Microelectrochemical investigation of pit initiation and selective dissolution between MnS and stainless steel

In a solution with Cl-ions, the trench at the MnS/steel boundary was found to be formed by the dissolution of the stainless steel as a precursor of pit initiation. The synergistic effect of the MnS dissolution products with Cl-ions caused dissolution on the stainless steel side of the boundary. The proposed pit initiation mechanism at the MnS inclusions is follows: 1) the dissolution of the stainless steel is caused by the synergistic effect of the MnS dissolution products with Cl-ions, which made the trench at the boundary; 2) the pits initiate in this trench because the trench is the occluded area, and the preferred site for pit initiation.