Method for producing low thermal expansion Ni-base superalloy
View Patent ↗A method for producing a low thermal expansion Ni-base superalloy including the steps of subjecting the alloy to a solution heat treatment under the condition of at a temperature of 1000 to 1200° C. and subjecting the alloy to either a carbide stabilizing treatment for making aggregated carbides on grain boundaries and stabilizing the carbides under the conditions of at a temperature of not less than 850° C. and less than 1000° C. and for 1 to 50 hours, or a carbide stabilizing treatment for making aggregated carbides on grain boundaries and stabilizing the carbides by cooling from the temperature in the solution heat treatment to 850° C. at a cooling rate of 100° C. or less per hour. The method also including the steps of subjecting the alloy to a first aging treatment for precipitating y′ phase under the conditions of at a temperature of 720 to 900° C. and for 1 to 50 hours, and subjecting the alloy to a second aging treatment for precipitating A 2 B phase under the conditions of at a temperature of 550 to 700° C. and for 5 to 100 hours.
1. A method for producing a forged low thermal expansion Ni-base superalloy with a high creep fracture strength, the superalloy comprising a nickel containing γ′ phase, a nickel containing A 2 B phase and, as a matrix, an austenite phase wherein Ni is the main component and Mo, W and Re are solid-solved therein, and a carbide phase in the form of aggregated carbides on grain boundaries, said method comprising:
preparing an alloy comprising, by weight %,
C: 0.02 to 0.15%,
Si: 1% or less,
Mn: 1% or less,
Cr: 5 to 20%,
at least one of Mo, W and Re, which satisfy the relationship Mo+½(W+Re): 17 to 27%,
Al: 0.1 to 1.22%,
Ti: 0.1 to 2%,
Nb and Ta, which satisfy the relationship
Nb+Ta/2: 1.5% or less,
Fe: 10% or less,
Co: 5% or less,
B: 0.001 to 0.02%,
Zr: 0.001 to 0.2%,
a remainder of Ni and inevitable components;
subjecting the alloy to a solution heat treatment under the condition of at a temperature of 1000 to 1200° C.;
subjecting the alloy to either a carbide stabilizing treatment to form the aggregated carbides on grain boundaries and to stabilize the aggregated carbides under the conditions of at a temperature of not less than 850° C. and less than 1000° C. and for 1 to 50 hours, or a carbide stabilizing treatment to form the aggregated carbides on grain boundaries to stabilize the aggregated carbides by cooling from the temperature in the solution heat treatment to 850° C. at a cooling rate of 100° C. or less per hour;
subjecting the alloy to a first aging treatment to precipitate the γ′ phase under the conditions of at a temperature of 720 to 900° C. and for 1 to 50 hours; and
subjecting the alloy to a second aging treatment to precipitate the A 2 B phase under the conditions of at a temperature of 550 to 700° C. and for 5 to 100 hours.
2. The method of claim 1 wherein the alloy is subjected to a carbide stabilizing treatment to form the aggregated carbides on grain boundaries and stabilizing the carbides under the conditions of a temperature of not less than 850° C. and less than 1000° C. for 1 to 50 hours, and the solution heat treatment is from 1050° C. to 1150° C.
3. The method of claim 1 wherein the alloy is subjected to a carbide stabilizing treatment to form the aggregated carbides on grain boundaries and stabilizing the carbides by cooling from the temperature in the solution heat treatment to 850° C. at a cooling rate of 100° C. or less per hour, and the solution heat treatment is from 1050° C. to 1150° C.
4. The method of claim 1 wherein the alloy has enhanced creep rupture strength under high temperature.
5. The method of claim 1 wherein the carbon content is from 0.02 to 0.10.
6. The method of claim 1 , wherein the alloy contains Mo.
7. A method for producing a forged low thermal expansion Ni-base superalloy with high creep fracture strength, the superalloy comprising an nickel containing γ′ phase, a nickel containing A 2 B phase and, as a matrix, an austenite phase wherein Ni is the main component and Mo, W and Re are solid-solved therein, and a carbide phase in the form of aggregated carbides on grain boundaries, said method comprising:
preparing an alloy comprising, by weight %,
C: 0.02 to 0.15%,
Si: 1% or less,
Mn: 1% or less,
Cr: 5 to 20%,
at least one of Mo, W and Re, which satisfy the relationship Mo+½(W+Re): 17 to 27%,
Al: 0 to 1.22%,
Ti: 0.1 to 2%,
Nb and Ta, which satisfy the relationship
Nb+Ta/2: 1.5% or less,
Fe: 10% or less,
Co: 5% or less,
B: 0.001 to 0.02%,
Zr: 0.001 to 0.2%,
a remainder of Ni and inevitable components;
subjecting the alloy to a solution heat treatment under the condition of at a temperature of 1000 to 1200° C.;
subjecting the alloy to a carbide stabilizing treatment to form the aggregated carbides on grain boundaries and to stabilize the aggregated carbides under the conditions of at a temperature of not less than 850° C. and less than 1000° C. and for 1 to 50 hours, subjecting the alloy to a first aging treatment to precipitate the γ′ phase under the conditions of at a temperature of 720 to 900° C. and for 1 to 50 hours; and
subjecting the alloy to a second aging treatment to precipitate the A 2 B phase under the conditions of at a temperature of 550 to 700° C. and for 5 to 100 hours.
8. The method of claim 7 , wherein the alloy has enhanced creep rupture strength under high temperature.
9. The method of claim 7 wherein the carbon content is from 0.02 to 0.10.
10. The method of claim 7 , wherein the carbon content is from 0.02 to 0.10.
11. The method of claim 7 , wherein the alloy contains Mo.
12. A method for producing a forged low thermal expansion Ni-base superalloy with high creep fracture strength, the superalloy comprising a nickel containing γ′ phase, a nickel containing A 2 B phase and, as a matrix, an austenite phase wherein Ni is the main component and Mo, W and Re are solid-solved therein, and a carbide phase in the form of aggregated carbides on grain boundaries, said method comprising:
preparing an alloy comprising, by weight %,
C: 0.02 to 0.15%,
Si: 1% or less,
Mn: 1% or less,
Cr: 5 to 20%,
at least one of Mo, W and Re, which satisfy the relationship Mo+½(W+Re): 17 to 27%,
Al: 0.1 to 1.22%,
Ti: 0.1 to 2%,
Nb and Ta, which satisfy the relationship
Nb+Ta/2: 1.5% or less,
Fe: 10% or less,
Co: 5% or less,
B: 0.001 to 0.02%,
Zr: 0.001 to 0.2%,
a remainder of Ni and inevitable components;
subjecting the alloy to a solution heat treatment under the condition of at a temperature of 1000 to 1200° C.;
a carbide stabilizing treatment to form the aggregated carbides on grain boundaries and to stabilize the aggregated carbides by cooling from the temperature in the solution heat treatment to 850° C. at a cooling rate of 100° C. or less per hour,
subjecting the alloy to a first aging treatment to precipitate the γ′ phase under the conditions of at a temperature of 720 to 900° C. and for 1 to 50 hours; and
subjecting the alloy to a second aging treatment to precipitate the A 2 B phase under the conditions of at a temperature of 550 to 700° C. and for 5 to 100 hours.
13. The method of claim 12 , wherein the alloy has enhanced creep rupture strength under high temperature and contains Mo.
14. The method of claim 13 wherein the carbon content is from 0.02 to 0.10.