Abstract: The corrosion fatigue crack growth properties in aluminum alloy 2l24T85l in both L一Tand T-L orientations were studied,primarily,in 3.5%NaCl solution and at frequencies of l and l0 Hz with stress ratios of 0.5,0.06 and-1.The results show that the fatigue crack growth rate (FCGR) in 3.5%NaCl solution is higher than that in air. FCGR in TL orientation is slight-y higher than that in L一Torientation,FCGR for all test conditions are well correlated with Keff derived from equation based on crack closure theory proposed by Schijive. This implies that crack closure role is negligible by Auger spectroscopy because of the thinner corrosion prod-uct on the crack surface. Little effect of a test frequency between l Hz and l0 Hz on FCGR was observerved a possible explanation is offered.

Key words: aluminium alloys. corrosion, fatigue life, crack propagation, crack closure