Nickel-base alloy for turbine rotor of steam turbine and turbine rotor of steam turbine using the same

Abstract

A nickel (Ni)-base alloy for a turbine rotor of a steam turbine containing, in mass %, carbon (C): 0.01% to 0.15%, chromium (Cr): 18% to 28%, cobalt (Co): 10% to 15%, molybdenum (Mo): 8% to 12%, aluminum (Al): 0.5% to less than 1.5%, titanium (Ti): 0.7% to 3.0%, and boron (B): 0.001% to 0.006%, the balance being nickel (Ni) and unavoidable impurities.

1 . A nickel-base alloy for a turbine rotor of a steam turbine, the nickel-base alloy containing, in mass %: carbon (C): 0.01% to 0.15%; chromium (Cr): 18% to 28%; cobalt (Co): 10% to 15%; molybdenum (Mo): 8% to 12%; aluminum (Al): 0.5% to less than 1.5%; titanium (Ti): 0.7% to 3.0%; and boron (B): 0.001% to 0.006%, the balance being nickel (Ni) and unavoidable impurities. 
     
     
         2 . The nickel-base alloy for a turbine rotor of a steam turbine according to  claim 1 , further containing tantalum (Ta): 0.1% to 0.7% by mass. 
     
     
         3 . The nickel-base alloy for a turbine rotor of a steam turbine according to  claim 1 , further containing niobium (Nb): 0.1% to 0.4% by mass. 
     
     
         4 . The nickel-base alloy for a turbine rotor of a steam turbine according to  claim 2 , further containing niobium (Nb): 0.1% to 0.4% by mass. 
     
     
         5 . The nickel-base alloy for a turbine rotor of a steam turbine according to  claim 1 , further containing tantalum+2niobium (Ta+2Nb) (mole ratio of tantalum and niobium being 1:2): 0.1% to 0.7% by mass. 
     
     
         6 . The nickel-base alloy for a turbine rotor of a steam turbine according to  claim 1 ,
 wherein the unavoidable impurities include silicon (Si): 0.1% or less and manganese (Mn): 0.1% or less by mass.   
     
     
         7 . A turbine rotor provided to penetrate through a steam turbine to which high-temperature steam is introduced,
 wherein at least a predetermined portion is constituted of the nickel-base alloy for a turbine rotor of a steam turbine according to  claim 1 .