Fatigue Behavior of Crack Initiating from Corrosion Damage

摘要

The initiation and growth of fatigue crack emanating from corrosion pits was investigated by conducting fatigue experiments on standard dog-bone specimens of high strength aluminum alloy AA2024-T3. The corrosion pits were created in an electrochemical cell under specific polarization conditions. Samples were prepared with varying pit depth and pits were initially characterized using a white light interferometer. The fractured surface was analyzed under scanning electron microscope after the fatigue test. These cracks were treated as surface cracks for stress intensity calculations. A linear relationship between stress intensity factor and critical pit depth was observed. The crack growth behavior of the crack nucleating from these pits was typical of a short crack.