Method for producing Ni-based superalloy material

Patent metadata

Field	Value
Publication number	US-10260137-B2
Application number	US-201715708594-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Nov 28, 2016
Publication date	Apr 16, 2019
Grant date	Apr 16, 2019

Abstract

The present invention relates to a method for producing a precipitation strengthened Ni-based superalloy material having a predetermined composition, containing a blooming forging step of performing a forging at a temperature range of from Ts to Tm and performing an air cooling to form a billet having an average crystal grain size of #1 or more, an overaging thermal treatment step of heating and holding the billet at a temperature range of from Ts to Ts+50° C. and slowly cooling it to a temperature of Ts or lower, and a crystal grain fining forging step of performing another forging at a temperature range of from Ts−150° C. to Ts and performing another air cooling, in which Ts is from 1,030° C. to 1,100° C., and an overall average crystal grain size is #8 or more after the crystal grain fining forging step.

First claim

What is claimed is:

1. A method for producing a precipitation strengthened Ni-based superalloy material having a component composition consisting of, in terms of % by mass:
C: more than 0.001% and less than 0.100%,
Cr: 11% or more and less than 19%,
Co: more than 5% and less than 25%,
Fe: 0.1% or more and less than 4.0%,
Mo: more than 2.0% and less than 5.0%,
W: more than 1.0% and less than 5.0%,
Nb: 2.0% or more and less than 4.0%,
Al: more than 3.0% and less than 5.0%,
Ti: more than 1.0% and less than 2.5%, and
with the balance being unavoidable impurities and Ni,
wherein, when a content of an element M in terms of atomic % is represented by [M], a value of ([Ti]+[Nb])/[Al]×10 is 3.5 or more and less than 6.5, and a value of [Al]+[Ti]+[Nb] is 9.5 or more and less than 13.0,
the method comprising:
a blooming forging step of performing a forging at a temperature range of from a solvus temperature Ts that is a solid solution temperature of the γ′ phase to a melting point Tm, and performing an air cooling to form a billet having an average crystal grain size of #1 or more,
an overaging thermal treatment step of heating and holding the billet at a temperature range of from Ts to Ts+50° C. and then slowly cooling it to a temperature Ts′ that is Ts or lower so that γ′-phase grains are allowed to precipitate and grow and to increase an average interval thereof, and
a crystal grain fining forging step of performing another forging at a temperature range of from Ts−150° C. to Ts and performing another air cooling,
wherein Ts is from 1,030° C. to 1,100° C., and
wherein crystal growth is suppressed by the γ′-phase grains resulting from the overaging thermal treatment to result in an overall average crystal grain size of #8 or more after the crystal grain fining forging step.

2. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 1 ,
wherein the average interval of the γ′-phase grains after the overaging thermal treatment is 0.5 μm or more.

3. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 1 ,
wherein in the overaging thermal treatment step, a cooling rate to Ts′ is 20° C./h or less and Ts′ is less than Ts−50.

4. A method for producing a precipitation strengthened Ni-based superalloy material having a component composition consisting of, in terms of % by mass:
C: more than 0.001% and less than 0.100%,
Cr: 11% or more and less than 19%,
Co: more than 5% and less than 25%,
Fe: 0.1% or more and less than 4.0,
Mo: more than 2.0% and less than 5.0%,
W: more than 1.0% and less than 5.0%,
Nb: 2.0% or more and less than 4.0%,
Al: more than 3.0% and less than 5.0%,
Ti: more than 1.0% and less than 2.5%, and
at least one selected from the group consisting of
B: less than 0.03%,
Zr: less than 0.1%,
Mg: less than 0.030%,
Ca: less than 0.030%, and
REM: 0.200% or less,

with the balance being unavoidable impurities and Ni,
wherein, when a content of an element M in terms of atomic % is represented by [M], a value of ([Ti]+[Nb])/[Al]×10 is 3.5 or more and less than 6.5, and a value of [Al]+[Ti]+[Nb] is 9.5 or more and less than 13.0,
the method comprising:
a blooming forging step of performing a forging at a temperature range of from a solvus temperature Ts that is a solid solution temperature of the γ′ phase to a melting point Tm, and performing an air cooling to form a billet having an average crystal grain size of #1 or more,
an overaging thermal treatment step of heating and holding the billet at a temperature range of from Ts to Ts+50° C. and then slowly cooling it to a temperature Ts′ that is Ts or lower so that γ′-phase grains are allowed to precipitate and grow and to increase an average interval thereof, and
a crystal grain fining forging step of performing another forging at a temperature range of from Ts−150° C. to Ts and performing another air cooling,
wherein Ts is from 1,030° C. to 1,100° C., and
wherein crystal growth is suppressed by the γ′-phase grains resulting from the overaging thermal treatment to result in an overall average crystal grain size of #8 or more after the crystal grain fining forging step.

5. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 4 ,
wherein the average interval of the γ′-phase grains after the overaging thermal treatment is 0.5 μm or more.

6. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 4 ,
wherein in the overaging thermal treatment step, a cooling rate to Ts′ is 20° C./h or less and Ts′ is less than Ts−50.

7. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 4 ,
wherein the component composition comprises, in terms of % by mass, at least one element selected from the group consisting of:
B: 0.0001% or more and less than 0.03% and
Zr: 0.0001% or more and less than 0.1%.

8. The method for producing a precipitation strengthened Ni-based superalloy material according to claim 4 ,
wherein the component composition comprises, in terms of % by mass, at least one element selected from the group consisting of:
Mg: 0.0001% or more and less than 0.030%,
Ca: 0.0001% or more and less than 0.030% and
REM: 0.001% or more and 0.200% or less.

Assignees

• Daido Steel Co Ltd

Inventors

• Narita Shuji
• Izumi Kohki
• Yamashita Kenta
• Ueta Shigeki

Classifications

• C22F1/10 Primary

  of nickel or cobalt or alloys based thereon · CPC title

• C22C30/00

  Alloys containing less than 50% by weight of each constituent · CPC title

• C22C19/056 Primary

  with the maximum Cr content being at least 10% but less than 20% · CPC title

• B21J5/06

  for performing particular operations · CPC title

• C22F1/16

  of other metals or alloys based thereon · CPC title