Surface analysis of corrosion pits initiated at MnS inclusions in 304 stainless steel
- Illinois Univ., Urbana, IL (United States). Dept. of Chemical Engineering
This paper reports on the formation of pits near MnS inclusions on 304 stainless steel in NaCl (0.1 and 0.3M) and Na{sub 2}S{sub 2}O{sub 3} (0 and 2 mM) solutions that was investigated by a combination of surface analyses (Auger electron spectroscopy, scanning electron microscopy, and energy dispersive x-ray analyses) and electrochemical methods. Microlithography techniques were developed to monitor a single corrosion pit initiated at a single preselected inclusion. Pits were observed to form primarily at MnS inclusions. It was found that chemical dissolution of MnS occurred at the rest potential. Sulfur species were found to spread onto the adjacent passive surface over an area having a diameter about four times the size of the inclusion. Subsequent dissolution of metal was observed to occur only at MnS inclusions larger than about 1 {mu}m. The surface of the microcavity adjacent to the inclusion was found to be enriched in S and, in later stages of dissolution, by Cr. These observations indicated that S-species play a key role in the processes that lead to pit initiation in this system.
- OSTI ID:
- 7306563
- Journal Information:
- Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 139:6; ISSN JESOA; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360102 -- Metals & Alloys-- Structure & Phase Studies
360105* -- Metals & Alloys-- Corrosion & Erosion
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400101 -- Activation
Nuclear Reaction
Radiometric & Radiochemical Procedures
400400 -- Electrochemistry
ALLOYS
AUGER ELECTRON SPECTROSCOPY
AUSTENITIC STEELS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM ALLOYS
CHROMIUM-NICKEL STEELS
CORROSION
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
CRACK PROPAGATION
DISSOLUTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HIGH ALLOY STEELS
INCLUSIONS
IRON ALLOYS
IRON BASE ALLOYS
KINETICS
MANGANESE COMPOUNDS
MANGANESE SULFIDES
MATERIALS
MICROSCOPY
NICKEL ALLOYS
NONDESTRUCTIVE ANALYSIS
NONMETALS
PITTING CORROSION
REACTION KINETICS
SCANNING ELECTRON MICROSCOPY
SPECTROSCOPY
STAINLESS STEEL-304
STAINLESS STEELS
STEEL-CR19NI10
STEELS
SULFIDES
SULFUR
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
X-RAY EMISSION ANALYSIS