Time-lapse, in-situ observation of crevice corrosion of duplex stainless steel under potentiostatic and galvanostatic control

Aoki, So  ; Engelberg, D.*

This presentation will address recent progress in providing a mechanistic understanding of differences in crevice corrosion initiation and propagation behaviour of duplex stainless steels when exposed via potentio-static and galvano-static polarization by means of time-lapse, in-situ observations. In the potentiostatic test, the crevice corrosion initiated underneath the edge of the washer, and then grew towards the edge of the crevice concentrically with time. It suggested for crevice corrosion to initiate at the site of a very tight crevice gap, with propagation in a stable manner towards the crevice mouth, where the crevice gap is wider. In the galvanostatic test, the crevice corrosion initiated all over at the circumference of the washer. Based on these results, the differences in crevice corrosion initiation and propagation behaviour between potentiostatic and galvanostatic conditions will be discussed.