Acoustic emission monitoring during open-morphological pitting corrosion of 304 stainless steel passivated in dilute nitric acid

• Published in: Corrosion science Vol. 180; p. 109224
• Main Authors: Wu, Kaige, Kim, Jae-Yeon
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.03.2021; Elsevier BV
• Subjects: A. Stainless steel; Acoustic emission; Austenitic stainless steels; B. Polarization; C. Pitting corrosion; Corrosion; Corrosion products; Dilution; Evolution; Morphology; Nitric acid; Pitting (corrosion); Signal monitoring; Stainless steel; Submerging; Acoustic emission; C. Pitting corrosion; A. Stainless steel; B. Polarization
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2020.109224

•Combination of nitric acid passivation and specimen position produces open pits.•The open pit specifically develops with a pit “head” and a pit “tail”.•Rupture of salt film and deposition of corrosion products are proposed as AE sources.•A three-stage propagation mechanism for pitting corrosion is suggested. Knowledge gaps exist concerning the acoustic emission (AE) during the pitting corrosion of open morphology. Here, we proposed a simple yet effective strategy to control the pitting evolution uncovered by lacy covers or corrosion products in a vertically positioned 304 stainless steel (304 SS) specimen that was pretreated by immersion in dilute nitric acid. The corrosion pit developed with a “head” and a “tail”, i.e., the open cavity and the corrosion products deposited below the pit head respectively, the evolution of which was monitored with by-stage AE signals. The AE sources associated with the open-morphology of pitting corrosion were discussed.