Hydrogen Permeation in Carbon Steels

Abstract

The atomic hydrogen generally comes from corrosion reactions that take place between the steel surface and the sour media. These reactions generate atomic hydrogen that due to its small size can be adsorbed and diffuse through interstitial sites of the crystalline lattice of steel, where it accumulates in nonmetallic discontinuities such as inclusions, dislocations and second phases, where atomic hydrogen begins to combine and form molecular hydrogen, which can no longer diffuse in the steel and over time produces high internal pressures in localized areas of the thickness of the material, leading to the nucleation and propagation of cracks and/or blisters in the absence of applied external stresses. This depends on the type of interaction that occurs between hydrogen and the metal, environmental conditions, heterogeneities of the metal, and the state of stress to which the components are subjected. Due to the increase in sour media in the petroleum industry, it was necessary to reconsider the application of electrochemical techniques and sensors to control and predict hydrogen-induced cracking (HIC).