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The Electrochemical and Stress Corrosion Behaviour of an Austenitic Stainless Steel in phosphate solutions at high temperatures and pressures
Author(s) -
Tischner H.,
WendlerKalsch E.,
Kaesche H.
Publication year - 1980
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19800310402
Subject(s) - materials science , corrosion , stress corrosion cracking , metallurgy , austenitic stainless steel , alloy , polarization (electrochemistry) , stress (linguistics) , electrochemistry , austenite , ultimate tensile strength , composite material , microstructure , chemistry , electrode , linguistics , philosophy
The present investigation concerns the effects of stress corrosion on the behaviour of high‐alloy steels in high‐pressure, high‐temperature phosphate solutions, with the view on service conditions in the secondary loop of pressurized water reactors. An apparatus is described which enables electrochemical and electrochemically controlled stress‐corrosion experiments up to 300° C with tensile specimens stressed with a defined stress by a bellows arrangement. The polarization curves of a model system of X 5 CrNi 189 stainless steel (AISI Type 304) and 0.4 M Na 2 HPO 4 /0.4 M NaH 2 PO 4 solution exhibit a large increase in current densities at higher temperatures at all potentials investigated. However, the material proves to be spontaneously passive even at 300° C, although the passive current densities are about 10–15 times higher than those at room temperature. Stress‐corrosion experiments at open circuit potential and under potentiostatic control show that high stresses and exposure times of more than 100 h are necessary to cause cracking. In addition, some possible effects of thick phosphate layers on the sample surface on the corrosion behaviour of the material are mentioned.