Pitting corrosion of sensitised type 304 stainless steel under wet-dry cycling condition

The pitting corrosion of sensitised stainless steel (SS) 304 during wet-dry cycling were investigated and compared with that of AR one. The average relative humidity for pitting corrosion during drying and repassivation during wetting correspondingly increased from 56% to 65% and from 67% to 79% by sensitisation. The decrease in pit potential and critical chloride concentration provides the degradation evidence of sensitised SS 304. The pitting probability and pit average size were promoted by sensitisation. The pit morphology changed from round to irregular shape. Such modification was possibly induced by preferential corrosion along grain boundaries where the pit initiated.