Morphological estimation of pitting corrosion on vertically positioned 304 stainless steel using acoustic-emission duration parameter

A morphological estimation of the pitting corrosion of type 304 stainless steel using the acoustic emission (AE) duration parameter is proposed in the present work. The pit morphology depending on Cl- concentration and gravity was investigated. Occluded pits in low-concentration NaCl solution were observed to develop with more long-duration AEs, while elongated pits with ruptured cover in high-concentration NaCl solution were predominantly concurrent with short-duration AEs. The morphological descriptor "eta" derived from the AE duration amplitude plots reflected the morphological transition from occluded to elongated open pits. An AE-based correspondence among the environmental factors and corrosion morphologies was proposed.