SCANNING MICROELECTRODE STUDIES OF EARLY PITTING CORROSION OF 18 8-STAINLESS-STEEL/

The scanning microreference electrode (SMRE) technique was used to stu dy the early stage of pitting corrosion of 18/8 stainless steel (SS) i n solutions containing chloride (Cl-) ions. Local breakdown of passivi ty and micropitting corrosion occurred in the potential region that wa s much more negative than the ordinary pitting potential (E-p). A crit ical potential (E-r) was measured by imaging the potential near the me tal surface in solution to characterize the local rupture of passivity or micropitting initiation. The concept of metastable micropitting wa s adopted to discuss the mechanism of pitting corrosion in its early s tage.