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Approaches to fatigue lifing in a high strength polycrystalline nickel alloy
International Journal of Fatigue, Volume: 166, Start page: 107239
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The development of high strength alloys with complex chemistries has led to modern nickel disc alloys being produced through a powder metallurgy process which often produces melt anomalies within the material microstructure. The current research investigates the effect of these melt anomalies on ove...
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The development of high strength alloys with complex chemistries has led to modern nickel disc alloys being produced through a powder metallurgy process which often produces melt anomalies within the material microstructure. The current research investigates the effect of these melt anomalies on overall lifing approaches for the alloy RR1000, utilised here in its fine grained form. A Walker strain approach is applied to investigate the effect of temperature and R ratio on lifing parameters, and a temperature dependent version of the equation is suggested and used to produce predictions of notched specimen fatigue behaviour. It is found that hard particle inclusions dominate fatigue failures at long fatigue lives whereas failure occurred at the peened surface for shorter fatigue lives. However, lifing approaches were able to provide good fits across the entire data set irrespective of this behaviour change.
Fatigue; Melt anomaly; Notches; Walker strain
College of Engineering
This work was supported by the UK Technology Strategy Board (SILOET II Project 6 - High Temperature Capability – Compressors and Discs, TP110120). A PhD stipend for Emily Duffy under the EPSRC Rolls-Royce Strategic Partnership in Structural Metallic Systems for Gas Turbines (grants EP/H500383/1 and EP/H022309/1) is also gratefully acknowledged along with funding from Rolls-Royce plc. The input of Dr Mark Evans is also gratefully acknowledged.