Another major example
of dealloying is graphitic corrosion that
occurs in gray cast iron. Gray cast iron has a continuous
graphite network in its microstructure
that is cathodic to iron and remains behind as a
weak, porous network as the iron is selectively
removed from the alloy. Graphitic corrosion is
observed on buried pipelines after many years
of service. Examples of graphitic corrosion are
shown in Fig. 4.