High temperature alloy particularly suitable for a long-life turbocharger nozzle ring

Abstract

An iron-based alloy that contains the elements of cobalt, carbon, silicon, manganese, chromium, molybdenum, niobium, cobalt, and tungsten, and optionally also minor amounts of one or more of aluminum, nickel, vanadium, nitrogen and titanium, on the condition that the combined amount of chrome and cobalt is at least 34.5 percent by weight of the total alloy, preferably at least 36 percent by weight and at most 41.5 percent by weight of the total alloy. The alloy is particularly suitable for use in mechanical parts which are thermally highly stressed and exposed to oxidizing and/or corroding effects. The alloy preferably comprises C: 0.3-0.5% by weight, Si: 0.0-1.5% by weight, Mn: 0.0-3.0% by weight, Cr: 19-28% by weight, Mo: 1-3% by weight, Nb: 2-4% by weight, Co: 12-18% by weight, and W: 2-4% by weight measured as a percentage of total weight of the alloy.

1 . An iron-based alloy, comprising: 
 C: 0.3-0.5% by weight,    Si: 0.0-1.5% by weight,    Mn: 0.0-3.0% by weight,    Cr: 19-28% by weight,    Mo: 1-3% by weight,    Nb: 2-4% by weight,    Co: 12-18% by weight, and    W: 2-4% by weight    measured as a percentage of total weight of the alloy:    
     
     
         2 . The iron-based alloy of  claim 1 , comprising: 
 C: 0.35-0.45% by weight,    Si: 0.0-1.0% by weight,    Mn: 0.0-2.0% by weight,    Cr: 21-25% by weight,    Mo: 1.8-2.2% by weight,    Nb: 2.8-3.2% by weight,    Co: 13.5-16.5% by weight, and    W: 2.3-3.0% by weight.    
     
     
         3 . An iron-based alloy, comprising the elements of cobalt, carbon, silicon, manganese, chromium, molybdenum, niobium, cobalt, and tungsten, and optionally also minor amounts of one or more of aluminum, nickel, vanadium, nitrogen and titanium, wherein the amount of chromium is at least 19% by weight, the amount of cobalt is at least 12% by weight, and the combined amount of chrome and cobalt is at least 34.5 percent by weight of the total alloy.  
     
     
         4 . The iron based alloy as in  claim 3 , wherein the amount of chromium is at least 21% by weight, the amount of cobalt is at least 13.5% by weight, and the combined amount of chrome and cobalt is at least 34.5 percent by weight of the total alloy, the remainder being iron and metallurgical admixtures for the production of an alloy particularly suitable for use in mechanical parts which are thermally highly stressed and exposed to oxidizing and/or corroding effects.  
     
     
         5 . A process of using the iron-based alloy of  claim 1 , comprising: 
 manufacturing at least one machine part from said iron-based alloy; and    installing said at least one machine part to function under conditions of high thermal stress and exposure to oxidizing and/or corroding effects.    
     
     
         6 . The process according to  claim 4 , wherein said manufacturing said at least one machine part comprises manufacturing at least one turbocharger nozzle ring.  
     
     
         7 . A process of making a machine part for functioning under conditions of severe thermal stress and exposure to oxidizing and/or corroding effects, comprising: 
 forming an alloy comprising:    C: 0.3-0.5% by weight,    Si: 0.0-1.5% by weight,    Mn: 0.0-3.0% by weight,    Cr: 19-28% by weight,    Mo: 1-3% by weight,    Nb: 2-4% by weight,    Co: 12-18% by weight, and    W: 2-4% by weight    measured as a percentage of total weight of the alloy;    (b) tempering the machine part; and    (c) forming a hardened layer on at least a portion of a surface of the machine part.    
     
     
         8 . The process of making a machine part according to  claim 7 , wherein said forming a hardened layer comprises forming a nitride layer on at least a portion of the machine part.  
     
     
         9 . The process of making a machine part according to  claim 7 , wherein said forming a hardened layer comprises forming a carbonitride layer on at least a portion of the machine part.  
     
     
         10 . The process of making a machine part according to  claim 7 , wherein said forming a hardened layer comprises vapor depositing an aluminum-based carbide layer on at least a portion of the machine part.  
     
     
         11 . A turbocharger nozzle ring comprising by weight: 
 C: 0.3-0.5% by weight,    Si: 0.0-1.5% by weight,    Mn: 0.0-3.0% by weight,    Cr: 19-28% by weight,    Mo: 1-3% by weight,    Nb: 2-4% by weight,    Co: 12-18% by weight, and    W: 2-4% by weight    measured as a percentage of total weight of the alloy.    
     
     
         12 . A turbocharger comprising a turbocharger nozzle ring and a turbine housing, wherein said nozzle ring and at least a part of the housing comprises: 
 C: 0.3-0.5% by weight,    Si: 0.0-1.5% by weight,    Mn: 0.0-3.0% by weight,    Cr: 19-28% by weight,    Mo: 1-3% by weight,    Nb: 2-4% by weight,    Co: 12-18% by weight, and    W: 2-4% by weight    measured as a percentage of total weight of the alloy.    
     
     
         13 . An exhaust-gas turbine of a turbocharger comprising: 
 a turbine casing having a gas-inlet casing a gas-outlet casing and at least one turbine-side casing component;    a turbine wheel rotatably mounted on a shaft and having moving blades an inflow passage formed in the turbine casing upstream of the turbine wheel for the exhaust gases of an internal combustion engine connected to the turbocharger; and    a nozzle ring arranged in the inflow passage, wherein the nozzle ring is formed of an alloy comprising:    C: 0.3-0.5% by weight,    Si: 0.0-1.5% by weight,    Mn: 0.0-3.0% by weight,    Cr: 19-28% by weight,    Mo: 1-3% by weight,    Nb: 2-4% by weight,    Co: 12-18% by weight, and    W: 2-4% by weight    measured as a percentage of total weight of the alloy.