Graphite and nitrogen-free cast alloys

Abstract

The present invention is related to an air melted, substantially graphite and nitrogen-free alloy, aged or not aged by precipitation hardening, specially adapted for gas turbine or internal combustion engine exhaust system parts, comprising a graphite-free microstructure of the following composition: Carbon max 0.4 wt. % Silicon 0.5 to 6 wt. % Manganese 0.1 to 4.5 wt. % Phosphorous 0.01 to 0.08 wt. % Nickel 13 to 38 wt. % Chromium 0 to 6 wt. % Sulphur max 0.12 wt. % Nitrogen max 0.02 wt. % Iron balance

1 . An air melted, substantially graphite and nitrogen-free alloy, aged or not aged by precipitation hardening, specially adapted for gas turbine or internal combustion engine exhaust system parts, comprising a graphite-free microstructure of the following composition:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   Carbon 
                   max 0.4 
                   wt. % 
                 
                     
                   Silicon 
                   0.5 to 6 
                   wt. % 
                 
                     
                   Manganese 
                   0.1 to 4.5 
                   wt. % 
                 
                     
                   Phosphorous 
                   0.01 to 0.08 
                   wt. % 
                 
                     
                   Nickel 
                   13 to 38 
                   wt. % 
                 
                     
                   Chromium 
                   0 to 6 
                   wt. % 
                 
                     
                   Sulphur 
                   max 0.12 
                   wt. % 
                 
                     
                   Nitrogen 
                   max 0.02 
                   wt. % 
                 
                 
                 
                 
               
                     
                   Iron 
                   balance 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
                
                
                
               
            
             
                
                
                
               
            
           
         
       
     
     
         2 . Alloy as in  claim 1  further comprising: Molybdenum in the range of 0.1 to 4 wt. %.  
     
     
         3 . Alloy as in  claim 1  further comprising maximum 1 wt. % of copper.  
     
     
         4 . Alloy as in  claim 1  or  2  further comprising Copper in a range of 0.5 to 8 wt. % and wherein the nickel concentration is in a range of 13 to 22 wt. %  
     
     
         5 . Alloy as in  claim 1  further comprising:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   Niobium 
                   1 to 5 
                   wt. % 
                 
                     
                   Titanium 
                   max 1 
                   wt. % 
                 
                     
                   Aluminium 
                   max 1 
                   wt. % 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
         6 . Alloy as in  claim 1  further comprising:  
       
         
           
                 
                 
                 
                 
               
                     
                     
                 
                     
                     
                 
                     
                   Niobium 
                   max 2 
                   wt. % 
                 
                     
                   Tungsten 
                   max 4 
                   wt. % 
                 
                     
                   Zirconium 
                   max 1 
                   wt. % 
                 
                     
                   Vanadium 
                   max 1 
                   wt. % 
                 
                     
                     
                 
                     
                     
                 
             
                
                
               
               
                
                
                
                
                
                
               
            
           
         
       
     
     
         7 . Process for the manufacturing of the composition disclosed in  claim 5 , wherein said alloy is strengthened by precipitation hardening of (Ni 3 [Al,Ti]), (Ni 3 [Nb,Al,Ti]), or (Ni 3 Nb).  
     
     
         8 . Process for the manufacturing of the composition disclosed in  claim 1 ,  2 ,  3  or  4 , wherein said alloy is strengthened by precipitation hardening of MO 2 C.  
     
     
         9 . Process for the manufacturing of the composition disclosed in  claim 2 ,  3  or  4 , wherein said alloy is not strengthened by ageing and precipitation hardening.