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Abstract
The fracture morphology and fatigue life of pre-corroded 7050 aluminium alloys were studied under constant and block amplitude loading. It was found that the pits depth/radius ratio is mainly distributed between 0·05 and 20 after 12 hours corrosion. A thermal infrared imager was used to monitor the surface temperature of the sheet specimen during fatigue tests, which showed an increase of 0·7–1°C. This stage took up a small proportion of the overall fatigue cycle. The corrosion modified equivalent initial flaw size model was applied to back-calculate the initial crack size and to predict the fatigue life. The calculated crack size values were conservative with the error of 7·8–15%, compared with the measured results. The prediction error of fatigue life was 31% at high stress and 35% at low stress for the specimens under constant loading. For the specimens under block loading, the average error of fatigue life was 10·5% at σmax = 143 MPa, and 12·7% at σmax = 238 MPa.