Structure of rust on weathering steel in rural and industrial environments

Journal Article · Fri Jul 01 04:00:00 EDT 1994 · Corrosion (Houston); (United States)

DOI:https://doi.org/10.5006/1.3294356· OSTI ID:7229440

Townsend, H E; Simpson, T C ^[1]; Johnson, G L ^[2]

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1. Bethlehem Steel Corp., PA (United States). Homer Research Labs.
2. Air Products and Chemicals Inc., Allentown, PA (United States)

Rust on weathering steels exposed for up to 11 y in industrial and rural environments exhibited a spotty, nonuniform appearance as a result of contrast between light and dark areas on the surface. The area of the lighter regions increased with exposure time, as well as with increasing alloy content. Microscopic examination of cross sections revealed the dark regions had a porous appearance. The lighter regions were similar except for the presence of a relatively thin, smooth outer-surface layer. Raman spectroscopy indicated the dark, porous rust was comprised of goethite and lepidocrocite, while the smooth outer layer on the light areas was composed of hematite ([alpha]-Fe[sub 2]O[sub 3]) and magnetite (Fe[sub 3]O[sub 4]). Electrochemical potential measurements indicated the lighter areas were more passive. Results suggested formation of the thin outer layer of [alpha]-Fe[sub 2]O[sub 3] and Fe[sub 3]O[sub 4] is an important part of the mechanism of protective rust formation on weathering steels in the environments studied.

• OSTI ID: 7229440
• Journal Information: Corrosion (Houston); (United States), Journal Name: Corrosion (Houston); (United States) Vol. 50:7; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
ALLOYS
CHALCOGENIDES
COATINGS
CORROSION PROTECTION
IRON ALLOYS
IRON BASE ALLOYS
IRON COMPOUNDS
IRON OXIDES
LOW ALLOY STEELS
MORPHOLOGY
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
PROTECTIVE COATINGS
STEELS
TRANSITION ELEMENT COMPOUNDS
WEATHERING