The electrochemical and corrosion behavior of austenitic stainless steel containing Cu

The influence of Cu additions (0.4-3.0 wt%) on the electrochemical and corrosion behavior of 18-8 austenitic stainless steel was investigated. Both potentiodynamic polarization curves and potential decay curves, which were dependent upon the Cu content and the dissolved oxygen in the solution tested, were determined in both de-aerated and aerated 0.1 M H₂SO₄ solution. Surface characterization was examined by Auger electron spectroscopy (AES) and X-ray photo-electron spectroscopy (XPS). Cyclic polarization curves determined in 3.5 wt% NaCl solution showed that the pitting protection potential (E_pp) of the stainless steels tested increases with increasing Cu content. The constant extension rate test (CERT) in boiling 42 wt% MgCl₂ solution revealed that Cu had a detrimental effect on the stress corrosion cracking (SCC) resistance. The role of Cu on the corrosion behavior of the austenitic stainless steel observed in this investigation is discussed.