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Corrosion of stainless steel grades in H 2 O/KOH 50% at 120 °C: AISI304 austenitic and 2205 duplex
Author(s) -
Bozzini B.,
Bogani F.,
Giovannelli G.,
Natali S.,
Scarselli G.,
Boniardi M.
Publication year - 2013
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.201106469
Subject(s) - corrosion , materials science , intergranular corrosion , micrography , metallurgy , austenite , linear sweep voltammetry , acicular , dielectric spectroscopy , electrochemistry , anode , cathodic protection , scanning electron microscope , cyclic voltammetry , composite material , electrode , microstructure , chemistry
We report on the corrosion of austenitic (AISI304) and duplex (2205) stainless steels in H 2 O/KOH 50% at 120 °C. The research is based on a combination of electrochemical, structural and compositional analyses, aimed at assessing the surface modifications resulting from anodic attack and their impact on corrosion resistance. Linear sweep voltammetry and electrochemical impedance spectrometry measurements were carried out in an air‐tight high‐temperature cell. In‐plane and cross‐sectional SEM micrography, X‐ray diffractometry and EDX profiling were used to characterise samples attacked under electrochemically controlled conditions. Electrochemical results have shown that AISI304 exhibits a complex passivating behaviour, while the anodic electrokinetics of the duplex is characterised by mixed kinetic control. AISI304 was found to fail by intergranular corrosion and to be covered: in passive conditions by acicular compounds and in transpassive conditions by a compact layer of corrosion products. Duplex samples, instead, exhibit an uniform form of corrosion morphology and bear a compact layer of corrosion products both in passive and in transpassive conditions.