Characterizing the cracking behavior of hard alpha defects in rotor grade Ti-6-4 alloy
A program sponsored by the FAA is currently underway to develop predictive tools utilizing state-of-the-art damage tolerance and probabilistic methodologies that can be used in the life management of high energy rotors. The program is focusing on fatigue crack nucleation and growth from anomalies in titanium alloys known as hard alpha, an inclusion-like feature that can occur during the melting process. In the work detailed in this paper, two sizes of synthetic hard alpha defects are created in Ti-6Al-4V and subjected to static and fatigue loading. In addition, two different geometry anomalies are considered: one intersecting the surface of the specimen and another embedded internally. A number of crack detection transducers are used and shown to compare well to results from visual inspections on the surface defect specimens. These surface specimens tend to exhibit defect cracking at relatively low stress levels, typically on the order of 5--10 ksi. Although it appeared from the crack detection transducer that little or no cracking occurred in the interior anomaly specimens given an applied static stress of 100 ksi, subsequent metallographic sectioning demonstrated more extensive cracking and damage. The observed cracking behavior indicates that the diffusion zone may play an important role in the structural integrity of the hard alpha anomalies.
- Research Organization:
- Southwest Research Inst., San Antonio, TX (US)
- Sponsoring Organization:
- Federal Aviation Administration
- OSTI ID:
- 20013334
- Resource Relation:
- Conference: TMS Fall Meeting '98, Symposium on Fatigue Behavior of Titanium Alloys, Chicago, IL (US), 10/11/1998--10/15/1998; Other Information: PBD: 1999; Related Information: In: Fatigue behavior of titanium alloys, by Boyer, R.R.; Eylon, D.; Luetjering, G. [eds.], 382 pages.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Corrosion fatigue crack growth in aircraft structural materials. Final technical report, 1 Jun 1971--30 Jun 1973. [T0T5-T651 and T4T5-T651 aluminium, 6Al--4V (ELI) beta annealed and recrystallized annealed titanium, and 9Ni--4Co--0. 3C steel, T2, 175 and -65F and recrystallized annealed]
Investigation of rejuvenation of fatigue damage in Ti--6Al--4V. Interim report, 1 January 1976--15 March 1977