Effect of Complex Inclusions on Localized Corrosion Behavior in Ferritic Steel

The localized corrosion behavior of different inclusions in a simulated solution of coastal industrial pollution is investigated in this study. It is indicated in the results that the Al 2 O 3 –MnS composite inclusions of ordinary carbon Q345B steel have microcracks and induce severe lattice distortions in the surrounding matrix. The MnS in the Al 2 O 3 –MnS composite inclusions dissolves preferentially to induce pitting corrosion. The microcracks and severe lattice distortion of the surrounding matrix accelerate the corrosion propagation. The preferential dissolution of CeAlO 3 –Ce 2 O 2 S inclusions induces pitting in No. 2 steel. The inherent physical and chemical properties of the inclusions and the chemical corrosion of the simulated fluid are vital in the initiation and expansion of pitting corrosion. The TiN in the test steel exhibits excellent resistance to pitting corrosion, and the double‐layer composite inclusions completely covered by TiN do not form corrosion pits in the simulated solution and do not cause the dissolution of the adjacent matrix. The coordinated addition of Ti–Ce can reduce the size of the inclusions and improve the probability of complete cladding of TiN.