US2004261923A1PendingUtilityA1

Clean atmosphere heat treat for coated turbine components

32
Priority: Jun 25, 2003Filed: Jun 25, 2003Published: Dec 30, 2004
Est. expiryJun 25, 2023(expired)· nominal 20-yr term from priority
Inventors:Steven BurnsSteven Hahn
C21D 1/76C23C 8/80C21D 2241/01C21D 1/74C23C 8/06
32
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Claims

Abstract

A method for heat treating at least one workpiece, such as a coated turbine engine component, is provided. The method comprises the steps of cleaning a furnace to be used during the heat treating method, which cleaning method comprising injecting a gas at a workpiece center location and applying heat, and diffusion heat treating the at least one workpiece in a gas atmosphere with the gas being injected at the workpiece center location. After the diffusion heat treatment step, the coated workpiece(s) may be subjected to a surface finishing operation such as a peening operation.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
         1 . A method for heat treating at least one workpiece comprising the steps of: 
 cleaning a furnace to be used during said heat treating method;    said cleaning method comprising injecting a gas at a workpiece center location and applying heat; and    diffusion heat treating said at least one workpiece in a gas atmosphere with said gas being injected at said workpiece center location.    
     
     
         2 . A method according to  claim 1 , wherein said cleaning method comprises injecting said gas into said furnace at said workpiece center location at a flow rate sufficient to create a pressure differential which carries contaminants away from said workpiece center location toward an exit.  
     
     
         3 . A method according to  claim 2 , wherein said gas injecting step comprises injecting said gas at a partial pressure of at least 0.8 Torr.  
     
     
         4 . A method according to  claim 2 , wherein said gas injecting step comprises injecting said gas into said furnace at a rate of 30 liters per minute to 70 liters per minute.  
     
     
         5 . A method according to  claim 2 , wherein said gas injecting step comprises injecting an inert gas.  
     
     
         6 . A method according to  claim 2 , wherein said gas injecting step comprises injecting argon.  
     
     
         7 . A method according to  claim 2 , wherein said gas injecting step comprises injecting a reducing gas.  
     
     
         8 . A method according to  claim 1 , wherein said diffusion heat treatment step is carried out at a temperature in the range of 1900 degrees Fahrenheit to 2500 degrees Fahrenheit for a time period in the range of 1 to 24 hours.  
     
     
         9 . A method according to  claim 1 , wherein said diffusion heat treatment step comprises injecting said gas into said workpiece center location at a rate sufficient to carry away contaminants in said workpiece but less than a rate at which a door to said furnace is caused to open.  
     
     
         10 . A method according to  claim 9 , wherein said diffusion heat treatment step comprises injecting said gas into said workpiece center location at a partial pressure of at least 0.8 Torr.  
     
     
         11 . A method according to  claim 9 , wherein said gas is injected into said furnace at a flow rate of 30 liters per minute to 70 liters per minute.  
     
     
         12 . A method according to  claim 9 , wherein said diffusion heat treatment comprises injecting an inert gas.  
     
     
         13 . A method according to  claim 9 , wherein said diffusion treatment comprises injecting argon.  
     
     
         14 . A method according to  claim 9 , wherein said diffusion heat treatment comprises injecting a reducing gas.  
     
     
         15 . A method for providing at least one workpiece having a coating comprising the steps of: 
 diffusion heat treating said at least one workpiece in gas atmosphere within a furnace with said gas being injected at a workpiece center location;    removing said workpiece from said furnace; and    subjecting said coated workpiece to a surface finishing operation.    
     
     
         16 . A method according to  claim 15 , wherein said diffusion heat treatment step is carried out at a temperature in the range of 1900 degrees Fahrenheit to 2500 degrees Fahrenheit for a time period in the range of 1 to 24 hours.  
     
     
         17 . A method according to  claim 15 , wherein said diffusion heat treatment step comprises injecting said gas into said workpiece center location at a rate sufficient to carry away contaminants in said workpiece but less than a rate at which a door to said furnace is caused to open.  
     
     
         18 . A method according to  claim 17 , wherein said diffusion heat treatment step comprises injecting said gas into said workpiece center location at a partial pressure of at least 0.8 Torr.  
     
     
         19 . A method according to  claim 17 , wherein said gas is injected into said furnace at a flow rate of 30 liter per minute to 70 liters per minute.  
     
     
         20 . A method according to  claim 15 , wherein said surface finishing step comprising subjecting said coated workpiece to a peening operation.  
     
     
         21 . A method according to claim  1 S, wherein said diffusion heat treating step comprises injecting an inert gas into said workpiece center location.  
     
     
         22 . A method according to  claim 15 , wherein said diffusion heat treating step comprises injecting argon into said workpiece center location.  
     
     
         23 . A method according to  claim 15 , wherein said diffusion heat treating step comprises injecting a reducing gas into said workpiece center location.  
     
     
         24 . A system for heat treating a coated workpiece comprising: 
 a furnace having a chamber; and    means for injecting a gas into an interior of said furnace chamber at a workpiece center location.    
     
     
         25 . A system according to  claim 24 , wherein said gas injecting means comprises means for injecting said gas at a flow rate sufficient to carry any contaminants from said workpiece center location toward an exit.  
     
     
         26 . A system according to  claim 24 , wherein said injecting means comprises means for injecting at least one of an inert gas or a reducing gas.  
     
     
         27 . A system according to  claim 24 , wherein said injecting means comprises means for injecting argon gas.

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