Behavior of gamma TiAl subjected to impact damage and elevated temperature fatigue
Gamma titanium aluminide has received significant attention in recent years as a candidate material for use in aerospace and industrial gas turbine engine applications. It is well known that fatigue crack growth rates in {gamma}-TiAl alloys are very sensitive to stress intensity range and that there is a small difference between threshold stress intensity range and apparent fracture toughness in these materials. The result is limited damage tolerance and dramatic reductions in fatigue lifetime in the presence of extrinsic damage, such as that produced from an impact event. To apply a damage tolerance approach to this situation would require improved crack detection techniques and would increase the life cycle cost of the engine by decreasing the inspection interval. Using a threshold-based approach, on the other hand, would ensure that pre-existing or service indices cracks would not grow and that failure by fatigue would not occur. The present study investigates the feasibility of using a threshold calculation to estimate the fatigue strength reduction caused by impact damage at elevated temperatures (600 C). The results are part of a larger investigation into the feasibility of using {gamma}-TiAl for low-pressure turbine blades.
- Research Organization:
- Univ. of Michigan, Ann Arbor, MI (US)
- OSTI ID:
- 20023068
- Journal Information:
- Scripta Materialia, Vol. 42, Issue 2; Other Information: PBD: 31 Dec 1999; ISSN 1359-6462
- Country of Publication:
- United States
- Language:
- English
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