Such dispersion hardened cast iron structures generally fail by ductile fracture, however, clustered
regions of graphite have stress raising potential which will cause local interface fracture extending to failure
of the whole structure. As observed from the fracture surface, large dimples associated with graphite flakes
are clearly visible, no localized necking is seen. Cavities and dimples on the fracture surface are the sign of
weak internal interfaces between graphite flakes and ferrite