The electrochemical corrosion behavior of the epoxy heavy-duty coating immersed in seawater under the alternating pressure was investigated by electrochemical impedance spectroscopy (EIS) and local electrochemical impedance spectroscopy(LEIS). The results showed that compared with atmospheric pressure

the coating resistance was lower

but the coating capacitance was higher under the alternating pressure. The coating resistance remained above 107 Ω·cm2

showing that both coatings had good protective properties. The impedance around the defect region of the coating systems with artificial point defects was lower under the alternating pressure. It indicated that the permeation process of the electrolyte solution to the coating metal interface was easier under the alternating pressure

accelerating the corrosion of the steel under the coatings.