The early stages of fatigue and corrosion fatigue from pre-corroded 2024-T351 aluminium
alloy are investigated. Pre-corrosion is obtained by immersion in an aerated, pH = 7, 0.5 M
sodium chloride (NaCI) solution at free potential. Such exposures result in the formation of
shallow semi-elliptical defects in the 0.1 mm depth range with highly non-linear growth kinetic:
after a few hours, the growth kinetic is seen to drop by over an order of magnitude. Fatigue
crack propagation from these narrow corrosion defects is studied, particularly the transition
between intergranular corrosion and transgranular short fatigue crack. At each stage, the crack
growth rate and AK are estimated and the fracture mode is characterised.