Pitting Corrosion of Type 430 Stainless Steel in the Process of Drying of Chloride Solution Layer

Pitting corrosion of type 430 stainless steel under a chloride solution layer was investigated to clarify the pitting corrosion behavior. The solution layers containing 2 mol/dm3 chloride ion with four different thicknesses of 1000, 500, 250, and 125 μm were placed on the stainless steel surface and dried by decreasing the relative humidity at various rates at 300 K. The corrosion potential and solution resistance were simultaneously monitored during drying in order to determine the concentration of chloride ion at the commencement of pitting corrosion. The results showed that the lowest chloride concentration for occurrence of pitting corrosion for type 430 is about 4.5 mol/dm3, and that pitting corrosion occurs at higher chloride concentration as the drying rate increases.