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A B S T R A C T Periodic tensile overloads superposed on constant amplitude cycles were used on compact tension fracture mechanics specimens of an aluminum (Al-Cu-Mg) alloy. The delayed retardation of corrosion fatigue crack propagation in the low part of the Paris regime was investigated in a 3.5% NaCl environment. The aluminum alloy exhibits the intensive retardation effect of crack propagation under overload ratios from 1.3 to 2.0 and overload intervals from 10 2 to 10 4 cycles. The crack propagation under the periodic overloads can be treated as the base constant amplitude crack propagation, i.e. (da/dN) cf = B cf ( K − K thcf ) 2 . The periodic overloads decrease the crack propagation resistance coefficient of B cf , but have less effect on the threshold value of K thcf obtained by best fitting of this model. a = crack length a e = overload affected zone a = crack increment per overload period B = specimen thickness B cf = resistance coefficient of corrosion fatigue crack propagation CFCP = abbreviation of corrosion fatigue crack propagation C(T) = compact tension specimen (da/dN) cf = corrosion fatigue crack propagation rate under constant amplitude loading (da/dN) d = corrosion fatigue crack propagation rate under periodic overloads K, K max ,K OL = peak stress intensity factor and that of constant amplitude cycles and of overload cycles K = stress intensity factor range of constant amplitude cycles K thcf = threshold value of corrosion fatigue crack propagation N b = number of constant amplitude cycles P max ,P OL = peak load of constant amplitude cycles and overload cycles r = linear correlation coefficient r max ,r OL = peak plastic zone radius of constant amplitude cycles and of overload cycles R = stress ratio of constant amplitude cycles s = standard deviation U = retardation coefficient under periodic overloads σ y = yield strength η = overload ratio Correspondence: R. Wang.