Microelectrochemical measurements were carried out to ascertain the effect of stress on the dissolution morphology and pit initiation behavior of (Mn,Cr)S inclusions, which contained around 15 at. % chromium. Under anodic polarization, the selective dissolution of MnS and the composition change from the (Mn,Cr)S to CrS occurred in 1.5 mol kg-1 MgCl2. No stable pit was initiated under no applied stress, even though the MnS dissolution and the formation of meta-stable pits were observed. Under applied stress, a stable pit was initiated in the potential range of the MnS dissolution, and small cracks that were perpendicular to a tensile direction were generated. The cracks were thought to be induced by a mechano-chemical reaction, and propagated to the steel under the inclusion. The steel matrix was then exposed to the solutions, and stable pitting was initiated at the inclusions under applied stress.
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