Mechanical properties gradient in graphite nodules: influence on ferritic DCI damaging micromechanisms

Versatility and higher performances at lower cost if compared to these of steels with analogous performances are the main advantages of Ductile Cast Irons (DCIs). In the last years, the research group of Metallurgy of the Università di Cassino e del Lazio Meridionale deeply investigated the damaging micromechanisms in ferritic pearlitic and austempered DCIs by means of tensile and fatigue tests, mainly performing scanning electron microscope (SEM) or Digital Microscope (DM) observations of specimens lateral surfaces during the tests (“in situ” tests). In this work, graphite nodules mechanical behaviour is investigated by means of nano indentation tests and results are compared with the damaging micromechanisms observed in ferritic DCIs.