Ni-based superalloy and method for manufacturing Ni-based superalloy

1. A Ni-based superalloy having a composition comprising, in mass %, C: up to 0.10%, Si: up to 0.5%, Mn: up to 0.5%, P: up to 0.05%, S: up to 0.050%, Fe: up to 45%, Cr: 14.0 to 22.0%, Co: up to 18.0%, Mo: up to 8.0%, W: up to 5.0%, Al: 0.10 to 2.80%, Ti: 0.50 to 5.50%, Nb: up to 5.8%, Ta: up to 2.0%, V: up to 1.0%, B: up to 0.030%, Zr: up to 0.10%, Mg: up to 0.005%, and the balance of Ni with inevitable impurities, wherein the Ni-based superalloy has a grain orientation spread (GOS) of at least 0.7° as an intragranular misorientation parameter measured by an SEM-EBSD technique.

2. The Ni-based superalloy according to claim 1 , wherein the composition of the Ni-based superalloy comprises C: up to 0.08%, Si: up to 0.2%, Mn: up to 0.2%, P: up to 0.02%, S: up to 0.005%, Fe: up to 45%, Cr: 14.0 to 22.0%, Co: up to 18.0%, Mo: up to 8.0%, W: up to 5.0%, Al: 0.10 to 2.80%, Ti: 0.50 to 5.50%, Nb: up to 5.8%, Ta: up to 2.0%, V: up to 1.0%, B: up to 0.030%, Zr: up to 0.10%, Mg: up to 0.005%, and the balance of Ni with inevitable impurities.

3. A method for manufacturing a Ni-based superalloy, the Ni-based superalloy having a composition comprising, in mass %, C: up to 0.10%, Si: up to 0.5%, Mn: up to 0.5%, P: up to 0.05%, S: up to 0.050%, Fe: up to 45%, Cr: 14.0 to 22.0%, Co: up to 18.0%, Mo: up to 8.0%, W: up to 5.0%, Al: 0.10 to 2.80%, Ti: 0.50 to 5.50%, Nb: up to 5.8%, Ta: up to 2.0%, V: up to 1.0%, B: up to 0.030%, Zr: up to 0.10%, Mg: up to 0.005%, and the balance of Ni with inevitable impurities, and having a grain orientation spread (GOS) of at least 0.7° as an intragranular misorientation parameter measured by an SEM-EBSD technique, the method comprising:

carrying out a heat treatment before closed die forging by heating a material to be hot-worked having the composition at a temperature of 970 to 1,005° C. and holding at the temperature for 1 to 6 hours, and then carrying out closed die forging to produce a closed die forged material; and

carrying out an aging treatment step comprising a first aging treatment by holding the closed die forged material at a temperature of 700 to 750° C. for 2 to 20 hours, and a second aging treatment by holding at a temperature of 600 to 650° C. for 2 to 20 hours to produce an aging-treated material.

4. A method for manufacturing a Ni-based superalloy, the Ni-based superalloy having a composition comprising, in mass %, C: up to 0.10%, Si: up to 0.5%, Mn: up to 0.5%, P: up to 0.05%, S: up to 0.050%, Fe: up to 45%, Cr: 14.0 to 22.0%, Co: up to 18.0%, Mo: up to 8.0%, W: up to 5.0%, Al: 0.10 to 2.80%, Ti: 0.50 to 5.50%, Nb: up to 5.8%, Ta: up to 2.0%, V: up to 1.0%, B: up to 0.030%, Zr: up to 0.10%, Mg: up to 0.005%, and the balance of Ni with inevitable impurities, and having a grain orientation spread (GOS) of at least 0.7° as an intragranular misorientation parameter measured by an SEM-EBSD technique, the method comprising:

carrying out a heat treatment before four-face forging by heating a material to be hot-worked having this composition to a temperature of 980 to 1,050° C. and holding at the temperature for 1 to 6 hours, and then carrying out four-face forging to produce a four-face forged material;

carrying out a stabilizing treatment step by holding the four-face forged material at a temperature of 830 to 860° C. for 2 to 20 hours to produce a stabilizing-treated material; and

carrying out an aging treatment step by holding the stabilizing-treated material at a temperature of 740 to 780° C. for 2 to 20 hours to produce an aging-treated material,

wherein a cooling rate is faster than 15° C./min from a temperature at which the four-face forging is finished to 900° C.

5. The method for manufacturing a Ni-based superalloy according to claim 3 , wherein the composition of the Ni-based superalloy comprises C: up to 0.08%, Si: up to 0.2%, Mn: up to 0.2%, P: up to 0.02%, S: up to 0.005%, Fe: up to 45%, Cr: 14.0 to 22.0%, Co: up to 18.0%, Mo: up to 8.0%, W: up to 5.0%, Al: 0.10 to 2.80%, Ti: 0.50 to 5.50%, Nb: up to 5.8%, Ta: up to 2.0%, V: up to 1.0%, B: up to 0.030%, Zr: up to 0.10%, Mg: up to 0.005%, and the balance of Ni with inevitable impurities.