Environmentally assisted cracking of pipeline steels in CO2 containing environment at near-neutral pH

The paper summarizes the results obtained by authors concerning near-neutral stress corrosion crack- ing (SCC) phenomena on buried pipelines. Stress cor- rosion tests according to different methodologies and fatigue propagation tests were executed on traditional steel grades. Tests were performed also on specimens pre- corroded according to a procedure developed to produce localized attacks similar to those observed during failure analysis on pipelines, acting as preferential sites for crack nucleation. Electrochemical tests were carried out in order to evaluate the influence of environmental parameter on pit formation. The main role of continuous plastic defor- mations on near-neutral SCC is confirmed. The effect of pH, CO2, and bicarbonate concentrations on pitting for- mation is discussed.