Influence of sensitisation on the corrosion behaviour of Alloy 926 (UNS N08926) in concentrated aqueous lithium bromide solutions at different temperatures

Abstract

[EN] The aim of this work is to study the influence of sensitisation to intergranular corrosion on a highly alloyed austenitic stainless steel, Alloy 926 (UNS N08926). Some specimens of this steel have been heated in an argon atmosphere at 825 degrees C during 1 hour. The degree of sensitisation has been characterised by means of SEM, etching (with oxalic acid), and electrochemical reactivation methods (single and double loop tests). The corrosion behaviour of sensitised and unsensitised Alloy 926 has been analysed in a concentrated aqueous lithium bromide (LiBr) solution of 992 g/L by means of cyclic potentiodynamic curves at different temperatures. The results indicate that chromium carbide precipitates reduce the pitting potential value of Alloy 926. Besides, the pitting potential decreases with temperature. On the other hand, the corrosion potential and open circuit potential values increase with temperature and sensitisation.