METHOD OF FABRICATING INCONEL 718 TYPE NICKEL SUPERALLOYS
A method of fabricating Inconel 718 type nickel superalloys. A last forging operation to which the nickel superalloy is subjected is such: that it takes place at a temperature lower than the δ-solvus temperature; that at all points of the nickel superalloy the local deformation ratio is not less than a minimum value; and that the nickel superalloy is not subjected to any heat treatment at a temperature higher than a threshold temperature equal to 750° C. after a quenching.
1 - 6 . (canceled)
7 . A fabrication method of fabricating an Inconel 718 type nickel superalloy wherein a last forging operation to which the nickel superalloy is subjected is such:
that it takes place at a temperature lower than the δ-solvus temperature;
that at all points of the nickel superalloy the local deformation ratio is not less than a minimum value; and
the nickel superalloy is not subjected to any heat treatment at a temperature higher than a threshold temperature equal to 750° C. after a quenching.
8 . A fabrication method according to claim 7 , wherein the minimum value of the local deformation ratio is equal to 0.7.
9 . A fabrication method according to claim 7 , wherein the nickel superalloy is also subjected to tempering directly after the quenching following the forging operation.
10 . A fabrication method according to claim 7 , wherein all of forging operations preceding the last forging operation are performed at temperatures lower than the δ-solvus temperature.
11 . A fabrication method according to claim 7 , wherein at an end of the method, a size of all grains of the superalloy lies in a range of 5 μm to 30 μm.
12 . A fabrication method according to claim 11 , wherein at the end of the method, the size of all the grains of the superalloy lies in a range of 5 μm to 20 μm.