Assessment of electrochemical methods used on corrosion of superduplex stainless steel

• Published in: Corrosion science 2012-06, Vol.59, p.71-80
• Main Authors: de Assis, Kioshy S., de Sousa, Flávio V.V., Miranda, Marcelo, Margarit-Mattos, Isabel C.P., Vivier, Vincent, Mattos, Oscar R.
• Format: Article
• Language: English
• Subjects: A. Stainless steel; Applied sciences; B. Cyclic voltammetry; B. Polarization; B. SEM; C. Intergranular corrosion; Chemical Sciences; Corrosion; Corrosion environments; Exact sciences and technology; Metals. Metallurgy; Other
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2012.02.014

► It is possible to assure that the ferrite phase is always more active than austenite. ► The value of the ratio Ir/Ia reflects different dissolution processes. ► The best parameter to be used to evaluate the experiment is Qr/Qa. This paper addresses the electrochemical parameters proposed in ISO 12732 standard that are used to quantify undesirable phases in a superduplex stainless steel. The relationship among these electrochemical parameters (listed as the maximum current and overall charges ratio during the activation and reactivation polarization curves) and the quantity of undesirable phases were evaluated. It was shown that ferrite is always preferentially corroded in that steel. For aged conditions, the undesirable phases were satisfactorily detected by Double Loop Electrochemical Potentiokinetic Reactivation. A new experimental protocol developed made possible the characterization of the attack occurring at each polarization range.