Ductile cast irons (DCIs) are characterized by an interesting combination of mechanical properties: first of all, the good castability of gray irons and the toughness of steels. This is due to the peculiar graphite elements shape, obtained by means of a chemical composition control (mainly small addition of elements like Mg, Ca or Ce). Many DCIs microstructures are available: among them, ferritic DCIs are characterized by good ductility, with tensile strength values that are equivalent to a low carbon steel. In this work, fatigue damaging micromechanisms in a ferritic DCI have been investigated by means of in–situ scanning electron microscope observations. Specimens were ground and polished and fatigue loaded by means of an electromechanic testing machine: specimens lateral surfaces were observed “in situ” using a scanning electron microscope (SEM), focusing 20 graphite nodules and considering the ferritic matrix around them. During fatigue tests, specimen deformation and applied load were measured by means of a Linear Variable Differential Transformer (LVDT) and two miniature load cell (10 kN each), respectively.
Analysis of fatigue damaging micromechanisms in a ferritic ductile iron
DI COCCO, Vittorio;IACOVIELLO, Francesco;
2012-01-01
Abstract
Ductile cast irons (DCIs) are characterized by an interesting combination of mechanical properties: first of all, the good castability of gray irons and the toughness of steels. This is due to the peculiar graphite elements shape, obtained by means of a chemical composition control (mainly small addition of elements like Mg, Ca or Ce). Many DCIs microstructures are available: among them, ferritic DCIs are characterized by good ductility, with tensile strength values that are equivalent to a low carbon steel. In this work, fatigue damaging micromechanisms in a ferritic DCI have been investigated by means of in–situ scanning electron microscope observations. Specimens were ground and polished and fatigue loaded by means of an electromechanic testing machine: specimens lateral surfaces were observed “in situ” using a scanning electron microscope (SEM), focusing 20 graphite nodules and considering the ferritic matrix around them. During fatigue tests, specimen deformation and applied load were measured by means of a Linear Variable Differential Transformer (LVDT) and two miniature load cell (10 kN each), respectively.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
