Comparison of stainless steels in simulated paper machine environments
- VTT Manufacturing Technology (Finland)
The localized corrosion behavior of austenitic stainless steels (SS) UNS S30403 and UNS S31603, and duplex SS UNS S31803 was compared in simulated paper machine environments containing chloride, sulfate, and thiosulfate at pH 3 and 65 C. Electrochemical testing of the materials was performed by cyclic polarization scans and scratch tests. Thiosulfate caused a remarkable decrease in repassivation potentials (E{sub pp}) and a slight decrease in pitting potentials (E{sub np}) of UNS S30403 and UNS S31603, when compared to the corresponding E{sub pp} and E{sub np} values determined in similar solutions without thiosulfate addition. Pits on UNS S30403 and UNS S31603 steels were enriched in Cr and Cu and depleted in Fe when compared to the base metal. Thiosulfate being present in the solution pits contained also very high amounts of S. Thiosulfate was proposed to be reduced to hydrogen sulfide (H{sub 2}S) inside the pits enhancing the anodic dissolution process of SS. In the case of UNS S31803, test environments had hardly any influence on the determined high E{sub pp} and E{sub np} values. Chloride concentration had to be a minimum of 500 mg/L until any localized corrosion could be observed on UNS S31803.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 684443
- Journal Information:
- Corrosion, Vol. 55, Issue 9; Other Information: PBD: Sep 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of temperature and thiosulfate on chloride pitting of austenitic stainless steels
Conditions of growth of open corrosion pits in stainless steels -- Electrochemical experiments on model pits