Effect of Microporosity on Notched Specimen Fatigue Life

The present work examines notched fatigue performance of aluminum alloy 7050-T7451 thick plate containing microporosity. Open hole fatigue specimens from low microporosity and high microporosity plate locations were machined and fatigue tested to failure at three different stress levels. Scanning electron microscopy (SEM) studies on the failed specimens indicate that specimen life increases when the size and frequency of crack initiating micropores is decreased. An approach that incorporates microporosity into probabilistic life assessment is discussed. The results presented demonstrate that recent microporosity reductions in aluminum thick plate should increase fatigue reliability of parts containing engineering notches.