Dynamic pitting processes of 316 stainless steel in NaCl + Na2CO3 solution with digital holography
Boyu Yuan, Changqi Yan, Zhenhui Li, Liang Li, Chao Wang
Abstract
The initiation and propagation of a pit on the surface of 316 SS have been studied in the NaCl + Na2CO3 solution in the metastable region. The concentration was found to decrease around the pit with the digital holographic surface imaging. A heap of precipitants in the shape of a hat was observed on the spot by SEM. The main composition, Me(CO3)n/2, was verified by EDS. Inside the pit, with the hat as a cover, an occluded corrosion cell was formed, which enhanced the local acidification by the hydrolysis of metal cations and promoted the pit propagation.
Topics & Concepts
Pitting corrosionHolographyMetastabilityMaterials scienceCorrosionMetalMetallurgyChemistryAnalytical Chemistry (journal)OpticsChromatographyPhysicsOrganic chemistryHydrogen embrittlement and corrosion behaviors in metalsCorrosion Behavior and InhibitionForce Microscopy Techniques and Applications