Humidity Effects on Pitting of Ground Stainless Steel Exposed to Sea Salt Particles. Issue 11 (8th July 2019)

• Record Type: Journal Article
• Authors: Weirich, Timothy D.; Srinivasan, Jayendran; Taylor, Jason M.; Melia, Michael A.; Noell, Philip J.; Bryan, Charles R.; Frankel, Gerald S.; Locke, Jenifer S.; Schindelholz, Eric J.
• Is Part Of: Journal of the Electrochemical Society. Volume 167:Issue 11(2020)
• Page Start: C3477
• Page End: C3487
• Publication Date: 2019-07-08
• Subjects: Corrosion -- atmospheric corrosion -- chloride -- stress corrosion cracking; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0551911jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : The effect of relative humidity (RH) on the corrosion of coarse-ground 304 stainless steel exposed for one year under sea salt particles was investigated. Total corrosion damage accumulation was higher at 40% RH than at 76% RH. At 40% RH, pits were numerous and irregularly shaped with a rough, cross-hatched structure. At 76% RH, pits were much fewer in number and ellipsoidal with crystallographically faceted surfaces. Higher E pit resulting from lower [Cl − ] impeded initiation at 76% RH. Cathodic resource competition likely limited growth and resulted in lower total volume loss. At 40% RH, lower E pit due to higher [Cl − ] led to initiation of multiple pits supported by discrete cathodes under individual droplets. Despite more cathodic current available at 76% RH, higher damage accumulation at 40% RH was due to lower anodic stability requirements resulting from higher [Cl − ]. At 76% RH, pitting proceeded with increasing active area at conditions above critical stability, leading to ellipsoidal pits with facets. The cross-hatched morphology at 40% RH was ascribed to growth at the critical stability conditions, driven by constant current through a fixed active area. Small cracks at the 40% RH pits might have been caused by hydrogen environment assisted cracking.