A FEM model for simulating trenching process around a MnS inclusion embedded in stainless steel

A finite element method model has been elaborated to study the localized corrosion around a MnS inclusion particle in stainless steel, taking into account the three electrochemically active phases of the matrix, passive film and MnS inclusion. The simulation results show the evolution of this micro-galvanic corrosion process, which is initiated by MnS dissolution, followed by the simultaneous dissolution of the inclusion and matrix, and finally, the MnS inclusion stops dissolving and turns to be cathodic, leaving the matrix as the only corroding phase (“trenching” process). The deposition kinetics of the corrosion products and pH distribution around the corroding area are also predicted.