MODELLING CREVICE COROSSION OF STAINLESS STEEL

ABSTRACT A common misconception about stainless steel is that it is not affected by corrosion. Although one of the main reasons why stainless steels are used is corrosion resistance, they do in fact suffer from certain types of corrosion in some environments and one of such types is crevice corrosion.  Crevice corrosion is normally a consequence of a galvanic cell generated in specific areas with restricted flux. Crevice corrosion is a form of localized corrosion in which a metal in contact with an aqueous solution dissolves within a crevice at a much greater rate than at other crevice free surface.
In this project, the concentration dynamics of the creviced system is modeled. A 1D model is proposed, combining the mass transport equations written for each emerging chemical species with the electro-neutrality condition and the model was solved analytically.
The results gotten from the analytical solution of the model showed that the concentrations of the species in the bulk solution decrease with time largely due to electro-migration of ions in the electrolyte. It also showed that dissociation rate of the chlorine ions is unique compared to the rest.
At the end of the project, it was discovered that the concentration dynamics of the emerging species of a corroding stainless 304 crevice can be represented using a mathematical model and can be solved analytically using Excel spreadsheet.