Fatigue Variability of a Single Crystal Superalloy at Elevated Temperature (Preprint)
Journal article Preprint
AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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In order to develop more accurate life prediction tools, an improved understanding of the variability within the fatigue behavior of a material is required. Recent work has shown multiple failure mechanisms that drive the variability in fatigue life of polycrystalline titanium and nickel materials. In addition, the bimodal behavior in the fatigue response is not readily apparent when only a very small number of specimens are tested at each loading condition, as is normal practice. The objective of this work was to investigate the fatigue variability of a single crystal nickel-base superalloy at elevated temperature. PWA1484, a second generation single crystal alloy developed for advanced turbine airfoil applications, was the material of choice for this investigation. A large number of fatigue tests were performed at one condition stress level, stress ratio, frequency and temperature to determine the variability and identify the sources of uncertainty in life. Scanning electron microscopy was used to investigate the relationship between failure mechanisms and variability.
- Metallurgy and Metallography