Acoustic emission during fatigue crack propagation in the aluminium alloys 2024 and 2124

Abstract Acoustic emission (AE) detected during fatigue crack propagation in the aluminium alloys 2024-T351 and 2124-T351 was examined with the aim of identifying the source(s) of the emission. The AE activities of the two alloys were compared for crack propagation rates from 0.1 to 5 μm per load cycle; metallographic studies were used to assist in interpreting the AE results. It is concluded that inclusion fracture is the source of the detected emission in both alloys. Variability in AE activity from cycle to cycle is attributed to variations in the size of fractured inclusions and to their non-uniform spatial arrangement.