Manufacturing method of Ni-based superalloy preventing deterioration of oxidation resistance due to Sb, and Ni-based superalloy member preventing deterioration of oxidation resistance due to Sb

Abstract

The present invention provides a method for producing an Sb-containing Ni-based superalloy that is prevented from deterioration of the oxidation resistance by using an additive element which prevents deterioration of the oxidation resistance of an Ni-based superalloy due to an impurity element Sb. A method for producing an Ni-based superalloy according to the present invention comprises a step in which: a starting material for an Sb-containing Ni-based superalloy having a specific composition is put into a crucible and is high-frequency melted in vacuum by a high-frequency induction melting furnace, while adding Ca into the melt of the starting material for the Ni-based superalloy in such an amount that is necessary for preventing the oxidation resistance inhibitory effect of Sb; the melt is stabilized at 1560°C to 1640°C within the crucible for 10 minutes to 60 minutes in a state where the starting material for the Ni-based superalloy is completely melted; the melt is put into a mold that has been preheated to a predetermined temperature within a unidirectional solidification furnace, and the mold filled with the melt is withdrawn from the high-frequency induction melting furnace at a rate of 50 mm / h to 350 mm / h; and after unidirectionally solidifying the starting material for the Ni-based superalloy and cooling the unidirectionally solidified material to the room temperature, the cast unidirectionally solidified member is take out from the unidirectional solidification furnace.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a Ni-based superalloy that prevents the deterioration of oxidation resistance due to Sb, and to a Ni-based superalloy member that prevents the deterioration of oxidation resistance due to Sb. [Background technology]

[0002] Ni-based superalloys are used for turbine blades in jet engines and gas turbines. In recent years, there has been a demand for higher turbine inlet temperatures to improve the efficiency of turbine engines. This has led to a need to improve the high-temperature properties of Ni-based superalloys (e.g., creep properties and oxidation resistance). However, various elements are used to improve high-temperature properties, which has led to issues such as increased material costs and uneven supply of raw materials. In addition, elements known to impair the high-temperature properties of Ni-based superalloys include sulfur (S) and antimony (Sb). Standards specify upper limits for the content ratios of these elements that impair high-temperature properties.

[0003] For example, the allowable Sb content in the Ni-based superalloy AMS2280 for aerospace applications is 50 ppm (see Non-Patent Document 1). Furthermore, the allowable Sb content in Ni-based heat-resistant alloys used for boiler piping in thermal power plants and the like is 50 ppm (0.005 mass%) (see paragraphs

[0057] and

[0058] in Patent Document 1). In the case of boiler piping used in thermal power plants and the like, if the Sb content in the Ni-based heat-resistant alloy exceeds 50 ppm, a significant decrease in ductility and toughness after high-temperature, long-term heating at temperatures of 700°C or higher for 10,000 hours or longer becomes a problem. In the Ni-based superalloy for boiler piping described in Patent Document 1, Sb is mixed in as an impurity element during the raw material melting process.

[0004] On the other hand, in Ni-base superalloys for turbine blades, such as CMSX-4 (registered trademark), which are exposed to higher-temperature combustion gases than the above-mentioned Ni-base heat-resistant alloys for boiler piping, the Sb composition ratio in the Ni-base superalloy is set to 2 ppm or less (Patent Document 2, paragraph

[0047] , [Table 7]). In addition, since components made from Ni-base superalloys for turbine blades are exposed to high-temperature combustion gases of nearly 1600°C, the heat resistance of the Ni-base superalloy alone is insufficient, and therefore, in practical use, a thermal barrier coating material, for example, is applied to the surface. Therefore, it is necessary to use a higher purity material with a significantly lower impurity content than the Ni-based heat-resistant alloys for boiler piping mentioned above for CMSX-4, etc. However, because high purity materials require advanced refining, they are expensive and there are issues with limited sources of raw material procurement.

[0005] In fact, it has been revealed that the Ni-based single crystal superalloy TMS-238, which contains Sb, a low-melting-point metallic impurity element, has inferior oxidation resistance compared to the genuine material (see Non-Patent Document 2). Specifically, Non-Patent Document 2 describes that an alloy produced by adding Sb, a low-melting-point metallic impurity, to a master ingot and melting it in an Al2O3 crucible contained 1.1 ppm of Sb, and that in a cyclic oxidation test in which one cycle was performed at 1100°C for 1 hour and then at room temperature for 1 hour, a clear mass loss was observed after 50 cycles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2010-038826A1 [Patent Document 2] Patent Publication No. 2015-214744 [Non-patent literature]

[0007] [Non-Patent Document 1] RT Holt & W. Wallace, “Impurities and trace elements in nickel-base superalloys”, International Metals Reviews, 21:1 (1976), pp. 1-24 [Non-patent document 2] Yuji Takada et al., Effect of impurity element Sb on oxidation resistance and creep strength of 6th generation Ni-based single crystal superalloy TMS-238, Abstracts of the 166th Annual Meeting of the Japan Institute of Metals, Spring 2020, p. 210 Summary of the Invention [Problem to be solved by the invention]

[0008] As mentioned above, the oxidation resistance of Ni-based superalloys is impaired by the low-melting-point metallic impurity element Sb. However, the production of Ni-based superalloys poses the challenge of difficulty in removing Sb that is mixed in during the raw material melting process. Furthermore, it would be desirable from the standpoints of material cost and raw material procurement if Ni-based superalloys with oxidation resistance equivalent to that of conventional superalloys could be produced using materials with a relatively high impurity content (low grade), such as recycled materials, instead of the high-purity materials required for the production of conventional Ni-based superalloys for turbine blades. The present invention is intended to solve the above-mentioned problems, and aims to provide a method for producing a Ni-based superalloy in which degradation of oxidation resistance due to Sb is prevented by using an additive element that can prevent degradation of oxidation resistance of the Ni-based superalloy due to Sb, even if Sb is mixed in during the raw material melting process and / or even if a material with a relatively high impurity content is used in the production of the Ni-based superalloy, and a Ni-based superalloy member in which degradation of oxidation resistance due to Sb is prevented. [Means for solving the problem]

[0009] [1] A method for producing a Ni-base superalloy of the present invention includes the steps of: charging a Ni-base superalloy raw material containing Sb of a predetermined composition into a crucible; high-frequency melting the material in a vacuum using a high-frequency induction melting furnace; adding Ca (calcium) to the molten Ni-base superalloy raw material in an amount necessary to prevent the Sb from inhibiting oxidation resistance; stabilizing the molten Ni-base superalloy raw material in the crucible at 1560 to 1640°C for 10 to 60 minutes after the Ni-base superalloy raw material is completely melted; pouring the molten Ni-base superalloy raw material into a mold preheated to a predetermined temperature in a directional solidification furnace; and withdrawing the mold containing the poured Ni-base superalloy raw material from the high-frequency induction melting furnace at a rate of 50 to 350 mm / h; directionally solidifying the Ni-base superalloy raw material into a single crystal; or polycrystalline solidification; and cooling the Ni-base superalloy raw material to room temperature and removing the resulting cast, single crystal cast member, or polycrystalline solidified member from the directional solidification furnace. Here, "a raw material for a Ni-base superalloy containing Sb of a predetermined composition" refers to a material having a composition as defined in, for example,

[10] or

[11] . However, it is not required that the raw material satisfy the conditions for the Sb and Ca contents before being placed in the crucible. Furthermore, "adding an amount of Ca (calcium) necessary to prevent the oxidation resistance inhibiting effect of Sb" is intended to mean adding an amount of Ca to the molten metal of the raw material such that Ca-Sb-O inclusions are precipitated in a mass ratio of Ca:Sb:O = 1:3:2 to 1:4:3. Regarding "stabilizing the molten metal in the crucible at 1560-1640°C for 10-60 minutes while the raw materials for the Ni-base superalloy are completely melted," the conditions for such stabilization treatment are determined taking into consideration the fact that the casting temperature is generally set to +90-170°C above the solidification start temperature of the cast alloy, that the melting point of Ni is 1455°C, and that the melting points of each element used as a constituent element of the target Ni-base superalloy.

[0010] [2] In the method [1] for producing a Ni-base superalloy of the present invention, preferably, the crucible is a CaO crucible, and the Ca (calcium) is supplied to the molten Ni-base superalloy raw material by contact between the CaO crucible and the molten Ni-base superalloy raw material. [3] In the method [1] for producing a Ni-base superalloy of the present invention, preferably, the crucible is an Al2O3 crucible or an MgO crucible, and the Ca (calcium) is added to the Ni-base superalloy raw material or a molten metal of the Ni-base superalloy raw material by adding CaO in an amount equivalent to 0.2% to 5% by weight based on the Ni-base superalloy raw material. [4] In the method [3] for producing a Ni-based superalloy of the present invention, the CaO is preferably in the form of granules having a particle size of 1 to 10 mm. [5] In the method [1] for producing a Ni-base superalloy of the present invention, preferably, the crucible is an Al2O3 crucible or an MgO crucible, and the Ca (calcium) is added to the Ni-base superalloy raw material or a molten Ni-base superalloy raw material in an amount equivalent to 0.33 to 100 times the amount of Sb by mass. [6] In the method for producing a Ni-base superalloy according to the present invention [5], preferably, the Ca (calcium) is supplied as a component of CaF2, and CaF2 is added to the raw material for the Ni-base superalloy or to a molten metal of the raw material for the Ni-base superalloy. [7] In the method for producing a Ni-base superalloy according to the present invention [1] to [6], preferably, the mold is a mold for a single crystal, the predetermined temperature to which the mold is preheated in the unidirectional solidification furnace is 1400 to 1550°C, and the bottom of the mold for a single crystal is cooled by a water-cooled chill plate. [8] In the manufacturing method of the Ni-based superalloy according to the present invention [1] to [6], preferably, the mold is a polycrystalline mold, and the predetermined temperature to which the mold is preheated in the unidirectional solidification furnace is 1000 to 1100°C. [9] In the methods [1] to [8] for producing a Ni-base superalloy of the present invention, preferably, the single crystal cast member contains precipitated Ca-Sb-O inclusions in a mass ratio of Ca:Sb:O = 1:3:2 to 1:4:3, and the particle shape of the Ca-Sb-O inclusions has a particle size of 100 to 500 nm.

[0011]

[10] In the manufacturing method of the Ni-based superalloy according to the present invention [1] to [9], preferably, The raw material for the Ni-base superalloy is in a molten state before being poured into the mold, and contains, in mass %, Cr (chromium): 2% or more and 25% or less, Co (cobalt): 0% or more and 25% or less, Mo (molybdenum): 0% or more and 8% or less Re (rhenium): 0% or more and 10% or less Ru (ruthenium): 0% or more and 10% or less W (tungsten): 0% or more and 14% or less Nb (niobium): 0% or more and 5% or less V (vanadium): 0% or more and 3% or less Al (aluminum): 1% or more and 10% or less Ti (titanium): 0% or more and 10% or less Ta (tantalum): 0% or more and 13% or less, Hf (Hafnium): 0% or more and 2.5% or less C (carbon): 0% or more and 0.5% or less, B (boron): 0% or more and 0.1% or less, Zr (zirconium): 0% or more and 0.5% or less Fe (iron): 0% or more and 20% or less Si (silicon): 0% or more and 1% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and It is preferable that the content of Ca (calcium) is 5 PPM or more and 500 PPM or less, and the content ratio of Ca is greater than 1 / 4 of the content ratio of Sb.

[11] In the method for producing a Ni-based superalloy according to the present invention

[10] , preferably, the raw material for the Ni-based superalloy is in a molten state before being poured into the mold, and contains, in mass%, Cr (chromium): 4% or more and 10% or less, Co (cobalt): 0% or more and 12% or less, Mo (molybdenum): 0% or more and 4% or less Re (rhenium): 2% or more and 10% or less Ru (ruthenium): 2% or more and 8% or less W (tungsten): 2% or more and 8% or less Nb (niobium): 0% or more and 2.5% or less V (vanadium): 0% or more and 0.5% or less Al (aluminum): 3% or more and 8% or less Ti (titanium): 0% or more and 3% or less Ta (tantalum): 4% or more and 10% or less Hf (Hafnium): 0% or more and 1% or less C (carbon): 0% or more and 0.05% or less, B (boron): 0% or more and 0.02% or less, Zr (zirconium): 0% or more and 0.1% or less Fe (iron): 0% or more and 5% or less Si (silicon): 0% or more and 0.5% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and It is preferable that the content of Ca (calcium) is 5 PPM or more and 500 PPM or less, and the content ratio of Ca is greater than 1 / 4 of the content ratio of Sb.

[12] In the method

[10] or

[11] for producing a Ni-base superalloy of the present invention, the Ca content is preferably greater than 1 / 3 of the Sb content.

[0012]

[13] The Ni-based superalloy member of the present invention, which prevents the deterioration of oxidation resistance due to Sb, comprises, in mass%, Cr (chromium): 2% or more and 25% or less, Co (cobalt): 0% or more and 25% or less, Mo (molybdenum): 0% or more and 8% or less Re (rhenium): 0% or more and 10% or less Ru (ruthenium): 0% or more and 10% or less W (tungsten): 0% or more and 14% or less Nb (niobium): 0% or more and 5% or less V (vanadium): 0% or more and 3% or less Al (aluminum): 1% or more and 10% or less Ti (titanium): 0% or more and 10% or less Ta (tantalum): 0% or more and 13% or less, Hf (Hafnium): 0% or more and 2.5% or less C (carbon): 0% or more and 0.5% or less, B (boron): 0% or more and 0.1% or less, Zr (zirconium): 0% or more and 0.5% or less Fe (iron): 0% or more and 20% or less Si (silicon): 0% or more and 1% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 PPM or more and 500 PPM or less, and the Ca content is greater than 1 / 4 of the Sb content, and in mass ratio, Ca:Sb:O=1:3:2~1:4:3 The Ca-Sb-O inclusions are precipitated, and the particle shape of the Ca-Sb-O inclusions is 100 to 500 nm in diameter.

[0013]

[14] In the Ni-based superalloy member

[13] of the present invention, which prevents the deterioration of oxidation resistance due to Sb, preferably, in mass%, Cr (chromium): 4% or more and 10% or less, Co (cobalt): 0% or more and 12% or less, Mo (molybdenum): 0% or more and 4% or less Re (rhenium): 2% or more and 10% or less Ru (ruthenium): 2% or more and 8% or less W (tungsten): 2% or more and 8% or less Nb (niobium): 0% or more and 2.5% or less V (vanadium): 0% or more and 0.5% or less Al (aluminum): 3% or more and 8% or less Ti (titanium): 0% or more and 3% or less Ta (tantalum): 4% or more and 10% or less Hf (Hafnium): 0% or more and 1% or less C (carbon): 0% or more and 0.05% or less, B (boron): 0% or more and 0.02% or less, Zr (zirconium): 0% or more and 0.1% or less Fe (iron): 0% or more and 5% or less Si (silicon): 0% or more and 0.5% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 PPM or more and 500 PPM or less, and the Ca content is greater than 1 / 4 of the Sb content, and in mass ratio, Ca:Sb:O=1:3:2~1:4:3 The Ca-Sb-O inclusions are precipitated, and the particle shape of the Ca-Sb-O inclusions preferably has a particle size of 100 to 500 nm.

[15] In the Ni-based superalloy component

[13] or

[14] of the present invention, which prevents the deterioration of oxidation resistance due to Sb, the Ni-based superalloy component is preferably a directionally solidified component, a single crystal cast component, or a polycrystalline solidified component.

[16] In the Ni-based superalloy component

[13] or

[14] of the present invention, which prevents the deterioration of oxidation resistance due to Sb, the component is preferably a turbine blade or turbine vane component produced by sintering or 3D printing using a powdered Ni-based superalloy raw material that satisfies the composition conditions described in

[10] or

[11] .

[17] In the Ni-based superalloy component

[13] or

[14] of the present invention, which has been prevented from deteriorating in oxidation resistance due to Sb, it is preferable that an oxidation test piece of 9 mm in diameter and 5 mm in height is prepared from the Ni-based superalloy component, and in a repeated oxidation test in which one cycle is 1100°C-1 hour, and then held at room temperature-1 hour, no mass loss is observed up to 100 cycles. [Effects of the Invention]

[0014] According to the method for producing a Ni-base superalloy of the present invention, while maintaining the high-temperature properties (e.g., creep properties and oxidation resistance) of the Ni-base superalloy, even if Sb is mixed in during the raw material melting process and / or even if low-grade materials containing relatively high concentrations of Sb (approximately 50 ppm) are used, the deterioration of the oxidation resistance of the Ni-base superalloy due to Sb can be masked by the additive element Ca. Therefore, even if low-grade materials or recycled materials used for Ni-base heat-resistant alloys for boiler piping are used, it is expected that the Ni-base superalloy will exhibit oxidation resistance equivalent to that of Ni-base superalloys produced using high-grade materials for Ni-base superalloys for turbine blades, which require an Sb content of 2 ppm or less. This avoids limitations on raw material sources in the production of Ni-base superalloys, making it possible to reduce material costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of the essential components of a vacuum high-frequency induction melting furnace for casting directionally solidified test pieces or single crystal test pieces made of an Sb-containing Ni-based superalloy according to one embodiment of the present invention. [Figure 2] 1 shows Ca—Sb—O inclusions (FE-EPMA) observed in an alloy melted in a CaO crucible according to an embodiment of the present invention. [Figure 3] FIG. 1 is a perspective view showing an example of an oxidation test piece. [Figure 4] FIG. 1 shows the results of a repeated oxidation test in which one cycle consisted of 1100° C.-1 hour and room temperature retention-1 hour. DETAILED DESCRIPTION OF THE INVENTION

[0016] The compositional components and their composition ratios of the raw materials for the Ni-base superalloy used in the method for producing the Ni-base superalloy of the present invention are based on the following viewpoints: In this specification, numerical ranges are defined as including the upper and lower limit endpoints, and are therefore generally interpreted as being equal to or greater than the lower limit and equal to or less than the upper limit. However, when the upper and lower limit endpoints are not included, the range is explicitly stated as being greater than the lower limit or less than the upper limit. Cr (chromium) improves the high-temperature corrosion resistance and high-temperature oxidation resistance of Ni-based superalloys. The Cr composition ratio is 2% by mass or more and 25% by mass or less. If the composition ratio is less than 2% by mass, it is difficult to ensure high-temperature corrosion resistance and high-temperature oxidation resistance, while if it exceeds 25% by mass, harmful phases such as σ phase and μ phase are generated, reducing high-temperature strength. The Cr composition ratio is preferably 4% by mass or more and 10% by mass or less, and more preferably 8% by mass or more and 10% by mass or less.

[0017] Co (cobalt) increases the solid solubility limit in parent phases such as Al and Ta at high temperatures, disperses and precipitates fine γ' phases upon heat treatment, and improves the high-temperature strength of Ni-based superalloys. Co is an optional element, and its composition ratio is 0% by mass or more and 25% by mass or less. A composition ratio exceeding 25% by mass is not preferable because the desired high-temperature strength cannot be ensured.

[0018] Mo (molybdenum) dissolves in the matrix and contributes to increasing the high-temperature strength of Ni-based superalloys through precipitation hardening. Mo is an optional element, and its composition ratio is 0% by mass or more and 8% by mass or less. If the composition ratio exceeds 8% by mass, harmful phases are formed, resulting in a decrease in high-temperature strength. The composition ratio of Mo is preferably 0% by mass or more and 4% by mass or less, and more preferably 0.4% by mass or more and 2% by mass or less.

[0019] Re (rhenium) dissolves in the gamma phase, improving not only the high-temperature strength of Ni-based superalloys through solid-solution strengthening, but also the corrosion resistance. However, if a large amount of Re is added, TCP phases may precipitate at high temperatures, reducing high-temperature strength. Furthermore, Re is expensive, so from a cost-performance perspective, it is desirable that a small amount of Re be effective in improving high-temperature strength and corrosion resistance. It is necessary to narrow the range of Re that suppresses TCP phase precipitation without forming harmful phases. To achieve this, a balance with other additive elements is required. Re is an optional composition element, and its composition ratio is 0% by mass or more and 10% by mass or less. The composition ratio of Re is preferably 2% by mass or more and 10% by mass or less. Here, TCP phase is an abbreviation for topological close-packed phase, also known as Frank-Kasper (FK) phases, and in the case of Ni-based superalloys, it refers to the σ phase and μ phase.

[0020] Ru (ruthenium) dissolves in the γ-phase matrix, improving the high-temperature strength of Ni-based superalloys through solid-solution strengthening. Ru also suppresses the precipitation of TCP phases, which are formed by the addition of elements such as Re, thereby improving the high-temperature strength of Ni-based superalloys. Ru is an optional element, and its composition ratio is preferably 0% by mass to 10% by mass, and more preferably 0% by mass to 8% by mass. A Ru composition ratio exceeding 10% by mass is undesirable because it leads to the precipitation of ε-phase, reducing the high-temperature strength. Furthermore, since Ru is expensive, with a metal price approximately 200 to 300 times higher than that of Ni and the like, it is preferable to use as little Ru as possible within the range that improves high-temperature strength through solid-solution strengthening, and economically, an upper limit of 8% by mass is preferable.

[0021] Like Mo, W (tungsten) has the effects of solid solution strengthening and precipitation hardening, improving the high-temperature strength of Ni-based superalloys. W is an optional element, and its composition ratio is 0% by mass or more and 14% by mass or less. If the composition ratio exceeds 14% by mass, harmful phases are formed, deteriorating the TMF and creep properties of the Ni-based superalloy. The W composition ratio is preferably 2% by mass or more and 8% by mass or less, and more preferably 4% by mass or more and 7% by mass or less. Here, TMF characteristics refer to thermo-mechanical fatigue characteristics, such as the crack initiation life (cracks of about 2 mm depth) under multiaxial thermal fatigue conditions in turbine blades. Creep characteristics refer to the creep strength of a material, and creep tests or creep rupture tests are used. Creep rupture tests aim to determine the time until rupture under a certain stress, and multiple-type testing machines (multiple test pieces per testing machine) are often used, but single-type machines (single test piece per testing machine) are also acceptable.

[0022] Nb (niobium) substitutes for the Al site of the γ' phase and contributes to precipitation strengthening. Furthermore, when Mo and W coexist, Nb improves the high-temperature strength of Ni-based superalloys through the effects of solid solution strengthening and precipitation strengthening in the presence of Mo and W. Nb is an optional element, and its composition ratio is 0% by mass or more and 5% by mass or less, more preferably 0% by mass or more and 2.5% by mass or less. If the composition ratio exceeds 5% by mass, harmful phases are formed at high temperatures, resulting in deterioration of TMF and creep properties.

[0023] Vanadium (V) is an element that dissolves in the γ' phase and strengthens it. V is an optional element, and its composition ratio is 0% by mass or more and 3% by mass or less, more preferably 0% by mass or more and 0.5% by mass or less. If the composition ratio of V exceeds 3% by mass, creep properties are degraded, which is undesirable.

[0024] Al (aluminum) combines with Ni to form an intermetallic compound represented by NiAl, which constitutes the γ' phase that precipitates in the γ matrix, and improves the TMF and creep properties of Ni-based superalloys, particularly at low temperatures below 1000°C. The Al composition ratio is 1% by mass to 10% by mass, and more preferably 3% by mass to 8% by mass. If the composition ratio is less than 1% by mass, the amount of γ' phase is small and the required TMF and creep properties cannot be obtained, while if it exceeds 10% by mass, the required TMF and creep properties cannot be obtained.

[0025] Ti (titanium) strengthens the γ' phase and improves the creep properties of Ni-based superalloys. Ti is an optional element, and its composition ratio is 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 3% by mass or less. A composition ratio exceeding 10% by mass is not preferable because it is not possible to ensure the desired high-temperature strength.

[0026] Ta (tantalum) strengthens the γ' phase and improves the creep properties of Ni-based superalloys. Ta is an optional element, and its composition ratio is 0 to 13 mass%, more preferably 4 to 10 mass%. If the composition ratio exceeds 13 mass%, it promotes the formation of the eutectic γ' phase, making solution heat treatment difficult.

[0027] Hf (hafnium) contributes to grain boundary strengthening during columnar crystallization during normal solidification and directional solidification, improves the oxidation resistance of Ni-based superalloys, and may also improve TMF properties. Furthermore, when Ni-based superalloys are used as single crystals, it can prevent the grain boundaries from weakening even if recrystallization occurs for some reason. Hf is an optional element, and its composition ratio is 0% to 2.5% by mass, more preferably 0% to 1% by mass. A composition ratio exceeding 2.5% by mass promotes the formation of harmful phases, resulting in decreased TMF and creep properties.

[0028] Carbon (C) segregates at grain boundaries to improve grain boundary strength, and some of it forms carbides such as TaC and precipitates in clumps. To increase grain boundary strength by segregating at grain boundaries, adding 0.08% by mass or more is recommended. However, adding more than 0.5% by mass results in the formation of excess carbides, which reduces the high-temperature strength and ductility of the Ni-based superalloy and also reduces its corrosion resistance. Furthermore, the crystallization temperature of carbides during solidification increases, which can lead to pinning of carbides between dendrites and the formation of porosity, a casting defect. Therefore, C is an optional element, and its composition ratio is 0% by mass or more and 0.5% by mass or less, more preferably 0% by mass or more and 0.05% by mass or less.

[0029] During columnar crystallization due to normal solidification and unidirectional solidification, boron (B) segregates at grain boundaries to improve grain boundary strength. Some of the B also forms borides, such as (Cr, Ni, Mo)3B2, which precipitate at the grain boundaries of the alloy. To achieve the grain boundary strengthening effect, an addition of 0.01% by mass or more is necessary. However, the resulting borides have melting points lower than the alloy's melting point, lowering the alloy's melting point and narrowing the solution treatment temperature range. Therefore, B is an optional element, and its composition ratio is 0% by mass or more and 0.1% by mass or less, and more preferably 0% by mass or more and 0.02% by mass or less.

[0030] Zr (zirconium) segregates at grain boundaries during columnar crystallization due to normal solidification and directional solidification, enhancing grain boundary strength. However, it mostly forms the intermetallic compound Ni3Zr with nickel, the alloy's main component. This compound reduces the alloy's ductility and, due to its extremely low melting point, has many harmful effects, including making solution treatment of the alloy difficult. For this reason, Zr is an optional element, with a composition ratio of 0% to 0.5% by mass, and more preferably 0% to 0.1% by mass.

[0031] Fe (iron) substitutes for Ni and has the effect of improving the hot workability of Ni-based superalloys. Furthermore, raw materials are easily procured, which is effective in reducing material costs. While the above-mentioned recycled materials may contain a certain amount of Fe, materials containing excessive amounts are unsuitable as raw materials for Ni-based superalloys. Fe is an optional element, and its composition ratio is 0% by mass or more and 20% by mass or less, more preferably 0% by mass or more and 5% by mass or less. If the composition ratio exceeds 20% by mass, harmful phases are generated, resulting in a decrease in high-temperature strength.

[0032] Silicon (Si) has the effect of improving the oxidation resistance of Ni-based superalloys. Si is an optional element, and its composition ratio is 0% by mass or more and 1% by mass or less, more preferably 0% by mass or more and 0.5% by mass or less. If the composition ratio exceeds 1% by mass, harmful phases are generated, resulting in a decrease in high-temperature strength.

[0033] Antimony (Sb) significantly reduces the ductility and toughness of Ni-based superalloys after extended heating at temperatures above 700°C for 10,000 hours. Therefore, to ensure good workability, such as bending and weldability, of long-term aged materials, the Sb content in Ni-based superalloy raw materials must be limited to 50 ppm or less. Sb can be treated as an unavoidable impurity if its content is less than 0.5 ppm, and its effect on the oxidation resistance of the resulting Ni-based superalloy is within the acceptable range. Like Sb, Sn (tin), Pb (lead), Zn (zinc), and As (arsenic) are known to cause a significant decrease in the ductility and toughness of Ni-based superalloys after prolonged heating at high temperatures. The contents of these elements in Ni-based superalloy raw materials must be limited to 0.020 mass% or less of Sn, 0.010 mass% or less of Pb, 0.005 mass% or less of Zn, and 0.005 mass% or less of As, respectively.

[0034] Ca (calcium) has the effect of improving the hot workability of Ni-based superalloys by fixing S (sulfur), which inhibits hot workability, as sulfides. To achieve this effect, Ni-based superalloy raw materials may contain Ca. However, if the Ca content exceeds 0.05% by mass (500 ppm), the cleanliness of the Ni-based superalloy decreases, and the hot workability and ductility are impaired. Therefore, when Ca is added to Ni-based superalloy raw materials, the Ca content should be 0.05% by mass or less. The upper limit of the Ca content is preferably 0.02% by mass, and more preferably 0.01% by mass. On the other hand, to ensure the above-mentioned effects of Ca, the Ca content in the raw material for the Ni-base superalloy is preferably 0.0005% by mass (5 ppm) or more, and more preferably 0.001% by mass (10 ppm) or more. Since the precipitation of Ca-Sb-O inclusions in a mass ratio of Ca:Sb:O = 1:3:2 to 1:4:3 in the produced Ni-base superalloy prevents the deterioration of oxidation resistance due to Sb, the Ca content in the raw material for the Ni-base superalloy must be greater than 1 / 4 of the Sb content, and more preferably greater than 1 / 3.

[0035] Next, we will explain the process for manufacturing Ni-based superalloy components such as turbine blades and turbine vane parts using Ni-based superalloy raw materials with the above-mentioned composition and composition ratios. Known manufacturing processes for Ni-based superalloy components include conventional casting, directional solidification, single-crystal solidification, and sintering or 3D printing using powdered Ni-based superalloy raw materials. For turbine blades and turbine vane parts manufactured by various casting methods or sintering / 3D printing, it is recommended to perform the following heat treatment.

[0036] First, turbine blades and turbine vane parts made by conventional casting can be manufactured by the following heat treatment: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by air cooling or cooling in an inert gas atmosphere at 150°C / min to 400°C / min, primary aging treatment, in which the material is held at 1000°C to 1150°C for 2 to 5 hours, followed by air cooling or cooling in an inert gas atmosphere, and secondary aging treatment, in which the material is held at 800°C to 950°C for 10 to 30 hours, followed by air cooling or cooling in an inert gas atmosphere.

[0037] Turbine blades and turbine vane parts made by the unidirectional solidification method can be manufactured by the following heat treatments: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by air cooling or cooling in an inert gas atmosphere at 200°C / min to 400°C / min, primary aging treatment, in which the material is held at 1000°C to 1150°C for 2 to 5 hours, followed by air cooling or cooling in an inert gas atmosphere, and secondary aging treatment, in which the material is held at 800°C to 950°C for 10 to 30 hours, followed by air cooling or cooling in an inert gas atmosphere.

[0038] Turbine blades and turbine vane parts made by the single crystal solidification method can be manufactured by applying the following heat treatments: solution treatment, in which the material is held at 1280°C to 1300°C for 2 to 40 hours, followed by air cooling or cooling in an inert gas atmosphere at 200°C / min to 400°C / min, primary aging treatment, in which the material is held at 1000°C to 1150°C for 2 to 5 hours, followed by air cooling or cooling in an inert gas atmosphere, and secondary aging treatment, in which the material is held at 850°C to 950°C for 10 to 30 hours, followed by air cooling or cooling in an inert gas atmosphere.

[0039] Furthermore, turbine blades and turbine vane components fabricated by sintering or 3D printing using powdered Ni-based superalloy raw materials that satisfy the above-mentioned compositional conditions can be manufactured by the following heat treatments: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by air cooling or cooling in an inert gas atmosphere at 200°C / min to 400°C / min; primary aging treatment, in which the material is held at 1000°C to 1150°C for 2 to 5 hours, followed by air cooling or cooling in an inert gas atmosphere; and secondary aging treatment, in which the material is held at 850°C to 950°C for 10 to 30 hours, followed by air cooling or cooling in an inert gas atmosphere.

[0040] It is preferable to carry out the series of holding times at predetermined temperatures in a vacuum or in an inert gas atmosphere from the viewpoint of avoiding the influence of high-temperature oxidation. Next, as an exemplary embodiment of the present invention, a process for producing Ni-based superalloy components such as turbine blades and turbine vane components using a casting mold with a Ni-based superalloy as a raw material for the Ni-based superalloy will be described. Here, the Ni-based superalloy used as the raw material may be a Ni-based superalloy that contains a certain amount of Sb in advance within a range that satisfies the above-mentioned conditions. For convenience, such materials will also be referred to as "Sb-containing Ni-based superalloys" in this specification. Note that the Ni-based single crystal superalloy TMS-238 used in the examples described below normally contains less than 0.5 ppm of Sb (the level of unavoidable impurities). Therefore, a predetermined amount of Sb was intentionally added to the molten metal to simulate an Sb-containing Ni-based superalloy. Furthermore, in these examples, Sb was added after the molten metal was stabilized at a predetermined temperature. However, it will be understood that adding Sb is not necessary when the raw material for the Ni-based superalloy is a Sb-containing Ni-based superalloy.

[0041] 1 is a cross-sectional view of the essential components of a vacuum high-frequency induction melting furnace for casting directionally solidified or single-crystal test pieces from an Sb-containing Ni-based superalloy, illustrating one embodiment of the present invention. The vacuum exhaust system, temperature measurement device, melting material charging chamber, crucible tilting device, and mold lifting device are not shown. The casting of directionally solidified or single-crystal turbine blades from Ni-based superalloys using a vacuum high-frequency induction melting furnace is described in "Lost-Wax Precision Casting" (edited by the Japan Foundry Association, published by Sangyo Tosho, 2015). In this specification, the sections on melting and casting (pages 78-82) and solidification control (pages 85-90) are particularly cited. Furthermore, "The Superalloys Fundamentals and Applications" (Roger C. Reed, Cambridge University Press, 2006) also describes the casting of turbine blades using Ni-based superalloys, and in this specification, the section "3.1 Processing of turbine blading by solidification processing" (pages 122 to 147) is particularly cited.

[0042] 1, a vacuum high-frequency induction melting furnace 10 is installed in the melting chamber, and uses the electromagnetic induction of a high-frequency melting coil 14 to induce a high-density induction current in the metal material inside the furnace, which then heats and melts the material using the Joule heat generated by this induced current. High-frequency induction melting furnaces have the advantage of being highly thermally efficient because they directly heat the metal material using electromagnetic induction, and also have the advantage of homogenizing the composition of the molten metal because the electromagnetic force stirs the molten metal. However, because they have a limited refining function, high-quality metal material is required for melting.

[0043] The CaO crucible 12 is installed in the vacuum high-frequency induction melting furnace 10. The CaO crucible 12 is held upright and receives the Ni-based superalloy metal material to be melted from a melting material charging chamber (not shown), which melts the metal material to form a molten metal. In the examples described below, a C-1 model CaO crucible manufactured by Eight Ceramics Co., Ltd. was used as the CaO crucible 12. The melting high-frequency coil 14 is provided around the periphery of the CaO crucible 12 in the vacuum high-frequency induction melting furnace 10, and induces a high-current-density induced current in the metal material in the CaO crucible 12. The crucible tilting device (not shown) is a mechanism for tilting the CaO crucible 12 in the crucible tilting direction 16 so that the molten metal in the CaO crucible 12 can be poured from the pouring spout 28 into a mold 30 for a single crystal rod-shaped test piece.

[0044] The directional solidification furnace 20 has the same configuration as the vacuum high-frequency induction melting furnace 10 and is installed in the mold chamber. In the examples described below, a directional solidification furnace 20 manufactured by Nisshin Giken Co., Ltd., model NEV-5DSNIA, was used. The mold high-frequency coil 22 is installed around the periphery of the directional solidification furnace 20 and induces a high-density induced current in the metal material in the mold 30 for single crystal rod specimens located in the mold chamber, supplying the energy necessary to maintain the molten state. The graphite resistance heating element 24 is installed on the inner wall surface of the side wall of the directional solidification furnace 20 and serves as a heater for heating the interior of the furnace. The upper lining 25 is installed on the ceiling surface of the directional solidification furnace 20 and is made of, for example, zirconia or alumina. The sidewall insulator 26 is installed between the mold high-frequency coil 22 and the graphite resistance heating element 24 and is made of, for example, a mica sheet. The upper insulator 27 is installed between the upper lining 25 and the ceiling surface of the directional solidification furnace 20 and is made of, for example, firebrick. The pouring spout 28 is provided in the upper lining 25 and the upper insulating material 27, and is an opening for pouring the molten metal from the CaO crucible 12 in the melting chamber into the mold 30 for single crystal rod-shaped test pieces located in the mold chamber. The bottom insulating material 29 is provided on the bottom surface of the directional solidification furnace 20, and is made of, for example, firebrick.

[0045] The single crystal rod-shaped specimen mold 30 is a mold for casting single crystal rod-shaped specimens using a Ni-based superalloy. While FIG. 1 illustrates a mold using a selector 32, a mold using a seed crystal may also be used. The mold base 34 is called a chill plate, and is provided with a cooling water flow path to ensure the temperature gradient necessary for crystal growth of the single crystal. In the examples described below, a homemade mold was used for the single crystal rod-shaped specimen mold 30. The manufacturing of the mold is explained in the aforementioned Lost Wax Precision Casting Method (edited by the Japan Foundry Association, published by Sangyo Tosho, 2015). In this specification, the section on molding method (pages 9 to 78) is particularly cited. The above-mentioned "The Superalloys Fundamentals and Applications" (Roger C. Reed, Cambridge University Press, 2006) also contains an explanation of mold manufacturing, and in this specification, the section "3.1.1 The practice of investment casting" (pages 122 to 125) is particularly cited. A mold lifting device (not shown) realizes the mold lifting direction 36 and ensures the cooling rate required to grow the Ni-based superalloy into a single crystal. Generally, to unidirectionally solidify an Ni-based superalloy or grow it into a single crystal, it is necessary to appropriately maintain the ratio between the temperature gradient at the solid-liquid interface and the solidification rate as solidification progresses unidirectionally within the mold.

[0046] The conditions for casting a directionally solidified test piece or a single crystal test piece from an Sb-containing Ni-based superalloy using the vacuum high-frequency induction melting furnace 10 configured as described above will be explained below. The casting temperature of the vacuum high-frequency induction melting furnace 10 is set to +90 to 170°C above the solidification start temperature of the cast alloy, and the mold preheat temperature is set to 1400 to 1550°C. The melting point of Ni is 1455°C, and the melting points of the elements used as constituent elements of the Ni-based superalloy are 1495°C for Co (cobalt), 1907°C for Cr (chromium), 3440°C for W (tungsten), 660°C for Al (aluminum), 3020°C for Ta (tantalum), 3182°C for Re (rhenium), and 2334°C for Ru (ruthenium). Therefore, a temperature condition of 1560 to 1640°C is preferable for completely melting the Sb-containing Ni-based superalloy and stabilizing the molten metal in the CaO crucible 12. [Example]

[0047] The metallic material used was the Ni-based single crystal superalloy TMS-238. Table 1 shows the compositional elements and composition ratios of TMS-238, and Table 2 shows its mechanical properties. For reference, Table 1 also shows the compositional elements and composition ratios of the conventional alloys CMSX-4 and MX-4 / PWA1497, and Table 2 shows the mechanical properties of CMSX-4. [Table 1] [Table 2] The above metal material (TMS-238) was subjected to high-frequency melting in a vacuum according to the following procedure to cast a single crystal test piece. The vacuum degree was 6 × 10 -2 It was Pa.

[0048] 2000 g of Ni-based single crystal superalloy TMS-238 was placed in a CaO crucible 12 and subjected to high-frequency melting. Next, with the Ni-based single crystal superalloy TMS-238 in a completely melted state, the molten metal was stabilized at 1600°C. Next, Sb equivalent to 10 ppm was added to the molten metal. The molten metal was poured into a mold 30 for single crystal rod-shaped test pieces that had been preheated to 1400 to 1550°C in a directional solidification furnace 20. The mold 30 for single crystal rod-shaped test pieces into which the molten metal had been poured was pulled out of the directional solidification furnace 20 at a speed of 200 mm / h and directionally solidified. After the directionally solidified sample had solidified and cooled to room temperature, the cast single crystal rod-shaped test pieces were removed from the directional solidification furnace.

[0049] On the other hand, for comparison, single crystal rod-shaped specimens were also prepared, which were cast from alloys melted in Al2O3 crucibles. Except for the use of an Al2O3 crucible instead of the CaO crucible 12, the Ni-based single crystal superalloy TMS-238 was used as the metallic material, an amount of Sb equivalent to 10 ppm was added (injected into the molten metal), the molten metal was poured into a mold 30 for single crystal rod-shaped test pieces preheated to 1400 to 1550°C, and the mold 30 was pulled out of the unidirectional solidification furnace 20 at a speed of 200 mm / h, in the same manner as in the above-mentioned Example.

[0050] Glow discharge mass spectrometry confirmed that the single crystal rod specimens of the alloy melted in the CaO crucible contained 9.5 ppm Sb, and the single crystal rod specimens of the alloy melted in the Al2O3 crucible contained 3.8 ppm Sb. Glow discharge mass spectrometry was performed on a Thermo Scientific, Model VG9000.

[0051] Figure 2 shows Ca-Sb-O inclusions (FE-EPMA: Field Emission Electron Probe Microanalyzer) observed in an alloy melted in a CaO crucible according to one embodiment of the present invention. (A) is a backscattered electron image, (B) shows O (oxygen), (C) shows Ca (calcium), and (D) shows Sb (antimony). EPMA (Electron Probe Microanalysis) measures the elements that make up the sample and their amounts by irradiating the sample with an electron beam and detecting the characteristic X-rays that are generated. FE (Field Emission)-EPMA, equipped with a field emission electron gun, enables elemental analysis of microscopic areas of approximately 100 nm. Data acquisition using the EBSD (Electron Backscattered Diffraction Pattern) method was performed using a TEAM (TEAM) microscope, manufactured by AMETEK, Inc., EDAX Division. TM Conducted by EDS.

[0052] Microstructural observation (FE-EPMA) of the alloy melted in a CaO crucible revealed the presence of Ca-Sb-O inclusions (Ca:Sb:O = 1:3:2 to 1:4:3 mass ratio). Ca:Sb:O = 1:3:2 (mass ratio) corresponds to the chemical formula CaSbO5. Ca:Sb:O = 1:4:3 (mass ratio) corresponds to the chemical formula Ca3Sb4O. 23 The particle shape of the Ca-Sb-O inclusions was 100 to 500 nm in diameter.

[0053] Oxidation test specimens (Fig. 3) with a diameter of 9 mm and a height of 5 mm were prepared from the single crystal rod specimens and subjected to a cyclic oxidation test consisting of 1 hour at 1100°C and 1 hour at room temperature. Figure 4 shows the results of the cyclic oxidation test. As shown in Figure 4, the mass of the alloy specimen melted in the Al2O3 crucible decreased by 0.2 mg / cm from the first cycle compared to the initial value at the start of the cyclic oxidation test. 2 ] increases, and mass loss begins from the 15th cycle, and the mass loss at 100 cycles is 3.8 [mg / cm 2 ] was. On the other hand, for the alloy specimen melted in the CaO crucible, the mass decreased by 0.2 mg / cm from the first cycle compared to the initial value at the start of the cyclic oxidation test. 2 ] increased, and at the 100th cycle, the mass was 0.3 [mg / cm 2 In other words, there was no mass loss of the oxidation test specimens up to 100 cycles of repeated oxidation testing. In the alloy melted in a CaO crucible, the elements constituting the oxidized test specimen and their amounts were measured using EBSD. As a result, no segregation of Sb was observed at the oxide film-base material interface, which suggests that the Ca-Sb-O inclusions suppressed the diffusion of Sb to the interface. From the above, it was confirmed that the formation of Ca-Sb-O inclusions in Ni-based superalloys prevents the deterioration of the oxidation resistance of Ni-based superalloys containing the low-melting-point metallic impurity element Sb.

[0054] In the above example, a CaO crucible is used to supply Ca and O that mask the oxidation resistance degradation caused by the impurity Sb contained in the Ni-base superalloy raw material through contact between the CaO crucible and the molten Ni-base superalloy raw material, but the present invention is not limited to this. In another embodiment, for example, an Al2O3 crucible or an MgO crucible may be used as the crucible for melting the Ni-base superalloy raw material, and Ca and O that perform the masking action may be separately supplied to the Ni-base superalloy raw material or the molten Ni-base superalloy raw material.

[0055] When calcium is supplied to a raw material (or its melt) for a Ni-base superalloy, a substantial amount of calcium fluoride or a calcium compound may be mixed to provide calcium in an amount of 0.33 to 100 times the mass of the impurity Sb. In this case, the constituent elements of the calcium compound must not contain harmful elements such as As (arsenic) and S (sulfur), which would impair the heat resistance and oxidation resistance of the target Ni-base superalloy.

[0056] It is assumed that O is supplied to the raw material for Ni-based superalloys by elution from an Al2O3 crucible or MgO crucible into the raw material for Ni-based superalloys (or its molten metal). In addition, even in the case of vacuum high-frequency melting, it is assumed that O is supplied to the raw material for Ni-based superalloys by elution from an Al2O3 crucible or MgO crucible into the raw material for Ni-based superalloys (or its molten metal). -2 If the vacuum level is below 1 Pa, it is thought that O2 atoms remaining in the vacuum will dissolve into the raw material (or its molten metal) for the Ni-based superalloy.

[0057] In the above examples, a vacuum high-frequency induction melting furnace is used to cast a Ni-based superalloy member by unidirectional solidification or single crystallization using a Ni-based superalloy as a raw material for the Ni-based superalloy. However, conventional casting may also be used to produce polycrystalline turbine components. In the case of conventional casting, a polycrystalline mold is used. Polycrystalline molds do not have the selectors or chill plates that are provided in molds for single crystal rod specimens. In addition, in vacuum high-frequency induction melting furnaces for conventional casting, the molds are generally preheated to a temperature of 800 to 1100°C.

[0058] Furthermore, in the above examples, 2 kg of Ni-based single crystal superalloy was placed in a CaO crucible, but in cases where it is difficult to prepare a CaO crucible, such as for large-scale melting (e.g., 3-ton melting) at a manufacturing site, the required Ca content can be achieved by melting in a crucible made of a standard material such as an Al2O3 crucible or MgO, and adding CaO granules (e.g., approximately 5 mm in diameter, preferably 1 to 10 mm in diameter) to the molten metal. In this case, the amount of CaO added should be, for example, 2 kg per 100 kg of molten metal as a standard value, preferably a ratio equivalent to 0.2% to 5% by weight of the Ni-based superalloy raw material. The key point is that the molten Ni-based superalloy raw material is brought into contact with CaO, and excess CaO does not dissolve into the molten Ni-based superalloy raw material as slag, so that the effect on the Ca composition ratio of the directionally solidified component, single crystal cast component, or polycrystalline solidified component to be produced is negligible. Note that, although the case where CaO granules are added to the molten Ni-based superalloy raw material has been shown, the present invention is not limited to this, and CaO granules may be added to the Ni-based superalloy raw material before melting. Moreover, CaF2 (fluorite) may be used in place of CaO. [Industrial Applicability]

[0059] According to the method for producing a Ni-base superalloy of the present invention, the additive element Ca can mask the oxidation resistance degradation effect of Sb. Therefore, even if a low-grade material for a Ni-base heat-resistant alloy for boiler piping is used, it can be expected that the Ni-base superalloy will exhibit oxidation resistance equivalent to that of a Ni-base superalloy produced using a high-grade material for a conventional Ni-base superalloy for turbine blades. [Explanation of symbols]

[0060] 10. Vacuum high frequency induction melting furnace 12 CaO crucible 14 High frequency melting coil 16 Crucible tilt direction 20 Unidirectional solidification furnace 22 High frequency coil for casting 24 Graphite resistance heating element 25 Upper Lining 26 Sidewall insulation material (mica sheet) 27 Upper insulation material (firebrick) 28 spout 29 Bottom insulation (firebrick) 30 Mold for single crystal rod specimens 32 Selectors 34 Mold base 36 Mold lifting direction

Claims

1. A Ni-based superalloy raw material containing Sb of a predetermined composition is placed in an Al 2 O 3 crucible or an MgO crucible, and high-frequency melted in a vacuum using a high-frequency induction melting furnace. At the same time, an amount of Ca (calcium) equivalent to 0.33 times or more and 100 times or less the amount of Sb by mass is added to the Ni-based superalloy raw material or the molten Ni-based superalloy raw material; With the Ni-based superalloy raw material completely melted, the molten metal is stabilized in the crucible at 1560 to 1640°C for 10 to 60 minutes; The molten metal is poured into a mold preheated to a predetermined temperature in a unidirectional solidification furnace, The mold into which the molten metal has been poured is withdrawn from the high-frequency induction melting furnace at a speed of 50 to 350 mm / h, and the Ni-base superalloy raw material is subjected to unidirectional solidification, single crystal solidification, or polycrystal solidification. After cooling to room temperature, the cast directionally solidified portion, single crystal cast portion, or polycrystalline solidified portion is removed from the directionally solidified furnace. A method for producing a Ni-based superalloy, comprising the steps of:

2. The Ca (calcium) is CaO or CaF ２ and the CaO or CaF ２ is added to the raw material for the Ni-base superalloy, or to a molten metal of the raw material for the Ni-base superalloy, A method for producing the Ni-based superalloy according to claim 1.

3. 3. The method for producing a Ni-based superalloy according to claim 2, wherein the CaO is in the form of granules having a particle size of 1 to 10 mm.

4. a Ni-base superalloy raw material containing Sb of a predetermined composition is placed in a CaO crucible, and high-frequency melted in a vacuum using a high-frequency induction melting furnace; and an amount of Ca (calcium) corresponding to 0.33 to 100 times the amount of Sb in terms of mass ratio is supplied to the molten Ni-base superalloy raw material by contact between the CaO crucible and the molten Ni-base superalloy raw material; With the Ni-based superalloy raw material completely melted, the molten metal is stabilized in the crucible at 1560 to 1640°C for 10 to 60 minutes; The molten metal is poured into a mold preheated to a predetermined temperature in a unidirectional solidification furnace, The mold into which the molten metal has been poured is withdrawn from the high-frequency induction melting furnace at a speed of 50 to 350 mm / h, and the Ni-base superalloy raw material is subjected to unidirectional solidification, single crystal solidification, or polycrystal solidification. After cooling to room temperature, the cast directionally solidified portion, single crystal cast portion, or polycrystalline solidified portion is removed from the directionally solidified furnace. A method for producing a Ni-based superalloy, comprising the steps of:

5. the mold is a single crystal mold, The predetermined temperature to which the mold is preheated in the unidirectional solidification furnace is 1400 to 1550°C; The single crystal mold is cooled at the bottom by a water-cooled chill plate. A method for producing the Ni-based superalloy according to any one of claims 1 to 4.

6. the mold is a polycrystalline mold, The predetermined temperature to which the mold is preheated in the unidirectional solidification furnace is 1000 to 1100°C. A method for producing the Ni-based superalloy according to any one of claims 1 to 4.

7. The directionally solidified portion, the single crystal cast portion, or the polycrystalline solidified portion has a mass ratio of Ca:Sb:O=1:3:2 to 1:4:3 Ca—Sb—O inclusions are precipitated, and the particle shape of the Ca—Sb—O inclusions has a particle size of 100 to 500 nm. A method for producing the Ni-based superalloy according to any one of claims 1 to 4.

8. The raw material for the Ni-base superalloy contains, in mass %, in a molten state before being poured into the mold: Cr (chromium): 2% or more and 25% or less, Co (cobalt): 0% or more and 25% or less, Mo (molybdenum): 0% or more and 8% or less, Re (rhenium): 0% or more and 10% or less, Ru (ruthenium): 0% or more and 10% or less, W (tungsten): 0% or more and 14% or less, Nb (niobium): 0% or more and 5% or less, V (vanadium): 0% or more and 3% or less, Al (aluminum): 1% or more and 10% or less, Ti (titanium): 0% or more and 10% or less, Ta (tantalum): 0% or more and 13% or less, Hf (hafnium): 0% or more and 2.5% or less, C (carbon): 0% or more and 0.5% or less, B (boron): 0% or more and 0.1% or less, Zr (zirconium): 0% or more and 0.5% or less, Fe (iron): 0% or more and 20% or less, Si (silicon): 0% or more and 1% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 ppm or more and 500 ppm or less, and the Ca content is greater than 1 / 4 of the Sb content; A method for producing the Ni-based superalloy according to any one of claims 1 to 4.

9. The raw material for the Ni-base superalloy contains, in mass %, in a molten state before being poured into the mold: Cr (chromium): 4% or more and 10% or less, Co (cobalt): 0% or more and 12% or less, Mo (molybdenum): 0% or more and 4% or less, Re (rhenium): 2% or more and 10% or less, Ru (ruthenium): 2% or more and 8% or less, W (tungsten): 2% or more and 8% or less, Nb (niobium): 0% or more and 2.5% or less, V (vanadium): 0% or more and 0.5% or less, Al (aluminum): 3% or more and 8% or less, Ti (titanium): 0% or more and 3% or less, Ta (tantalum): 4% or more and 10% or less, Hf (hafnium): 0% or more and 1% or less, C (carbon): 0% or more and 0.05% or less, B (boron): 0% or more and 0.02% or less, Zr (zirconium): 0% or more and 0.1% or less, Fe (iron): 0% or more and 5% or less, Si (silicon): 0% or more and 0.5% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 ppm or more and 500 ppm or less, and the Ca content is greater than 1 / 4 of the Sb content; The method for producing the Ni-based superalloy according to claim 8.

10. 9. The method for producing a Ni-base superalloy according to claim 8, wherein the Ca content is greater than one-third of the Sb content.

11. In mass%, Cr (chromium): 2% or more and 25% or less, Co (cobalt): 0% or more and 25% or less, Mo (molybdenum): 0% or more and 8% or less, Re (rhenium): 0% or more and 10% or less, Ru (ruthenium): 0% or more and 10% or less, W (tungsten): 0% or more and 14% or less, Nb (niobium): 0% or more and 5% or less, V (vanadium): 0% or more and 3% or less, Al (aluminum): 1% or more and 10% or less, Ti (titanium): 0% or more and 10% or less, Ta (tantalum): 0% or more and 13% or less, Hf (hafnium): 0% or more and 2.5% or less, C (carbon): 0% or more and 0.5% or less, B (boron): 0% or more and 0.1% or less, Zr (zirconium): 0% or more and 0.5% or less, Fe (iron): 0% or more and 20% or less, Si (silicon): 0% or more and 1% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 PPM or more and 500 PPM or less, the Ca content ratio is greater than 1 / 4 of the Sb content ratio, and in mass ratio, Ca:Sb:O=1:3:2 to 1:4:3 Ca—Sb—O inclusions are precipitated, and the particle shape of the Ca—Sb—O inclusions has a particle size of 100 to 500 nm. A Ni-based superalloy member that prevents the deterioration of oxidation resistance due to Sb.

12. The Ni-based superalloy member comprises, in mass%, Cr (chromium): 4% or more and 10% or less, Co (cobalt): 0% or more and 12% or less, Mo (molybdenum): 0% or more and 4% or less, Re (rhenium): 2% or more and 10% or less, Ru (ruthenium): 2% or more and 8% or less, W (tungsten): 2% or more and 8% or less, Nb (niobium): 0% or more and 2.5% or less, V (vanadium): 0% or more and 0.5% or less, Al (aluminum): 3% or more and 8% or less, Ti (titanium): 0% or more and 3% or less, Ta (tantalum): 4% or more and 10% or less, Hf (hafnium): 0% or more and 1% or less, C (carbon): 0% or more and 0.05% or less, B (boron): 0% or more and 0.02% or less, Zr (zirconium): 0% or more and 0.1% or less, Fe (iron): 0% or more and 5% or less, Si (silicon): 0% or more and 0.5% or less, The balance is Ni (nickel) and unavoidable impurities, and Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): Contains 5 ppm or more and 500 ppm or less, the Ca content is greater than 1 / 4 of the Sb content, and the mass ratio is Ca:Sb:O=1:3:2 to 1:4:3 Ca—Sb—O inclusions are precipitated, and the particle shape of the Ca—Sb—O inclusions has a particle size of 100 to 500 nm. The Ni-based superalloy member according to claim 11, which is prevented from having its oxidation resistance deteriorated by Sb.

13. The Ni-based superalloy member comprises: a directionally solidified component, a single crystal cast component, or a polycrystalline solidified component; The Ni-based superalloy member according to claim 11 or 12, which prevents the deterioration of oxidation resistance due to Sb.

14. A turbine blade or turbine vane part manufactured by sintering or 3D printing using a powdered Ni-based superalloy raw material satisfying the composition conditions of claim 8. The Ni-based superalloy member according to claim 11 or 12, which prevents the deterioration of oxidation resistance due to Sb.

15. The Ni-based superalloy member comprises: An oxidation test piece having a diameter of 9 mm and a height of 5 mm is prepared from the Ni-based superalloy member, and in a repeated oxidation test in which one cycle is 1100 ° C.-1 hour, room temperature holding-1 hour, no mass loss is observed up to 100 cycles. The Ni-based superalloy member according to claim 11 or 12, which prevents the deterioration of oxidation resistance due to Sb.

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