Abstract: An experimental investigation on corrosion fatigue crack propagation (CFCP) under periodic overloads in LY12CZ oluminum alloy is carried out.The retardation under periodic overloads depends on overload ratios and overload periods.When the crack propagation in each overload period is less than the plastic zone caused by overloads,the CFCP rates under periodic overloads follow closely the constant amplitude CFCP behavior so that they can be modeled as a pseudo-constant amplitude CFCP behavior.In the high-low loading sequence,the retardation of CFCPmainly takes place near to the threshold range.

Key words: fatigue, corrosion, crack propation.