Graphite nodule morphology evolution as an indicator of DCI macroscopic damage level

Ductile cast irons (DCI) mechanical properties are strongly influenced both by the matrix and by the graphite elements morphological peculiarities. These elements cannot be merely considered as “microvoids embedded in a metal matrix”, but their presence implies a modification of the damaging micromechanisms, depending on the metal matrix microstructure. In this work, a ferritic DCI has been considered. Tensile tests have been performed on notched tensile specimen: quantitative image analysis approach has been applied in order to analyze the possibility to consider the graphite nodules as indicators of the damaging level evolution.