Yaker, Charles., Garrett, Floyd B., Sikora, Paul F.
The effect of controlled grain size and increased carbon content on engine performance and high temperature properties of precision-cast Stellite 21 turbine blades was investigated. Blades were cast to result in controlled grain sizes, classed fine, medium, and coarse; others were cast of high-carbon Stellite 21. The blades operated in a turbojet engine. Laboratory stress-rupture tests of specimens cut from blades were conducted at the stress and temperature encountered during rated-speed engine operation. The results of the engine and laboratory tests indicated that (1) fine-grain Stellite 21 blades had lower life and creep resistance than the medium- and coarse-grain blades, and all three grain sizes blades showed less scatter than the production blades; and (2) higher-carbon Stellite 21 had higher blade life than the production Stellite.
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