CREEP, STRESS RUPTURE AND HOLD-TIMEFATIGUE CRACK RESISTANT ALLOYS AND METHOD FOR MAKING

摘要

Improved, creep-stress rupture and hold-time fatigue resistant nickel base alloys for use at elevated temperatures are disclosed. The alloys consists essentially of, in weight percent, 10.9 to 12.9% Co; 11.8 to 13. 8% Cr; 4.6 to 5.6% Mo; 2.1 to 3.1% Al; 4.4 to 5.4% Ti; 1.1 to 2.1% Nb; 0. 005 to 0.025% B; 0.01 to 0.06% C; 0 to 0.6% Zr; 0.1 to 0.3% Hf; balance nickel. The article is characterized by a microstructure having an average grain size of from about 20 to 40 microns, with carbides, borides, and 0.3 to 0.4 micron-sized coarse gamma prime located at the grain boundaries, and 30 nanometer-sized fine gamma prime uniformly distributed throughout the grains. The alloys are suitable for use as turbine disks in gas turbine engines of the type used in jet engines, or for use as rim sections of dual alloy turbine disks for advanced turbine engines and are capable of operation at temperatures up to about 1500° F. A method for achieving the desired properties in such turbine disks is also disclosed.