In situ study on the influence of bicarbonate, chloride and outer electrode potential on crevice corrosion occurrence and development of X70 steel

Abstract

Purpose The purpose of this paper is to clarify the influence of bicarbonate, chloride and outer electrode potential on crevice corrosion occurrence and development of X70 steel. Design/methodology/approach The crevice corrosion behavior in NaHCO3 and NaCl solutions was investigated through modeling and experiments. The electrode potential and current density distribution were simulated, and the acidification of crevice solution was monitored in situ. Findings The bicarbonate concentration and outer electrode potential remarkably influenced the occurrence of crevice corrosion. The former changes the passivation curves, and the latter alters the initial potential. Moreover, chloride concentration exerted minimal influence. The location of acidification and pitting occurrences depended on the potential difference between the outer electrode and electrode at the active dissolution current peak. Originality/value This study provides a better understanding of the crevice corrosion behavior and mechanism under natural conditions.