Powder metal rotating components for turbine engines and process therefor

Abstract

A process for producing turbine rotors and other large rotating components of power-generating gas turbine engines using powder metallurgy techniques. The process involves forming a powder of a gamma prime or gamma double prime precipitation-strengthened nickel-based superalloy whose particles are about 0.100 mm in diameter or smaller. The powder is placed in a can and consolidated to produce an essentially fully dense consolidation, which is then hot worked to produce a billet of a size sufficient to form a forging of at least 2300 kg. The billet is forged at a temperature and strain rate to produce a forging with a uniform fine grain of ASTM 10 or finer. Thereafter, the forging may undergo a heat treatment to achieve a desired balance of mechanical properties while retaining a uniform grain size of ASTM 10 or finer.

1 . A process of producing a component from a gamma prime or gamma double prime precipitation-strengthened nickel-base superalloy, the process comprising the steps of: 
 forming a powder of the superalloy;    filling a can with the powder and evacuating and sealing the can in a controlled environment;    consolidating the can and the powder therein at a temperature, time, and pressure to produce a consolidation;    hot working the consolidation to produce a billet of a size sufficient to form a forging of at least 2300 kg; and then    forging the billet at a temperature and strain rate to produce a forging with a uniform fine grain of ASTM 10 or finer throughout.    
   
   
       2 . A process according to  claim 1 , wherein the nickel-based superalloy has a composition of, by weight, about 19 to about 23% chromium, about 7 to about 8% molybdenum, about 3 to about 4% niobium, about 4 to about 6% iron, about 0.3 to about 0.6% aluminum, about 1 to about 1.8% titanium, about 0.002 to about 0.004% boron, about 0.35% maximum manganese, about 0.2% maximum silicon, about 0.03% maximum carbon, the balance nickel and incidental impurities.  
   
   
       3 . A process according to  claim 1 , wherein the forming step comprises producing a melt of the nickel-based superalloy in a controlled environment and then rapidly cooling the melt to produce the powder.  
   
   
       4 . A process according to  claim 3 , wherein the forming step further comprises sieving the powder in a controlled environment to remove all particles larger than 0.100 mm in diameter.  
   
   
       5 . A process according to  claim 3 , wherein the forming step further comprises blending the powder with a second powder of the nickel-based superalloy.  
   
   
       6 . A process according to  claim 1 , wherein the consolidation formed by the consolidation step has a density of at least 99.9% of theoretical.  
   
   
       7 . A process according to  claim 1 , wherein the forging produced by the forging step weighs at least 2300 kg.  
   
   
       8 . A process according to  claim 1 , wherein the billet formed by the hot working step weighs about 1.2 to about 1.5 times the weight of the forging.  
   
   
       9 . A process according to  claim 1 , wherein the billet formed by the hot working step weighs about 1.8 to about 4 times the weight of the rotor component.  
   
   
       10 . A process according to  claim 1 , wherein the component is a rotor component of a gas turbine engine.  
   
   
       11 . A process according to  claim 1 , wherein the rotor component is chosen from the group consisting of turbine wheels and spacers.  
   
   
       12 . A process of producing a gas turbine engine rotor component from a gamma prime or gamma double prime precipitation-strengthened nickel-base nickel-based superalloy, the process comprising the steps of: 
 melting the nickel-based superalloy in a controlled environment to obtain a melt of the nickel-based superalloy;    convert the melt into a powder of generally spherical particles that are predominantly about 0.100 mm in diameter or smaller;    sieving the powder in a controlled environment to remove all particles larger than 0.100 mm in diameter;    filling a mild steel can with the sieved powder and evacuating and sealing the can in a controlled environment;    consolidating the can and the powder therein at a temperature, time, and pressure to produce a consolidation having a density of at least 99.9 percent of theoretical;    hot working the consolidation to produce a billet of a size sufficient to form a forging of at least 2300 kg with a uniform grain size of ASTM 10 or finer throughout the billet;    forging the billet into a forging at a temperature and strain rate to achieve a uniform fine grain of ASTM 10 or finer throughout the forging;    performing a heat treatment on the forging to achieve a desired balance of mechanical properties and maintain a uniform grain size throughout of ASTM 10 or finer; and    machining the forging to produce the gas turbine engine rotor component.    
   
   
       13 . A process according to  claim 12 , wherein the nickel-based superalloy has a composition of, by weight, about 19 to about 23% chromium, about 7 to about 8% molybdenum, about 3 to about 4% niobium, about 4 to about 6% iron, about 0.3 to about 0.6% aluminum, about 1 to about 1.8% titanium, about 0.002 to about 0.004% boron, about 0.35% maximum manganese, about 0.2% maximum silicon, about 0.03% maximum carbon, the balance nickel and incidental impurities.  
   
   
       14 . A process according to  claim 12 , further comprising the step of blending the powder with a second powder of the nickel-based superalloy before the filling step.  
   
   
       15 . A process according to  claim 12 , wherein the forging produced by the forging step weighs at least 2300 kg.  
   
   
       16 . A process according to  claim 12 , wherein the billet formed by the hot working step weighs about 1.2 to about 1.5 times the weight of the forging.  
   
   
       17 . A process according to  claim 12 , wherein the billet formed by the consolidation step weighs about 1.8 to about 4 times the weight of the rotor component.  
   
   
       18 . A process according to  claim 12 , wherein the rotor component is chosen from the group consisting of turbine wheels and spacers.  
   
   
       19 . A process according to  claim 18 , wherein the rotor component is a component of a land-based gas turbine engine.