THE PITTING AND CREVICE CORROSION OF 304 STAINLESS-STEEL IN PHOSPHATE BORATE BUFFER CONTAINING SODIUM-CHLORIDE

The pitting and crevice corrosion of AISI 304 stainless steel (304 SS) specimens are studied in phosphate-borate buffer containing 0.5 M NaCl by using potentiodynamic techniques combined with microscopy. The probabilites for pitting, P(p,n greater-than-or-equal-to 1), increase as the potential, E, of the sample moves in the positive direction. Crevice corrosion is observed at E > -0.25 V(SCE) and for E > 0.25 V, P(c,n greater-than-or-equal-to 1) --> 1. Pitting corrosion occurs at E > 0.2 V and for E > 0.3 V, P(p,n greater-than-or-equal-to 1) --> 1. The different potential range covered for these types of corrosion suggest that the corresponding mechanisms for the initiation of the corrosion are essentially different.