Method for manufacturing nickel-based alloy high-temperature component

1. A method for manufacturing a high temperature component formed of a Ni-based alloy, the method comprising:

a melting/casting step of melting and casting a material of the Ni-based alloy to form a workpiece;

a hot die forging step of subjecting the workpiece to hot die forging using predetermined dies to form a forge-molded article, the predetermined dies being formed of a precipitation-strengthened Ni-based superalloy comprising a γ phase as a matrix and a γ′ phase; and

a solution/aging treatment step of subjecting the forge-molded article to solution treatment and aging treatment to form a precipitation-strengthened molded article,

wherein the hot die forging step comprises:

a die/workpiece co-heating sub step of heating the workpiece to a forging temperature together with the dies using a heater with the workpiece interposed between the dies; and

a hot forging substep of taking the workpiece and the dies heated to the forging temperature out of the heater into a room temperature environment and immediately performing hot forging on the workpiece using a press machine,

wherein in the predetermined dies of the precipitation-strengthened Ni-based superalloy, the γ′ phase is precipitated in an amount of equal to or more than 10 vol. % with respect to the γ phase at 1050° C.,

wherein a solvus temperature of the γ′ phase is higher than 1050° C. and lower than 1250° C., and

wherein 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.

2. The method for manufacturing the component formed of the Ni-based alloy 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 equal to or less than 30% of Co;

1 to 6% of Al;

2.5 to 7% of Ti and 3 to 9% in total of Ti, Nb and Ta;

equal to or less than 4% of Mo;

equal to or less than 4% of W;

equal to or less than 0.08% of Zr;

equal to or less than 10% of Fe;

equal to or less than 0.03% of B;

equal to or less than 0.1% of C;

equal to or less than 2% of Hf;

equal to or less than 5% of Re; and

a balance of Ni with inevitable impurities.

3. The method for manufacturing the component formed of the Ni-based alloy according to claim 1 ,

wherein the forging temperature is equal to or higher than 900° C. and equal to or lower than a temperature lower than the solvus temperature of the γ′ phase in the precipitation-strengthened Ni-based superalloy by 20° C.

4. The method for manufacturing the component formed of the Ni-based alloy according to claim 1 ,

wherein the dies have a tensile strength of equal to or more than 450 MPa at 900° C.

5. The method for manufacturing the component formed of the Ni-based alloy according to claim 1 ,

wherein the method further comprises a softening step of preforming and softening the workpiece between the melting/casting step and the hot die forging step, the softening step comprising:

a preform forming substep of subjecting the workpiece to hot working at a temperature equal to or higher than 1000° C. and lower than a solvus temperature of a γ′ phase in the Ni-based alloy to form a preform in which crystal particles of the γ′ phase are precipitated between or among crystal grains of a γ phase as a matrix of the Ni-based alloy; and

a softened preform forming sub step of re-heating the preform to the temperature of the hot working to decrease γ′ phase crystal particles precipitated within the γ phase crystal grains and subsequently slowly cooling the heated preform at a cooling rate of equal to or less than 100° C./h to 500° C. to form a softened preform in which the inter-grain γ′ phase crystal particles have grown, and

wherein the hot die forging step is performed on the softened preform.