On the propagation of open and covered pit in 316L stainless steel.

Stéphane Heurtault (1, 2) , Raphaël Robin (2) , Fabien Rouillard (2) , Vincent Vivier (1)

1 LISE - Laboratoire Interfaces et Systèmes Electrochimiques
2 LECNA - Laboratoire d'Etude de la Corrosion Non Aqueuse

Pitting corrosion on stainless steel has been widely studied during the last decades, but since it is a stochastic process, it remains difficult to analyze experimentally such a phenomenon. In this work, reproducible single pits were performed on 316L steel by using an experimental setup based on the use of a glass microcapillary to locally supply chloride ions on the steel surface in order to characterize the pit propagation. This original approach allowed obtaining new results about pit propagation. Indeed, it was possible to control the presence of a metallic cap covering the pit by adjusting the experimental parameters (potential – chloride to sulfate ratio – temperature). The presence of this cover was shown to be an important issue concerning the propagation mechanism. It was also possible to study the evolution of both the pit depth and the pit diameter as a function of various parameters. Then, based on the simulation of the current densities at the pit bottom and at the pit aperture, a special attention has been paid for the investigation of the local propagation mechanism.

Mots clés: Pitting corrosion; single pit; pit propagation; salt film; stainless steel

Domaines: Autre; Matériaux

Stéphane Heurtault, Raphaël Robin, Fabien Rouillard, Vincent Vivier. On the propagation of open and covered pit in 316L stainless steel.. Electrochimica Acta, 2016, 203, pp.316-325. ⟨10.1016/j.electacta.2016.01.084⟩. ⟨hal-01313029⟩