Second Generation Columnar Grain Nickel-Base Superalloy

Abstract

High temperature strength capabilities similar to those of single crystal nickel-base alloys have been achieved in a second generation columnar grain alloy designed for advanced military and commercial turbine airfoil applications. This new alloy, designated PWA 1426, offers a 50F improvement in metal temperature capability (creep-rupture strength, thermal fatigue and oxidation resistance) over earlier columnar grain alloys (PWA 1422), and equivalent properties to current, production, first generation single crystal alloys, such as PWA 1480. In applications where PWA 1426 replaces PWA 1480, a major cost saving is realized due to the higher casting yields normally obtained with columnar grain castings relative to single crystals. Alloy properties have been fully characterized and demonstrate that PWA 1426 offers an outstanding combination of high temperature creep and fatigue strength, as well as excellent oxidation resistance and transverse ductility. Processing studies have shown it to have excellent castability and to be easy to solution heat treat in a production environment. The overall superior combination of properties, offered by PWA 1426, has been confirmed through an extensive series of engine tests leading to its incorporation in advanced military and commercial engines.