VI - Mesure de la sensibilité à la CSC intergranulaire d’un acier inoxydable duplex à l’aide d’essais électrochimiques (technique EPR)

Measure of susceptibility to intergranular stress corrosion cracking of a duplex stainless steel using electrochemical testings (EPR technique)

Abstract

Stress corrosion cracking can produce several modes of cracking : intergranular, transgranular or trans/intergranular. For the 2205 grade of duplex stainless steel, slow strain rate tests in boiling MgCl₂ (30% wt) lead to a transgranular mode of cracking with an intergranular propagation at interfaces ferrite/austenite. The crack initiation seems to take place at grain boundaries. This work tends to establish a correlation between the SCC test in its initiation phase, and the Electrochemical Potentiodynamic Reactivation test (EPR). The latest promotes a measure of a degree of susceptibility to intergranular corrosion, by getting a potential-current curve during anodic and cathodic scans. The EPR test is not standardized but presents the advantage to be non-destructive. This can promote in-situ applications of the test which could lead to a better checking of reliability and security of working materials.