During the piling of a cavity, an aluminium alloy is systematically covered by a thin film of oxide (alumina). Because this film is weak, it may be broken by the stresses generated by turbulence (velocity) during ping. When it breaks, it forms alumina skins within and/or on the surface of the castings. While the formation of these oxide skins and their impact on the static mechanical properties have been clearly established, there has so far been little work dealing with their influence on fatigue strength. In this article, we present the results we have obtained on specimens cast in AI Si7Mg and broken in fluctuating tension. Astonishingly, it seems that the eight modalities studied do not lead to statistically different means. On the other hand, the fatigue life is correlated, albeit slightly, with the dimensions of the defect that initiates the cracking.
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