The orientation dependence of fatigue-crack growth in 8090 Al-Li plate
- National Research Council of Canada, Ottawa, Ontario (Canada). Structures, Materials and Propulsion Lab.
A series of fatigue-crack growth rate (FCGR) tests was carried out on 8090 Al-Li plate to examine the effects of specimen orientation on fatigue-crack growth. The directionality of fatigue fracture behavior is found to be related to the strong [l brace]110[r brace]<112> texture in this alloy. Based on a previously developed transgranular FCGR model using restricted slip reversibility (RSR) concepts, a mechanistic model is developed for transgranular fatigue-crack growth in highly textured materials. The model takes the form of the Paris relationship with a power law exponent of 3, and the material texture is shown to strongly influence the proportional factor. The effect of texture on FCGR is related through a geometric factor cos[sup 2] [phi], where [phi] defines the angle between the load axis and the normal of the favorable slip plane. The effect of specimen orientation on FCGR in 8090 Al-Li alloy is shown to be related to a combination of its anisotropic mechanical properties and the variation of angle [phi] with specimen orientation. The model further predicts that fatigue-crack growth rates will be slower in many textured materials than texture-free materials because [phi] > 0 and cos[sup 2] [phi] < 1.
- OSTI ID:
- 7072923
- Journal Information:
- Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:3; ISSN 0360-2133; ISSN MTTABN
- Country of Publication:
- United States
- Language:
- English
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