Abstract: Stray current in town is the key factor that causes corrosion in buried natural gas pipeline. In this paper, based on the monitoring results of underground pipeline potential under the operation of the subway, the corrosion behavior of X65 steel under different DC interference conditions including anode interference, cathode interference, dynamic interference and cathodic protection was studied by electrochemical experiments and corrosion morphology analysis. The results showed that compared with the anode interference and dynamic interference, the corrosion potential of X65 steel was negative and the corrosion current density was smaller under the conditions of no interference and cathode interference. This indicated that the corrosion rate of X65 steel was smaller. Under dynamic interference, the corrosion rate of metal was slightly higher than that of anode interference. In this case, the metal surface was in the alternating process of positive-negative potentials, presenting serious pitting characteristics.

Key words: DC stray current, X65 steel, dynamic interference, electrochemistry