Ductile cast irons (DCIs) are characterized by a wide range of mechanical properties, mainly\uddepending on microstructural factors, as matrix microstructure (characterized by phases volume fraction, grains\udsize and grain distribution), graphite nodules (characterized by size, shape, density and distribution) and defects\udpresence (e.g., porosity, inclusions, etc.). Versatility and higher performances at lower cost if compared to steels\udwith analogous performances are the main DCIs advantages.\udIn the last years, the role played by graphite nodules was deeply investigated by means of tensile and fatigue\udtests, performing scanning electron microscope (SEM) observations of specimens lateral surfaces during the\udtests (“in situ” tests) and identifying different damaging micromechanisms.\udIn this work, a pearlitic DCIs fatigue resistance is investigated considering both fatigue crack propagation (by\udmeans of Compact Type specimens and according to ASTM E399 standard) and overload effects, focusing the\udinteraction between the crack and the investigated DCI microstructure (pearlitic matrix and graphite nodules).\udOn the basis of experimental results, and considering loading conditions and damaging micromechanisms, the\udapplicability of ASTM E399 standard on the characterization of fatigue crack propagation resistance in ferritic\udDCIs is critically analyzed, mainly focusing the stress intensity factor amplitude role.
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