Nickel-based alloy regenerated member, and method for manufacturing same
There is provided a regenerated member of a nickel-based alloy member for use in a turbine. The nickel-based alloy member is in a used condition. The regenerated member is a nickel-based alloy cast article including a γ phase as a matrix and a γ′ phase precipitating in the γ phase in a volume fraction of equal to or more than 30 vol % in an operational environment of the turbine. In a microstructure of the regenerated member, no recrystallized grains of the γ phase are present. And, when a GROD value of crystal grains of the γ phase of the used part undergone the solution/non-recrystallization heat treatment step is measured by electron back scattering diffraction analysis, the GROD value is equal to or more than 0.4° and equal to or less than 0.6°.
1. A method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine, the nickel-based alloy member being a nickel-based alloy cast article comprising a γ phase as a matrix and a γ′ phase as a precipitation-strengthening phase precipitating in the γ phase in a volume fraction of equal to or more than 30 vol % in an operational environment of the turbine, the method comprising:
a solution/non-recrystallization heat treatment step in order to partially relax internal strain of the γ phase of subjecting a used member to a solution/non-recrystallization heat treatment under a vacuum in which the used member is held at a temperature that is equal to or higher than a temperature higher than the solvus temperature of the γ′ phase by 10° C. and equal to or lower than a temperature lower than the melting temperature of the γ phase by 10° C. for a holding duration within a time range in which recrystallized grains of the γ phase do not occur, the used member being the nickel-based alloy member having operated for a predetermined period of time in the turbine; and
an aging heat treatment step of subjecting the used member having undergone the solution/non-recrystallization heat treatment to an aging heat treatment to allow the γ′ phase to precipitate in the γ phase,
wherein when a GROD (grain reference orientation deviation) value of crystal grains of the γ phase of the used part undergone the solution/non-recrystallization heat treatment step is measured by electron back scattering diffraction analysis, the GROD value is equal to or more than 0.4° and equal to or less than 0.6°.
2. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 1 , wherein
the nickel-based alloy member is a turbine blade.
3. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 1 , wherein
the cast article is a unidirectional solidification article or a single-crystal solidification article.
4. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 3 , wherein
the nickel-based alloy member is a turbine blade.
5. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 1 , wherein
the holding duration in the solution/non-recrystallization heat treatment step is equal to or more than 15 minutes and equal to or less than 2 hours.
6. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 5 , wherein
the cast article is a unidirectional solidification article or a single-crystal solidification article.
7. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 6 , wherein
the nickel-based alloy member is a turbine blade.
8. The method for manufacturing a regenerated member of a nickel-based alloy member for use in a turbine according to claim 5 , wherein
the nickel-based alloy member is a turbine blade.