Recently discovered, Ductile Cast Irons (DCIs) are able to combine the high toughness values of steels with the good castability of grey irons. These grades are also characterized by an interesting fatigue crack propagation resistance. Their fatigue crack propagation resistance depends on loading conditions, chemical composition, matrix microstructure and graphite elements morphology (e.g. graphite elements nodularity, volume fraction, density, distribution, dimension). DCIs are widely used in critical automotive parts (e.g. wheels, gears, crankshafts in cars and trucks) and in many other applications, like pumps, pipes or turbine components. Considering these applications, the possibility of an overload is not negligible. In this work, the microstructure influence on the damaging micromechanisms in overloaded fatigue cracks in a ferritic DCI was investigated considering fatigue precracked Compact Type (CT) specimens at room temperature. These specimens were metallographically prepared, chemical etched and, then, fatigue precracked and overloaded. According to a step by step procedure, lateral surfaces were observed by means of a Scanning Electron Microscope (SEM).
Ductile cast irons: Microstructure influence on the damaging micromechanisms in overloaded fatigue cracks
Di Cocco, Vittorio
Membro del Collaboration Group
;Iacoviello, FrancescoMembro del Collaboration Group
2017-01-01
Abstract
Recently discovered, Ductile Cast Irons (DCIs) are able to combine the high toughness values of steels with the good castability of grey irons. These grades are also characterized by an interesting fatigue crack propagation resistance. Their fatigue crack propagation resistance depends on loading conditions, chemical composition, matrix microstructure and graphite elements morphology (e.g. graphite elements nodularity, volume fraction, density, distribution, dimension). DCIs are widely used in critical automotive parts (e.g. wheels, gears, crankshafts in cars and trucks) and in many other applications, like pumps, pipes or turbine components. Considering these applications, the possibility of an overload is not negligible. In this work, the microstructure influence on the damaging micromechanisms in overloaded fatigue cracks in a ferritic DCI was investigated considering fatigue precracked Compact Type (CT) specimens at room temperature. These specimens were metallographically prepared, chemical etched and, then, fatigue precracked and overloaded. According to a step by step procedure, lateral surfaces were observed by means of a Scanning Electron Microscope (SEM).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.