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Etude de l'amorçage de fissures de fatigue dans le Ti-6Al-4V

Abstract : Crack initiation and growth have been investigated on a forged Ti-6Al-4V, which grain size is around 10μm. A “ghost” structure, constituted of millimetric grains, that we have labelled macrozones, is also observed. X-ray measurements point out the crystallographic character of the macrostructure, each macrozone being related to a dominant α-phase orientation. The cracking process is strongly inhomogeneous, since crack density, crack growth rate and crack orientation exhibit large variations from one macrozone to another. Furthermore, crack growth is found to result from two different mechanisms, “pure” crack propagation and crack coalescence. The importance of the crack coalescence contribution to crack growth is controlled by the macrozone crystallographic orientation and therefore differs from one macrozone to another. At the opposite, “pure” crack propagation seems to be nearly insensitive to crystallographic parameters and therefore does not depend on the macrozone considered. It also appears that “pure” crack propagation behaviour could be compared to short crack one, since “pure” propagation rate versus ΔK is constant for crack length less than 700μm.
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Submitted on : Tuesday, March 23, 2010 - 5:27:31 PM
Last modification on : Wednesday, July 8, 2020 - 11:10:20 AM
Long-term archiving on: : Monday, June 28, 2010 - 4:29:18 PM

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  • HAL Id : tel-00466425, version 1

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Kristell Le Biavant-Guerrier. Etude de l'amorçage de fissures de fatigue dans le Ti-6Al-4V. Mécanique [physics.med-ph]. Ecole Centrale Paris, 2000. Français. ⟨tel-00466425⟩

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