Effect of hydrogen peroxide on crack growth rate in X70 pipeline steel in weak acid solution

ABSTRACTAn investigation of the effect of hydrogen peroxide (H2O2) on corrosion crack growth can be considered as a necessary stage in a study of the SCC of pipeline steels in the presence of dissolved oxygen and other oxidants. It was found that the presence of hydrogen peroxide at a low concentration (5 mM) results in a deceleration of the crack growth. With an increase in the concentration of H2O2, the crack growth rate increases. The change in the steel corrosion rate at various H2O2 concentrations agrees with the dependence of the crack growth rate on the oxidant concentration. The conclusion has been made that the crack growth in a weakly acidic electrolyte (pH 5.5) is determined by the metal dissolution process. Hydrogen charging of the metal indirectly affects the crack growth by increasing the surface coverage with hydrogen, which decreases the steel dissolution rate.