It is known that stress corrosion cracking (SCC) of pipeline steels appear in anaerobic soils, which is probably related to activity of sulphate-reducing bacteria and formation of hydrogen sulphide. Oxygen and other oxidants direct influence on crack growth in pipeline steels data are few and controversial. This work describes the results of corrosion - mechanical tests on beam specimens under static stress. Specimens were made from X70 steel grade. Electrochemical measurements were carried out in a Devanathan – Stachurski cell using foil mild steel membranes. The citrate buffer solution (pH 5.5) was background electrolyte. Hydrogen peroxide (H2O2), model additive of oxidative type, was injected into background electrolyte. It was found that the presence of Н2О2 in a relatively small concentration (5 mM) results in the deceleration of the crack growth. With an increase in concentration of hydrogen peroxide, the crack growth rate increases. The phenomenon is explained by the effect of hydrogen peroxide on the penetration rate of hydrogen into the metal, which in turn determines the dissolution rate of iron.

Subject
Crack growth, Hydrogen concentration, Corrosion rate, Hydrogen peroxide, Pipelines, Dissolution, Corrosion cracking, Metals, Steel, Risk reduction, Corrosion potential, Electrolytes, Hydrogen
Keywords:
stress corrosion cracking, pipeline steel, crack growth, citrate buffer solution, hydrogen peroxide
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2016
Association for Materials Protection and Performance (AMPP)
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