Size dependency between the carbides and durability of X80 steel in acid solid environment

The size dependency between the carbides and durability of X80 steel was investigated by macro and micro electrochemical technique under a simulated acidic soil solution. Electrochemical impedance spectroscopy result revealed that the smaller precipitates size, the larger charge transfer resistance. The localized electrochemical result indicated that the cathodic phase area ratio plays an important role during the early corrosion initiation stage. Numerous tiny cathodic phases will provide sufficient active points for corrosion initiation. The size of cathodic phase plays a control role in the corrosion extension process. The larger-sized cathodic phases could inset in the steel stably and maintain a continuous galvanic couple effect. With the increase of larger sized cathodic phase space, the competitive effect between different galvanic couples decreased and accelerated the corrosion process.