[01] M. Benachour, Ingeniery of Mechanical Systems and Materials Laboratory, Mechanical Engineering Department, Faculty of Technology, University of Tlemcen, Tlemcen, Algeria. [02] N. Benachour, Ingeniery of Mechanical Systems and Materials Laboratory, Mechanical Engineering Department, Faculty of Technology, University of Tlemcen, Tlemcen, Algeria; Department of Physic, Faculty of Sciences, University of Tlemcen, Tlemcen, Algeria. [03] M. Benguediab, LMSR Laboratory, Mechanical Engineering Department, University of Sidi Bel Abbes, Sidi Bel Abbes, Algeria.

The present’s paper shows the effect of machining mode of the notch on fatigue crack growth and fractured surfaces. This investigation is conducted on 2024 T351 age hardening Al-alloy used extensively in aeronautic structures. The fatigue tests are conducted on four points bending according to ASTM method E399. Notches are produced by milling and electric discharge machining (EDM). The fatigue test is led to constant amplitude loading at R=0.1. The results show that the fatigue life is affected by machining method. A significant increase is shown in fatigue life for notch specimen machined by milling comparatively to the notch machined by EDM method. Additionally a reduction of fatigue crack growth rate (da/dN) is obtained by using milling process for machining notch. This finding is attributed to the presence of compressive residual stress at notch. The examination in various areas of the rough surface is carried out on SEM. The study of these fracture topographies shows the various mechanisms developed during the fatigue crack growth.

Fatigue Crack Growth, Al-alloy, Fractography, Milling Mode, EDM, SEM

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