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

•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...

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Bibliographic Details
Published in:Corrosion science 2021-03, Vol.180, p.109224, Article 109224
Main Authors: Wu, Kaige, Kim, Jae-Yeon
Format: Article
Language:English
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
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Summary:•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.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2020.109224