Nickel base heat resistant cast alloy and turbine wheels made thereof

Abstract

Disclosed is a nickel-base super heat resistant cast alloy, from which turbine wheels of automobile engines can be manufacture by casting. The alloy consists essentially of, by weight %, C: 0.02-0.50%, Si: up to 1.0%, Mn: up to 1.0%, Cr: 4.0-10.0%, Al: 2.0-8.0%, Co: up to 15.0%, W: 8.0-16.0%, Ta: 2.0-8.0%, Ti: up to 3.0%, Zr: 0.001-0.200% and B: 0.005-0.300% and the balance of Ni and inevitable impurities, provided that, [%Al]+[%Ti]+[%Ta], by atomic %, amounts to 12.0-15.5%, that it contains γ/γ′-eutectoid of, by area percentage, 1-15%, that it contains carbides of, by area percentage, 1-10%, and that the “M-value” determined by the alloy composition is in the range of 93-98. The turbine wheels withstand temperature increase of exhaust gas.

1 . A nickel-base heat resistant cast alloy, which consists essentially of, by weight %, C: 0.02-0.50%, Si: up to 1.0%, Mn: up to 1.0%, Cr: 4.0-10.0%, Al: 2.0-8.0%, Co: up to 15.0%, W: 8.0-16.0%, Ta: 2.0-8.0%, Ti: up to 3.0%, Zr: 0.001-0.200% and B: 0.005-0.300% and the balance of Ni and inevitable impurities, provided that, [%Al]+[%Ti]+[%Ta], by atomic %, amounts to 12.0-15.5%, that it contains γ/γ′-eutectoid of, by area percentage, 1-15%, that it contains carbides of, by area percentage, 1-10%, and that the “M-value” defined by the formula below (in which % is atomic %) is in the range of 93-98: 
 M=0.717[%Ni]+1.142[%Cr]+2.271 [%Ti]+1.9[%Al]+2.117[%Nb]+1.55[%Mo]+0.777 [%Co]+3.02[%Hf]+2.224[%Ta]+1.655[%W]+2.994[%Zr].  
 
     
     
         2 . The nickel-base heat resistant cast alloy according to  claim 1 , wherein the alloy further contains at least one of the group consisting of Mg: up to 0.01%, Ca: up to 0.01% and REM: up to 0.1%.  
     
     
         3 . The nickel-base heat resistant cast alloy according to  claim 1 , wherein the contents of the impurities are regulated to be up to the following respective upper limits: Fe: 5.0%, Mo: 1.0%, Cu: 0.3%, P: 0.03%, S: 0.03% and V: 1.0%  
     
     
         4 . The nickel-base heat resistant cast alloy according to  claim 1 , wherein the alloy further contains at least one of the group consisting of Mg: up to 0.01%, Ca: up to 0.01% and REM: up to 0.1%, and wherein the contents of the impurities are regulated to be up to the following respective upper limits: Fe: 5.0%, Mo: 1.0%, Cu: 0.3%, P: 0.03%, S: 0.03% and V: 1.0%.  
     
     
         5 . A turbine wheel for automobile engines made of the nickel-base heat resistant cast alloy according to  claim 4 .  
     
     
         6 . A turbine wheel for automobile engines made of the nickel-base heat resistant cast alloy according to  claim 2 .  
     
     
         7 . A turbine wheel for automobile engines made of the nickel-base heat resistant cast alloy according to  claim 3 .  
     
     
         8 . A turbine wheel for automobile engines made of the nickel-base heat resistant cast alloy according to  claim 4.