High-cycle fatigue of Ti-6Al-4V

The definition of the critical levels of microstructural damage that can lead to the propagation of fatigue cracks under high‐cycle fatigue loading conditions is a major concern with respect to the structural integrity of turbine‐engine components in military aircraft. The extremely high cyclic freq...

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Bibliographic Details
Published in:Fatigue & fracture of engineering materials & structures 1999-07, Vol.22 (7), p.621-631
Main Authors: RITCHIE, R. O, DAVIDSON, D. L, BOYCE, B. L, CAMPBELL, J. P, RODER, O
Format: Article
Language:English
Subjects:
Applied sciences
crack propagation
Exact sciences and technology
Fatigue
fatigue thresholds
foreign object damage
high-cycle fatigue
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
small cracks
titanium alloys
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Summary:The definition of the critical levels of microstructural damage that can lead to the propagation of fatigue cracks under high‐cycle fatigue loading conditions is a major concern with respect to the structural integrity of turbine‐engine components in military aircraft. The extremely high cyclic frequencies characteristic of in‐flight loading spectra, coupled with the presence of small cracks resulting from fretting or foreign object damage (FOD), necessitate that a defect‐tolerant design approach be based on a crack‐propagation threshold. The present study is focused on characterizing such near‐threshold fatigue‐crack propagation behaviour in a Ti–6Al–4V blade alloy (with ~60% primary α in a matrix of lamellar α + β), at high frequencies (20–1500 Hz) and load ratios (0.1–0.95) in both ambient temperature air and vacuum environments. Results indicate that ‘worst‐case’ thresholds, measured on large cracks, may be used as a practical lower bound to describe the onset of naturally initiated small‐crack growth and the initiation and early growth of small cracks emanating from sites of simulated FOD.
ISSN:8756-758X
1460-2695
DOI:10.1046/j.1460-2695.1999.00194.x