Abstract Experiments designed to determine the effect of an overload on the acoustic emission (AE) detected during subsequent fatigue crack propagation between fixed load limits in aluminium alloy 2024 in the T351 temper condition are described. AE measurements were made during cycling of the alloy between fixed load limits, during application of the overload and during subsequent cycling between the previous fixed load limits. Fractographic analysis was used in the interpretation of the AE data, together with the results of previous studies, showing that the fracture of brittle inclusions is the only source of detected emission. The post-overload AE activity is less than the pre-overload activity because application of the overload results both in a decrease in crack growth rate in the post-overload period and in material “quietening” in a large zone ahead of the crack tip.
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