Method for manufacturing nickel-based alloy high-temperature component
This method for manufacturing a high-temperature component formed of a Ni-based alloy includes a step of subjecting a workpiece of the Ni-based alloy to hot die forging using predetermined dies to form a forge-molded article, the step including: a die/workpiece co-heating substep of heating the workpiece interposed between the dies to a forging temperature; and a hot forging substep of taking out the workpiece and the dies into a room temperature environment and immediately performing hot forging on the workpiece using a press machine. The predetermined dies are formed of another Ni-based superalloy comprising γ and γ′ phases, and have features in that: a solvus temperature of the γ′ phase is 1050-1250° C.; and the γ′ phase precipitates at least 10 vol. % at 1050° C. and has two kinds of forms of intra-grain γ′ phase precipitations within the γ phase grains and inter-grain γ′ phase precipitations between/among the γ phase grains.
1. A method for repairing a die formed of a precipitation-strengthened Ni-based superalloy,
the die having a composition in which a γ′ phase is capable of precipitating in an amount of 10 volume % or more with respect to a γ phase as a matrix at 1050° C., and a solvus temperature of the γ′ phase is higher than 1050° C. and lower than 1250° C., and
the die having a structure in which the γ′ phase has two precipitation forms of intra-grain γ′ phase crystal particles that precipitate within crystal grains of the γ phase and inter-grain γ′ phase crystal particles that precipitate between or among crystal grains of the γ phase, and the inter-grain γ′ phase crystal particles precipitate in an amount of 10 volume % or more,
the method comprising the steps of:
subjecting the die being damaged to a softening heat treatment in which the die is heated up to 1000° C. or more but less than the solvus temperature of the γ′ phase so that the intra-grain γ′ phase crystal particles are decreased and followed by slow cooling the die to 500° C. at a rate of 100° C./h or less so that the inter-grain γ′ phase crystal particles grow;
subjecting the die being softening heat treated to a forming process in order to correct a shape of the die;
subjecting the die being shape corrected to a partial solution/aging treatment so that the inter-grain γ′ phase crystal particles remain in an amount of 10 volume % or more and the intra-grain γ′ phase crystal particles precipitate; and
subjecting the die being partial solution/aging treated to a finishing process.
2. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 1 , wherein the precipitation-strengthened Ni-based superalloy has a composition of: by mass,
10 to 25% of Cr;
more than 0% and 30% or less of Co;
1 to 6% of Al;
2.5 to 7% of Ti and 3 to 9% in total of Ti, Nb and Ta;
4% or less of Mo;
4% or less of W;
0.08% or less of Zr;
10% or less of Fe;
0.03% or less of B;
0.1% or less of C;
2% or less of Hf;
5% or less of Re; and
a balance of Ni with inevitable impurities.
3. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 1 , wherein
the die being softening heat treated has a Vickers hardness of 350 Hv or less.
4. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 2 , wherein
the die being softening heat treated has a Vickers hardness of 350 Hv or less.
5. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 1 , wherein
the die has a tensile strength of 450 MPa or more at 900° C.
6. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 2 , wherein
the die has a tensile strength of 450 MPa or more at 900° C.
7. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 3 , wherein
the die being partial solution/aging treated has a tensile strength of 450 MPa or more at 900° C.
8. The method for repairing the die formed of the precipitation-strengthened Ni-based superalloy according to claim 4 , wherein
the die being partial solution/aging treated has a tensile strength of 450 MPa or more at 900° C.