Effect of dissolved ozone on corrosion behavior of stainless steels in artificial seawater
- Rensselaer Polytechnic Inst., Troy, NY (United States). Materials Science and Engineering Dept.
Corrosion resistance of austenitic stainless steels (SS) in artificial seawater containing 0.2 mg/L to 0.4 mg/L dissolved ozone (O{sub 3}) was investigated. According to cyclic polarization data, types 304 SS (UNS S30400) and 316 SS (UNS S31600) were resistant to pit initiation after 8 weeks of exposure to ozonated artificial seawater. However, when crevices existed, crevice corrosion was more severe in ozonated vs aerated artificial seawater. Maximum crevice corrosion penetration rates of 8 mm/y and 5 mm/y (0.315 in./y and 0.197 in./y) were recorded for types 304 and 316 SS, respectively, in ozonated artificial seawater compared to only 0.4 mm/y to 0.5 mm/y (0.016 in./y to 0.020 in./y) under aerated conditions. Mixed-potential analysis of anodic and cathodic polarization predicted crevice corrosion rates for type 316 SS in excellent agreement with the immersion sample data. Highly alloyed nickel-, chromium-, molybdenum-, and nitrogen-bearing austenitic SS were resistant to crevice corrosion in aerated and ozonated artificial seawater. However, differential oxidation corrosion was observed between surfaces of high and low ozone concentration, leading to local transpassive dissolution manifested as surface etching and superficial intergranular corrosion (IGC). After 47 weeks of exposure to ozonated artificial seawater, microscopic pitting was observed in crevices of the highly alloyed SS. Although IGC and microscopic pitting of highly alloyed SS were not considered severe, these modes of corrosion warrant further investigation in the interest of corrosion resistance in long-term (>1 year) service under oxidizing conditions in seawater.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 669831
- Journal Information:
- Corrosion, Vol. 54, Issue 10; Other Information: PBD: Oct 1998
- Country of Publication:
- United States
- Language:
- English
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