Transgranular crack growth in the pipeline steels exposed to near-neutral pH soil aqueous solutions: Discontinuous crack growth mechanism

This investigation enabled the identification of a discontinuous crack growth mechanism of pipeline steels in near-neutral pH environments, which was determined from experimental simulations lasting more than 4 months, using a novel experimental setup that had incorporated the synergistic effects of realistic mechanical loading and the changes of environments affected by coating disbonding and CO2 level in the system. The discontinuous crack growth occurs by repeated crack dormancy-active growth cycles. Crack dormancy can be either mechanically or environmentally induced, while the active growth is initiated because of a combined effect of cyclic loading, stress concentration and hydrogen segregation and trapping.