Development of heat-treatment process for a P/M superalloy for turbine blades

Abstract

Powder metallurgy (P/M) superalloy turbine blades are increasingly being used in jet-aircraft engines. A notable advancement in the manufacture of P/M turbine blades is the development of a powder forge IN-792 nickel-based superalloy: APK-6. Although fatigue strength of the P/M material is 2 1 2 times superior as compared to cast blades, its creep strength is poor. The improvement in creep strength is ensured though microstructural control achieved by developing a suitable heat-treatment process. Heat-treatment experiments in the temperature range of 117–1270 °C for duration of 20 min–22 h are conducted. The microstructural characterization involved use of both optical as well as electron microscopes (SEM). Appropriate microstructural features (grain size and γ′ particles size) in the P/M material were achieved through the grain-growth heat-treatment experiments so as to render the material suitable for application in turbine blades of aircraft engines.