WO2024075560A1 - Method for producing ni-based superalloy prevented from deterioration of oxidation resistance due to sb, and ni-based superalloy member prevented from deterioration of oxidation resistance due to sb - Google Patents

Method for producing ni-based superalloy prevented from deterioration of oxidation resistance due to sb, and ni-based superalloy member prevented from deterioration of oxidation resistance due to sb Download PDF

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WO2024075560A1
WO2024075560A1 PCT/JP2023/034641 JP2023034641W WO2024075560A1 WO 2024075560 A1 WO2024075560 A1 WO 2024075560A1 JP 2023034641 W JP2023034641 W JP 2023034641W WO 2024075560 A1 WO2024075560 A1 WO 2024075560A1
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mass
raw material
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superalloy
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French (fr)
Japanese (ja)
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京子 川岸
広史 原田
忠晴 横川
千尋 田畑
裕俊 前澤
淳 埋橋
忠勝 大久保
高田　裕治
進補 鈴木
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国立研究開発法人物質・材料研究機構
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon

Definitions

  • the present invention relates to a method for producing a Ni-based superalloy that prevents the deterioration of oxidation resistance caused by Sb, and to a Ni-based superalloy component that prevents the deterioration of oxidation resistance caused by Sb.
  • Ni-base superalloys are used as turbine blades for jet engines, gas turbines, and the like.
  • various elements are used to improve high-temperature properties, and this has led to issues such as increased material costs and uneven supply of raw materials.
  • elements known to impair the high-temperature properties of Ni-base superalloys include sulfur (S) and antimony (Sb). Standards stipulate upper limits for the content ratios of these elements that impair high-temperature properties.
  • the allowable Sb ratio in the Ni-base superalloy AMS2280 for aerospace use is 50 ppm (see Non-Patent Document 1).
  • the allowable Sb ratio in Ni-base heat-resistant alloys used for boiler piping in thermal power plants and the like is 50 ppm (0.005 mass%) (see Patent Document 1, paragraphs [0057] and [0058]).
  • the composition ratio of Sb in the Ni-base 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 more becomes a problem.
  • Sb is mixed in as an impurity element during the raw material melting process.
  • Non-Patent Document 2 describes that an alloy produced by adding Sb, a low-melting point metal impurity, to a master ingot and melting it in an Al 2 O 3 crucible contains 1.1 ppm of Sb, and that in a repeated oxidation test in which one cycle was 1100°C-1h and room temperature-1h, a clear mass loss was observed after 50 cycles.
  • the problem is that the oxidation resistance of Ni-based superalloys is deteriorated by the low melting point metal impurity element Sb.
  • Sb low melting point metal impurity element
  • Ni-based superalloys having the same oxidation resistance as conventional ones using materials with a relatively high impurity content (low grade), such as recycled materials instead of the high purity materials required for the manufacture of conventional Ni-based superalloys for turbine blades, it would be desirable from the viewpoint of material costs and raw material suppliers.
  • the present invention is intended to solve the above-mentioned problems, and aims to provide a manufacturing method for a Ni-base superalloy in which the deterioration of oxidation resistance of the Ni-base superalloy due to the low-melting point metal impurity element Sb can be prevented by using an additive element that can prevent the deterioration of oxidation resistance of the Ni-base 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-base superalloy, and a Ni-base superalloy component in which the deterioration of oxidation resistance due to Sb is prevented.
  • the method for producing a Ni-base superalloy of the present invention includes the steps of: putting a Ni-base superalloy raw material containing Sb of a predetermined composition into a crucible, melting it in a vacuum by high-frequency induction melting furnace, adding a necessary amount of Ca (calcium) to the molten Ni-base superalloy raw material to prevent the oxidation resistance inhibiting action of Sb to the molten Ni-base superalloy raw material; stabilizing the molten metal at 1560 to 1640 ° C.
  • a raw material for Ni-base superalloys containing Sb of a predetermined composition refers to a material having a composition as specified in, for example, [10] or [11]. However, it is not required that the raw material satisfy the conditions regarding the content of Sb and Ca before being put into the crucible.
  • the conditions for such a 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 casting 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.
  • the crucible is a CaO crucible
  • 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.
  • the crucible is an Al 2 O 3 crucible or an MgO crucible
  • 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 equivalent to 0.2% to 5% by weight based on the Ni-base superalloy raw material.
  • the CaO is preferably in the form of granules having a particle size of 1 to 10 mm.
  • the crucible is an Al2O3 crucible or an MgO crucible
  • the Ca (calcium) is added to the Ni-base superalloy raw material or a molten metal of the Ni-base superalloy raw material in an amount equivalent to 0.33 to 100 times the amount of Sb by mass ratio.
  • 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.
  • 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, and the bottom of the single crystal mold is cooled by a water-cooled chill plate.
  • the mold is a polycrystalline mold, and the predetermined temperature to which the mold is preheated in the directional solidification furnace is 1000 to 1100°C.
  • 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
  • the raw material for the Ni-base superalloy is in a molten state before being poured into the mold, and is, 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 (H
  • 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
  • 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,
  • the Ni-base superalloy component is preferably a directionally solidified component, a single crystal cast component, or a polycrystalline solidified component.
  • the component is preferably a turbine blade or turbine vane component produced by sintering or 3D printing using a powdered Ni-base superalloy raw material satisfying the composition conditions described in [10] or [11].
  • an oxidation test piece having a diameter of 9 mm and a height of 5 mm is prepared from the Ni-base superalloy component, and in a repeated oxidation test in which one cycle is 1100°C-1h, room temperature holding-1h, no mass reduction is observed up to 100 cycles.
  • the method for producing the Ni-base superalloy of the present invention maintains the high-temperature properties (creep properties, oxidation resistance, etc.) of the Ni-base superalloy, and even if Sb is mixed in during the raw material melting process and/or a low-grade material containing a relatively high concentration of Sb of about 50 PPM is used, the deterioration of the oxidation resistance of the Ni-base superalloy due to Sb can be masked by the added element Ca.
  • Ni-base superalloy will exhibit oxidation resistance equivalent to that of a Ni-base superalloy produced using high-grade materials for Ni-base superalloys for turbine blades, which require an Sb content of 2 PPM or less. Therefore, in the production of Ni-base superalloys, it is possible to avoid limitations on the sources of raw material procurement, and to reduce material costs.
  • FIG. 1 is a cross-sectional view of the essential configuration of a melting furnace using a vacuum high-frequency induction melting furnace for casting a directionally solidified test piece or a single crystal test piece made of an Sb-containing Ni-based superalloy according to one embodiment of the present invention.
  • 1 shows Ca--Sb--O inclusions (FE-EPMA) observed in an alloy melted in a CaO crucible according to one embodiment of the present invention.
  • FIG. 2 is a perspective view showing an example of an oxidation test piece.
  • FIG. 1 is a graph showing the results of a repeated oxidation test in which one cycle is 1100° C.-1 hour and room temperature holding-1 hour.
  • 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:
  • the numerical ranges are defined as including the upper and lower limit values, and therefore are in principle interpreted as being equal to or greater than the lower limit value and equal to or less than the upper limit value.
  • the numerical ranges are clearly stated as being greater than the lower limit value or less than the upper limit value.
  • Cr chromium
  • the composition ratio of Cr is 2% by mass or more and 25% by mass or less.
  • composition ratio is less than 2% by mass, it is difficult to ensure high-temperature corrosion resistance and high-temperature oxidation resistance, and if it exceeds 25% by mass, harmful phases such as ⁇ phase and ⁇ phase are generated, resulting in a decrease in high-temperature strength.
  • the composition ratio of Cr 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.
  • Co increases the solid solubility limit in parent phases such as Al and Ta at high temperatures, disperses and precipitates fine ⁇ ' phases through heat treatment, and improves the high-temperature strength of Ni-based superalloys.
  • Co is an optional composition element, and its composition ratio is 0 mass% or more and 25 mass% or less. If the composition ratio exceeds 25 mass%, it is not preferable because the desired high-temperature strength cannot be secured.
  • Mo mobdenum
  • Mo dissolves in the matrix and contributes to increasing the high-temperature strength of Ni-based superalloys through precipitation hardening.
  • Mo is an optional composition element, and its composition ratio is 0 mass% or more and 8 mass% or less. If the composition ratio exceeds 8 mass%, harmful phases are generated and high-temperature strength decreases.
  • the composition ratio of Mo is preferably 0 mass% or more and 4 mass% or less, and more preferably 0.4 mass% or more and 2 mass% or less.
  • Re rhenium
  • Re is an optional composition element, and its composition ratio is 0 mass% or more and 10 mass% or less.
  • the composition ratio of Re is preferably 2 mass% or more and 10 mass% or less.
  • 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 ⁇ phase or ⁇ phase.
  • Ru dissolves in the gamma phase, which is the parent phase, and improves the high-temperature strength of Ni-based superalloys through solid-solution strengthening. Ru also suppresses the precipitation of TCP phases that are generated by the addition of Re and other elements, thereby improving the high-temperature strength of Ni-based superalloys.
  • Ru is an optional composition element, and its composition ratio is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 8% by mass or less. If the composition ratio of Ru exceeds 10% by mass, ⁇ phase will precipitate and the high-temperature strength will decrease, which is not preferable.
  • the price of Ru in bullion is about 200 to 300 times higher than that of Ni and other elements, it is preferable to use as little Ru as possible within the range in which high-temperature strength can be improved through solid-solution strengthening, and economically, it is preferable to set the upper limit at 8% by mass.
  • W has the effect of solid solution strengthening and precipitation hardening, similar to Mo, and improves the high temperature strength of Ni-based superalloys.
  • W is an optional composition element, and its composition ratio is 0 mass% or more and 14 mass% or less. If the composition ratio exceeds 14 mass%, harmful phases are generated and the TMF properties and creep properties of the Ni-based superalloy are deteriorated.
  • the composition ratio of W is preferably 2 mass% or more and 8 mass% or less, more preferably 4 mass% or more and 7 mass% or less.
  • the TMF characteristic refers to the thermo-mechanical fatigue characteristic, and for example refers to the crack initiation life (cracks of about 2 mm depth) under multiaxial thermal fatigue conditions in a turbine blade.
  • the creep characteristic refers to the creep strength of a material, and creep tests or creep rupture tests are used.
  • the creep rupture test aims to determine the time until rupture under a certain stress, and a multiple type test machine (multiple test pieces per test machine) is often used, but a single type (single test piece per test machine) can also be used.
  • Nb niobium substitutes for the Al site of the ⁇ ' phase and contributes to precipitation strengthening. When Mo and W coexist, it improves the high-temperature strength of the Ni-based superalloy through the effects of solid solution strengthening and precipitation strengthening in the presence of Mo and W.
  • Nb is an optional composition element, and its composition ratio is 0 mass% or more and 5 mass% or less, and more preferably 0 mass% or more and 2.5 mass% or less. If the composition ratio exceeds 5 mass%, harmful phases are generated at high temperatures, and the TMF properties and creep properties are reduced.
  • V vanadium
  • V vanadium
  • V is an element that dissolves in the ⁇ ' phase and strengthens it.
  • V is an optional composition element, and its composition ratio is 0 mass% or more and 3 mass% or less, and more preferably 0 mass% or more and 0.5 mass% or less. If the composition ratio of V exceeds 3 mass%, it is not preferable because the creep properties are reduced.
  • Al combines with Ni to form an intermetallic compound represented by Ni 3 Al which constitutes the ⁇ ' phase precipitated in the ⁇ matrix phase, improving the TMF and creep properties of Ni-based superalloys, particularly at low temperatures below 1000° C.
  • the Al composition ratio is 1 mass % or more and 10 mass % or less, and more preferably 3 mass % or more and 8 mass % or less. If the composition ratio is less than 1 mass %, the amount of ⁇ ' phase is small and the required TMF and creep properties cannot be obtained, whereas if it exceeds 10 mass %, the required TMF and creep properties cannot be obtained.
  • Ti strengthens the ⁇ ' phase and improves the creep properties of Ni-based superalloys.
  • Ti is an optional composition element, and its composition ratio is 0 mass% or more and 10 mass% or less, and more preferably 0 mass% or more and 3 mass% or less. If the composition ratio exceeds 10 mass%, it is not preferable because the desired high-temperature strength cannot be secured.
  • Ta strengthens the ⁇ ' phase and improves the creep properties of Ni-based superalloys.
  • Ta is an optional element, and its composition ratio is 0 mass% or more and 13 mass% or less, and more preferably 4 mass% or more and 10 mass% or less. If the composition ratio exceeds 13 mass%, it promotes the formation of eutectic ⁇ ' phase, making solution heat treatment difficult.
  • Hf (hafnium) contributes to strengthening grain boundaries during columnar crystallization due to normal solidification and unidirectional solidification, and may improve the oxidation resistance of Ni-based superalloys and also improve the TMF properties. In addition, when Ni-based superalloys are used as single crystals, it is possible to prevent the grain boundaries from weakening even if recrystallization occurs for some reason.
  • Hf is an optional composition element, and its composition ratio is 0 mass% or more and 2.5 mass% or less, and more preferably 0 mass% or more and 1 mass% or less. If the composition ratio exceeds 2.5 mass%, the formation of harmful phases is promoted, and the TMF properties and creep properties are deteriorated.
  • C carbon segregates at the grain boundaries to improve grain boundary strength, and some of it forms carbides such as TaC and precipitates in clumps.
  • carbides such as TaC and precipitates in clumps.
  • it is recommended to add 0.08 mass% or more.
  • adding more than 0.5 mass% will form excess carbides, reducing the high-temperature strength and ductility of the Ni-based superalloy and also reducing corrosion resistance.
  • the crystallization temperature of the carbides during solidification will increase, which can lead to pinning of the carbides between dendrites and the generation of porosity, a casting defect.
  • C is an optional composition element, and its composition ratio is 0 mass% or more and 0.5 mass% or less, and more preferably 0 mass% or more and 0.05 mass% or less.
  • B boron segregates to the grain boundaries to improve grain boundary strength, and some of it forms borides such as (Cr, Ni, Mo) 3 B 2 and precipitates at the grain boundaries of the alloy.
  • borides such as (Cr, Ni, Mo) 3 B 2 and precipitates at the grain boundaries of the alloy.
  • B is an optional composition element, and its composition ratio is 0 mass% or more and 0.1 mass% or less, more preferably 0 mass% or more and 0.02 mass% or less.
  • Zr zirconium segregates at grain boundaries during columnar crystallization due to normal solidification and unidirectional solidification, and has the effect of increasing grain boundary strength, but in most cases it forms an intermetallic compound Ni 3 Zr with nickel, the main component of the alloy. This compound reduces the ductility of the alloy and has a significantly low melting point, making solution treatment of the alloy difficult, among other harmful effects. Therefore, Zr is an optional composition element, and its composition ratio is 0% by mass or more and 0.5% by mass or less, and more preferably 0% by mass or more and 0.1% by mass or less.
  • Fe replaces Ni and has the effect of improving the hot workability of Ni-based superalloys.
  • raw materials are easy to procure, which is effective in reducing material costs.
  • the above-mentioned recycled materials may contain a certain amount of Fe, but materials that contain an excessive amount are not suitable as raw materials for Ni-based superalloys.
  • Fe is an optional composition element, and its composition ratio is 0 mass% or more and 20 mass% or less, and more preferably 0 mass% or more and 5 mass% or less. If the composition ratio exceeds 20 mass%, harmful phases are generated and high-temperature strength decreases.
  • Si has the effect of improving the oxidation resistance of Ni-based superalloys.
  • Si is an optional composition element, and its composition ratio is 0 mass% or more and 1 mass% or less, and more preferably 0 mass% or more and 0.5 mass% or less. If the composition ratio exceeds 1 mass%, harmful phases are generated and high-temperature strength decreases.
  • Sb antimony
  • Sb causes a significant decrease in ductility and toughness in Ni-based superalloys after long-term heating at high temperatures of 700°C or higher for 10,000 hours or more. Therefore, in order to ensure good workability such as bending and weldability of long-term aged materials, it is necessary to first limit the Sb content in the raw materials for Ni-based superalloys to 50 PPM or less. If the content of Sb is less than 0.5 PPM, it can be treated as an unavoidable impurity, and its effect on the deterioration of the oxidation resistance of the manufactured Ni-based superalloy is within an acceptable range.
  • Sn (tin), Pb (lead), Zn (zinc) and As (arsenic) are known to be low melting point metal elements that, like Sb, cause a significant decrease in ductility and toughness of Ni-based superalloys after long-term heating at high temperatures.
  • the contents of these elements in the raw materials for Ni-based superalloys 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.
  • Ca (calcium) has the effect of fixing S (sulfur), which inhibits hot workability, as sulfide to improve the hot workability of Ni-based superalloys, so in order to obtain this effect, the raw material for Ni-based superalloys may contain Ca.
  • the Ca content exceeds 0.05 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 the raw material for Ni-based superalloys, the Ca content is set to 0.05 mass% or less.
  • the upper limit of the Ca content is preferably 0.02 mass%, and more preferably 0.01 mass%.
  • the content of Ca in the raw material for the Ni-base superalloy is desirably 0.0005 mass% (5 PPM) or more, and more desirably 0.001 mass% (10 PPM) or more.
  • Ni-base superalloy components such as turbine blades and turbine vane parts using Ni-base superalloy raw materials having the above compositional components and their composition ratios.
  • Known manufacturing processes for Ni-base superalloy components include conventional casting, directional solidification, single-crystal solidification, and sintering or 3D printing using powdered Ni-base superalloy raw materials.
  • sintering or 3D printing, it is recommended to carry out the following heat treatment.
  • turbine blades and turbine vane parts made by normal casting methods can be manufactured by applying the following heat treatments. That is, the heat treatments are a series of steps: 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.
  • 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
  • turbine blades and turbine vane parts made by the unidirectional solidification method can be manufactured by carrying out the following heat treatments. That is, the heat treatments are a series of steps: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or 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 cooling in air or 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 cooling in air or in an inert gas atmosphere.
  • solution treatment in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or 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 cooling
  • Turbine blades and turbine vane parts made by the single crystal solidification method can be manufactured by applying the following heat treatments. That is, the heat treatments are a series of steps: 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.
  • 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
  • turbine blades and turbine vane parts made by sintering or 3D printing using powdered Ni-based superalloy raw materials that satisfy the above compositional conditions can be manufactured by carrying out the following heat treatments. That is, the heat treatments are a series of steps: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or 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 cooling in air or 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 cooling in air or in an inert gas atmosphere.
  • solution treatment in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or in an inert gas atmosphere at 200°C/min to 400°C/min
  • primary aging treatment in which
  • Ni-based superalloy members such as turbine blades and turbine vane parts using a casting mold by using a Ni-based superalloy as a raw material for the Ni-based superalloy will be described.
  • the Ni-based superalloy 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, and such a material is conveniently referred to as an "Sb-containing Ni-based superalloy" in this specification.
  • the Ni-based single crystal superalloy TMS-238 used in the examples described below usually contains less than 0.5 PPM of Sb (the level of unavoidable impurities), so a predetermined amount of Sb was intentionally added to the molten metal to simulate an Sb-containing Ni-based superalloy.
  • Figure 1 is a cross-sectional view of the essential components of a melting furnace using a vacuum high-frequency induction melting furnace for casting directionally solidified test pieces or single crystal test pieces from Sb-containing Ni-based superalloys according to one embodiment of the present invention, with the vacuum exhaust system, temperature measurement device, molten raw material charging chamber, crucible tilting device, and mold lifting device not shown.
  • a vacuum high-frequency induction melting furnace 10 is installed in a melting chamber, and uses the electromagnetic induction effect of a high-frequency melting coil 14 to induce a high-current-density induced current in the metal material inside the furnace, which then heats and melts using the Joule heat generated by this induced current.
  • High-frequency induction melting furnaces have good thermal efficiency because they directly heat the metal material using electromagnetic induction, and also have the advantage of homogenizing the components because the molten metal is stirred by electromagnetic force, but they have a small refining function, so high-quality metal materials are required for melting.
  • the CaO crucible 12 is provided in the vacuum high-frequency induction melting furnace 10, and is in a vertical position into which the metal material of the Ni-based superalloy to be melted is fed from a melting material charging chamber (not shown), and the metal material is melted to become molten metal.
  • a C-1 model manufactured by Eight Ceramics Co., Ltd. was used as the CaO crucible 12.
  • the high-frequency melting coil 14 is provided on the periphery of the CaO crucible 12 in the vacuum high-frequency induction melting furnace 10, and induces an induced current with a high current density 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 a pouring spout 28 into a mold 30 for a single crystal rod-shaped test piece.
  • the directional solidification furnace 20 has the same structure as the vacuum high-frequency induction melting furnace 10, and is provided in the mold chamber.
  • a NEV-5DSNIA model manufactured by Nisshin Giken Co., Ltd. was used as the directional solidification furnace 20.
  • the high frequency coil for mold 22 is provided on the periphery of the directional solidification furnace 20, and induces a high current density induced current in the metal material in the mold 30 for single crystal rod-shaped specimens located in the mold chamber, thereby supplying energy necessary for maintaining the molten state.
  • the graphite resistance heating element 24 is provided on the inner wall surface of the side wall of the directional solidification furnace 20, and is a heater for heating the inside of the directional solidification furnace 20.
  • the upper lining 25 is provided on the ceiling surface on the ceiling side of the directional solidification furnace 20, and is made of, for example, zirconia or alumina.
  • the side wall insulating material 26 is provided between the high frequency coil for mold 22 and the graphite resistance heating element 24, and is made of, for example, a mica sheet.
  • the upper insulating material 27 is provided between the upper lining 25 and the ceiling surface of the directional solidification furnace 20, and is made of, for example, a 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, firebricks.
  • the mold 30 for single crystal rod-shaped test pieces is a mold for casting single crystal rod-shaped test pieces using a Ni-based superalloy.
  • FIG. 1 illustrates a mold of the type using a selector 32, a mold using a seed crystal may be used.
  • the mold base 34 is called a chill plate, and is provided with a cooling water flow path to ensure a temperature gradient necessary for crystal growth of the single crystal.
  • a self-made mold was used for the mold 30 for single crystal rod-shaped test pieces.
  • the manufacture of the mold is described in the above-mentioned Lost Wax Precision Casting Method (edited by Japan Foundry Association, published by Sangyo Tosho, 2015), and in this specification, the section on the molding method (pages 9 to 78) is particularly cited.
  • the manufacture of the mold is also described in the above-mentioned "The Superalloys Fundamentals and Applications” (written by Roger C. Reed, Cambridge University Press, 2006), and in this specification, the section on the molding method (pages 122 to 125) is particularly cited.
  • a mold lifting device (not shown) realizes the mold lifting direction 36 and ensures a cooling rate required for growing the Ni-based superalloy into a single crystal.
  • the conditions for casting a directionally solidified test piece or a single crystal test piece of an Sb-containing Ni-base superalloy using the vacuum high-frequency induction melting furnace 10 thus constructed will be described below.
  • the casting temperature of the vacuum high-frequency induction melting furnace 10 is +90 to 170°C of the solidification start temperature of the cast alloy, and the preheating temperature of the mold is set to 1400 to 1550°C.
  • the melting point of Ni is 1455°C, and the melting points of each element used as a constituent element 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, the temperature condition for stabilizing the molten metal in the CaO crucible 12 with the Sb-containing Ni-based superalloy completely melted is preferably 1560 to 1640°C.
  • the metallic material used was Ni-based single crystal superalloy TMS-238.
  • Table 1 shows the compositional elements and compositional ratios of TMS-238, and Table 2 shows the mechanical properties.
  • Table 1 shows the compositional elements and compositional ratios of conventional alloys CMSX-4 and MX-4/PWA1497, and Table 2 shows the mechanical properties of CMSX-4.
  • the above metal material (TMS-238) was melted by high frequency in a vacuum to cast a single crystal test piece according to the following procedure. The degree of vacuum was 6 ⁇ 10 ⁇ 2 Pa.
  • single crystal rod-shaped test pieces were also prepared by casting the alloys melted in an Al 2 O 3 crucible.
  • the metal material was Ni-based single crystal superalloy TMS-238, 10 ppm of Sb was added (injected into the molten metal), the molten metal was poured into a single crystal rod-shaped test piece mold 30 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 example.
  • Glow discharge mass spectrometry confirmed that the single crystal bars of the alloy melted in the CaO crucible contained 9.5 ppm Sb, and the single crystal bars 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.
  • FIG. 2 shows Ca-Sb-O inclusions (FE-EPMA: Field Emission Electron Probe Microanalyzer) observed in an alloy melted in a CaO crucible according to an embodiment of the present invention, where (A) is a backscattered electron image, (B) is O (oxygen), (C) is Ca (calcium), and (D) is Sb (antimony).
  • EPMA Electro Probe Micro Analysis
  • an electron beam is irradiated onto a sample, and the elements constituting the sample and their amounts are measured by detecting the characteristic X-rays that are generated.
  • FE-EPMA equipped with a field emission electron gun enables elemental analysis of a microscopic area of about 100 nm.
  • Data acquisition by the EBSD (Electron Back Scattered Diffraction Pattern) method was performed using a TEAM TM EDS, EDAX Division, manufacturer name, AMETEK, Inc.
  • Ca-Sb:O 1:3:2 to 1:4:3 mass ratio
  • the particle shape of the Ca-Sb-O inclusions had a particle size of 100 to 500 nm.
  • Oxidation test pieces with a diameter of 9 mm and a height of 5 mm were prepared from the single crystal rod-shaped test pieces, and a cyclic oxidation test was carried out in which one cycle consisted of 1100°C-1h, room temperature holding-1h.
  • Fig. 4 shows the results of the cyclic oxidation test. As shown in Figure 4, the mass of the alloy test piece melted in the Al2O3 crucible increased by 0.2 [mg/ cm2 ] from the first cycle compared to the initial state of the repeated oxidation test, and the mass began to decrease from the 15th cycle, resulting in a mass decrease of 3.8 [mg/ cm2 ] at 100 cycles.
  • the mass of the test piece of the alloy melted in the CaO crucible increased by 0.2 [mg/ cm2 ] from the first cycle compared to the beginning of the cyclic oxidation test, and increased by 0.3 [mg/ cm2 ] at the 100th cycle.
  • the elements constituting the oxidized test piece and their amounts were measured using EBSD. As a result, no segregation of Sb was observed at the interface between the oxide film and the base material. It is considered that the diffusion of Sb to the interface was suppressed by Ca-Sb-O inclusions.
  • a CaO crucible is used to supply Ca and O that mask the oxidation resistance deterioration caused by the impurity Sb contained in the Ni-base superalloy raw material by contacting the CaO crucible with the molten Ni-base superalloy raw material, but the present invention is not limited to this.
  • 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 have the above-mentioned masking effect may be separately supplied to the Ni-base superalloy raw material or the molten Ni-base superalloy raw material.
  • a significant amount of calcium fluoride or a calcium compound may be mixed in to supply Ca (calcium) in a mass ratio of 0.33 to 100 times the content of the impurity Sb.
  • the composition elements of the calcium compound must not contain harmful elements that impair the heat resistance and oxidation resistance of the target Ni-base superalloy, such as As (arsenic) and S (sulfur).
  • a vacuum high-frequency induction melting furnace is used to cast Ni-based superalloy components by unidirectional solidification or single crystallization using Ni-based superalloys as raw materials for the Ni-based superalloy, but polycrystalline turbine parts may also be manufactured by conventional casting.
  • a polycrystalline mold is used. A polycrystalline mold does not have a selector or chill plate that is provided in a mold for single crystal rod-shaped test pieces.
  • the mold is preheated to a temperature of 800 to 1100°C.
  • the required Ca can be added by melting in a crucible made of a normal material such as an Al 2 O 3 crucible or MgO, and adding CaO granules (e.g., about 5 mm in diameter, preferably 1 to 10 mm in diameter) to the molten metal.
  • CaO granules e.g., about 5 mm in diameter, preferably 1 to 10 mm in diameter
  • the amount of CaO added is preferably 2 kg per 100 kg of molten metal as a standard value, and preferably a ratio equivalent to 0.2% to 5% by weight based on the raw material for the Ni-based superalloy. The point is to bring the molten Ni-base superalloy raw material into contact with CaO, and since excess CaO does not dissolve in the molten metal as slag, the effect on the Ca composition ratio of the directionally solidified component, single crystal cast component, or polycrystalline solidified component to be manufactured is minor.
  • CaO granules are added to the molten Ni-base superalloy raw material
  • the present invention is not limited to this, and CaO granules may be added to the Ni-base superalloy raw material before melting.
  • CaF 2 fluorite
  • the additive element Ca can mask the oxidation resistance degradation effect caused by Sb, so that even if a low-grade material for Ni-base heat-resistant alloys for boiler piping is used, it is expected that the Ni-base superalloys will exhibit oxidation resistance equivalent to that of Ni-base superalloys made using high-grade materials for conventional Ni-base superalloys for turbine blades.

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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

Ｓｂによる耐酸化性の劣化を予防したＮｉ基超合金の製造方法、Ｓｂによる耐酸化性の劣化を予防したＮｉ基超合金部材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
　本発明は、Ｓｂによる耐酸化性の劣化を予防したＮｉ基超合金の製造方法及びＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材に関する。 The present invention relates to a method for producing a Ni-based superalloy that prevents the deterioration of oxidation resistance caused by Sb, and to a Ni-based superalloy component that prevents the deterioration of oxidation resistance caused by Sb.
　Ｎｉ基超合金は、ジェットエンジンやガスタービンなどのタービンブレードとして用いられている。近年、タービン用エンジンの高効率化のため、タービン入口温度を高くすることが求められている。そこで、Ｎｉ基超合金の高温特性（クリープ特性や耐酸化性など）を改良する必要がある。しかし、高温特性改良のために様々な元素が用いられ、材料コストの増加や原料の調達先の偏在が課題となっている。また、Ｎｉ基超合金の高温特性を阻害する元素として、例えば硫黄（Ｓ）、アンチモン（Ｓｂ）が知られている。これら高温特性を阻害する元素の含有比率については、規格で上限値が規定されている。 Ni-base superalloys are used as turbine blades for jet engines, gas turbines, and the like. In recent years, there has been a demand to increase the turbine inlet temperature in order to improve the efficiency of turbine engines. This has led to a need to improve the high-temperature properties of Ni-base superalloys (creep properties, oxidation resistance, etc.). However, various elements are used to improve high-temperature properties, and this 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-base superalloys include sulfur (S) and antimony (Sb). Standards stipulate upper limits for the content ratios of these elements that impair high-temperature properties.
　例えば、航空宇宙用のＮｉ基超合金ＡＭＳ２２８０でのＳｂの許容比率は５０ｐｐｍとされている（非特許文献１参照）。また、火力発電所等で用いられるボイラ配管に用いられるＮｉ基耐熱合金でのＳｂの許容比率は５０ｐｐｍ（０．００５質量％）とされている（特許文献１　段落番号［００５７］、［００５８］参照）。火力発電所等で用いられるボイラ配管の場合、Ｎｉ基耐熱合金中のＳｂの組成比率が５０ｐｐｍを超えると、温度が７００℃以上かつ１万時間以上という高温長時間加熱後の延性および靱性の著しい低下が問題となる。なお、特許文献１に記載のボイラ配管用Ｎｉ基超合金では、Ｓｂは、原料の溶解工程で不純物元素として混入するものである。 For example, the allowable Sb ratio in the Ni-base superalloy AMS2280 for aerospace use is 50 ppm (see Non-Patent Document 1). Also, the allowable Sb ratio in Ni-base heat-resistant alloys used for boiler piping in thermal power plants and the like is 50 ppm (0.005 mass%) (see Patent Document 1, paragraphs [0057] and [0058]). In the case of boiler piping used in thermal power plants and the like, if the composition ratio of Sb in the Ni-base 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 more becomes a problem. In the Ni-base superalloy for boiler piping described in Patent Document 1, Sb is mixed in as an impurity element during the raw material melting process.
　他方で、上述のボイラ配管用Ｎｉ基耐熱合金と比較してより高温の燃焼ガスに曝されるタービン翼用Ｎｉ基超合金であるＣＭＳＸ－４（登録商標）等では、Ｎｉ基超合金中のＳｂの組成比率は２ｐｐｍ以下とされている（特許文献２　段落番号［００４７］、［表７］）。加えて、タービン翼用Ｎｉ基超合金から作製される部材は、１６００℃近くの高温燃焼ガスに曝されるため、Ｎｉ基超合金が有する耐熱性だけでは不充分なので、実用においては例えば遮熱コーティング材が表面に塗布されている。
　そこで、ＣＭＳＸ－４等の原料には、上述のボイラ配管用Ｎｉ基耐熱合金と比較して不純物の含有比率が格段に低い、より純度の高い材料を用いる必要がある。しかし、純度の高い材料は、高度な精製が必要であるため、高価であると共に、原料の調達先が限られるという課題があった。 On the other hand, in the case of CMSX-4 (registered trademark), which is a Ni-base superalloy for turbine blades that is exposed to higher temperature combustion gas compared to the above-mentioned Ni-base heat-resistant alloy for boiler piping, the composition ratio of Sb in the Ni-base superalloy is set to 2 ppm or less (Patent Document 2, paragraph number [0047], [Table 7]). In addition, since members made of Ni-base superalloys for turbine blades are exposed to high-temperature combustion gas of nearly 1600°C, the heat resistance of the Ni-base superalloy alone is insufficient, and in practical use, for example, a thermal barrier coating material is applied to the surface.
Therefore, it is necessary to use materials with a much lower impurity content and higher purity as the raw materials for CMSX-4 and the like, compared to the above-mentioned Ni-base heat-resistant alloys for boiler piping. However, high-purity materials require advanced refining, which makes them expensive and limits the sources of raw material procurement.
　実際、低融点金属系不純物元素であるＳｂが含まれるＮｉ基単結晶超合金ＴＭＳ－２３８は、純正材に比べ、耐酸化性が劣ることが明らかとなっている（非特許文献２参照）。具体的に、非特許文献２には、マスターインゴットに低融点金属系不純物であるＳｂを添加し、Ａｌ２Ｏ３るつぼ内で溶解後作製した合金には、Ｓｂが１．１ｐｐｍ含まれており、１１００℃－１ｈ、室温保持－１ｈを１サイクルとした繰り返し酸化試験において、５０サイクル以降に明らかな質量減少が見られたことが記載されている。 In fact, it has been revealed that the Ni-based single crystal superalloy TMS-238, which contains Sb, a low-melting point metal impurity element, has inferior oxidation resistance compared to genuine materials (see Non-Patent Document 2). Specifically, Non-Patent Document 2 describes that an alloy produced by adding Sb, a low-melting point metal impurity, to a master ingot and melting it in an Al 2 O 3 crucible contains 1.1 ppm of Sb, and that in a repeated oxidation test in which one cycle was 1100°C-1h and room temperature-1h, a clear mass loss was observed after 50 cycles.
ＷＯ２０１０－０３８８２６Ａ１WO2010-038826A1 特開２０１５－２１４７４４号JP 2015-214744 A
　上述したように、低融点金属系不純物元素Ｓｂにより、Ｎｉ基超合金の耐酸化性が劣化することが問題点である。しかし、Ｎｉ基超合金の製造にあたり、原料の溶解工程で混入するＳｂを除去することは困難であるという課題があった。また、従来のタービン翼用Ｎｉ基超合金の製造に必要とされる純度の高い材料に代えて、不純物の含有比率が比較的高い（グレードの低い）材料、例えばリサイクル材を用いて、従来と同等の耐酸化性を有するＮｉ基超合金を製造することができれば、材料コストや原料の調達先の観点で望ましい。
　本発明は、上述の課題を解決するもので、Ｎｉ基超合金の製造にあたり、原料の溶解工程でＳｂが混入しても、及び／又は不純物の含有比率が比較的高い材料を用いても、低融点金属系不純物元素ＳｂによるＮｉ基超合金の耐酸化性の劣化が防止できるような、添加元素を用いることで、Ｓｂによる耐酸化性の劣化を予防したＮｉ基超合金の製造方法及びＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材を提供することを目的とする。 As described above, the problem is that the oxidation resistance of Ni-based superalloys is deteriorated by the low melting point metal impurity element Sb. However, there is a problem that it is difficult to remove Sb mixed in during the melting process of raw materials when manufacturing Ni-based superalloys. In addition, if it is possible to manufacture Ni-based superalloys having the same oxidation resistance as conventional ones using materials with a relatively high impurity content (low grade), such as recycled materials, instead of the high purity materials required for the manufacture of conventional Ni-based superalloys for turbine blades, it would be desirable from the viewpoint of material costs and raw material suppliers.
The present invention is intended to solve the above-mentioned problems, and aims to provide a manufacturing method for a Ni-base superalloy in which the deterioration of oxidation resistance of the Ni-base superalloy due to the low-melting point metal impurity element Sb can be prevented by using an additive element that can prevent the deterioration of oxidation resistance of the Ni-base 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-base superalloy, and a Ni-base superalloy component in which the deterioration of oxidation resistance due to Sb is prevented.
［１］本発明のＮｉ基超合金の製造方法は、所定組成のＳｂ含有のＮｉ基超合金用原料をるつぼに投入し、高周波誘導溶解炉により、真空中で高周波溶解させると共に、前記Ｎｉ基超合金用原料の溶湯に対して前記Ｓｂの耐酸化性阻害作用を防止するに必要な量のＣａ（カルシウム）を添加し、前記Ｎｉ基超合金用原料が完全に溶解した状態で、１５６０～１６４０℃で溶湯を前記るつぼ内で１０～６０分の間安定させ、一方向凝固炉内で所定温度に予熱した鋳型に前記溶湯を投入すると共に、注湯した前記鋳型を５０～３５０ｍｍ／ｈの速度で前記高周波誘導溶解炉より引き抜き、前記Ｎｉ基超合金用原料を一方向凝固、単結晶凝固、又は多結晶凝固させ、室温まで冷却後、鋳造された一方向凝固部材、単結晶鋳造部材又は多結晶凝固部材を前記一方向凝固炉より取り出す工程を含むものである。
　ここで、「所定組成のＳｂ含有のＮｉ基超合金用原料」とは、例えば［１０］や［１１］に規定される組成を有するものをいう。但し、Ｓｂ及びＣａの含有に関する条件については、当該原料がるつぼに投入される前の状態でこれを満足することは要求されない。また、「前記Ｓｂの耐酸化性阻害作用を防止するに必要な量のＣａ（カルシウム）を添加」については、質量比でＣａ：Ｓｂ：Ｏ＝１：３：２～１：４：３のＣａ－Ｓｂ－Ｏ介在物が析出する程度の量のＣａが上記原料の溶湯に対して添加されることが意図される。「Ｎｉ基超合金用原料が完全に溶解した状態で、１５６０～１６４０℃で溶湯を前記るつぼ内で１０～６０分の間安定させ」については、一般的に鋳造合金の凝固開始温度の＋９０～１７０℃が鋳造温度とされていること、Ｎｉの融点が１４５５℃であること、及び目的のＮｉ基超合金の組成元素として用いられる各元素の融点を考慮して、このような安定化処理の条件が定められている。 [1] The method for producing a Ni-base superalloy of the present invention includes the steps of: putting a Ni-base superalloy raw material containing Sb of a predetermined composition into a crucible, melting it in a vacuum by high-frequency induction melting furnace, adding a necessary amount of Ca (calcium) to the molten Ni-base superalloy raw material to prevent the oxidation resistance inhibiting action of Sb to the molten Ni-base superalloy raw material; stabilizing the molten metal at 1560 to 1640 ° C. in the crucible for 10 to 60 minutes while the Ni-base superalloy raw material is completely melted; pouring the molten metal into a mold preheated to a predetermined temperature in a directional solidification furnace; and withdrawing the poured mold from the high-frequency induction melting furnace at a speed of 50 to 350 mm / h; solidifying the Ni-base superalloy raw material into a unidirectional, single-crystal, or polycrystalline form; cooling it to room temperature, and then removing the cast unidirectionally solidified member, single-crystal cast member, or polycrystalline solidified member from the directional solidification furnace.
Here, "a raw material for Ni-base superalloys containing Sb of a predetermined composition" refers to a material having a composition as specified in, for example, [10] or [11]. However, it is not required that the raw material satisfy the conditions regarding the content of Sb and Ca before being put into the crucible. In addition, "adding an amount of Ca (calcium) necessary to prevent the oxidation resistance inhibiting action 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 with a mass ratio of Ca:Sb:O = 1:3:2 to 1:4:3 are precipitated. Regarding "with the raw materials for the Ni-base superalloy in a completely melted state, the molten metal is stabilized in the crucible at 1560-1640°C for 10-60 minutes," the conditions for such a 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 casting 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.
［２］本発明のＮｉ基超合金の製造方法［１］において、好ましくは、前記るつぼはＣａＯるつぼであり、前記Ｃａ（カルシウム）は、前記ＣａＯるつぼと前記Ｎｉ基超合金用原料の溶湯との接触により、前記Ｎｉ基超合金用原料の溶湯に対して供給されるとよい。
［３］本発明のＮｉ基超合金の製造方法［１］において、好ましくは、前記るつぼはＡｌ２Ｏ３るつぼ又はＭｇＯるつぼであり、前記Ｃａ（カルシウム）は、前記Ｎｉ基超合金用原料又は前記Ｎｉ基超合金用原料の溶湯中に、重量比で前記Ｎｉ基超合金用原料を基準に０．２％～５％に相当するＣａＯを添加することにより行われるとよい。
［４］本発明のＮｉ基超合金の製造方法［３］において、好ましくは、ＣａＯは、粒径１～１０ｍｍの顆粒状であるとよい。
［５］本発明のＮｉ基超合金の製造方法［１］において、好ましくは、前記るつぼはＡｌ２Ｏ３るつぼ又はＭｇＯるつぼであり、前記Ｃａ（カルシウム）は、前記Ｎｉ基超合金用原料又は前記Ｎｉ基超合金用原料の溶湯中に、質量比で前記Ｓｂの０．３３倍以上１００倍以下のＣａ（カルシウム）に相当する量を添加することにより行われるとよい。
［６］本発明のＮｉ基超合金の製造方法［５］において、好ましくは、前記Ｃａ（カルシウム）は、ＣａＦ２の成分として供給され、ＣａＦ２が前記Ｎｉ基超合金用原料に添加され、又は前記Ｎｉ基超合金用原料の溶湯に対して添加されるとよい。
［７］本発明のＮｉ基超合金の製造方法［１］乃至［６］において、好ましくは、前記鋳型は、単結晶用鋳型であり、前記鋳型を前記一方向凝固炉内で、予熱する所定温度は１４００～１５５０℃であり、前記単結晶用鋳型は水冷チルプレートにより底部が冷却されるものであるとよい。
［８］本発明のＮｉ基超合金の製造方法［１］乃至［６］において、好ましくは、前記鋳型は、多結晶用鋳型であり、前記鋳型を前記一方向凝固炉内で、予熱する所定温度は１０００～１１００℃であるとよい。
［９］本発明のＮｉ基超合金の製造方法［１］乃至［８］において、好ましくは、前記単結晶鋳造部材は、質量比でＣａ：Ｓｂ：Ｏ＝１：３：２～１：４：３のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍであるとよい。 [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 Al 2 O 3 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 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-base 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 metal of the Ni-base superalloy raw material in an amount equivalent to 0.33 to 100 times the amount of Sb by mass ratio.
[6] In the method [5] for producing a Ni-base superalloy of the present invention, 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 single crystal mold, the predetermined temperature to which the mold is preheated in the unidirectional solidification furnace is 1400 to 1550°C, and the bottom of the single crystal mold is cooled by a water-cooled chill plate.
[8] In the method for producing a Ni-base 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 directional solidification furnace is 1000 to 1100°C.
[9] In any of the methods [1] to [8] for producing a Ni-base superalloy of the present invention, preferably, the single crystal cast component 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 grain size of 100 to 500 nm.
［１０］本発明のＮｉ基超合金の製造方法［１］乃至［９］において、好ましくは、
　前記Ｎｉ基超合金用原料は、前記鋳型に投入される前の溶解状態で、質量％で、
Ｃｒ（クロム）：２％以上２５％以下、
Ｃｏ（コバルト）：０％以上２５％以下、
Ｍｏ（モリブデン）：０％以上８％以下、
Ｒｅ（レニウム）：０％以上１０％以下、
Ｒｕ（ルテニウム）：０％以上１０％以下、
Ｗ（タングステン）：０％以上１４％以下、
Ｎｂ（ニオブ）：０％以上５％以下、
Ｖ（バナジウム）：０％以上３％以下、
Ａｌ（アルミニウム）：１％以上１０％以下、
Ｔｉ（チタン）：０％以上１０％以下、
Ｔａ（タンタル）：０％以上１３％以下、
Ｈｆ（ハフニウム）：０％以上２．５％以下、
Ｃ（炭素）：０％以上０．５％以下、
Ｂ（ホウ素）：０％以上０．１％以下、
Ｚｒ（ジルコニウム）：０％以上０．５％以下、
Ｆｅ（鉄）：０％以上２０％以下、
Ｓｉ（ケイ素）：０％以上１％以下、
残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きい、とよい。
［１１］本発明のＮｉ基超合金の製造方法［１０］において、好ましくは、前記Ｎｉ基超合金用原料は、前記鋳型に投入される前の溶解状態で、質量％で、
Ｃｒ（クロム）：４％以上１０％以下、
Ｃｏ（コバルト）：０％以上１２％以下、
Ｍｏ（モリブデン）：０％以上４％以下、
Ｒｅ（レニウム）：２％以上１０％以下、
Ｒｕ（ルテニウム）：２％以上８％以下、
Ｗ（タングステン）：２％以上８％以下、
Ｎｂ（ニオブ）：０％以上２．５％以下、
Ｖ（バナジウム）：０％以上０．５％以下、
Ａｌ（アルミニウム）：３％以上８％以下、
Ｔｉ（チタン）：０％以上３％以下、
Ｔａ（タンタル）：４％以上１０％以下、
Ｈｆ（ハフニウム）：０％以上１％以下、
Ｃ（炭素）：０％以上０．０５％以下、
Ｂ（ホウ素）：０％以上０．０２％以下、
Ｚｒ（ジルコニウム）：０％以上０．１％以下、
Ｆｅ（鉄）：０％以上５％以下、
Ｓｉ（ケイ素）：０％以上０．５％以下、
残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きい、とよい。
［１２］本発明のＮｉ基超合金の製造方法［１０］又は［１１］において、好ましくは、前記Ｃａの含有比はＳｂの含有比の１／３よりも大きいとよい。 [10] In the method for producing a 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,
It is preferable that the composition contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 5 PPM or more and 500 PPM or less, and the Ca content is greater than 1/4 of the Sb content.
[11] In the method for producing a Ni-base superalloy of the present invention [10], preferably, the raw material for the Ni-base superalloy is in a molten state before being poured into the mold, and is, 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,
It is preferable that the composition contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 5 PPM or more and 500 PPM or less, and the Ca content is greater than 1/4 of the Sb content.
[12] In the method for producing a Ni-base superalloy according to the present invention [10] or [11], the Ca content is preferably greater than 1/3 of the Sb content.
［１３］本発明のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材は、質量％で、
Ｃｒ（クロム）：２％以上２５％以下、
Ｃｏ（コバルト）：０％以上２５％以下、
Ｍｏ（モリブデン）：０％以上８％以下、
Ｒｅ（レニウム）：０％以上１０％以下、
Ｒｕ（ルテニウム）：０％以上１０％以下、
Ｗ（タングステン）：０％以上１４％以下、
Ｎｂ（ニオブ）：０％以上５％以下、
Ｖ（バナジウム）：０％以上３％以下、
Ａｌ（アルミニウム）：１％以上１０％以下、
Ｔｉ（チタン）：０％以上１０％以下、
Ｔａ（タンタル）：０％以上１３％以下、
Ｈｆ（ハフニウム）：０％以上２．５％以下、
Ｃ（炭素）：０％以上０．５％以下、
Ｂ（ホウ素）：０％以上０．１％以下、
Ｚｒ（ジルコニウム）：０％以上０．５％以下、
Ｆｅ（鉄）：０％以上２０％以下、
Ｓｉ（ケイ素）：０％以上１％以下、
残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きく、且つ質量比で、
Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３
のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍである。 [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,
The composition contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 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
The 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.
［１４］本発明のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材［１３］において、好ましくは、質量％で、
Ｃｒ（クロム）：４％以上１０％以下、
Ｃｏ（コバルト）：０％以上１２％以下、
Ｍｏ（モリブデン）：０％以上４％以下、
Ｒｅ（レニウム）：２％以上１０％以下、
Ｒｕ（ルテニウム）：２％以上８％以下、
Ｗ（タングステン）：２％以上８％以下、
Ｎｂ（ニオブ）：０％以上２．５％以下、
Ｖ（バナジウム）：０％以上０．５％以下、
Ａｌ（アルミニウム）：３％以上８％以下、
Ｔｉ（チタン）：０％以上３％以下、
Ｔａ（タンタル）：４％以上１０％以下、
Ｈｆ（ハフニウム）：０％以上１％以下、
Ｃ（炭素）：０％以上０．０５％以下、
Ｂ（ホウ素）：０％以上０．０２％以下、
Ｚｒ（ジルコニウム）：０％以上０．１％以下、
Ｆｅ（鉄）：０％以上５％以下、
Ｓｉ（ケイ素）：０％以上０．５％以下、
残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きく、且つ質量比で、
Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３
のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍであるとよい。
［１５］本発明のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材［１３］又は［１４］において、好ましくは、前記Ｎｉ基超合金用部材は、一方向凝固部材、単結晶鋳造部材、又は多結晶凝固部材であるとよい。
［１６］本発明のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材［１３］又は［１４］において、好ましくは、［１０］又は［１１］に記載の組成条件を満足する粉末状のＮｉ基超合金用原料を用いて焼結または３Ｄ造形で作製されたタービンブレード又はタービンベーン部品であるとよい。
［１７］本発明のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材［１３］又は［１４］において、好ましくは、前記Ｎｉ基超合金用部材から直径９ｍｍ、高さ５ｍｍの酸化試験片を作製し、１１００℃－１ｈ、室温保持－１ｈを１サイクルとする繰り返し酸化試験で、１００サイクルまで質量減少が見られないものであるとよい。 [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,
The composition contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 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
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-base superalloy component [13] or [14] of the present invention in which the deterioration of oxidation resistance due to Sb is prevented, the Ni-base superalloy component is preferably a directionally solidified component, a single crystal cast component, or a polycrystalline solidified component.
[16] In the Ni-base superalloy component [13] or [14] of the present invention in which degradation of oxidation resistance due to Sb is prevented, the component is preferably a turbine blade or turbine vane component produced by sintering or 3D printing using a powdered Ni-base superalloy raw material satisfying the composition conditions described in [10] or [11].
[17] In the Ni-base superalloy component [13] or [14] of the present invention in which the deterioration of oxidation resistance due to Sb has been prevented, preferably, an oxidation test piece having a diameter of 9 mm and a height of 5 mm is prepared from the Ni-base superalloy component, and in a repeated oxidation test in which one cycle is 1100°C-1h, room temperature holding-1h, no mass reduction is observed up to 100 cycles.
　本発明のＮｉ基超合金の製造方法によれば、Ｎｉ基超合金の高温特性（クリープ特性や耐酸化性など）を維持しながら、原料の溶解工程でＳｂが混入しても、及び／又は５０ＰＰＭ程度の比較的高濃度のＳｂを含有する低グレードの材料を使用しても、ＳｂによるＮｉ基超合金の耐酸化性の劣化を添加元素Ｃａによってマスキングすることができる。そのため、例えばボイラ配管用Ｎｉ基耐熱合金用の低グレードの材料やリサイクル材を使用しても、Ｓｂの含有比率として２ＰＰＭ以下であることが必要とされるタービン翼用Ｎｉ基超合金用の高グレードの材料を使用して作製したＮｉ基超合金と同等の耐酸化性を発揮することが期待できる。したがって、Ｎｉ基超合金の製造において、原料の調達先が限定されることが回避され、材料コストを低減することが可能となる。 The method for producing the Ni-base superalloy of the present invention maintains the high-temperature properties (creep properties, oxidation resistance, etc.) of the Ni-base superalloy, and even if Sb is mixed in during the raw material melting process and/or a low-grade material containing a relatively high concentration of Sb of about 50 PPM is used, the deterioration of the oxidation resistance of the Ni-base superalloy due to Sb can be masked by the added element Ca. Therefore, even if low-grade materials or recycled materials are used for Ni-base heat-resistant alloys for boiler piping, for example, it is expected that the Ni-base superalloy will exhibit oxidation resistance equivalent to that of a Ni-base superalloy produced using high-grade materials for Ni-base superalloys for turbine blades, which require an Sb content of 2 PPM or less. Therefore, in the production of Ni-base superalloys, it is possible to avoid limitations on the sources of raw material procurement, and to reduce material costs.
本発明の一実施形態を示すＳｂ含有Ｎｉ基超合金による一方向凝固試験片又は単結晶試験片を鋳造する為の真空高周波誘導溶解炉を用いた溶解炉の要部構成断面図である。FIG. 1 is a cross-sectional view of the essential configuration of a melting furnace using a vacuum high-frequency induction melting furnace for casting a directionally solidified test piece or a single crystal test piece made of an Sb-containing Ni-based superalloy according to one embodiment of the present invention. 本発明の一実施例を示すＣａＯるつぼ溶解した合金内で観察されたＣａ－Ｓｂ－Ｏ介在物（ＦＥ－ＥＰＭＡ）を示している。1 shows Ca--Sb--O inclusions (FE-EPMA) observed in an alloy melted in a CaO crucible according to one embodiment of the present invention. 酸化試験片の一例を示す構成斜視図である。FIG. 2 is a perspective view showing an example of an oxidation test piece. １１００℃－１ｈ、室温保持－１ｈを１サイクルとする繰り返し酸化試験結果を示す図である。FIG. 1 is a graph showing the results of a repeated oxidation test in which one cycle is 1100° C.-1 hour and room temperature holding-1 hour.
　本発明のＮｉ基超合金の製造方法に用いられる、Ｎｉ基超合金用原料の組成成分およびその組成比は、以下の観点に基づいている。なお、本明細書において、数値範囲に関しては、上下限値の端点を含むものとし、従って下限値以上、上限値以下と解釈するのを原則とするが、上下限値の端点を含まない場合は下限値を超え、又は上限値未満と明記する。
　Ｃｒ（クロム）は、Ｎｉ基超合金の高温耐食性および高温耐酸化性を向上させる。Ｃｒの組成比は、２質量％以上２５質量％以下である。組成比が、２質量％未満であると、高温耐食性および高温耐酸化性を確保することが難しく、２５質量％を超えると、σ相やμ相の有害相が生成して高温強度が低下する。Ｃｒの組成比は、好ましくは４質量％以上１０質量％以下であり、より好ましくは８質量％以上１０質量％以下である。 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, the numerical ranges are defined as including the upper and lower limit values, and therefore are in principle interpreted as being equal to or greater than the lower limit value and equal to or less than the upper limit value. However, when the upper and lower limit values are not included, the numerical ranges are clearly stated as being greater than the lower limit value or less than the upper limit value.
Cr (chromium) improves the high-temperature corrosion resistance and high-temperature oxidation resistance of Ni-based superalloys. The composition ratio of Cr 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, and if it exceeds 25% by mass, harmful phases such as σ phase and μ phase are generated, resulting in a decrease in high-temperature strength. The composition ratio of Cr 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.
　Ｃｏ（コバルト）は、Ａｌ、Ｔａ等の母相に対する高温下での固溶限度を大きくし、熱処理によって微細なγ’相を分散析出させ、Ｎｉ基超合金の高温強度を向上させる。Ｃｏは、任意的組成元素とし、その組成比は、０質量％以上２５質量％以下である。組成比が、２５質量％を超えると、所望の高温強度を確保できないので好ましくない。 Co (cobalt) increases the solid solubility limit in parent phases such as Al and Ta at high temperatures, disperses and precipitates fine γ' phases through heat treatment, and improves the high-temperature strength of Ni-based superalloys. Co is an optional composition element, and its composition ratio is 0 mass% or more and 25 mass% or less. If the composition ratio exceeds 25 mass%, it is not preferable because the desired high-temperature strength cannot be secured.
　Ｍｏ（モリブデン）は、素地中に固溶し、かつ析出硬化によりＮｉ基超合金の高温強度の上昇に寄与する。Ｍｏは、任意的組成元素とし、その組成比は、０質量％以上８質量％以下である。組成比が、８質量％を超えると、有害相が生成して高温強度が低下する。Ｍｏの組成比は、好ましくは０質量％以上４質量％以下であり、より好ましくは０．４質量％以上２質量％以下である。 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 composition element, and its composition ratio is 0 mass% or more and 8 mass% or less. If the composition ratio exceeds 8 mass%, harmful phases are generated and high-temperature strength decreases. The composition ratio of Mo is preferably 0 mass% or more and 4 mass% or less, and more preferably 0.4 mass% or more and 2 mass% or less.
　Ｒｅ（レニウム）は、γ相に固溶して固溶強化によりＮｉ基超合金の高温強度を向上させるだけでなく耐食性を向上させる効果もある。ただ、Ｒｅを多量に含有すると、高温時にＴＣＰ相が析出して高温強度を低下させるおそれがある。また、Ｒｅは高価でありコストパフォーマンスの点から少量で高温強度と耐食性に効果が発揮されることが望ましい。ＴＣＰ相の析出を抑制しつつも有害相を生成しないＲｅの範囲を絞り込む必要がある。そのためには他の添加元素とのバランスが必要である。Ｒｅは、任意的組成元素とし、その組成比は、０質量％以上１０質量％以下である。Ｒｅの組成比は、好ましくは２質量％以上１０質量％以下である。
　ここで、ＴＣＰ相とは、topological close-packed phaseの略称であり、Frank-Kasper (FK) phasesともいい、Ｎｉ基超合金の場合はσ相やμ相をいう。 Re (rhenium) not only improves the high-temperature strength of Ni-based superalloys by dissolving in the gamma phase and strengthening the solid solution, but also improves the corrosion resistance. However, if a large amount of Re is contained, there is a risk that the TCP phase will precipitate at high temperatures, reducing the high-temperature strength. In addition, Re is expensive, and from the viewpoint of cost performance, it is desirable that a small amount of Re is effective in high-temperature strength and corrosion resistance. It is necessary to narrow down the range of Re that suppresses the precipitation of the TCP phase while not generating 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 mass% or more and 10 mass% or less. The composition ratio of Re is preferably 2 mass% or more and 10 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 or μ phase.
　Ｒｕ（ルテニウム）は、母相であるγ相に固溶し、固溶強化によりＮｉ基超合金の高温強度を向上させる。また、Ｒｕは、Ｒｅ等の添加によって生成するＴＣＰ相の析出を抑え、これによりＮｉ基超合金の高温強度を向上させる。Ｒｕは、任意的組成元素とし、その組成比は、０質量％以上１０質量％以下とすることが好ましく、さらには、０質量％以上８質量％以下の範囲とすることがより好ましい。Ｒｕの組成比が１０質量％を超えると、ε相が析出して高温強度が低下するので好ましくない。また、ＲｕはＮｉ等と比較して、地金価格が２００倍～３００倍程度と高額であるため、固溶強化により高温強度を向上させる範囲でできるだけ少量であることが好ましく、経済的には８質量％を上限とするのが好ましい。 Ru (ruthenium) dissolves in the gamma phase, which is the parent phase, and improves the high-temperature strength of Ni-based superalloys through solid-solution strengthening. Ru also suppresses the precipitation of TCP phases that are generated by the addition of Re and other elements, thereby improving the high-temperature strength of Ni-based superalloys. Ru is an optional composition element, and its composition ratio is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 8% by mass or less. If the composition ratio of Ru exceeds 10% by mass, ε phase will precipitate and the high-temperature strength will decrease, which is not preferable. In addition, since the price of Ru in bullion is about 200 to 300 times higher than that of Ni and other elements, it is preferable to use as little Ru as possible within the range in which high-temperature strength can be improved through solid-solution strengthening, and economically, it is preferable to set the upper limit at 8% by mass.
　Ｗ（タングステン）は、Ｍｏと同様に、固溶強化および析出硬化の作用があり、Ｎｉ基超合金の高温強度を向上させる。Ｗは、任意的組成元素とし、その組成比は、０質量％以上１４質量％以下である。組成比が、１４質量％を超えると、有害相が生成してＮｉ基超合金のＴＭＦ特性およびクリープ特性が低下する。Ｗの組成比は、好ましくは２質量％以上８質量％以下であり、より好ましくは４質量％以上７質量％以下である。
　ここで、ＴＭＦ特性とは、熱疲労（Thermo-mechanical fatigue）特性をいい、例えばタービン動翼における多軸熱疲労条件下でのき裂発生寿命（深さ２ｍｍ程度のき裂）を指す。クリープ特性とは、材料のクリープ強さであり、クリープ試験又はクリープ破断試験が用いられる。クリープ破断試験は、ある応力のもとで破断するまでの時間を求めることを目的とし、試験機にはマルチプル型（１試験機あたり多数の試験片）が多く使用されるが、シングル型（１試験機あたり単一の試験片）でもよい。 W (tungsten) has the effect of solid solution strengthening and precipitation hardening, similar to Mo, and improves the high temperature strength of Ni-based superalloys. W is an optional composition element, and its composition ratio is 0 mass% or more and 14 mass% or less. If the composition ratio exceeds 14 mass%, harmful phases are generated and the TMF properties and creep properties of the Ni-based superalloy are deteriorated. The composition ratio of W is preferably 2 mass% or more and 8 mass% or less, more preferably 4 mass% or more and 7 mass% or less.
Here, the TMF characteristic refers to the thermo-mechanical fatigue characteristic, and for example refers to the crack initiation life (cracks of about 2 mm depth) under multiaxial thermal fatigue conditions in a turbine blade. The creep characteristic refers to the creep strength of a material, and creep tests or creep rupture tests are used. The creep rupture test aims to determine the time until rupture under a certain stress, and a multiple type test machine (multiple test pieces per test machine) is often used, but a single type (single test piece per test machine) can also be used.
　Ｎｂ（ニオブ）は、γ’相のＡｌサイトに置換して析出強化に寄与する。また、Ｍｏ及びＷが共存する場合には、Ｍｏ及びＷの共存下にて固溶強化と析出強化の作用によりＮｉ基超合金の高温強度を向上させる。Ｎｂは、任意的組成元素とし、その組成比は、０質量％以上５質量％以下であり、より好ましくは０質量％以上２．５質量％以下である。組成比が、５質量％を超えると、高温において有害相が生成し、ＴＭＦ特性およびクリープ特性が低下する。 Nb (niobium) substitutes for the Al site of the γ' phase and contributes to precipitation strengthening. When Mo and W coexist, it improves the high-temperature strength of the Ni-based superalloy through the effects of solid solution strengthening and precipitation strengthening in the presence of Mo and W. Nb is an optional composition element, and its composition ratio is 0 mass% or more and 5 mass% or less, and more preferably 0 mass% or more and 2.5 mass% or less. If the composition ratio exceeds 5 mass%, harmful phases are generated at high temperatures, and the TMF properties and creep properties are reduced.
　Ｖ（バナジウム）は、γ’相に固溶し、γ’相を強化する元素である。Ｖは、任意的組成元素とし、その組成比は、０質量％以上３質量％以下であり、より好ましくは０質量％以上０．５質量％以下である。Ｖの組成比が３質量％を超えると、クリープ特性が低下するので好ましくない。 V (vanadium) is an element that dissolves in the γ' phase and strengthens it. V is an optional composition element, and its composition ratio is 0 mass% or more and 3 mass% or less, and more preferably 0 mass% or more and 0.5 mass% or less. If the composition ratio of V exceeds 3 mass%, it is not preferable because the creep properties are reduced.
　Ａｌ（アルミニウム）は、Ｎｉと化合して、γ母相中に析出するγ’相を構成するＮｉ３Ａｌで示される金属間化合物を形成し、Ｎｉ基超合金の、特に１０００℃以下の低温側のＴＭＦ特性およびクリープ特性を向上させる。Ａｌの組成比は、１質量％以上１０質量％以下であり、より好ましくは３質量％以上８質量％以下である。組成比が、１質量％未満であると、γ’相量が少なく、要求されるＴＭＦ特性およびクリープ特性が得られず、１０質量％を超えると、要求されるＴＭＦ特性およびクリープ特性が得られない。 Al (aluminum) combines with Ni to form an intermetallic compound represented by Ni 3 Al which constitutes the γ' phase precipitated in the γ matrix phase, improving the TMF and creep properties of Ni-based superalloys, particularly at low temperatures below 1000° C. The Al composition ratio is 1 mass % or more and 10 mass % or less, and more preferably 3 mass % or more and 8 mass % or less. If the composition ratio is less than 1 mass %, the amount of γ' phase is small and the required TMF and creep properties cannot be obtained, whereas if it exceeds 10 mass %, the required TMF and creep properties cannot be obtained.
　Ｔｉ（チタン）は、γ’相を強化してＮｉ基超合金のクリープ特性を向上させる。Ｔｉは、任意的組成元素とし、その組成比は、０質量％以上１０質量％以下であり、より好ましくは０質量％以上３質量％以下である。組成比が１０質量％を超えると、所望の高温強度を確保できないので好ましくない。 Ti (titanium) strengthens the γ' phase and improves the creep properties of Ni-based superalloys. Ti is an optional composition element, and its composition ratio is 0 mass% or more and 10 mass% or less, and more preferably 0 mass% or more and 3 mass% or less. If the composition ratio exceeds 10 mass%, it is not preferable because the desired high-temperature strength cannot be secured.
　Ｔａ（タンタル）は、γ’相を強化してＮｉ基超合金のクリープ特性を向上させる。Ｔａは、任意的組成元素とし、その組成比は、０質量％以上１３質量％以下であり、より好ましくは４質量％以上１０質量％以下である。組成比が、１３質量％を超えると、共晶γ’相の生成を促し、溶体化熱処理が困難となる。 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 mass% or more and 13 mass% or less, and more preferably 4 mass% or more and 10 mass% or less. If the composition ratio exceeds 13 mass%, it promotes the formation of eutectic γ' phase, making solution heat treatment difficult.
　Ｈｆ（ハフニウム）は、普通凝固および一方向凝固による柱状結晶化の際、粒界強化に寄与するものであり、かつＮｉ基超合金の耐酸化性を向上させ、そのうえＴＭＦ特性を改善する可能性がある。また、Ｎｉ基超合金を単結晶で用いる場合に、何らかの理由で再結晶してしまっても、粒界が弱くなるのを防ぐことが可能である。Ｈｆは、任意的組成元素とし、その組成比は、０質量％以上２．５質量％以下であり、より好ましくは０質量％以上１質量％以下である。組成比が、２．５質量％を超えると、有害相の生成が助長され、ＴＭＦ特性およびクリープ特性が低下する。 Hf (hafnium) contributes to strengthening grain boundaries during columnar crystallization due to normal solidification and unidirectional solidification, and may improve the oxidation resistance of Ni-based superalloys and also improve the TMF properties. In addition, when Ni-based superalloys are used as single crystals, it is possible to prevent the grain boundaries from weakening even if recrystallization occurs for some reason. Hf is an optional composition element, and its composition ratio is 0 mass% or more and 2.5 mass% or less, and more preferably 0 mass% or more and 1 mass% or less. If the composition ratio exceeds 2.5 mass%, the formation of harmful phases is promoted, and the TMF properties and creep properties are deteriorated.
　Ｃ（炭素）は、結晶粒界に偏析して粒界強度を向上させ、一部はＴａＣ等の炭化物を形成して塊状に析出する。結晶粒界に偏析して粒界強度を上げる場合には、０．０８質量％以上の添加をするとよい。しかし、０．５質量％を超えて添加すると過剰の炭化物が形成され、Ｎｉ基超合金の高温強度や延性が低下し、耐食性も低下する。また、凝固時における炭化物の晶出温度が高くなることから、デンドライト間に炭化物がピニングされ、鋳造欠陥であるポロシティの生成を招きうる。そのため、Ｃは、任意的組成元素とし、その組成比は、０質量％以上０．５質量％以下であり、より好ましくは０質量％以上０．０５質量％以下である。 C (carbon) segregates at the grain boundaries to improve grain boundary strength, and some of it forms carbides such as TaC and precipitates in clumps. When segregating at the grain boundaries to increase grain boundary strength, it is recommended to add 0.08 mass% or more. However, adding more than 0.5 mass% will form excess carbides, reducing the high-temperature strength and ductility of the Ni-based superalloy and also reducing corrosion resistance. In addition, the crystallization temperature of the carbides during solidification will increase, which can lead to pinning of the carbides between dendrites and the generation of porosity, a casting defect. For this reason, C is an optional composition element, and its composition ratio is 0 mass% or more and 0.5 mass% or less, and more preferably 0 mass% or more and 0.05 mass% or less.
　Ｂ（ホウ素）は、普通凝固および一方向凝固による柱状結晶化の際、結晶粒界に偏析して粒界強度を向上させるとともに、一部は（Ｃｒ、Ｎｉ、Ｍｏ）３Ｂ２等のホウ化物を形成し、合金の粒界に析出する。粒界強化の効果を得るには０．０１質量％以上の添加が必要であるが、生成するホウ化物は融点が合金の融点よりも低く、合金の融点温度を低下させ、溶体化処理温度範囲を狭くする。そのため、Ｂは、任意的組成元素とし、その組成比は、０質量％以上０．１質量％以下であり、より好ましくは０質量％以上０．０２質量％以下である。 During columnar crystallization by normal solidification and unidirectional solidification, B (boron) segregates to the grain boundaries to improve grain boundary strength, and some of it forms borides such as (Cr, Ni, Mo) 3 B 2 and precipitates at the grain boundaries of the alloy. To obtain the effect of grain boundary strengthening, it is necessary to add 0.01 mass% or more, but the resulting borides have a melting point lower than the melting point of the alloy, lowering the melting point temperature of the alloy and narrowing the solution treatment temperature range. Therefore, B is an optional composition element, and its composition ratio is 0 mass% or more and 0.1 mass% or less, more preferably 0 mass% or more and 0.02 mass% or less.
　Ｚｒ（ジルコニウム）は、普通凝固および一方向凝固による柱状結晶化の際、結晶粒界に偏析し、粒界強度を高める効果があるが、ほとんどは合金の主成分であるニッケルと金属間化合物Ｎｉ３Ｚｒを形成する。この化合物は合金の延性を低下させ、また著しく低融点であるため、合金の溶体化処理を困難にするなど、有害な作用が多い。そのため、Ｚｒは、任意的組成元素とし、その組成比は、０質量％以上０．５質量％以下であり、より好ましくは０質量％以上０．１質量％以下である。 Zr (zirconium) segregates at grain boundaries during columnar crystallization due to normal solidification and unidirectional solidification, and has the effect of increasing grain boundary strength, but in most cases it forms an intermetallic compound Ni 3 Zr with nickel, the main component of the alloy. This compound reduces the ductility of the alloy and has a significantly low melting point, making solution treatment of the alloy difficult, among other harmful effects. Therefore, Zr is an optional composition element, and its composition ratio is 0% by mass or more and 0.5% by mass or less, and more preferably 0% by mass or more and 0.1% by mass or less.
　Ｆｅ（鉄）は、Ｎｉを代替し、Ｎｉ基超合金の熱間加工性を改善する効果がある。また、原料の調達が容易であり、材料コストの低減に有効である。上述のリサイクル材には、一定量のＦｅが含有され得るが、過剰に含有する材料は、Ｎｉ基超合金用原料としては不向きである。Ｆｅは、任意的組成元素とし、その組成比は、０質量％以上２０質量％以下であり、より好ましくは０質量％以上５質量％以下である。組成比が２０質量％を超えると、有害相が生成して高温強度が低下する。 Fe (iron) replaces Ni and has the effect of improving the hot workability of Ni-based superalloys. In addition, raw materials are easy to procure, which is effective in reducing material costs. The above-mentioned recycled materials may contain a certain amount of Fe, but materials that contain an excessive amount are not suitable as raw materials for Ni-based superalloys. Fe is an optional composition element, and its composition ratio is 0 mass% or more and 20 mass% or less, and more preferably 0 mass% or more and 5 mass% or less. If the composition ratio exceeds 20 mass%, harmful phases are generated and high-temperature strength decreases.
　Ｓｉ（ケイ素）は、Ｎｉ基超合金の耐酸化性を向上させる効果がある。Ｓｉは、任意的組成元素とし、その組成比は、０質量％以上１質量％以下であり、より好ましくは０質量％以上０．５質量％以下である。組成比が１質量％を超えると、有害相が生成して高温強度が低下する。 Si (silicon) has the effect of improving the oxidation resistance of Ni-based superalloys. Si is an optional composition element, and its composition ratio is 0 mass% or more and 1 mass% or less, and more preferably 0 mass% or more and 0.5 mass% or less. If the composition ratio exceeds 1 mass%, harmful phases are generated and high-temperature strength decreases.
　Ｓｂ（アンチモン）は、Ｎｉ基超合金において、温度が７００℃以上かつ１万時間以上という高温長時間加熱後の延性および靱性の著しい低下を引き起こす。したがって、長期経年材の曲げ加工、溶接性等良好な加工性を確保するために、先ず、Ｎｉ基超合金用原料中のＳｂの含有量を５０ＰＰＭ以下に制限する必要がある。Ｓｂは、０．５ＰＰＭ未満の含有量であれば、不可避的不純物として扱うことができ、製造されるＮｉ基超合金の耐酸化性の劣化への影響は許容範囲である。
　Ｓｂと同様にＮｉ基超合金の高温長時間加熱後の延性および靱性の著しい低下を引き起こす低融点金属元素としては、Ｓｎ（錫）、Ｐｂ（鉛）、Ｚｎ（亜鉛）およびＡｓ（ヒ素）が知られている。Ｎｉ基超合金用原料中のこれらの元素の含有量は、それぞれ、Ｓｎ：０．０２０質量％以下、Ｐｂ：０．０１０質量％以下、Ｚｎ：０．００５質量％以下およびＡｓ：０．００５質量％以下に制限する必要がある。 Sb (antimony) causes a significant decrease in ductility and toughness in Ni-based superalloys after long-term heating at high temperatures of 700°C or higher for 10,000 hours or more. Therefore, in order to ensure good workability such as bending and weldability of long-term aged materials, it is necessary to first limit the Sb content in the raw materials for Ni-based superalloys to 50 PPM or less. If the content of Sb is less than 0.5 PPM, it can be treated as an unavoidable impurity, and its effect on the deterioration of the oxidation resistance of the manufactured Ni-based superalloy is within an acceptable range.
Sn (tin), Pb (lead), Zn (zinc) and As (arsenic) are known to be low melting point metal elements that, like Sb, cause a significant decrease in ductility and toughness of Ni-based superalloys after long-term heating at high temperatures. The contents of these elements in the raw materials for Ni-based superalloys 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.
　Ｃａ（カルシウム）は、熱間加工性を阻害するＳ（硫黄）を硫化物として固定してＮｉ基超合金の熱間加工性を改善する作用を有するので、この効果を得るために、Ｎｉ基超合金用原料は、Ｃａを含有してもよい。しかしながら、Ｃａの含有量が０．０５質量％（５００ＰＰＭ）を超えると、Ｎｉ基超合金の清浄性が低下し、かえって熱間加工性および延性が損なわれる。したがって、Ｎｉ基超合金用原料にＣａを添加する場合のＣａの含有量は、０．０５質量％以下とする。なお、Ｃａの含有量の上限は０．０２質量％とすることが好ましく、０．０１質量％とすればさらに好ましい。
　一方、前記したＣａの効果を確実に得るためには、Ｎｉ基超合金用原料中のＣａの含有量は、０．０００５質量％（５ＰＰＭ）以上とすることが望ましく、０．００１質量％（１０ＰＰＭ）以上とすれば一層望ましい。製造されるＮｉ基超合金において、質量比でＣａ：Ｓｂ：Ｏ＝１：３：２～１：４：３のＣａ－Ｓｂ－Ｏ介在物が析出していることで、Ｓｂによる耐酸化性の劣化が防止されることから、Ｎｉ基超合金用原料中のＣａの含有比は、Ｓｂの含有比の１／４よりも大きいことが必要であり、更に好ましくは１／３よりも大きいことが必要である。 Ca (calcium) has the effect of fixing S (sulfur), which inhibits hot workability, as sulfide to improve the hot workability of Ni-based superalloys, so in order to obtain this effect, the raw material for Ni-based superalloys may contain Ca. However, if the Ca content exceeds 0.05 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 the raw material for Ni-based superalloys, the Ca content is set to 0.05 mass% or less. The upper limit of the Ca content is preferably 0.02 mass%, and more preferably 0.01 mass%.
On the other hand, in order to reliably obtain the above-mentioned effect of Ca, the content of Ca in the raw material for the Ni-base superalloy is desirably 0.0005 mass% (5 PPM) or more, and more desirably 0.001 mass% (10 PPM) or more. In the Ni-base superalloy produced, the precipitation of Ca-Sb-O inclusions with a mass ratio of Ca:Sb:O=1:3:2 to 1:4:3 prevents the deterioration of oxidation resistance caused by Sb, so the content of Ca in the raw material for the Ni-base superalloy must be greater than 1/4 of the content of Sb, and more preferably greater than 1/3.
　次に、上記の組成成分およびその組成比を有するＮｉ基超合金用原料を用いて、タービンブレードやタービンベーン部品などのＮｉ基超合金部材を製造するプロセスについて、説明する。Ｎｉ基超合金部材の製造プロセスとしては、普通鋳造法（Conventional Casting）、一方向凝固法（Directional Solidification）、単結晶凝固法（Single-crystal Solidification）、並びに粉末状のＮｉ基超合金用原料を用いて焼結または３Ｄ造形で作製することが知られている。各種鋳造法や焼結・３Ｄ造形により作製するタービンブレードやタービンベーン部品では、以下のような熱処理を行うのがよい。 Next, we will explain the process for manufacturing Ni-base superalloy components such as turbine blades and turbine vane parts using Ni-base superalloy raw materials having the above compositional components and their composition ratios. Known manufacturing processes for Ni-base superalloy components include conventional casting, directional solidification, single-crystal solidification, and sintering or 3D printing using powdered Ni-base superalloy raw materials. For turbine blades and turbine vane parts manufactured by various casting methods, sintering, or 3D printing, it is recommended to carry out the following heat treatment.
　まず、普通鋳造法により作製するタービンブレードやタービンベーン部品では以下のような熱処理を施して製造することができる。すなわち、熱処理は、１２００℃～１３００℃で２時間～４０時間保持後に１５０℃／ｍｉｎ～４００℃／ｍｉｎで空冷または不活性ガス雰囲気中で冷却する溶体化処理、１０００℃～１１５０℃で２時間～５時間保持後に空冷または不活性ガス雰囲気中で冷却する１次時効処理、そして８００℃～９５０℃で１０時間～３０時間保持後に空冷または不活性ガス雰囲気中で冷却する２次時効処理という一連のものである。 First, turbine blades and turbine vane parts made by normal casting methods can be manufactured by applying the following heat treatments. That is, the heat treatments are a series of steps: 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.
　また、一方向凝固法により作製するタービンブレードやタービンベーン部品では以下のような熱処理を施して製造することができる。すなわち、熱処理は、１２００℃～１３００℃で２時間～４０時間保持後に２００℃／ｍｉｎ～４００℃／ｍｉｎで空冷または不活性ガス雰囲気中で冷却する溶体化処理、１０００℃～１１５０℃で２時間～５時間保持後に空冷または不活性ガス雰囲気中で冷却する１次時効処理、そして８００℃～９５０℃で１０時間～３０時間保持後に空冷または不活性ガス雰囲気中で冷却する２次時効処理という一連のものである。 Furthermore, turbine blades and turbine vane parts made by the unidirectional solidification method can be manufactured by carrying out the following heat treatments. That is, the heat treatments are a series of steps: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or 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 cooling in air or 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 cooling in air or in an inert gas atmosphere.
　そして、単結晶凝固法により作製するタービンブレードやタービンベーン部品では以下のような熱処理を施して製造することができる。すなわち、熱処理は、１２８０℃～１３００℃で２時間～４０時間保持後に２００℃／ｍｉｎ～４００℃／ｍｉｎで空冷または不活性ガス雰囲気中で冷却する溶体化処理、１０００℃～１１５０℃で２時間～５時間保持後に空冷または不活性ガス雰囲気中で冷却する１次時効処理、そして８５０℃～９５０℃で１０時間～３０時間保持後に空冷または不活性ガス雰囲気中で冷却する２次時効処理という一連のものである。 Turbine blades and turbine vane parts made by the single crystal solidification method can be manufactured by applying the following heat treatments. That is, the heat treatments are a series of steps: 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.
　さらに、上述の組成条件を満足する粉末状のＮｉ基超合金用原料を用いて焼結または３Ｄ造形で作製するタービンブレードやタービンベーン部品では以下のような熱処理を施して製造することができる。すなわち、熱処理は、１２００℃～１３００℃で２時間～４０時間保持後に２００℃／ｍｉｎ～４００℃／ｍｉｎで空冷または不活性ガス雰囲気中で冷却する溶体化処理、１０００℃～１１５０℃で２時間～５時間保持後に空冷または不活性ガス雰囲気中で冷却する１次時効処理、そして８５０℃～９５０℃で１０時間～３０時間保持後に空冷または不活性ガス雰囲気中で冷却する２次時効処理という一連のものである。 Furthermore, turbine blades and turbine vane parts made by sintering or 3D printing using powdered Ni-based superalloy raw materials that satisfy the above compositional conditions can be manufactured by carrying out the following heat treatments. That is, the heat treatments are a series of steps: solution treatment, in which the material is held at 1200°C to 1300°C for 2 to 40 hours, followed by cooling in air or 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 cooling in air or 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 cooling in air or in an inert gas atmosphere.
　このような一連の所定温度で所定時間の保持は、すべて真空中または不活性ガス雰囲気中で行うことが、高温酸化の影響を受けないという観点からも好ましい。
　次に、本発明の例示的な実施形態として、Ｎｉ基超合金用原料としてＮｉ基超合金を用いて、鋳造鋳型を用いてタービンブレードやタービンベーン部品などのＮｉ基超合金部材を製造するプロセスを説明する。ここで、原料としてのＮｉ基超合金は、上述の条件を満足する範囲で予め一定量のＳｂを含有するＮｉ基超合金であってもよく、そのような材料を本明細書では便宜的に「Ｓｂ含有Ｎｉ基超合金」とも称する。なお、後述する実施例で用いたＮｉ基単結晶超合金ＴＭＳ－２３８は、通常はＳｂの含有量が０．５ＰＰＭ未満（不可避的不純物のレベル）であるため、意図的に所定量のＳｂを溶湯に投入することで、模擬的にＳｂ含有Ｎｉ基超合金とした。また、当該実施例では、溶湯を所定の温度で安定させた後にＳｂを投入したが、Ｎｉ基超合金用原料がＳｂ含有Ｎｉ基超合金である場合には、当該Ｓｂの投入は不要であることが理解される。 It is preferable to carry out the series of holding at a predetermined temperature for a predetermined time in a vacuum or in an inert gas atmosphere from the viewpoint of not being affected by high-temperature oxidation.
Next, as an exemplary embodiment of the present invention, a process for manufacturing Ni-based superalloy members such as turbine blades and turbine vane parts using a casting mold by using a Ni-based superalloy as a raw material for the Ni-based superalloy will be described. Here, the Ni-based superalloy 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, and such a material is conveniently referred to as an "Sb-containing Ni-based superalloy" in this specification. Note that the Ni-based single crystal superalloy TMS-238 used in the examples described below usually contains less than 0.5 PPM of Sb (the level of unavoidable impurities), so a predetermined amount of Sb was intentionally added to the molten metal to simulate an Sb-containing Ni-based superalloy. In addition, in the examples, Sb was added after the molten metal was stabilized at a predetermined temperature, but it is understood that when the raw material for the Ni-based superalloy is an Sb-containing Ni-based superalloy, it is not necessary to add Sb.
　図１は、本発明の一実施形態を示すＳｂ含有Ｎｉ基超合金による一方向凝固試験片又は単結晶試験片を鋳造する為の真空高周波誘導溶解炉を用いた溶解炉の要部構成断面図で、真空排気系・温度測定装置、溶解原料装入チャンバ、るつぼ傾注装置、鋳型昇降装置は図示を省略してある。なお、真空高周波誘導溶解炉を用いたＮｉ基超合金による一方向凝固又は単結晶によるタービン翼の鋳造については、ロストワックス精密鋳造法（日本鋳造協会編、産業図書刊、２０１５年）に説明があり、本明細書においては、特に溶解と鋳込み（７８頁～８２頁）及び凝固制御（８５頁～９０頁）の項を引用する。また、“The Superalloys Fundamentals and Applications”（Roger C. Reed著、Cambridge University Press、2006）にもＮｉ基超合金を用いたタービン翼の鋳造に関する説明があり、本明細書においては、特に“3.1 Processing of turbine blading by Solidification Processing”（１２２頁～１４７頁）の項を引用する。 Figure 1 is a cross-sectional view of the essential components of a melting furnace using a vacuum high-frequency induction melting furnace for casting directionally solidified test pieces or single crystal test pieces from Sb-containing Ni-based superalloys according to one embodiment of the present invention, with the vacuum exhaust system, temperature measurement device, molten raw material charging chamber, crucible tilting device, and mold lifting device not shown. The casting of turbine blades using directionally solidified or single crystal Ni-based superalloys using a vacuum high-frequency induction melting furnace is explained in Lost Wax Precision Casting Method (edited by Japan Foundry Association, published by Sangyo Tosho, 2015), and in this specification, the sections on melting and casting (pages 78-82) and solidification control (pages 85-90) are particularly cited. Additionally, "The Superalloys Fundamentals and Applications" (Roger C. Reed, Cambridge University Press, 2006) also contains an explanation of the casting of turbine blades using Ni-base superalloys, and in this specification, we particularly quote the section "3.1 Processing of turbine blading by Solidification Processing" (pp. 122-147).
　図１において、真空高周波誘導溶解炉１０は、溶解用高周波コイル１４の電磁誘導作用により、炉内の金属材料に高い電流密度の誘導電流を誘起させ、この誘導電流によって発生するジュール熱により加熱溶解を行うもので、溶解室に設けられる。高周波誘導溶解炉は電磁誘導作用により直接金属材料を加熱するので熱効率が良く、また電磁力によって溶湯が攪拌されるため、成分が均一化されるという利点があるが、精錬機能が小さい為、溶解には良質な金属材料が必要である。 In Figure 1, a vacuum high-frequency induction melting furnace 10 is installed in a melting chamber, and uses the electromagnetic induction effect of a high-frequency melting coil 14 to induce a high-current-density induced current in the metal material inside the furnace, which then heats and melts using the Joule heat generated by this induced current. High-frequency induction melting furnaces have good thermal efficiency because they directly heat the metal material using electromagnetic induction, and also have the advantage of homogenizing the components because the molten metal is stirred by electromagnetic force, but they have a small refining function, so high-quality metal materials are required for melting.
　ＣａＯるつぼ１２は、真空高周波誘導溶解炉１０に設けられるもので、立てた姿勢で溶解原料装入チャンバ（図示せず）から溶解対象となるＮｉ基超合金の金属材料が送られ、当該金属材料が溶解されて溶湯となる。後述する実施例では、ＣａＯるつぼ１２には、エイトセラミックス株式会社、型式　Ｃ－１を用いた。
　溶解用高周波コイル１４は、真空高周波誘導溶解炉１０のＣａＯるつぼ１２の周縁部に設けられるもので、ＣａＯるつぼ１２内の金属材料に高い電流密度の誘導電流を誘起させる。るつぼ傾注装置（図示せず）は、ＣａＯるつぼ１２内の溶湯を注ぎ口２８から単結晶棒状試験片用鋳型３０に流し込めるように、るつぼ傾注方向１６にＣａＯるつぼ１２を傾ける機構である。 The CaO crucible 12 is provided in the vacuum high-frequency induction melting furnace 10, and is in a vertical position into which the metal material of the Ni-based superalloy to be melted is fed from a melting material charging chamber (not shown), and the metal material is melted to become molten metal. In the examples described below, a C-1 model manufactured by Eight Ceramics Co., Ltd. was used as the CaO crucible 12.
The high-frequency melting coil 14 is provided on the periphery of the CaO crucible 12 in the vacuum high-frequency induction melting furnace 10, and induces an induced current with a high current density 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 a pouring spout 28 into a mold 30 for a single crystal rod-shaped test piece.
　一方向凝固炉２０は、真空高周波誘導溶解炉１０と同様の構成を有するもので、鋳型室に設けられる。後述する実施例では、一方向凝固炉２０には、日新技研株式会社、型式　ＮＥＶ－５ＤＳＮＩＡ型を用いた。
　鋳型用高周波コイル２２は、一方向凝固炉２０の周縁部に設けられるもので、鋳型室に位置している単結晶棒状試験片用鋳型３０内の金属材料に高い電流密度の誘導電流を誘起させ、溶湯状態を維持するのに必要なエネルギーを供給する。グラファイト抵抗発熱体２４は、一方向凝固炉２０の側壁の内壁表面に設けられるもので、一方向凝固炉２０の内部を加熱するヒーターである。上部ライニング２５は、一方向凝固炉２０の天井側の天井面に設けられるもので、例えばジルコニアやアルミナが使用される。側壁絶縁材２６は、鋳型用高周波コイル２２とグラファイト抵抗発熱体２４の間に設けられるもので、例えばマイカシートが使用される。上部絶縁材２７は、上部ライニング２５と一方向凝固炉２０の天井面との間に設けられるもので、例えば耐火レンガが使用される。注ぎ口２８は、上部ライニング２５・上部絶縁材２７に設けられるもので、溶解室にあるＣａＯるつぼ１２から溶湯を鋳型室に位置している単結晶棒状試験片用鋳型３０内に注ぎ込むための開口部である。底部絶縁材２９は、一方向凝固炉２０の底面に設けられるもので、例えば耐火レンガが使用される。 The directional solidification furnace 20 has the same structure as the vacuum high-frequency induction melting furnace 10, and is provided in the mold chamber. In the examples described below, a NEV-5DSNIA model manufactured by Nisshin Giken Co., Ltd. was used as the directional solidification furnace 20.
The high frequency coil for mold 22 is provided on the periphery of the directional solidification furnace 20, and induces a high current density induced current in the metal material in the mold 30 for single crystal rod-shaped specimens located in the mold chamber, thereby supplying energy necessary for maintaining the molten state. The graphite resistance heating element 24 is provided on the inner wall surface of the side wall of the directional solidification furnace 20, and is a heater for heating the inside of the directional solidification furnace 20. The upper lining 25 is provided on the ceiling surface on the ceiling side of the directional solidification furnace 20, and is made of, for example, zirconia or alumina. The side wall insulating material 26 is provided between the high frequency coil for mold 22 and the graphite resistance heating element 24, and is made of, for example, a mica sheet. The upper insulating material 27 is provided between the upper lining 25 and the ceiling surface of the directional solidification furnace 20, and is made of, for example, a 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, firebricks.
　単結晶棒状試験片用鋳型３０は、Ｎｉ基超合金を用いた単結晶棒状試験片を鋳造する為の鋳型で、図１ではセレクタ３２を用いる型式の鋳型を図示しているが、種結晶を用いる鋳型でもよい。鋳型基台部３４は、チルプレートと呼ばれるもので、単結晶の結晶成長をさせるのに必要な温度傾斜を確保する為に、冷却水の流路が設けられている。後述する実施例では、単結晶棒状試験片用鋳型３０には、自作の鋳型を用いた。なお、鋳型の製造については、上述のロストワックス精密鋳造法（日本鋳造協会編、産業図書刊、２０１５年）に説明があり、本明細書においては、特に造形法（９頁～７８頁）の項を引用する。また、上述の“The Superalloys Fundamentals and Applications”（Roger C. Reed著、Cambridge University Press、2006）にも鋳型の製造に関する説明があり、本明細書においては、特に“3.1.1 The practice of investment casting”（１２２頁～１２５頁）の項を引用する。
　鋳型昇降装置（図示せず）は、鋳型昇降方向３６を実現させるもので、Ｎｉ基超合金を単結晶に結晶成長させるのに必要な冷却速度を確保する。一般に、Ｎｉ基超合金を一方向凝固又は単結晶に結晶成長させる為には、鋳型内で凝固が一方的に進行していくときの固液界面の温度勾配と凝固速度の比を適切に保持する必要がある。 The mold 30 for single crystal rod-shaped test pieces is a mold for casting single crystal rod-shaped test pieces using a Ni-based superalloy. Although FIG. 1 illustrates a mold of the type using a selector 32, a mold using a seed crystal may be used. The mold base 34 is called a chill plate, and is provided with a cooling water flow path to ensure a temperature gradient necessary for crystal growth of the single crystal. In the examples described below, a self-made mold was used for the mold 30 for single crystal rod-shaped test pieces. The manufacture of the mold is described in the above-mentioned Lost Wax Precision Casting Method (edited by Japan Foundry Association, published by Sangyo Tosho, 2015), and in this specification, the section on the molding method (pages 9 to 78) is particularly cited. The manufacture of the mold is also described in the above-mentioned "The Superalloys Fundamentals and Applications" (written by Roger C. Reed, Cambridge University Press, 2006), and in this specification, the section on the molding method (pages 122 to 125) is particularly cited.
A mold lifting device (not shown) realizes the mold lifting direction 36 and ensures a cooling rate required for growing the Ni-based superalloy into a single crystal. In general, to unidirectionally solidify a Ni-based superalloy or to grow the Ni-based superalloy into a single crystal, it is necessary to appropriately maintain the ratio of the temperature gradient at the solid-liquid interface and the solidification rate when solidification progresses in one direction in the mold.
　このように構成された真空高周波誘導溶解炉１０を用いて、Ｓｂ含有Ｎｉ基超合金による一方向凝固試験片又は単結晶試験片を鋳造する条件を説明する。
　真空高周波誘導溶解炉１０の鋳造温度は、鋳造合金の凝固開始温度の＋９０～１７０℃であり、鋳型の予熱温度は、１４００～１５５０℃に設定される。Ｎｉの融点は１４５５℃であり、Ｎｉ基超合金の組成元素として用いられる各元素の融点は、Ｃｏ（コバルト）が１４９５℃、Ｃｒ（クロム）が１９０７℃、Ｗ（タングステン）が３４４０℃、Ａｌ（アルミニウム）が６６０℃、Ｔａ（タンタル）が３０２０℃、Ｒｅ（レニウム）が３１８２℃、Ｒｕ（ルテニウム）が２３３４℃等である。したがって、Ｓｂ含有Ｎｉ基超合金が完全に溶解した状態で、溶湯をＣａＯるつぼ１２内で安定させる温度条件としては、１５６０～１６４０℃とすることが好ましい。 The conditions for casting a directionally solidified test piece or a single crystal test piece of an Sb-containing Ni-base superalloy using the vacuum high-frequency induction melting furnace 10 thus constructed will be described below.
The casting temperature of the vacuum high-frequency induction melting furnace 10 is +90 to 170°C of the solidification start temperature of the cast alloy, and the preheating temperature of the mold is set to 1400 to 1550°C. The melting point of Ni is 1455°C, and the melting points of each element used as a constituent element 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, the temperature condition for stabilizing the molten metal in the CaO crucible 12 with the Sb-containing Ni-based superalloy completely melted is preferably 1560 to 1640°C.
　金属材料として、Ｎｉ基単結晶超合金ＴＭＳ－２３８を用いた。表１はＴＭＳ－２３８の組成元素および組成比、表２は機械的特性を表している。参考として、表１には従来合金であるＣＭＳＸ－４、ＭＸ－４／ＰＷＡ１４９７の組成元素および組成比を示し、表２にはＣＭＳＸ－４の機械的特性を示した。
　上記金属材料（ＴＭＳ－２３８）を、以下に示す手順に従い、真空中で高周波溶解して、単結晶試験片を鋳造した。真空度は、６×１０－２Ｐａであった。 The metallic material used was Ni-based single crystal superalloy TMS-238. Table 1 shows the compositional elements and compositional ratios of TMS-238, and Table 2 shows the mechanical properties. For reference, Table 1 shows the compositional elements and compositional ratios of conventional alloys CMSX-4 and MX-4/PWA1497, and Table 2 shows the mechanical properties of CMSX-4.
The above metal material (TMS-238) was melted by high frequency in a vacuum to cast a single crystal test piece according to the following procedure. The degree of vacuum was 6×10 −2 Pa.
　２０００ｇのＮｉ基単結晶超合金ＴＭＳ－２３８をＣａＯるつぼ１２内に設置し、高周波溶解した。次に、Ｎｉ基単結晶超合金ＴＭＳ－２３８が完全に溶解した状態で、１６００℃で溶湯を安定させた。次に、この溶湯内に１０ｐｐｍ相当量のＳｂを投入した。
　一方向凝固炉２０内で、１４００～１５５０℃に予熱した単結晶棒状試験片用鋳型３０に溶湯を投入した。注湯した単結晶棒状試験片用鋳型３０を２００ｍｍ／ｈの速度で一方向凝固炉２０より引き抜き、一方向凝固させた。一方向凝固させたサンプルを凝固、室温まで冷却後、鋳造された単結晶棒状試験片を一方向凝固炉より取り出した。 2000 g of Ni-based single crystal superalloy TMS-238 was placed in a CaO crucible 12 and melted by high frequency. Next, in a state where the Ni-based single crystal superalloy TMS-238 was completely melted, the molten metal was stabilized at 1600° C. Next, Sb in an amount 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 was solidified and cooled to room temperature, the cast single crystal rod-shaped test pieces were removed from the directional solidification furnace.
　他方で、比較対象として、Ａｌ２Ｏ３るつぼ内で溶解した合金から鋳造した単結晶棒状試験片も用意した。
　なお、ＣａＯるつぼ１２に代えてＡｌ２Ｏ３るつぼを用いた点を除き、金属材料としてＮｉ基単結晶超合金ＴＭＳ－２３８を用い、１０ｐｐｍ相当量のＳｂを添加（溶湯内に投入）し、１４００～１５５０℃に予熱した単結晶棒状試験片用鋳型３０に溶湯を投入し、鋳型３０を２００ｍｍ／ｈの速度で一方向凝固炉２０より引き抜いた点は、上記実施例と同じとした。 On the other hand, for comparison, single crystal rod-shaped test pieces were also prepared by casting the alloys melted in an Al 2 O 3 crucible.
In addition, except for the use of an Al 2 O 3 crucible instead of a CaO crucible 12, the metal material was Ni-based single crystal superalloy TMS-238, 10 ppm of Sb was added (injected into the molten metal), the molten metal was poured into a single crystal rod-shaped test piece mold 30 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 example.
　グロー放電質量分析により、ＣａＯるつぼ内で溶解した合金の単結晶棒状試験片には９．５ｐｐｍのＳｂが含まれていることを確認した。また、Ａｌ２Ｏ３るつぼ内で溶解した合金の単結晶棒状試験片には３．８ｐｐｍのＳｂが含まれていた。グロー放電質量分析は、Ｔｈｅｒｍｏ　Ｓｃｉｅｎｔｉｆｉｃ、型式　ＶＧ９０００型により行われた。 Glow discharge mass spectrometry confirmed that the single crystal bars of the alloy melted in the CaO crucible contained 9.5 ppm Sb, and the single crystal bars 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.
　図２は、本発明の一実施例を示すＣａＯるつぼ溶解した合金内で観察されたＣａ－Ｓｂ－Ｏ介在物（ＦＥ－ＥＰＭＡ：電界放出型電子線マイクロアナライザ）を示すもので、（Ａ）は反射電子像、（Ｂ）はＯ（酸素）、（Ｃ）はＣａ（カルシウム）、（Ｄ）はＳｂ（アンチモン）を示している。ＥＰＭＡ（Electron Probe Micro Analysis）では、電子線を試料に照射して、発生する特性Ｘ線を検出することで、試料を構成している元素とその量を測定する。電界放出型の電子銃を搭載したＦＥ(Field Emission)－ＥＰＭＡにより、１００ｎｍ程度の微小領域の元素分析が可能となっている。ＥＢＳＤ(電子線後方散乱回折：Electron Back Scattered Diffraction Pattern)法でのデータ取得は、メーカー名　ＡＭＥＴＥＫ、Ｉｎｃ．　ＥＤＡＸ事業部、型式　ＴＥＡＭＴＭ　ＥＤＳにより行われた。 FIG. 2 shows Ca-Sb-O inclusions (FE-EPMA: Field Emission Electron Probe Microanalyzer) observed in an alloy melted in a CaO crucible according to an embodiment of the present invention, where (A) is a backscattered electron image, (B) is O (oxygen), (C) is Ca (calcium), and (D) is Sb (antimony). In EPMA (Electron Probe Micro Analysis), an electron beam is irradiated onto a sample, and the elements constituting the sample and their amounts are measured by detecting the characteristic X-rays that are generated. FE (Field Emission)-EPMA equipped with a field emission electron gun enables elemental analysis of a microscopic area of about 100 nm. Data acquisition by the EBSD (Electron Back Scattered Diffraction Pattern) method was performed using a TEAM TM EDS, EDAX Division, manufacturer name, AMETEK, Inc.
　ＣａＯるつぼ内で溶解した合金の微細組織観察（ＦＥ－ＥＰＭＡ）によって、Ｃａ－Ｓｂ－Ｏ介在物（Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３　質量比）が観察された。Ｃａ：Ｓｂ：Ｏ＝１：３：２（質量比）は、化学式でＣａＳｂＯ５に相当している。Ｃａ：Ｓｂ：Ｏ＝１：４：３（質量比）は、化学式でＣａ３Ｓｂ４Ｏ２３に相当している。Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍであった。 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 CaSbO 5. Ca:Sb:O = 1:4:3 (mass ratio) corresponds to the chemical formula Ca 3 Sb 4 O 23. The particle shape of the Ca-Sb-O inclusions had a particle size of 100 to 500 nm.
　単結晶棒状試験片から直径９ｍｍ、高さ５ｍｍの酸化試験片（図３）を作製し、１１００℃－１ｈ、室温保持－１ｈを１サイクルとする繰り返し酸化試験を行った。図４は、繰り返し酸化試験の結果を示す図である。
　図４に示されるように、Ａｌ２Ｏ３るつぼ内で溶解した合金の試験片では、繰り返し酸化試験開始当初と比較して、１サイクル目から質量が０．２［ｍｇ／ｃｍ２］増加し、１５サイクル目から質量減少が始まり、１００サイクルでの質量減少は３．８［ｍｇ／ｃｍ２］であった。
　一方、ＣａＯるつぼ内で溶解した合金の試験片では、繰り返し酸化試験開始当初と比較して、１サイクル目から質量が０．２［ｍｇ／ｃｍ２］増加し、１００サイクル目では質量が０．３［ｍｇ／ｃｍ２］増加した。即ち、繰り返し酸化試験が１００サイクルまで酸化試験片の質量減少が無かった。
　ＣａＯるつぼ溶解した合金では、ＥＢＳＤを用いて酸化試験片を構成している元素とその量を測定した結果によると、酸化膜－母材界面にＳｂの偏析が見られなかったため、Ｃａ－Ｓｂ－Ｏ介在物により界面へのＳｂの拡散を抑制したと考えられる。
　以上から、Ｎｉ基超合金内でのＣａ－Ｓｂ－Ｏ介在物生成により、低融点金属系不純物元素Ｓｂが含まれるＮｉ基超合金の耐酸化性の劣化が防止されることが確認された。 Oxidation test pieces with a diameter of 9 mm and a height of 5 mm (Fig. 3) were prepared from the single crystal rod-shaped test pieces, and a cyclic oxidation test was carried out in which one cycle consisted of 1100°C-1h, room temperature holding-1h. Fig. 4 shows the results of the cyclic oxidation test.
As shown in Figure 4, the mass of the alloy test piece melted in the Al2O3 crucible increased by 0.2 [mg/ cm2 ] from the first cycle compared to the initial state of the repeated oxidation test, and the mass began to decrease from the 15th cycle, resulting in a mass decrease of 3.8 [mg/ cm2 ] at 100 cycles.
On the other hand, the mass of the test piece of the alloy melted in the CaO crucible increased by 0.2 [mg/ cm2 ] from the first cycle compared to the beginning of the cyclic oxidation test, and increased by 0.3 [mg/ cm2 ] at the 100th cycle. In other words, there was no mass reduction of the oxidized test piece up to the 100th cycle of the cyclic oxidation test.
In the alloy melted in a CaO crucible, the elements constituting the oxidized test piece and their amounts were measured using EBSD. As a result, no segregation of Sb was observed at the interface between the oxide film and the base material. It is considered that the diffusion of Sb to the interface was suppressed by Ca-Sb-O inclusions.
From the above, it was confirmed that the formation of Ca--Sb--O inclusions in the Ni-base superalloy prevents the deterioration of the oxidation resistance of the Ni-base superalloy containing the low-melting point metallic impurity element Sb.
　なお、上記の実施例においては、ＣａＯるつぼを用いて、ＣａＯるつぼとＮｉ基超合金用原料の溶湯との接触により、当該Ｎｉ基超合金用原料に含有する不純物Ｓｂによる耐酸化性劣化作用をマスキングするＣａとＯを供給する場合を示したが、本発明はこれに限定されるものではない。別の実施形態としては、例えば、Ｎｉ基超合金用原料を溶解するるつぼにＡｌ２Ｏ３るつぼ又はＭｇＯるつぼを用い、上述のマスキング作用をするＣａとＯを別途、Ｎｉ基超合金用原料又は当該Ｎｉ基超合金用原料の溶湯に供給するようにしても良い。 In the above embodiment, a CaO crucible is used to supply Ca and O that mask the oxidation resistance deterioration caused by the impurity Sb contained in the Ni-base superalloy raw material by contacting the CaO crucible with the molten Ni-base superalloy raw material, but the present invention is not limited to this. As 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 have the above-mentioned masking effect may be separately supplied to the Ni-base superalloy raw material or the molten Ni-base superalloy raw material.
　ＣａをＮｉ基超合金用原料（又はその溶湯）に供給するものとして、不純物Ｓｂの含有量の質量比で０．３３倍以上１００倍以下のＣａ（カルシウム）を供給するべく、相当量のフッ化カルシウムやカルシウム化合物を混合してもよい。この場合、カルシウム化合物の組成元素は、目的のＮｉ基超合金の耐熱性や耐酸化性を阻害する有害元素、例えばＡｓ（ヒ素）、Ｓ（硫黄）等を含まないものである必要がある。 When Ca is supplied to the raw material (or its molten metal) for the Ni-base superalloy, a significant amount of calcium fluoride or a calcium compound may be mixed in to supply Ca (calcium) in a mass ratio of 0.33 to 100 times the content of the impurity Sb. In this case, the composition elements of the calcium compound must not contain harmful elements that impair the heat resistance and oxidation resistance of the target Ni-base superalloy, such as As (arsenic) and S (sulfur).
　ＯをＮｉ基超合金用原料に供給するものとしては、Ａｌ２Ｏ３るつぼ又はＭｇＯるつぼからＮｉ基超合金用原料（又はその溶湯）への溶出が想定されることに加え、真空高周波溶解であっても、上記実施例のように６×１０－２Ｐａ以下の真空度であれば、この真空中に残存したＯ２原子からＮｉ基超合金用原料（又はその溶湯）へ溶け込むことが考えられる。 As a source of supplying O to the Ni-base superalloy raw material, it is assumed that O dissolves from an Al 2 O 3 crucible or an MgO crucible into the Ni-base superalloy raw material (or its molten metal). In addition, even in the case of vacuum high-frequency melting, if the degree of vacuum is 6×10 −2 Pa or less as in the above example, it is thought that O dissolves from O 2 atoms remaining in the vacuum into the Ni-base superalloy raw material (or its molten metal).
　また、上記の実施例においては、真空高周波誘導溶解炉を用いて、Ｎｉ基超合金用原料としてＮｉ基超合金を用いて一方向凝固又は単結晶によりＮｉ基超合金部材を鋳造をする場合を示したが、普通鋳造により多結晶のタービン部品を製造するものでもよい。普通鋳造の場合は、多結晶用鋳型を用いる。多結晶用鋳型には、単結晶棒状試験片用鋳型に設けられていたセレクタやチルプレートが、設けられていない。また、一般に、普通鋳造による真空高周波誘導溶解炉では、鋳型の予熱温度は８００～１１００℃で行われる。 In the above examples, a vacuum high-frequency induction melting furnace is used to cast Ni-based superalloy components by unidirectional solidification or single crystallization using Ni-based superalloys as raw materials for the Ni-based superalloy, but polycrystalline turbine parts may also be manufactured by conventional casting. In the case of conventional casting, a polycrystalline mold is used. A polycrystalline mold does not have a selector or chill plate that is provided in a mold for single crystal rod-shaped test pieces. In addition, in general, in a vacuum high-frequency induction melting furnace for conventional casting, the mold is preheated to a temperature of 800 to 1100°C.
　さらに、上記の実施例においては、２ｋｇのＮｉ基単結晶超合金をＣａＯるつぼ内に設置する場合を示したが、製造現場での大型溶解（例えば３トン溶解）のようにＣａＯるつぼの作製が困難な場合、Ａｌ２Ｏ３るつぼやＭｇＯなどの通常の材質のるつぼにて溶解し、溶湯に顆粒（例えば約５ｍｍ径であり、好ましくは粒径１～１０ｍｍの顆粒状であるとよい）のＣａＯを添加することによって、所要のＣａの添加を行うことができる。この場合、ＣａＯの添加量は、例えば基準値として溶湯１００ｋｇ当たり２ｋｇの比率とするのが良く、好ましくはＮｉ基超合金用原料を基準に重量比で０．２％～５％に相当する比率であるとよい。
　ポイントは、Ｎｉ基超合金用原料の溶湯とＣａＯを接触させることであり、余剰のＣａＯはスラグとして当該溶湯には溶け込まないため、製造される一方向凝固部材、単結晶鋳造部材、又は多結晶凝固部材のＣａの組成比に対する影響は軽微である。なお、Ｎｉ基超合金用原料の溶湯にＣａＯ顆粒を添加する場合を示したが、本発明はこれに限定されるものではなく、Ｎｉ基超合金用原料にＣａＯ顆粒を添加してから、溶解するものでもよい。
　また、ＣａＯに代えてＣａＦ２（蛍石）を用いても良い。 Furthermore, in the above embodiment, 2 kg of Ni-based single crystal superalloy is placed in a CaO crucible, but when it is difficult to prepare a CaO crucible, such as in a large melting operation (e.g., 3 ton melting) at a manufacturing site, the required Ca can be added by melting in a crucible made of a normal material such as an Al 2 O 3 crucible or MgO, and adding CaO granules (e.g., about 5 mm in diameter, preferably 1 to 10 mm in diameter) to the molten metal. In this case, the amount of CaO added is preferably 2 kg per 100 kg of molten metal as a standard value, and preferably a ratio equivalent to 0.2% to 5% by weight based on the raw material for the Ni-based superalloy.
The point is to bring the molten Ni-base superalloy raw material into contact with CaO, and since excess CaO does not dissolve in the molten metal as slag, the effect on the Ca composition ratio of the directionally solidified component, single crystal cast component, or polycrystalline solidified component to be manufactured is minor. Note that, although the case where CaO granules are added to the molten Ni-base superalloy raw material has been shown, the present invention is not limited to this, and CaO granules may be added to the Ni-base superalloy raw material before melting.
Moreover, CaF 2 (fluorite) may be used in place of CaO.
　本発明のＮｉ基超合金の製造方法によれば、添加元素Ｃａによって、Ｓｂによる耐酸化性劣化作用をマスキングすることができ、例えばボイラ配管用Ｎｉ基耐熱合金用の低グレードの材料を使用しても、従来のタービン翼用Ｎｉ基超合金用の高グレードの材料を使用して作製したＮｉ基超合金と同等の耐酸化性を発揮することが期待できる。 　According to the manufacturing method of the Ni-base superalloy of the present invention, the additive element Ca can mask the oxidation resistance degradation effect caused by Sb, so that even if a low-grade material for Ni-base heat-resistant alloys for boiler piping is used, it is expected that the Ni-base superalloys will exhibit oxidation resistance equivalent to that of Ni-base superalloys made using high-grade materials for conventional Ni-base superalloys for turbine blades.
１０　真空高周波誘導溶解炉
１２　ＣａＯるつぼ
１４　溶解用高周波コイル
１６　るつぼ傾注方向
２０　一方向凝固炉
２２　鋳型用高周波コイル
２４　グラファイト抵抗発熱体
２５　上部ライニング
２６　側壁絶縁材（マイカシート）
２７　上部絶縁材（耐火レンガ）
２８　注ぎ口
２９　底部絶縁材（耐火レンガ）
３０　単結晶棒状試験片用鋳型
３２　セレクタ
３４　鋳型基台部
３６　鋳型昇降方向 10 Vacuum high-frequency induction melting furnace 12 CaO crucible 14 Melting high-frequency coil 16 Crucible tilt direction 20 Directional solidification furnace 22 Mold high-frequency coil 24 Graphite resistance heating element 25 Upper lining 26 Side wall insulating material (mica sheet)
27 Upper insulation material (firebrick)
28 spout 29 bottom insulation material (firebrick)
30: mold for single crystal rod-shaped test piece 32: selector 34: mold base 36: mold lifting direction

Claims (17)

  1. 　所定組成のＳｂ含有のＮｉ基超合金用原料をるつぼに投入し、高周波誘導溶解炉により、真空中で高周波溶解させると共に、前記Ｎｉ基超合金用原料の溶湯に対して前記Ｓｂの耐酸化性阻害作用を防止するに必要な量のＣａ（カルシウム）を添加し、
    　前記Ｎｉ基超合金用原料が完全に溶解した状態で、１５６０～１６４０℃で溶湯を前記るつぼ内で１０～６０分の間安定させ、
    　一方向凝固炉内で所定温度に予熱した鋳型に前記溶湯を投入すると共に、
    　注湯した前記鋳型を５０～３５０ｍｍ／ｈの速度で前記高周波誘導溶解炉より引き抜き、前記Ｎｉ基超合金用原料を一方向凝固、単結晶凝固、又は多結晶凝固させ、
    　室温まで冷却後、鋳造された一方向凝固部材、単結晶鋳造部材又は多結晶凝固部材を前記一方向凝固炉より取り出す、
    　工程を含むＮｉ基超合金の製造方法。     A Ni-base superalloy raw material containing Sb of a predetermined composition is placed in a crucible and high-frequency melted in a vacuum using a high-frequency induction melting furnace, and Ca (calcium) is added to the molten Ni-base superalloy raw material in an amount necessary to prevent the oxidation resistance inhibiting action of Sb,
    With the Ni-base 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 directional 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 raw material for the Ni-base superalloy is unidirectionally solidified, solidified as a single crystal, or solidified as a polycrystal.
    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-base superalloy comprising the steps of:
  2. 　前記るつぼはＣａＯるつぼであり、
    　前記Ｃａ（カルシウム）は、前記ＣａＯるつぼと前記Ｎｉ基超合金用原料の溶湯との接触により、前記Ｎｉ基超合金用原料の溶湯に対して供給される、
    　請求項１に記載のＮｉ基超合金の製造方法。     The crucible is a CaO crucible,
    The Ca (calcium) is supplied to the molten metal of the Ni-base superalloy raw material by contact between the CaO crucible and the molten metal of the Ni-base superalloy raw material.
    A method for producing the Ni-base superalloy according to claim 1.
  3. 　前記るつぼはＡｌ２Ｏ３るつぼ又はＭｇＯるつぼであり、
    　前記Ｃａ（カルシウム）は、前記Ｎｉ基超合金用原料又は前記Ｎｉ基超合金用原料の溶湯中に、重量比で前記Ｎｉ基超合金用原料を基準に０．２％～５％に相当するＣａＯを添加することにより行われる、
    　請求項１に記載のＮｉ基超合金の製造方法。     The crucible is an Al2O3 crucible or an MgO crucible,
    The Ca (calcium) is added to the Ni-based superalloy raw material or the molten Ni-based superalloy raw material by adding CaO equivalent to 0.2% to 5% by weight based on the Ni-based superalloy raw material;
    A method for producing the Ni-base superalloy according to claim 1.
  4. 　前記ＣａＯは、粒径１～１０ｍｍの顆粒状である請求項３に記載のＮｉ基超合金の製造方法。 The method for producing a Ni-based superalloy according to claim 3, wherein the CaO is in the form of granules having a particle size of 1 to 10 mm.
  5. 　前記るつぼはＡｌ２Ｏ３るつぼ又はＭｇＯるつぼであり、
    　前記Ｃａ（カルシウム）は、前記Ｎｉ基超合金用原料又は前記Ｎｉ基超合金用原料の溶湯中に、質量比で前記Ｓｂの０．３３倍以上１００倍以下のＣａ（カルシウム）に相当する量を添加することにより行われる、
    　請求項１に記載のＮｉ基超合金の製造方法。     The crucible is an Al2O3 crucible or an MgO crucible,
    The Ca (calcium) is added to the Ni-based superalloy raw material or the molten metal of the Ni-based superalloy raw material in an amount equivalent to 0.33 times or more and 100 times or less of the Sb in mass ratio.
    A method for producing the Ni-base superalloy according to claim 1.
  6. 　前記Ｃａ（カルシウム）は、ＣａＦ２の成分として供給され、ＣａＦ２が前記Ｎｉ基超合金用原料に添加され、又は前記Ｎｉ基超合金用原料の溶湯に対して添加される、
    　請求項５に記載のＮｉ基超合金の製造方法。     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;
    A method for producing the Ni-base superalloy according to claim 5.
  7. 　前記鋳型は、単結晶用鋳型であり、
    　前記鋳型を前記一方向凝固炉内で、予熱する所定温度は１４００～１５５０℃であり、
    　前記単結晶用鋳型は水冷チルプレートにより底部が冷却されるものである、
    　請求項１乃至６の何れかに記載のＮｉ基超合金の製造方法。     the template is a single crystal template,
    The predetermined temperature to which the mold is preheated in the directional 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-base superalloy according to any one of claims 1 to 6.
  8. 　前記鋳型は、多結晶用鋳型であり、
    　前記鋳型を前記一方向凝固炉内で、予熱する所定温度は１０００～１１００℃である、
    　請求項１乃至６の何れかに記載のＮｉ基超合金の製造方法。     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-base superalloy according to any one of claims 1 to 6.
  9. 　前記一方向凝固部材、単結晶鋳造部材、又は多結晶凝固部材は、質量比で
    Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３
    のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍである、
    　請求項１乃至８の何れかに記載のＮｉ基超合金の製造方法。     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-base superalloy according to any one of claims 1 to 8.
  10. 　前記Ｎｉ基超合金用原料は、前記鋳型に投入される前の溶解状態で、質量％で、
    Ｃｒ（クロム）：２％以上２５％以下、
    Ｃｏ（コバルト）：０％以上２５％以下、
    Ｍｏ（モリブデン）：０％以上８％以下、
    Ｒｅ（レニウム）：０％以上１０％以下、
    Ｒｕ（ルテニウム）：０％以上１０％以下、
    Ｗ（タングステン）：０％以上１４％以下、
    Ｎｂ（ニオブ）：０％以上５％以下、
    Ｖ（バナジウム）：０％以上３％以下、
    Ａｌ（アルミニウム）：１％以上１０％以下、
    Ｔｉ（チタン）：０％以上１０％以下、
    Ｔａ（タンタル）：０％以上１３％以下、
    Ｈｆ（ハフニウム）：０％以上２．５％以下、
    Ｃ（炭素）：０％以上０．５％以下、
    Ｂ（ホウ素）：０％以上０．１％以下、
    Ｚｒ（ジルコニウム）：０％以上０．５％以下、
    Ｆｅ（鉄）：０％以上２０％以下、
    Ｓｉ（ケイ素）：０％以上１％以下、
    残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
    Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
    Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きい、
    　請求項１乃至９の何れかに記載のＮｉ基超合金の製造方法。     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,
    Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 5 PPM or more and 500 PPM or less, the Ca content ratio being greater than 1/4 of the Sb content ratio,
    A method for producing the Ni-base superalloy according to any one of claims 1 to 9.
  11. 　前記Ｎｉ基超合金用原料は、前記鋳型に投入される前の溶解状態で、質量％で、
    Ｃｒ（クロム）：４％以上１０％以下、
    Ｃｏ（コバルト）：０％以上１２％以下、
    Ｍｏ（モリブデン）：０％以上４％以下、
    Ｒｅ（レニウム）：２％以上１０％以下、
    Ｒｕ（ルテニウム）：２％以上８％以下、
    Ｗ（タングステン）：２％以上８％以下、
    Ｎｂ（ニオブ）：０％以上２．５％以下、
    Ｖ（バナジウム）：０％以上０．５％以下、
    Ａｌ（アルミニウム）：３％以上８％以下、
    Ｔｉ（チタン）：０％以上３％以下、
    Ｔａ（タンタル）：４％以上１０％以下、
    Ｈｆ（ハフニウム）：０％以上１％以下、
    Ｃ（炭素）：０％以上０．０５％以下、
    Ｂ（ホウ素）：０％以上０．０２％以下、
    Ｚｒ（ジルコニウム）：０％以上０．１％以下、
    Ｆｅ（鉄）：０％以上５％以下、
    Ｓｉ（ケイ素）：０％以上０．５％以下、
    残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
    Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
    Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きい、
    　請求項１０に記載のＮｉ基超合金の製造方法。     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): 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,
    Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 5 PPM or more and 500 PPM or less, the Ca content ratio being greater than 1/4 of the Sb content ratio,
    The method for producing the Ni-base superalloy according to claim 10.
  12. 　前記Ｃａの含有比はＳｂの含有比の１／３よりも大きい請求項１０又は１１に記載のＮｉ基超合金の製造方法。 The method for producing a Ni-based superalloy according to claim 10 or 11, wherein the Ca content is greater than 1/3 of the Sb content.
  13. 　質量％で、
    Ｃｒ（クロム）：２％以上２５％以下、
    Ｃｏ（コバルト）：０％以上２５％以下、
    Ｍｏ（モリブデン）：０％以上８％以下、
    Ｒｅ（レニウム）：０％以上１０％以下、
    Ｒｕ（ルテニウム）：０％以上１０％以下、
    Ｗ（タングステン）：０％以上１４％以下、
    Ｎｂ（ニオブ）：０％以上５％以下、
    Ｖ（バナジウム）：０％以上３％以下、
    Ａｌ（アルミニウム）：１％以上１０％以下、
    Ｔｉ（チタン）：０％以上１０％以下、
    Ｔａ（タンタル）：０％以上１３％以下、
    Ｈｆ（ハフニウム）：０％以上２．５％以下、
    Ｃ（炭素）：０％以上０．５％以下、
    Ｂ（ホウ素）：０％以上０．１％以下、
    Ｚｒ（ジルコニウム）：０％以上０．５％以下、
    Ｆｅ（鉄）：０％以上２０％以下、
    Ｓｉ（ケイ素）：０％以上１％以下、
    残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
    Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
    Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きく、且つ質量比で、
    Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３
    のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍである、
    　Ｓｂによる耐酸化性の劣化を予防したＮｉ基超合金部材。     In mass percent,
    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,
    The composition contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 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.
    A Ni-based superalloy component that prevents the deterioration of oxidation resistance caused by Sb.
  14. 　前記Ｎｉ基超合金用部材は、質量％で、
    Ｃｒ（クロム）：４％以上１０％以下、
    Ｃｏ（コバルト）：０％以上１２％以下、
    Ｍｏ（モリブデン）：０％以上４％以下、
    Ｒｅ（レニウム）：２％以上１０％以下、
    Ｒｕ（ルテニウム）：２％以上８％以下、
    Ｗ（タングステン）：２％以上８％以下、
    Ｎｂ（ニオブ）：０％以上２．５％以下、
    Ｖ（バナジウム）：０％以上０．５％以下、
    Ａｌ（アルミニウム）：３％以上８％以下、
    Ｔｉ（チタン）：０％以上３％以下、
    Ｔａ（タンタル）：４％以上１０％以下、
    Ｈｆ（ハフニウム）：０％以上１％以下、
    Ｃ（炭素）：０％以上０．０５％以下、
    Ｂ（ホウ素）：０％以上０．０２％以下、
    Ｚｒ（ジルコニウム）：０％以上０．１％以下、
    Ｆｅ（鉄）：０％以上５％以下、
    Ｓｉ（ケイ素）：０％以上０．５％以下、
    残部をＮｉ（ニッケル）及び不可避的不純物とする組成で表されると共に、
    Ｓｂ（アンチモン）：０．５ＰＰＭ以上５０ＰＰＭ以下、及び
    Ｃａ（カルシウム）：５ＰＰＭ以上５００ＰＰＭ以下を含有し、Ｃａの含有比はＳｂの含有比の１／４よりも大きく、且つ質量比で
    Ｃａ：Ｓｂ：Ｏ＝１：３：２～１：４：３
    のＣａ－Ｓｂ－Ｏ介在物が析出しており、前記Ｃａ－Ｓｂ－Ｏ介在物の粒子形状は粒径が１００～５００ｎｍである、
    　請求項１３に記載のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材。     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,
    The alloy contains Sb (antimony): 0.5 PPM or more and 50 PPM or less, and Ca (calcium): 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 of Ca:Sb:O is 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 13, which is prevented from deterioration of oxidation resistance due to Sb.
  15. 　前記Ｎｉ基超合金用部材は、
    　一方向凝固部材、単結晶鋳造部材、又は多結晶凝固部材である、
    　請求項１３又は１４に記載のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材。     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 13 or 14, which is prevented from deterioration of oxidation resistance due to Sb.
  16. 　請求項１０又は１１に記載の組成条件を満足する粉末状のＮｉ基超合金用原料を用いて焼結または３Ｄ造形で作製されたタービンブレード又はタービンベーン部品である、
    　請求項１３又は１４に記載のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材。     A turbine blade or turbine vane part manufactured by sintering or 3D molding using a powdered Ni-based superalloy raw material satisfying the composition conditions according to claim 10 or 11.
    The Ni-based superalloy member according to claim 13 or 14, which is prevented from deterioration of oxidation resistance due to Sb.
  17. 　前記Ｎｉ基超合金用部材は、
    　前記Ｎｉ基超合金用部材から直径９ｍｍ、高さ５ｍｍの酸化試験片を作製し、１１００℃－１ｈ、室温保持－１ｈを１サイクルとする繰り返し酸化試験で、１００サイクルまで質量減少が見られないものである、
    　請求項１３又は１４に記載のＳｂによる耐酸化性の劣化を予防したＮｉ基超合金部材。     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 h, room temperature holding-1 h, no mass loss is observed up to 100 cycles.
    The Ni-based superalloy member according to claim 13 or 14, which is prevented from deterioration of oxidation resistance due to Sb.
PCT/JP2023/034641 2022-10-03 2023-09-25 Method for producing ni-based superalloy prevented from deterioration of oxidation resistance due to sb, and ni-based superalloy member prevented from deterioration of oxidation resistance due to sb WO2024075560A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6299427A (en) * 1985-10-28 1987-05-08 Mitsui Eng & Shipbuild Co Ltd Method for regulating content of trace metal in alloy
JP2013108166A (en) * 2011-11-17 2013-06-06 Cannon-Muskegon Corp Rhenium-free single crystal superalloy for turbine blade and vane application
JP2013119668A (en) * 2011-12-06 2013-06-17 Cannon-Muskegon Corp Low rhenium single crystal superalloy for turbine blade and vane
JP2015214744A (en) * 2014-05-08 2015-12-03 キャノン−マスキーゴン コーポレイション High strength single crystal superalloy

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6299427A (en) * 1985-10-28 1987-05-08 Mitsui Eng & Shipbuild Co Ltd Method for regulating content of trace metal in alloy
JP2013108166A (en) * 2011-11-17 2013-06-06 Cannon-Muskegon Corp Rhenium-free single crystal superalloy for turbine blade and vane application
JP2013119668A (en) * 2011-12-06 2013-06-17 Cannon-Muskegon Corp Low rhenium single crystal superalloy for turbine blade and vane
JP2015214744A (en) * 2014-05-08 2015-12-03 キャノン−マスキーゴン コーポレイション High strength single crystal superalloy

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