Abstract: The pitting susceptibilities of six manganese steels with different metallurgical characteristics were compared by means of potentiodynamic polarization testing and electrochemical impedance spectroscopy testing in 3% NaCl solution.The pitting propagation rate was evaluated by simulating occluded corrosion cell tests in artificial sea water.The results indicated that the weaker the deoxidization degree,the stronger the passive film stability and the thermodynamic stability and thus the stronger the resistance to initiation of pitting corrosion.Under the condition of the same deoxidization degree,the steel treated with Ca exhibited weaker pitting initiation susceptibility than the steel without Ca treatment.Additionally,pitting initiation susceptibility would not be influenced by the content of P in the steel,however,extremely low content of P would accelerate the pitting propagation.