Corrosion Fatigue Crack Growth Rate Theoretical Model ofE690 Steel under Mechanics-Electrochemistry Interaction

Based on the energy conversion during the mechanics-electrochemistry interaction in corrosion fatigue, the change of kinetic energy, potential energy and anodic dissolution electrochemical energy in corrosion fatigue system was studied by the energy conservation, electrochemical thermodynamics and corrosion electrochemical principles. A theoretical model of corrosion fatigue crack growth rate for E690 high strength steel was established, and the accuracy of the theoretical model was verified by corrosion fatigue crack growth test. The results show that 3.5wt% NaCl solution accelerated the initial propagation of fatigue crack of E690 high strength steel and reduced the fatigue life. The increase of stress ratio could significantly accelerate the corrosion fatigue crack propagation and reduce the threshold of crack propagation. The fatigue crack growth rate calculated by the theoretical model was basically consistent with the experimental results, and the relative error was less than 10%, indicating that the model could well describe the corrosion fatigue crack growth behavior of E690 high strength steel.