Precipitation Hardenable Cobalt-Nickel Base Superalloy And Article Made Therefrom

Abstract

A precipitation hardenable, cobalt-nickel base superalloy is disclosed. The is characterized by the following weight percent composition. C about 0.01 to about 0.15 Cr about 6.00 to about 15.00 Ni about 30.00 to about 45.00 W about 3.00 to about 15.00 Ti about 0.50 to about 4.00 Al about 3.00 to about 7.00 Nb up to about 2.50 Ta up to about 6.00 Hf up to about 1.50 Zr up to about 1.50 B up to about 0.20 Mo up to about 2.50 Si up to about 1.50 The balance of the alloy is cobalt and usual impurities. The alloy provides a novel combination of strength and ductility after long-term exposure to elevated operating temperatures as found in gas turbines and jet engines. A fine-grain steel article made from the alloy is also disclosed. The steel article is also characterized by a continuous surface layer of Al 2 O 3 and Cr 2 O 3 that protects the alloy from oxidation at the elevated operating temperatures.

1 . A precipitation hardenable, cobalt-nickel base superalloy comprising in weight percent:
 C about 0.01 to about 0.15   Cr about 6.00 to about 15.00   Ni about 30.00 to about 45.00   W about 3.00 to about 15.00   Ti about 0.50 to about 4.00   Al about 3.00 to about 7.00   Nb up to about 2.50   Ta up to about 6.00   Hf up to about 1.50   Zr up to about 1.50   B up to about 0.20   Mo up to about 2.50   Si up to about 1.50   
       the balance being cobalt and usual impurities. 
     
     
         2 . The alloy as claimed in  claim 1  which contains at least about 0.50% tantalum. 
     
     
         3 . The alloy as claimed in  claim 1  which contains not more than about 9.8% chromium. 
     
     
         4 . The alloy as claimed in  claim 3  which contains at least about 7.00% chromium. 
     
     
         5 . The alloy as claimed in  claim 1  which contains at least about 34.00% nickel. 
     
     
         6 . The alloy as claimed in  claim 1  which contains not more than about 12.00% tungsten. 
     
     
         7 . A precipitation hardenable, cobalt-nickel base superalloy comprising in weight percent:
 C about 0.01 to about 0.15   Cr about 6.00 to about 15.00   Ni about 30.00 to about 45.00   W about 3.00 to about 15.00   Ti about 0.50 to about 4.00   Ta about 0.50 to about 6.00   Al about 3.00 to about 7.00   Nb up to about 2.50   Zr up to about 1.50   B up to about 0.20   Mo up to about 2.50   Si up to about 1.50   
       the balance being cobalt and usual impurities. 
     
     
         8 . The alloy as claimed in  claim 6  which contains not more than about 9.8% chromium. 
     
     
         9 . The alloy as claimed in  claim 8  which contains at least about 7.00% chromium. 
     
     
         10 . The alloy as claimed in  claim 7  which contains at least about 34.00% nickel. 
     
     
         11 . The alloy as claimed in  claim 7  which contains not more than about 12.00% tungsten. 
     
     
         12 . A precipitation hardenable, cobalt-nickel base superalloy consisting essentially of, in weight percent:
 C about 0.02 to about 0.10   Cr about 7.00 to about 9.80   Ni about 34.00 to about 41.00   W about 3.00 to about 12.00   Ti about 0.60 to about 2.00   Al about 3.00 to about 7.00   Ta about 0.50 to about 5.00   Nb up to about 2.00   Hf up to about 0.50   Zr up to about 1.00   B up to about 0.10   Mo up to about 2.00   Si up to about 1.00   
       the balance being cobalt and usual impurities. 
     
     
         13 . A precipitation hardenable, cobalt-nickel base superalloy consisting essentially of, in weight percent:
 C about 0.02 to about 0.10   Cr about 8.00 to about 12.00   Ni about 34.00 to about 41.00   W about 3.00 to about 12.00   Ti about 0.60 to about 2.00   Ta about 2.00 to about 5.00   Al about 3.00 to about 5.00   Nb up to about 2.00   Zr up to about 1.00   B up to about 0.10   Mo up to about 2.00   Si up to about 1.00   
       the balance being cobalt and usual impurities. 
     
     
         14 . An article made from the alloy claimed in  claim 1  in which the alloy has a grain size not greater than about ASTM grain size number  6 . 
     
     
         15 . The article as claimed in  claim 14  in which the alloy has a grain size not greater than about ASTM grain size number  8 . 
     
     
         16 . An article made from the alloy claimed in  claim 1  which has a continuous protective surface layer comprising Al 2 O 3  and Cr 2 O 3 .