Abstract:The corrosion behaviour and principle of 316L stainless steel exposed with different times in harsh marine atmosphere of Xisha Islands were investigated by means of cyclic anodic polarization(CAP),Electrochemical Impedance Spectroscopy(EIS) and Scanning Kelvin Probe(SKP). The results showed that the exposure time has no significantly effect on both the corrosion process and passivation behaviour with respect to 316L stainless steel.The electric polarization curve experiments consistently indicate a characteristic of activated anodic dissolution.The protective function of the passive film is invalid and the passive film breakages on 316L stainless steel increase with the exposure time.The distribution of Kelvin potentials on the surfaces also decline with the exposure time, and the EKP distributions tend to be nonuniform with larger variance.These might be due to the breakdown of passive film in chloride-featured environment and then the occurrence of pitting and the rust products accumulated at the surfaces.