to that of a single crystal material, and high-temperature oxidation resistance and high-temperature corrosion resistance are equivalent to or superior to conventional unidirectional solidification materials. provide.
SOLUTION: By weight: Cr: 3.0-8.0%, Co: 3.0-18.0%, W: 4.5-10.0%, Re: 0.5-6.0%, Ta: 4.0-10.0%, Ti: 0.8-4.0%, Al: 2.5-6.5%, Hf: 0.1-2.0%, C: 0.01- 0.15%, B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, balance Ni and Consisting of inevitable impurities,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : Restricted to 0.005% or less.
[Selection figure] None

Description

  The present invention relates to a nickel-base superalloy suitable for use as a material for parts and products that are required to have excellent strength, toughness, corrosion resistance, and oxidation resistance at high temperatures, and a method for producing the same.

  In recent years, in a power engine such as a jet engine or a gas turbine, it is indispensable to increase the turbine inlet temperature in order to improve its performance and efficiency, and to increase the temperature to 1500 ° C. or higher. Development of a turbine blade material that can withstand is an important issue.

  The main properties required for turbine blade materials are excellent creep rupture strength, toughness to withstand centrifugal forces at high temperatures, and excellent oxidation and corrosion resistance to high temperature combustion gas atmospheres. In order to satisfy these required characteristics, unidirectionally solidified materials and single crystal materials of nickel-base superalloys are currently in practical use.

  Unlike conventional cast materials with equiaxed crystals and unidirectionally solidified materials with columnar crystals, nickel-base superalloy single crystal materials have no grain boundaries and can be solution heat treated just below the melting point. is there. For this reason, it is possible to obtain a homogeneous structure in which solid segregation is completely removed by adding a large amount of W or Ta having a high degree of solid solution strengthening. Thereby, it has the characteristic that a creep rupture strength and toughness can be made high compared with a normal cast material and a unidirectional solidification material.

  On the other hand, the unidirectionally solidified material is not as high in creep rupture strength as a single crystal material, but has significantly higher creep rupture strength and toughness than ordinary cast material. Also, casting is much easier than a single crystal material, and the cost is low. Therefore, many castings are used in portions that do not require the same strength as a single crystal material. Known examples described for unidirectionally solidified nickel-base superalloys include, for example, Patent Documents 1 and 2.

Japanese Patent Laid-Open No. 3-97822 JP-A-6-57359

  As described above, the single crystal nickel-base superalloy has excellent characteristics, but is difficult to cast and expensive. For this reason, it is very difficult to monocrystalize the rotor blades of large gas turbines for power generation, and this is a major factor that prevents the widespread use of single crystal blades having various characteristics.

  On the other hand, unidirectionally solidified nickel-base superalloy is easy to cast, and it is easy to cast moving blades of large-sized gas turbines for power generation, and many are used as moving blades of existing large-sized gas turbines for power generation. However, the unidirectionally solidified material currently used is not as high as the creep rupture strength, so that it is no longer possible to increase the combustion temperature of the gas turbine and improve the thermal efficiency. It is a fact.

  For this reason, it is extremely important to develop a nickel-base superalloy for unidirectional solidification with excellent creep strength, in order to further improve the thermal efficiency of the power generation gas turbine due to an increase in the combustion gas temperature.

  The present invention has been made in view of the above-mentioned background, and its purpose is that the creep rupture strength at high temperature is equivalent to that of a single crystal material, and oxidation resistance and corrosion resistance at high temperature are conventional unidirectionally solidified materials. It is an object of the present invention to provide a unidirectionally solidified nickel-base superalloy and a method for producing a unidirectionally solidified nickel-base superalloy that are equivalent to or superior to the above.

The present invention, by weight, Cr: 3.0-8.0%, Co: 3.0-18.0%, W: 4.5-10.0%, Re: 0.5-6.0%, Ta: 4.0-10.0%, Ti: 0.8-4.0%, Al: 2.5-6.5%, Hf: 0.1-2.0%, C: 0.01- 0.15%, B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, balance Ni and Consisting of inevitable impurities,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : A nickel-base superalloy for unidirectional solidification characterized by being restricted to 0.005% or less.

The preferred component composition of the nickel-base superalloy for unidirectional solidification according to the present invention is Cr: 3.0-7.0%, Co: 3.0-18.0%, W: 4.5-8. 0%, Re: 1.0 to 6.0%, Ta: 4.0 to 10.0%, Ti: 0.8 to 2.0%, Al: 4.5 to 6.5%, Hf: 0 0.1 to 2.0%, C: 0.01 to 0.15%, B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5% Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : Restricted to 0.005% or less.

Moreover, the more preferable component composition of the nickel-base superalloy for unidirectional solidification according to the present invention is Cr: 3.8 to 7.0% by weight, Co: 3.0 to 18.0%, W: 5.5. -8.0%, Re: 3.3-5.2%, Ta: 5.0-10.0%, Ti: 0.8-2.0%, Al: 5.0-6.0%, Hf: 1.0-2.0%, C: 0.01-0.15%, B: 0.001-0.05%, Zr: 0.001-0.05%, Mo: 0-0. Less than 5%, Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities,
The amounts of SI, P, S, O and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : Restricted to 0.005% or less.

The most preferable component composition is Cr: 5.0 to 7.0% by weight, Co: 10.0 to 18.0%, W: 5.5 to 7.6%, Re: 3.5 to 5 0.2%, Ta: 5.8 to 10.0%, Ti: 1.2 to 2.0%, Al: 5.0 to 6.0%, Hf: 1.0 to 1.8%, C: 0.05 to 0.10%, B: 0.01 to 0.02%, Zr: 0.001 to 0.02%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less The balance Ni and inevitable impurities,
The amounts of Si, P, S, 0 and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : Restricted to 0.005% or less.

  The present invention unidirectionally solidifies and casts a nickel-base superalloy having the above-mentioned composition, and after performing solution heat treatment in a temperature range of 1250 ° C. to 1280 ° C. in a vacuum or an inert gas, A method for producing a unidirectionally solidified nickel-base superalloy, characterized in that a one-step aging heat treatment is performed in a temperature range of 1100 ° C to 1200 ° C, and further a two-step aging heat treatment is performed at a temperature lower than the one-step aging heat treatment. is there.

Next, the reason for limiting the component range of the nickel-base superalloy for unidirectional solidification according to the present invention will be described.
[Cr: 3.0 to 8.0% by weight]
Cr is an element effective for improving the corrosion resistance of nickel-base superalloys at high temperatures, and the effect is more prominent because it is contained in an amount of 3.0% by weight or more. As the Cr content increases, the effect of improving corrosion resistance increases, but as the content increases, the solid solution limit of the solid solution strengthening element is lowered, and the TCP phase, which is an embrittlement phase, precipitates, resulting in high temperature strength and high temperature. In order to impair the corrosion resistance, the upper limit must be 8.0% by weight. In consideration of the balance between strength and corrosion resistance in this composition range, it is more preferably in the range of 3.8 to 7.0% by weight, still more preferably in the range of 5.0 to 7.0% by weight.
[Co: 3.0 to 18.0 wt%]
Co has the effect of lowering the solid solution temperature of the γ ′ phase made of the intermetallic compound Ni ₃ Al to facilitate solution treatment, strengthening the γ phase in solid solution, and improving high-temperature corrosion resistance. Such an effect appears from the content of 3.0% by weight or more. On the other hand, when the Co content exceeds 18.0%, the solid solution temperature of the γ 'phase is remarkably lowered, the precipitation amount of the γ' phase, which is a precipitation strengthening phase, is reduced, and the high temperature strength is lowered. Therefore, it is necessary to make it 18.0% by weight or less. In this composition range, when considering the balance between the ease of solution heat treatment and the strength, the range of 10.0 to 18.0% by weight is more preferable.
[W: 4.5 to 10.0% by weight]
W is an element effective for increasing the creep strength by solid solution strengthening by forming a solid solution in the matrix γ phase and the precipitated γ ′ phase. In order to obtain such an effect sufficiently, a content of 4.5% by weight or more is necessary. However, W has a large specific gravity, which not only increases the weight of the alloy, but also reduces the corrosion resistance of the alloy at high temperatures. On the other hand, if it exceeds 10.0% by weight, acicular α-W precipitates and the creep strength, high-temperature corrosion resistance and toughness are lowered, so the upper limit must be 10.0% by weight. In this composition range, when considering the balance between strength at high temperature, corrosion resistance and structural stability at high temperature, it is preferably in the range of 5.5 to 8.0% by weight, more preferably 5.5 to 7.6. It is in the range of wt%.
[Re: 0.5 to 6.0% by weight]
Re is an element effective for improving the corrosion resistance of nickel-base superalloys as well as increasing the creep strength by solid solution strengthening and almost solid solution in the matrix γ phase. In order to sufficiently obtain such an effect, a content of 0.5% by weight or more is necessary. However, Re is expensive, has a large specific gravity, and increases the weight of the alloy. On the other hand, when the amount exceeds 6.0% by weight, acicular α-W or α-Re precipitates and decreases the creep strength and toughness, so the upper limit must be 6.0% by weight. In this composition range, when considering the balance between strength at high temperature, corrosion resistance, and structure stability at high temperature, a preferable range is 1.0 to 6.0% by weight, and a more preferable range is 3.3 to 5.2. % By weight, and an even more preferred range is 3.5 to 5.2% by weight.
[Ta: 4.0 to 10.0% by weight]
Ta forms a solid solution in the form of Ni ₃ (Al, Ta) in the γ ′ phase and strengthens the solution. This improves the creep strength. In order to sufficiently obtain this effect, a content of 4.0% by weight or more is necessary. When the content exceeds 10.0% by weight, supersaturation occurs and acicular δ phase, that is, Ni ₈ Ta precipitates, and creep occurs. Reduce strength. Therefore, the upper limit needs to be 10.0 weight%. In this composition range, when considering the balance between strength and structure stability at high temperature, it is preferably in the range of 5.0 to 10.0% by weight, more preferably in the range of 5.8 to 10.0% by weight. is there.
[Ti: 0.8 to 4.0% by weight]
Ti, like Ta, dissolves in the γ ′ phase in the form of Ni ₃ (Al, Ta, Ti) and strengthens it, but is not as effective as Ta. Rather, Ti has the effect of improving the corrosion resistance of the alloy at high temperatures, so the content is 0.8% by weight or more. However, if the content exceeds 4.0% by weight, the oxidation resistance deteriorates, so the upper limit must be 4.0% by weight. In this composition range, when considering the balance between strength at high temperature, corrosion resistance, and oxidation resistance, it is preferably in the range of 0.8 to 2.0% by weight, more preferably 1.2 to 2.0% by weight. It is a range.
[Al: 2.5 to 6.5% by weight]
Al is a constituent element of the γ ′ phase, which is a precipitation strengthening phase, thereby improving the creep strength. It also greatly contributes to the improvement of oxidation resistance. In order to obtain these effects sufficiently, a content of 2.5% by weight or more is necessary. However, if it exceeds 6.5% by weight, the γ ′ phase is excessively precipitated, and the strength is rather increased. Therefore, it is necessary to set the range of 2.5 to 6.5% by weight. In this composition range, when considering the balance between strength at high temperature and oxidation resistance, it is preferably in the range of 4.5 to 6.0% by weight, more preferably in the range of 5.0 to 6.0% by weight. is there.
[Ru: 0 to 6.0%]
Ru does not necessarily need to be contained, but if contained, it expands the region where the γ ′ phase can be dissolved to facilitate solution treatment, and has the effect of strengthening the γ phase by solid solution strengthening and improving high-temperature corrosion resistance. However, Ru is expensive, and increasing the content increases the price of the material. Further, if the Ru content exceeds 6.0% by weight, the precipitation of the γ ′ phase, which is a precipitation strengthening phase, is reduced and the high-temperature strength is lowered. is there.
[Hf: 0.1 to 2.0% by weight]
Hf has the effect of improving corrosion resistance and oxidation resistance at high temperatures. By containing Hf, adhesion of a protective film formed on the alloy surface, for example, Cr ₂ O ₃ or Al ₂ O ₃ is improved. In addition, eutectic Ni ₃ Hf is formed at the crystal grain boundary to improve the strength of the crystal grain boundary. In order to improve the adhesion of the protective film, a content of 0.1% by weight or more is necessary. When the Hf content is increased, the adhesion of the protective film is remarkably improved and the grain boundary strength is also improved. However, if the Hf content exceeds 2.0% by weight, the melting point of the Ni-base superalloy is remarkably lowered, and solution heat treatment is performed. Make it difficult. Further, oxygen and HfO ₂ in the atmosphere are formed at the time of casting, which becomes a surface defect of the cast product and lowers the casting yield, so it is necessary to make it 2.0% by weight or less. In this composition range, when considering the balance between the corrosion resistance, oxidation resistance, grain boundary strength and the heat treatment temperature range of the alloy, the range is preferably 1.0 to 2.0% by weight, more preferably 1 The range is from 0.0 to 1.8% by weight.
[Mo: 0 to less than 0.5% by weight]
Since Mo has the same effect as W, it can be replaced with a part of W if necessary. Further, since the solid solution temperature of the γ ′ phase is raised, there is an effect of improving the creep strength. Since Mo has a smaller specific gravity than W, the weight of the alloy can be reduced. However, since Mo reduces the oxidation resistance and corrosion resistance of the alloy, even if it is contained, the upper limit thereof needs to be less than 0.5% by weight. In this composition range, when considering the balance of strength at high temperature, corrosion resistance and oxidation resistance at high temperature, it is preferably less than 0.1% by weight, more preferably not substantially contained.
[C: 0.01 to 0.15% by weight]
C is necessary as a strengthening element. C partially dissolves in the alloy, but most forms carbides such as TiC and TaC at the crystal grain boundaries and precipitates in a lump shape, thereby improving the strength of the crystal grain boundaries. In order to form carbides such as TiC and TaC and improve the strength of the grain boundaries, a content of 0.01% or more is required. However, if it exceeds 0.15% by weight, the apparent content of the solid solution strengthened Ta is reduced by forming a carbide with Ta which is a solid solution strengthening element, and the creep strength at high temperature is lowered. Therefore, the upper limit of C is set to 0.15% by weight. In this composition range, when considering the balance between the grain boundary strength and the creep strength at high temperature, the range is more preferably 0.05 to 0.10% by weight.
[B: 0.001 to 0.05% by weight]
B is necessary as a strengthening element like C. B hardly dissolves in the alloy and segregates at the grain boundaries to improve the strength of the grain boundaries. In order to improve the strength of the grain boundary by segregating at the grain boundary, a content of 0.001% or more is necessary. However, if it exceeds 0.05% by weight, (Cr, Ni, A boride composed of (Ti, Mo) ₃ B ₂ is formed. Since the boride has a remarkably lower melting point than the melting point of the alloy, it makes the solution heat treatment of the alloy difficult, so the upper limit was made 0.05% by weight. In this composition range, when considering the balance between the grain boundary strength and the solution heat treatment, the range is more preferably 0.01 to 0.02% by weight.
[Zr: 0.001 to 0.05% by weight]
Zr, like B, is necessary as a strengthening element. A part of Zr is dissolved in the alloy, but most of the Zr is not dissolved but segregates at the grain boundary to improve the strength of the grain boundary. A content of 0.001% or more is necessary for segregating at the grain boundaries to improve the strength of the grain boundaries. However, if the content exceeds 0.05% by weight, Ni ₃ may be present at the grain boundaries. An intermetallic compound with Ni typified by Zr is formed. Since the intermetallic compound of Ni and Zr has a remarkably low melting point compared to the melting point of the alloy, it makes the solution heat treatment of the alloy difficult, so the upper limit was made 0.05% by weight. In this composition range, when considering the balance between the grain boundary strength and the solution heat treatment, the range is more preferably 0.01 to 0.02% by weight.

Next, among the unavoidable impurities mixed from the crucible or brought from the alloy raw material during melting production, Si, P.I. The reason why the allowable amounts of S, O, and N are limited will be described.
[Si: 0.1% by weight or less]
Si is brought from the alloy raw material and exists as an impurity. Although Si has an effect of improving oxidation resistance, it is not as effective as Hf, and when it is present in excess, it forms an intermetallic compound with a refractory alloy element such as Mo. If these intermetallic compounds are present in the alloy, they become the starting point of cracks during creep deformation, and the creep rupture life is reduced. Therefore, the upper limit was set to 0.1% by weight.
[P: 0.01% by weight or less]
[S: 0.005% by weight or less]
All of these elements are brought from the alloy raw material and exist as impurities. Since these elements reduce the corrosion resistance of the alloy, it is desirable that they be as few as possible. However, since the raw material cost of these elements is high, the material cost is high, so that P is 0.01 wt% or less and S is 0.005 wt% or less in balance with corrosion resistance.
[O: 0.005% by weight or less]
[N: 0.005% by weight or less]
These elements are often brought from alloy raw materials, and O enters from the crucible. These elements exist in the form of oxides such as Al ₂ O ₃ and nitrides such as TiN or AlN in the alloy. If these oxides or nitrides are present in the alloy, they become the starting point of cracks during creep deformation, and the creep rupture life is reduced. Therefore, the upper limit of both elements is set to 0.005% by weight.

  Next, the reason for limiting the manufacturing process and heat treatment temperature of the unidirectionally solidified nickel-base superalloy will be described.

  In the present invention, the precipitation amount of the γ 'phase is increased to increase the high temperature creep strength. For this purpose, first, the cast material was subjected to solution heat treatment, and the γ ′ phase was re-dissolved in the γ phase of the parent phase to make the structure uniform. Next, an aging heat treatment was performed to precipitate a γ 'phase from the structure re-dissolved by the solution heat treatment. Aging heat treatment is performed in two stages. In the first stage aging, the size and shape of the γ 'phase are adjusted. In the second stage aging, the composition of the γ' phase precipitated in the first stage aging is stabilized and the γ phase is supersaturated and dissolved. The γ ′ phase forming element was precipitated to increase the amount of γ ′ phase precipitated.

  In the solution heat treatment, when the temperature is too low, the solution treatment becomes insufficient, and the creep strength is lost. If the temperature is too high, a part of the alloy starts to melt and the strength is not obtained. A temperature range of 1250 ° C. to 1280 ° C. was selected as a temperature range in which solutionization is possible to some extent and melting does not occur.

  The size and shape of the γ ′ phase vary greatly depending on the temperature of the aging heat treatment. When the temperature is low, the shape becomes spherical, and when the temperature is too high, the shape becomes lumpy. In order to increase the creep strength, it is desirable that the shape of the γ ′ phase is a cube, and the alloy composition of the present invention is achieved by performing a one-step aging heat treatment in a temperature range of 1120 ° C. to 1180 ° C.

  Since the main aim of the two-stage aging heat treatment is to stabilize the composition of the γ 'phase, in order to allow elements dissolved in the γ phase to diffuse within a certain amount of time, The temperature was set lower than aging.

  The nickel-base superalloy for unidirectional solidification according to the present invention is excellent in creep rupture strength, corrosion resistance and oxidation resistance at high temperatures. For this reason, for example, it is possible to sufficiently cope with the case where the turbine inlet temperature is increased in order to achieve high performance and high efficiency in a power engine such as a jet engine or a gas turbine.

  Hereinafter, specific examples will be described, but the present invention is not limited to the following examples.

  In Table 1, the chemical composition of this invention Example alloy (No. A1-A18) and the existing alloy (No. B1-B2, No. C1-C5) of a comparative example are shown. Existing alloy No. B1 to B2 are single crystal materials. C1 to C4 are unidirectionally solidified materials.

  First, after blending the materials of each alloy, an ingot having a diameter of 70 mm and a length of 200 mm was melted in a vacuum induction furnace using a refractory crucible having a capacity of 15 kg. Table 2 shows the amount of impurities in the melted ingot. In this ingot state, it has an equiaxed crystal structure.

  The casting of the unidirectional solidification test piece was performed by the mold drawing type unidirectional solidification method using the above ingot. Specifically, a unidirectional solidification test piece having a diameter of 15 mm and a length of 100 mm was cast using an alumina ceramic mold at a mold heating temperature of 1500 ° C. and a mold drawing speed of 20 cm / h. All castings were performed in a vacuum.

  The single crystal test piece was also cast by the same method as the unidirectional solidification test piece except that the shape of the mold was different.

  The cast unidirectionally solidified test piece and single crystal test piece were subjected to solution heat treatment and aging heat treatment under the conditions shown in Table 3. These heat treatment conditions were determined from a macrostructure and a microstructure by conducting a separate preliminary test. In Table 3, GFC refers to gas flow cooling, which indicates that gas cooling was performed.

  From the heat-treated unidirectionally solidified test piece and the single crystal test piece, a creep test piece having a parallel part diameter of 6.0 mm and a parallel part length of 30 mm, a length of 25 mm, a width of 10 mm, and a thickness of 1.5 mm are obtained by machining. A high temperature oxidation test piece and a high temperature corrosion test piece having a diameter of 8 mm and a length of 40 mm were cut out.

  Table 4 shows the characteristic evaluation test conditions. The creep rupture test was performed under two conditions of 982 ° C.-206 MPa and 920 ° C.-314 MPa. In the oxidation test, after heating and holding at 1040 ° C. for 600 hours, the operation of cooling to room temperature and heating again at 1040 ° C. for 600 hours is repeated five times, and the oxidation test is performed for a total of 3000 hours, and the weight change after 3000 hours of oxidation Was measured. In the corrosion resistance test, 80 ppm of NaCl was added to the combustion gas, heated and maintained at 900 ° C for 7 hours, cooled to room temperature, and then heated again at 900 ° C for 7 hours. The test was repeated 5 times for a total of 35 hours. The weight change after the 35 hour corrosion test was measured.

  The test results are summarized in Table 5. The samples after the oxidation test and the corrosion test in Table 5 show an increase or decrease in weight, but the increase in weight indicates that the oxide film formed during the test is in close contact with the sample surface. The decrease indicates that the oxide film was peeled off from the sample surface. The smaller the weight increase, the better the characteristics. Moreover, the result of the creep breaking test was shown by the fracture life. A longer rupture life means higher creep strength.

  As apparent from Table 5, the alloy Nos. Of Examples of the present invention A1 to A18 are existing single crystal materials No. Compared to B1, the creep rupture life is not inferior, and the high-temperature oxidation resistance is rather excellent. No. Compared to B2, the creep rupture life at 982 ° C. is short, but the creep rupture life at 920 ° C. is almost the same, and the high-temperature oxidation resistance is excellent. In addition, the existing unidirectional solidified material No. Compared to C1 to C4, they are all excellent in terms of creep rupture life and high-temperature oxidation resistance, and equivalent or excellent in high-temperature corrosion resistance. That is, it was recognized that the alloy of the present invention is a well-balanced alloy having excellent high temperature strength, high temperature corrosion resistance and high temperature oxidation resistance. As described above, since each of the above-described characteristics is excellent, the alloy of the present invention is suitable as a turbine blade material that can withstand high temperatures of 1500 ° C. or higher.

Claims (5)

By weight: Cr: 3.0-8.0%, Co: 3.0-18.0%, W: 4.5-10.0%, Re: 0.5-6.0%, Ta: 4. 0 to 10.0%, Ti: 0.8 to 4.0%, Al: 2.5 to 6.5%, Hf: 0.1 to 2.0%, C: 0.01 to 0.15% B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities ,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : A nickel-base superalloy for unidirectional solidification excellent in strength, corrosion resistance, and oxidation resistance, characterized by being regulated to 0.005% or less. By weight: Cr: 3.0-7.0%, Co: 3.0-18.0%, W: 4.5-8.0%, Re: 1.0-6.0%, Ta: 4. 0 to 10.0%, Ti: 0.8 to 2.0%, Al: 4.5 to 6.5%, Hf: 0.1 to 2.0%, C: 0.01 to 0.15% B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities ,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : A nickel-base superalloy for unidirectional solidification excellent in strength, corrosion resistance, and oxidation resistance, characterized by being regulated to 0.005% or less. Cr: 3.8 to 7.0% by weight, Co: 3.0 to 18.0%, W: 5.5 to 8.0%, Re: 3.3 to 5.2%, Ta: 5. 0 to 10.0%, Ti: 0.8 to 2.0%, Al: 5.0 to 6.0%, Hf: 1.0 to 2.0%, C: 0.01 to 0.15% B: 0.001 to 0.05%, Zr: 0.001 to 0.05%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities ,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : A nickel-base superalloy for unidirectional solidification excellent in strength, corrosion resistance, and oxidation resistance, characterized by being regulated to 0.005% or less. By weight: Cr: 5.0 to 7.0%, Co: 10.0 to 18.0%, W: 5.5 to 7.6%, Re: 3.5 to 5.2%, Ta: 5. 8 to 10.0%, Ti: 1.2 to 2.0%, Al: 5.0 to 6.0%, Hf: 1.0 to 1.8%, C: 0.05 to 0.10% B: 0.01 to 0.02%, Zr: 0.001 to 0.02%, Mo: 0 to less than 0.5%, Ru: 0 to 6.0% or less, remaining Ni and inevitable impurities ,
The amounts of Si, P, S, O, and N in the impurities are respectively Si: 0.1% or less, P: 0.01% or less, S: 0.005 or less, O: 0.005% or less, N : A nickel-base superalloy for unidirectional solidification excellent in strength, corrosion resistance, and oxidation resistance, characterized by being regulated to 0.005% or less.   A unidirectionally solidified material comprising the nickel-base superalloy having the component composition according to any one of claims 1 to 4 is subjected to a solution heat treatment in a temperature range of 1250 ° C to 1280 ° C in a vacuum or in an inert gas. Unidirectional solidification characterized by performing rapid cooling after performing, then performing one-stage aging heat treatment in a temperature range of 1100 ° C. to 1200 ° C., and then performing two-stage aging heat treatment at a temperature lower than the one-stage aging heat treatment A method for producing a nickel-base superalloy.