Effects of temperature and thiosulfate on chloride pitting of austenitic stainless steels

Journal Article · Tue Jun 01 04:00:00 EDT 1999 · Corrosion

DOI:https://doi.org/10.5006/1.3280500· OSTI ID:6387966

Laycock, N J ^[1]

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1. Materials Performance Technologies, Ltd., Lower Hutt (New Zealand)

Potentiodynamic polarization curves were measured for types 304 (UNS S30400), 316L (UNS S31603), and 904L (UNS N08904) stainless steels (SS) in 1 M sodium chloride (NaCl) solutions with various thiosulfate additions at temperatures from 20 C to 90 C. A minimum concentration of thiosulfate was required for activation of pitting corrosion in each alloy, and this critical value was shown to increase with increasing molybdenum content and to decrease with increasing temperature. Above the critical thiosulfate concentration for type 904L SS, stable pitting occurred at temperatures up to 30 C below the chloride-only critical pitting temperature. In addition, polarization data at high thiosulfate levels exhibited an anodic peak thought to represent the oxidation of elemental sulfur, produced by prior reduction of thiosulfate at potentials < [minus]450 mV[sub Ag-AgCl].

• OSTI ID: 6387966
• Journal Information: Corrosion, Journal Name: Corrosion Vol. 55:6; ISSN 0010-9312; ISSN CORRAK
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals &amp; Alloys-- Corrosion &amp; Erosion
ALKALI METAL COMPOUNDS
ALLOYS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CONCENTRATION RATIO
CORROSION
HALIDES
HALOGEN COMPOUNDS
HIGH ALLOY STEELS
IRON ALLOYS
IRON BASE ALLOYS
PITTING CORROSION
POTENTIOMETRY
QUANTITATIVE CHEMICAL ANALYSIS
SODIUM CHLORIDES
SODIUM COMPOUNDS
STAINLESS STEELS
STEELS
TEMPERATURE DEPENDENCE
THIOSULFATES
TITRATION
VOLUMETRIC ANALYSIS