Abstract:As an irreversible thermodynamics process, the corrosion pit evolution of corrosion fatigue is controlled by the combined action of surface energy, elastic energy and electrochemical energy stored in the solid. Based on energy principle, the exploratory study of energy issues for corrosion fatigue pit evolution is carried on. A two-variable semi-ellipsoid model is proposed to describe the pit evolution, and shape parameter of semi-ellipsoid pit as a function of pit depth is derived in the process of corrosion fatigue. The stress intensity factor criterion is introduced to build the critical condition for pit transition to fatigue crack, At the same time, the effects of stress amplitude on corrosion fatigue crack nucleation life is discussed.