WO2023243146A1

WO2023243146A1 - Ni-based alloy member manufacturing method

Info

Publication number: WO2023243146A1
Application number: PCT/JP2023/005820
Authority: WO
Inventors: 大地赤間; 正樹種池
Original assignee: 三菱重工業株式会社
Priority date: 2022-06-17
Filing date: 2023-02-17
Publication date: 2023-12-21
Also published as: JP2023184086A

Abstract

An Ni-based alloy member manufacturing method according to the present disclosure comprises a casting step, a first strain removing heat treatment step, a solutionizing heat treatment step, and an aging step. In the casting step, an Ni-based alloy casting material is casted, in which a γ'-phase in an amount of 50 vol.% or more can be deposited in a γ-phase in the aging step. In the first strain removing heat treatment step, the Ni-based alloy casting material obtained after the casting step is heated for 1 hour or longer in a first strain removing temperature range of Ts×0.90°C to Ts°C, when Ts°C represents the solid solution temperature of the 'γ-phase. In the solutionizing heat treatment step, the Ni-based alloy casting material obtained after the first strain removing heat treatment step is heated from the first strain removing temperature range to a solutionizing temperature range of higher than Ts+t1°C but not higher than Tm°C, when Tm°C represents the melting point of the γ-phase and t1 represents a temperature 10°C or lower, and the temperature is held in the solutionizing temperature range for 2 hours or longer.

Description

Manufacturing method of Ni-based alloy member

The present disclosure relates to a method for manufacturing a Ni-based alloy member.
This application claims priority to Japanese Patent Application No. 2022-98014 filed in Japan on June 17, 2022, the contents of which are incorporated herein.

High-temperature components (such as turbine blades) used in thermal power plants and aircraft turbines often use Ni-based alloys in order to satisfy mechanical properties in high-temperature environments.

In Ni-based alloys used for high-temperature parts, the γ' (gamma prime) phase (L1 ₂ structure), whose crystal lattice matches the γ phase, is precipitated in the γ (gamma) phase (FCC phase), which is the parent phase. Obtains high strength.

In parts using γ' phase precipitation strengthened Ni-based alloys (Ni-based alloy members), which are strengthened by precipitation of the γ' phase, solid solution is used to dissolve the γ' phase precipitated during casting into the base material. Perform heat treatment. When casting a Ni-based alloy member, internal strain occurs because there is a difference in coefficient of thermal expansion between the Ni-based alloy, the mold, and the core. When solid solution heat treatment is performed at a high temperature in a state where internal strain exists, the internal strain is used as a driving force to generate recrystallized grains that cause deterioration of strength properties.

As a method for suppressing recrystallization, Patent Document 1 discloses a step of casting a nickel-based superalloy single crystal article in which a coarse γ' phase is present in a γ phase matrix; solidification after said casting or subsequent handling. during which stress concentrations are formed in the single-crystal article, during which recrystallization is performed when the single-crystal article is heated to a solution treatment temperature to cause the γ' phase to form a solid solution within the γ phase. forming a stress concentration strong enough to cause the stress concentration to occur; heating the single crystal article at a recovery temperature lower than the recrystallization temperature in the area where the stress concentration exists to reduce the strength of the stress concentration; After the stress concentration reduction, heating the article at a temperature lower than the solidus temperature of the article but higher than the recrystallization temperature and recovery temperature to dissolve the γ' phase into the γ phase. and a precipitation step in which the refined γ' phase is then precipitated into the γ phase matrix, but the single crystal structure of the article can be maintained. A method of manufacturing an alloy article is disclosed.

Furthermore, Patent Document 2 states that a used member, which is a Ni-based alloy member used in a turbine for a predetermined period of time, is heated to a temperature that is 10°C higher than the solid solution temperature of the γ' phase and 10°C lower than the melting point of the γ phase. A solution/non-recrystallization heat treatment step S2 in which solution/non-recrystallization heat treatment is performed at the following temperature and for a holding time within a time range in which recrystallization grains of the γ phase do not occur; and an aging step S3 in which the used member is subjected to an aging treatment to precipitate the γ' phase in the γ phase, and the used member after the solution treatment/non-recrystallization heat treatment step S2 is When the rocking curve of a predetermined crystal plane of the γ-phase crystal grains is measured by the XRD method, the half width of the rocking curve is 0.25° or more and 0.30° or less. A manufacturing method is disclosed.

Japanese Unexamined Patent Publication No. 59-64593 JP 2019-112702 Publication

However, in the manufacturing methods disclosed in Patent Documents 1 and 2, if 50% by volume or more of the γ' phase precipitates, recrystallization may not be sufficiently suppressed in some cases.

The present disclosure has been made in order to solve the above-mentioned problems, and an object of the present disclosure is to provide a method for manufacturing a Ni-based alloy member that can suppress the generation of recrystallized grains even when 50 volume % or more of the γ' phase is precipitated. purpose.

The method for manufacturing a Ni-based alloy member of the present disclosure includes a casting step, a first strain removal heat treatment step, a solution heat treatment step, and an aging step, and in the casting step, in the aging step, a γ phase is formed. A Ni-based alloy cast material having a chemical composition in which 50% by volume or more of the γ' phase can be precipitated is cast, and in the first strain removal heat treatment step, when the solid solution temperature of the γ' phase is Ts°C, Ts The Ni-based alloy cast material after the casting step is heated for at least 1 hour in a first strain relief temperature range of ×0.90°C or higher and Ts°C or lower, and in the solution heat treatment step, the melting point of the γ phase is lowered. When Tm°C, the Ni-based alloy cast material after the first strain removal heat treatment step is heated from the first strain removal temperature range to a solution temperature range of more than Ts+t1°C and below Tm°C, and the solution treatment is performed. The temperature is maintained in the temperature range for 2 hours or more, and the t1 is 10°C or less.

According to the above aspect of the present invention, it is possible to provide a method for manufacturing a Ni-based alloy member that can suppress the generation of recrystallized grains even when 50% by volume or more of the γ' phase is precipitated.

1 is a flowchart of a method for manufacturing a Ni alloy member according to a first embodiment of the present invention. It is an electron micrograph of the Ni alloy member based on 1st Embodiment of this invention. It is a flow chart of the manufacturing method of the Ni alloy member concerning a 2nd embodiment of the present invention. FIG. 3 is a diagram for explaining the observation direction of a sample after a heat treatment test. It is an appearance observation photograph after heat treatment under condition A. It is an appearance observation photograph after heat treatment under condition B. It is an appearance observation photograph after heat treatment under condition C.

As a result of intensive studies by the present inventors, the strain that causes recrystallization is removed within a predetermined temperature range in a Ni-based alloy that has a chemical composition that allows precipitation of 50 volume % or more of the γ' phase (e.g., NiAl phase). However, it was found that recrystallization can be greatly reduced by allowing the γ' phase to form a solid solution without subsequent cooling. The present invention is based on the above knowledge. Note that the Ni-based alloy is, for example, an alloy containing 50% by mass or more of Ni and selected from the group consisting of Cr, W, Al, Ta, Co, Mo, Ti, C, and B. It is an alloy containing

<First embodiment>
Hereinafter, with reference to FIG. 1, a method S100 for manufacturing a Ni-based alloy member according to the first embodiment will be described. FIG. 1 is a flowchart of a method S100 for manufacturing a Ni-based alloy member according to an embodiment. The method S100 for manufacturing a Ni-based alloy member includes a casting step S10, a first strain removal heat treatment step S11, a solution heat treatment step S13, and an aging step S14. Each step will be explained below. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower limit and upper limit. Note that in this specification, the temperature such as heating temperature is the temperature of the surface of the Ni-based alloy cast material.

(Casting process S10)
In the casting step S10, a Ni-based alloy cast material is cast in which 50% by volume or more of the γ' phase can be precipitated in the γ phase in the aging step S14. The casting method is not particularly limited. The Ni-based alloy cast material can be manufactured, for example, by a lost wax method. Since it contains active metals such as Al, it is preferable to melt and cast it in a vacuum. For example, a Ni-based alloy casting material is obtained by melting the composition components constituting the Ni-based alloy and injecting the resulting molten metal into a void formed by a mold, a core, and the like.

The chemical composition of the Ni-based alloy cast material is not particularly limited as long as 50% by volume or more of the γ' phase can be precipitated in the γ phase in the aging step S14. Such a Ni-based alloy casting material has, for example, a chemical composition in mass % of Cr: 5 to 15%, W: 3 to 10%, Al: 3.0 to 7.0%, Ta: 3 to 15%. %, Co: 0 to 15%, Mo: 0 to 5%, Ti: 0 to 5.0%, C: 0 to 0.10%, B: 0 to 0.05%, the balance being Ni and impurities. It is a Ni-based alloy consisting of

Cr: 5-15%
Cr is an element that forms M ₂₃ C ₆ precipitates that improve strength at high temperatures. Moreover, by containing Cr, oxidation resistance in a high temperature environment is also improved. In order to obtain the above effects, the Cr content is preferably 5% or more. The Cr content is preferably 8% or more. If the Cr content exceeds 15%, harmful phases will precipitate, causing a decrease in strength and ductility of the Ni-based alloy member, so the Cr content is preferably 15% or less.

W: 3-10%
W is an element that dissolves in the γ phase, which is the matrix of the Ni-based alloy, and contributes to improving the strength of the Ni-based alloy member through solid solution strengthening. In order to obtain the above effects, the W content is preferably 3% or more. A more preferable W content is 4% or more. If the W content exceeds 10%, harmful phases will precipitate, causing a decrease in strength and ductility of the Ni-based alloy member, so the W content is preferably 10% or less. A more preferable W content is 8% or less.

Al: 3.0-7.0%
Al is an element that generates a γ' phase that improves the strength of Ni-based alloy members at high temperatures. Furthermore, Al is an element that is effective in improving oxidation resistance and corrosion resistance at high temperatures. In order to obtain the above effects, the Al content is preferably 3.0% or more. A more preferable Al content is 3.5% or more. If the Al content exceeds 7.0%, the weldability of the Ni-based alloy member will be reduced, and there is a risk that cracks will occur during manufacture or repair of the Ni-based alloy member. Therefore, the Al content is preferably 7.0% or less. A more preferable Al content is 5.5% or less.

Ta: 3-15%
Ta is an element that generates a γ' phase that improves the strength of Ni-based alloy members at high temperatures. In order to obtain the above effects, the Ta content is preferably 3% or more. A more preferable Ta content is 4% or more. When the Ta content exceeds 15%, MC carbides that are stable at high temperatures are generated within the crystal grains, and M ₂₃ C ₆ , which contributes to the strength of the Ni-based alloy member at high temperatures, is less likely to be generated. Therefore, the Ta content is preferably 15% or less. A more preferable Ta content is 11% or less.

Co: 0-15%
Co is an element that has the effect of increasing the solid solution temperature of the γ' phase, which improves the strength of the Ni-based alloy member at high temperatures. Further, Co is an element that contributes to stabilizing the γ' phase at high temperatures. If the Co content exceeds 15%, harmful phases of the Ni-based alloy member will be precipitated, causing a decrease in strength and ductility of the Ni-based alloy member. Therefore, the Co content is preferably 15% or less. A more preferable Co content is 10% or less. Since Co does not need to be contained, the lower limit of the Co content is 0%.

Mo: 0-5%
Mo is an element that dissolves in the γ phase, which is the matrix of the Ni-based alloy, and contributes to improving the strength of the Ni-based alloy member through solid solution strengthening. If the Mo content exceeds 5%, harmful phases will precipitate, leading to a decrease in strength and ductility of the Ni-based alloy member. Therefore, the Mo content is preferably 5% or less. A more preferable Mo content is 3% or less. Since Mo does not need to be contained, the lower limit of the Mo content is 0%.

Ti: 0-5.0%
Ti is an element that generates a γ' phase that improves the strength of Ni-based alloy members at high temperatures. It is also an element that contributes to improving the oxidation resistance and corrosion resistance of Ni-based alloy members at high temperatures. If the Ti content exceeds 5%, the weldability of the Ni-based alloy member will be reduced, and there is a risk that cracks will occur in the Ni-based alloy member during manufacturing or repair. Therefore, the Ti content is preferably 5.0% or less. A more preferable Ti content is 3.5% or less. Since Ti may not be contained, the lower limit of the Ti content is 0%.

C: 0-0.10%
C is an element constituting M ₂₃ C ₆ precipitates that contribute to improving the strength of Ni-based alloy members at high temperatures. When the C content exceeds 0.10%, there is a possibility that the amount of MC carbide precipitated within the crystal grains increases, the intragranular strength increases, and the ductility decreases. Therefore, the C content is preferably 0.10% or less. Since C does not need to be contained, the lower limit of the C content is 0%.

B: 0-0.05%
B is an element that strengthens the grain boundaries by being present in the grain boundaries and is effective in improving the high-temperature creep strength of the Ni-based alloy member. When the B content exceeds 0.05%, borides are generated, which may reduce the ductility of the Ni-based alloy member. Therefore, the B content is preferably 0.05% or less. Since B does not need to be contained, the lower limit of the B content is 0%.

Remaining portion: Ni and impurities The remaining portion of the Ni-based alloy casting material of the present disclosure is Ni and impurities. Here, impurities are components that are mixed into the raw materials or during the manufacturing process when casting the Ni-based alloy casting material. Impurities are allowed as long as the effects of the Ni-based alloy member of the present disclosure can be obtained.

The chemical composition of the Ni-based alloy cast material can be analyzed using a known method. For example, analysis can be performed using inductively coupled plasma mass spectrometry.

(First strain removal heat treatment step)
In the first strain removal heat treatment step S11, when the solid solution temperature of the γ' phase is Ts°C, the first strain removal temperature range of Ts×0.90°C or more and Ts°C or less is applied for 1 hour or more after the casting step S10. The Ni-based alloy casting material is heated. Internal strain formed inside the Ni-based alloy cast material formed in casting process S10 (accumulated due to the thermal expansion difference between the Ni-based alloy cast material and the mold and core during cooling after casting) internal distortion) can be removed. The solid solution temperature of the γ' phase refers to the temperature at which the γ' phase completely dissolves in the parent phase. The solid solution temperature of the γ' phase can be obtained by calculation using thermodynamic calculation software (for example, JMatPro manufactured by Sente Software) based on the chemical composition.

If the first strain removal temperature is less than Ts x 0.9°C, the internal strain of the Ni-based alloy member cannot be removed sufficiently because the temperature is low and the volume fraction of the γ' phase becomes too high. . Therefore, the first strain removal temperature is Ts×0.9° C. or higher. When the first strain removal temperature exceeds Ts° C., the temperature is high and the γ' phase (disappears) becomes a solid solution, making it easier to form recrystallized grains. Therefore, the first strain removal temperature is below Ts°C.

In the first strain removal heat treatment step S11, the heating time in the first strain removal temperature range is 1 hour or more. If the heating time is less than 1 hour, internal strain in the Ni-based alloy cast material cannot be sufficiently removed.

The rate of temperature increase from room temperature (5 to 35°C) to the first strain removal temperature range is preferably 50°C/min or less. When the Ni-based alloy cast material is rapidly heated, the temperature may rise above the first strain relief temperature range. If the temperature exceeds the first strain relief temperature range, recrystallized grains may occur, so the temperature increase rate from room temperature to the first strain relief temperature range is 50° C./min or less.

(Solution heat treatment process)
In the solution heat treatment step S13, when the melting point of the γ phase is Tm°C, the Ni group after the first strain removal heat treatment step S11 is expanded from the first strain removal temperature range to a solution temperature range of more than Ts+t1°C and below Tm°C. The alloy casting material is heated and maintained at a temperature in the solution temperature range for 2 hours or more. t1 is 10°C or less. It is preferable that t1 is 1° C. or higher. More preferably, t1 is 5°C or higher. In the solution heat treatment step S13, the Ni-based alloy cast material is heated from the first strain removal temperature range to the solution temperature range without being cooled. This allows the γ' phase to be dissolved in solid solution without generating strain due to the difference in thermal expansion between the γ phase and the γ' phase. Therefore, the number of recrystallized grains can be greatly reduced. The melting point Tm of the γ phase can be obtained by calculation using thermodynamic calculation software (for example, JMatPro manufactured by Sente Software) based on the chemical composition.
Further, in the Ni-based alloy cast material after casting, the γ' phase is precipitated in a coarse state, and chemical components are unevenly distributed. By converting the γ' phase into a solid solution in the solution heat treatment step S13, homogenization can be achieved. In the solution heat treatment step S13, the γ phase is preferably 100%, but other phases may be included as long as the strength at high temperatures does not decrease. Note that when the Ni-based alloy cast material is observed under a microscope after the first strain removal heat treatment step S11 and the solution heat treatment step S13 are completed, it is possible to confirm that there are no recrystallized grains and a single γ phase exhibiting a dendrite pattern. can.

If the solution temperature is below Ts+t1°C, the γ' phase may not be sufficiently dissolved in solid solution. Therefore, the solution temperature is higher than Ts+t1°C. t1 is 10°C or less. It is preferable that t1 is 1° C. or higher. More preferably, t1 is 5°C or higher. If the solution temperature exceeds the melting point Tm° C. of the γ phase, the γ phase will melt. Therefore, the solution temperature is below Tm°C.

It is preferable that the temperature increase rate from the first strain relief temperature range to the solution temperature range is 50° C./min or less. When a Ni-based alloy cast material is heated rapidly, the temperature may rise above the solution temperature range. If the temperature exceeds the solution temperature range, the γ phase may melt, so the temperature increase rate from the first strain relief temperature range to the solution temperature range is 50° C./min or less.

After raising the temperature to the solution temperature range, maintain the temperature in the solution temperature range for a certain period of time. If the temperature is maintained for less than 2 hours, the γ' phase may not be sufficiently dissolved. Therefore, in the solution heat treatment step S13, the temperature is maintained for 2 hours or more.

After maintaining the temperature in the solution temperature range, cool from the solution temperature range to room temperature. The cooling method is, for example, gas cooling. The γ' phase, which is the strengthening phase, is adjusted to a target volume fraction in the subsequent aging step S14. Since there is a risk that unexpected γ' phase may precipitate during cooling after temperature maintenance in the solution temperature range, it is preferable to set the cooling rate as fast as possible. Therefore, the cooling rate is preferably 10° C./min or more.

(Aging process)
By performing the aging step S14 on the Ni-based alloy cast material after the solution heat treatment step S13, the γ' phase can be precipitated, and the Ni-based alloy member of the present disclosure can be obtained. In the aging step S14, it is preferable to heat the Ni-based alloy cast material after the solution heat treatment step S13 for 2 to 20 hours in an aging temperature range of 850° C. or higher and 870° C. or lower. This makes it possible to easily precipitate 50% by volume or more of the γ' phase in the γ phase.

The aging temperature range (aging temperature range) of the Ni-based alloy cast material after the solution heat treatment step S13 is preferably 850°C or higher and 870°C or lower. This aging temperature range is preferable because it facilitates increasing the volume fraction of the γ' phase precipitated in the γ phase to 50% by volume or more.

The time for heating the Ni-based alloy cast material in the aging temperature range after the solution heat treatment step S13 is preferably 2 hours to 20 hours. This heating time is preferable because it facilitates increasing the volume fraction of the γ' phase precipitated in the γ phase to 50% by volume or more.

The volume fraction of the γ phase and γ' phase after the aging step S14 can be evaluated by observing the cross section of the Ni-based alloy member with a scanning electron microscope (SEM). FIG. 2 shows an electron micrograph obtained by SEM observation of the Ni-based alloy member after the aging step S14. As shown in FIG. 2, in the Ni-based alloy member of the present disclosure, a rectangular γ' phase and a lattice-shaped γ phase in the gaps between the rectangular γ' phases are observed. For example, by using image processing software on the obtained observed image, the area ratio of the γ' phase can be evaluated. The volume fraction of the γ' phase can be the area fraction of the γ' phase obtained from an electron micrograph of this cross section.

As explained above, according to the method for manufacturing a Ni-based alloy member according to the present embodiment, recrystallized grains can be suppressed.

<Second embodiment>
Hereinafter, with reference to FIG. 3, a method S100B for manufacturing a Ni-based alloy member according to the second embodiment will be described. FIG. 3 is a flowchart of the Ni-based alloy member manufacturing method S100B according to the embodiment. The Ni-based alloy member manufacturing method S100B includes a casting step S10, a first strain relief heat treatment step S11, a second strain relief heat treatment step S12, a solution heat treatment step S13, and an aging step S14. Each step will be explained below.

(Second strain removal heat treatment step)
In the second strain removal heat treatment step S12, when the second strain removal temperature range is defined as a temperature range exceeding Ts°C and below Tm°C and t1°C lower than the solution temperature range, the first strain removal temperature range is The Ni-based alloy cast material after the first strain relief heat treatment step S11 is heated to a second strain relief temperature range from . Thereafter, the Ni-based alloy cast material is maintained at a temperature in the second strain removal temperature range for one hour or more. In the second strain relief heat treatment step, the Ni-based alloy cast material is heated from the first strain relief temperature range to the second strain relief temperature range without being cooled. Thereby, the internal strain remaining after the first strain removal heat treatment step S11 can be removed.

In the second strain removal heat treatment step S12, the heating time in the second strain removal temperature range is 1 hour or more. If the heating time is less than 1 hour, internal strain in the Ni-based alloy cast material may not be sufficiently removed in some cases.

The temperature increase rate from the first strain relief temperature range to the second strain relief temperature range is preferably 50° C./min or less. When the Ni-based alloy cast material is rapidly heated, the temperature may rise above the second strain relief temperature range. If the temperature exceeds the second strain relief temperature range, the strain may not be removed sufficiently, so the temperature increase rate from the first strain relief temperature range to the second strain relief temperature range should be 50°C/min or less. It is preferable that there be.

(Solution heat treatment process)
In the solution heat treatment step S13, when the melting point of the γ phase is Tm°C, the Ni-based alloy cast material after the second strain removal heat treatment step S12 is heated from the second strain removal temperature range to the solution temperature range, and Maintain the temperature in the temperature range for 2 hours or more. In the solution heat treatment step S13, the Ni-based alloy cast material is heated from the second strain removal temperature range to the solution temperature range without being cooled. This allows the γ' phase to be dissolved in solid solution without generating strain due to the difference in thermal expansion between the γ phase and the γ' phase. Therefore, the number of recrystallized grains can be greatly reduced. The melting point Tm of the γ phase can be obtained by calculation using thermodynamic calculation software (for example, JMatPro manufactured by Sente Software) based on the chemical composition.
Further, in the Ni-based alloy cast material after casting, the γ' phase is precipitated in a coarse state, and chemical components are unevenly distributed. By converting the γ' phase into a solid solution in the solution heat treatment step S13, homogenization can be achieved. In the solution heat treatment step S13, the γ phase is preferably 100%, but other phases may be included as long as the strength at high temperatures does not decrease. Note that when the Ni-based alloy cast material is observed under a microscope after the first strain relief heat treatment step S11, the second strain relief heat treatment step S12, and the solution heat treatment step S13 are completed, it is found that there are no recrystallized grains and a γ phase exhibiting a dendrite pattern. single phase can be confirmed.

If the solution temperature is below Ts+t1°C, the γ' phase may not be sufficiently dissolved in solid solution. Therefore, the solution temperature is higher than Ts+t1°C. Here, t1 is 10°C or less. It is preferable that t1 is 1° C. or higher. More preferably, t1 is 5°C or higher. If the solution temperature exceeds the melting point Tm° C. of the γ phase, the γ phase will melt. Therefore, the solution temperature is below Tm°C.

The temperature increase rate from the second strain relief temperature range to the solution temperature range is preferably 50°C/min or less. When a Ni-based alloy cast material is heated rapidly, the temperature may rise above the solution temperature range. If the temperature exceeds the solution temperature range, the γ phase may melt, so the temperature increase rate from the second strain relief temperature range to the solution temperature range is 50° C./min or less.

After maintaining the temperature in the solution temperature range, cool from the solution temperature range to room temperature. The cooling method is, for example, gas cooling. The γ' phase, which is the strengthening phase, is adjusted to a target volume fraction in the subsequent aging step S14. Since there is a risk that an unexpected γ' phase may precipitate during cooling after the temperature is maintained in the solution temperature range, it is preferable to set the cooling rate as fast as possible. Therefore, the cooling rate is preferably 10° C./min or more.

(Aging process)
By performing the aging step S14 on the Ni-based alloy cast material after the solution heat treatment step S13, the γ' phase can be precipitated, and the Ni-based alloy member of the present disclosure can be obtained. In the aging step S14, it is preferable to heat the Ni-based alloy cast material after the solution heat treatment step S13 for 2 to 20 hours in an aging temperature range of 850° C. or higher and 870° C. or lower. Thereby, it is possible to easily precipitate 50% by volume or more of the γ' phase in the γ phase.

As explained above, according to the method for manufacturing a Ni-based alloy member according to the second embodiment, recrystallized grains can be suppressed. The second strain removal heat treatment step S12 can remove internal strain remaining after the first strain removal heat treatment step S11, and can further suppress recrystallization.

Note that the technical scope of the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention. In addition, it is possible to appropriately replace the components in the embodiments with well-known components without departing from the spirit of the present invention.

Next, an example of the present invention will be described. The conditions in the example are examples of conditions adopted to confirm the feasibility and effects of the present invention, and the present invention is based on this example of conditions. It is not limited. The present invention can adopt various conditions as long as the purpose of the present invention is achieved without departing from the gist of the present invention.

(Example 1)
A Ni-based alloy casting material having a chemical composition in mass % of Cr: 8%, W: 8%, Al: 5.5%, Ta: 11%, and the balance being Ni and impurities was cast. The solid solution temperature Ts of the γ' phase obtained by thermodynamic calculation from these chemical compositions was 1305°C, Ts×0.9°C was 1175°C, and the melting point Tm of the γ phase was 1336°C.

The resulting Ni-based alloy cast material is heated at a temperature increase rate of 50°C/min or less to a first strain relief temperature range of 1175°C or higher and 1305°C or lower, and is kept in the first strain removal temperature range for 1 hour or more. A first strain removal heat treatment was performed. Thereafter, without cooling, the temperature was raised from the first strain removal temperature range to a solution temperature range of more than 1305°C and less than 1336°C at a heating rate of 50°C/min or less. After raising the temperature, it was maintained in the solution temperature range for 2 hours, and then cooled at 10° C./min. When the Ni-based alloy cast material was observed under a microscope after cooling, it was confirmed that there were no recrystallized grains and a single γ phase with a dendrite pattern was observed.
After cooling, it was heated in an aging temperature range of 850° C. to 870° C. for 2 hours to 20 hours to obtain the Ni-based alloy member of Example 1.

(Example 2)
The chemical composition is in mass%, Cr: 15%, W: 4%, Al: 3.5%, Ta: 4%, Co: 10%, Mo: 3%, Ti: 3.5%, C: 0 ~0.10%, B: 0~0.03%, and the balance was Ni-based alloy casting material consisting of Ni and impurities. The solid solution temperature Ts of the γ' phase obtained by thermodynamic calculation from these chemical compositions was 1136°C, Ts×0.9°C was 1022°C, and the melting point Tm of the γ phase was 1274°C.

The resulting Ni-based alloy cast material is heated to a first strain relief temperature range of 1022°C or higher and 1136°C or lower at a temperature increase rate of 50°C/min or less, and is maintained in the first strain relief temperature range for 1 hour or more. A first strain removal heat treatment was performed. Thereafter, without cooling, the temperature was raised from the first strain relief temperature range to a solution temperature range of more than 1136°C and less than 1274°C at a temperature increase rate of less than 50°C/min. After raising the temperature, it was maintained in the solution temperature range for 2 hours, and then cooled at 10° C./min. When the Ni-based alloy cast material was observed under a microscope after cooling, it was confirmed that there were no recrystallized grains and a single γ phase with a dendrite pattern was observed.
After cooling, it was heated in the aging temperature range of 850° C. to 870° C. for 2 hours to 20 hours to obtain the Ni-based alloy member of Example 2.

(Example 3)
A Ni-based alloy casting material having a chemical composition in mass % of Cr: 8%, W: 8%, Al: 5.5%, Ta: 11%, and the balance being Ni and impurities was cast. The solid solution temperature Ts of the γ' phase obtained by thermodynamic calculation from these chemical compositions was 1305°C, Ts×0.9°C was 1175°C, and the melting point Tm of the γ phase was 1336°C.

The resulting Ni-based alloy cast material is heated at a temperature increase rate of 50°C/min or less to a first strain relief temperature range of 1175°C or higher and 1305°C or lower, and is kept in the first strain removal temperature range for 1 hour or more. A first strain removal heat treatment was performed. After that, the temperature is increased at a rate of 50°C/min or less from the first strain relief temperature range to the second strain relief temperature range (1305°C or higher, 1336°C or lower, and 10°C lower than the solution temperature range) without cooling. The temperature was raised at a rapid rate, and second strain removal heat treatment was performed for over 1 hour. Next, the temperature is raised from the second strain relief temperature range to the solution temperature range (a temperature range above 1305°C, 1336°C or less, and 10°C higher than the second strain removal temperature range) at a temperature increase rate of 50°C/min or less. did. After raising the temperature, it was maintained in the solution temperature range for 2 hours, and then cooled at 10° C./min. When the Ni-based alloy cast material was observed under a microscope after cooling, it was confirmed that there were no recrystallized grains and a single γ phase with a dendrite pattern was observed.
After cooling, it was heated in the aging temperature range of 850° C. to 870° C. for 2 hours to 20 hours to obtain the Ni-based alloy member of Example 3.

(Volume fraction of γ phase)
From thermodynamic calculations, the volume fraction of the γ' phase in Example 1 was 70%, the volume fraction of the γ' phase in Example 2 was 51%, and the volume fraction of the γ' phase in Example 3 was 70%. In addition, in all of Example 1, Example 2, and Example 3, no recrystallized grains were observed.

(Pre-straining experiment)
Bending deformation was applied to simulate the internal strain that occurs during casting. The chemical composition of the test piece subjected to bending deformation was the same as that of Example 1. After applying bending deformation to the sample, heat treatment was performed under the following conditions A, B, and C, and the size of the recrystallized grains was etched to reveal the metal structure, and then external observation photographs were taken and evaluated. did. Note that other conditions not described such as temperature increase were the same as in Example 1.
Condition A: First strain removal heat treatment step (heating at Ts × 0.9°C or higher and Ts°C or lower for 1 hour or more), second strain removal heat treatment step (heating at Ts × 0.9°C or higher and Ts°C or lower, and higher than the solution heat treatment step) heating at a temperature 10°C lower for 1 hour or more) and solution heat treatment process (heating at temperatures above Ts+10°C and below Tm°C for 2 hours or more)
Condition B: Heat treatment step below the first strain removal heat treatment temperature range (heating at less than Ts x 0.9°C for 1 hour or more), and solution heat treatment step (heating at more than Ts°C and below Tm°C for 2 hours or more)
Condition C: Solution heat treatment step (heating at temperatures above Ts°C and below Tm°C for 2 hours or more)

FIG. 4 is a diagram for explaining the observation direction of the sample after heat treatment. An appearance observation photograph of the sample after heat treatment was taken from the direction of the arrow in FIG. The obtained photographs are shown in FIGS. 5 to 7. In each photograph, the metal structure was revealed by etching. FIG. 5 is an appearance observation photograph after heat treatment under condition A. FIG. 6 is an appearance observation photograph after heat treatment under condition B. FIG. 7 is an appearance observation photograph after heat treatment under condition C. As shown in FIG. 5, no recrystallized grains were generated in the samples that were heat-treated to satisfy the temperature conditions of the present disclosure. As shown in FIG. 6, under condition B in which the heat treatment was performed at a temperature below the first strain removal heat treatment temperature range, a recrystallized structure was generated in the bending deformation part. As shown in FIG. 7, under condition C in which the first strain removal heat treatment was not performed, a recrystallized structure was significantly generated in the bending deformation part. From the above results, it was confirmed that by using the method for manufacturing a Ni-based alloy member of the present disclosure, the generation of recrystallized grains can be significantly reduced even when the γ' phase is 50% by volume or more.

<Additional notes>
The method for manufacturing the Ni-based alloy member described in the above embodiment can be understood as follows.

(1) A method for manufacturing a Ni-based alloy member according to the first aspect of the present disclosure includes a casting step S10, a first strain removal heat treatment step S11, a solution heat treatment step S13, and an aging step S14, In the casting step S10, in the aging step S14, a Ni-based alloy cast material having a chemical composition in which 50% by volume or more of the γ' phase can be precipitated in the γ phase is cast, and in the first strain removal heat treatment step S11, the γ' When the solid solution temperature of the phase is Ts°C, the Ni-based alloy cast material after the casting step S10 is heated in the strain removal temperature range of Ts × 0.90°C or higher and Ts°C or lower for 1 hour or more, and solution heat treatment is performed. In step S13, when the melting point of the γ phase is Tm°C, the Ni-based alloy cast material after the strain removal heat treatment step S11 is heated from the strain removal temperature range to a solution temperature range of more than Ts + t1°C and below Tm°C, The temperature is maintained in the solution temperature range for 2 hours or more, and t1 is 10°C or less.

By doing so, it is possible to suppress the generation of recrystallized grains in the solution heat treatment step.

(2) A method for manufacturing a Ni-based alloy member according to a second aspect of the present disclosure is a method for manufacturing a Ni-based alloy member according to the first aspect, comprising a first strain removal heat treatment step S11 and a solution heat treatment step. A second strain removal heat treatment step S12 is further provided between step S13, and the temperature range which is higher than Ts°C and lower than Tm°C and lower by t1°C than the solution temperature range is set as a second strain removal temperature. In the second strain relief heat treatment step S12, the Ni-based alloy cast material after the first strain relief heat treatment step S11 is heated from the first strain relief temperature region to the second strain relief temperature region, and The temperature is maintained in the second strain relief temperature range for 1 hour or more, and in the solution heat treatment step S13, the Ni-based alloy cast material after the second strain relief heat treatment step S12 is heated from the second strain relief temperature region to the solution temperature region. Heat and maintain the temperature in the solution temperature range for 2 hours or more.

By including the second strain removal heat treatment step, strain can be further removed.

(3) The method for manufacturing a Ni-based alloy member according to the third aspect of the present disclosure is the method for manufacturing the Ni-based alloy member according to the first or second aspect, wherein in the aging step S14, 850° C. or higher; The Ni-based alloy cast material after the solution heat treatment step S13 is heated in an aging temperature range of 870° C. or lower for 2 to 20 hours.

By doing so, the volume fraction of the γ' phase can be adjusted.

(4) A method for manufacturing a Ni-based alloy member according to a fourth aspect of the present disclosure is a method for manufacturing a Ni-based alloy member according to any one of the first to third aspects, including the first strain removal heat treatment. In step S11, the rate of temperature increase from room temperature to the first strain removal temperature range is 50° C./min or less.

(5) A method for manufacturing a Ni-based alloy member according to a fifth aspect of the present disclosure is a method for manufacturing a Ni-based alloy member according to any one of the first to fourth aspects, including the solution heat treatment step S13. In this case, the rate of temperature increase from the strain relief temperature range to the solution temperature range is 50° C./min or less.

By doing so, it is possible to suppress the dissolution of the γ phase in the solution heat treatment step.

(6) A method for manufacturing a Ni-based alloy member according to a sixth aspect of the present disclosure is a method for manufacturing a Ni-based alloy member according to any one of the first to fifth aspects, including the solution heat treatment step S13. After holding the temperature for 2 hours or more, it is cooled from the solution temperature range to room temperature at a cooling rate of 10° C./min or more.

By doing so, unexpected precipitation of the γ' phase during cooling can be suppressed.

(7) A method for manufacturing a Ni-based alloy member according to a seventh aspect of the present disclosure is a method for manufacturing a Ni-based alloy member according to any one of the first to sixth aspects, wherein the Ni-based alloy casting The chemical composition of the material is Cr: 5-15%, W: 3-10%, Al: 3.0-7.0%, Ta: 3-15%, Co: 0-15%, Mo :0 to 5%, Ti: 0 to 5.0%, C: 0 to 0.10%, B: 0 to 0.05%, and the remainder consists of Ni and impurities.

By doing so, it is possible to easily precipitate 50% by volume or more of the γ' phase in the γ phase.

The method for manufacturing a Ni-based alloy member of the present disclosure can reduce recrystallized grains, so it has high industrial applicability.

S100 Ni-based alloy member manufacturing method,
S10 Casting process,
S11 first strain removal heat treatment step,
S12 second strain removal heat treatment step,
S13 solution heat treatment step,
S14 Aging process

Claims

casting process,
a first strain removal heat treatment step;
a solution heat treatment step;
Aging process;
Equipped with
In the casting step, casting a Ni-based alloy casting material having a chemical composition that allows precipitation of 50 volume % or more of the γ' phase in the γ phase in the aging step,
In the first strain relief heat treatment step, the casting step is performed in a first strain relief temperature range of Ts×0.90°C or higher and Ts°C or lower for 1 hour or more, where the solid solution temperature of the γ' phase is Ts°C. heating the subsequent Ni-based alloy casting material,
In the solution heat treatment step, when the melting point of the γ phase is Tm°C, from the first strain removal temperature range to a solution temperature range of more than Ts+t1°C and below Tm°C after the first strain removal heat treatment step. heating the Ni-based alloy casting material and maintaining the temperature in the solution temperature range for 2 hours or more,
A method for manufacturing a Ni-based alloy member, wherein the t1 is 10°C or less.
Between the first strain removal heat treatment step and the solution heat treatment step,
further comprising a second strain removal heat treatment step,
When the second strain removal temperature range is a temperature range that is higher than Ts°C and lower than Tm°C and is lower than the solution temperature range by t1°C, in the second strain removal heat treatment step, the first strain removal heating the Ni-based alloy cast material after the first strain removal heat treatment step from the temperature range to the second strain removal temperature range, and maintaining the temperature in the second strain removal temperature range for 1 hour or more;
In the solution heat treatment step, the Ni-based alloy cast material after the second strain removal heat treatment step is heated from the second strain removal temperature range to the solution temperature range, and the temperature is maintained in the solution temperature range for 2 hours or more. The method for manufacturing a Ni-based alloy member according to claim 1, wherein the Ni-based alloy member retains the following.
The Ni-based alloy according to claim 1 or 2, wherein in the aging step, the Ni-based alloy cast material after the solution heat treatment step is heated for 2 to 20 hours in an aging temperature range of 850° C. or higher and 870° C. or lower. Method for manufacturing alloy parts.
The method for manufacturing a Ni-based alloy member according to claim 1 or 2, wherein in the first strain relief heat treatment step, the temperature increase rate from room temperature to the first strain relief temperature range is 50° C./min or less.
The method for manufacturing a Ni-based alloy member according to claim 1, wherein in the solution heat treatment step, a temperature increase rate from the first strain removal temperature range to the solution temperature range is 50° C./min or less.
Manufacturing the Ni-based alloy member according to claim 1 or 2, wherein in the solution heat treatment step, after holding the temperature for 2 hours or more, the Ni-based alloy member is cooled from the solution temperature range to room temperature at a cooling rate of 10° C./min or more. Method.
The chemical composition of the Ni-based alloy casting material is in mass%,
Cr: 5-15%,
W: 3-10%,
Al: 3.0-7.0%,
Ta: 3-15%,
Co: 0-15%,
Mo: 0-5%,
Ti: 0 to 5.0%,
C: 0-0.10%,
B: 0-0.05%
including;
The method for manufacturing a Ni-based alloy member according to claim 1 or 2, wherein the remainder consists of Ni and impurities.