Effects of Trace Elements on the Formation of Spheroidal Graphite in Ductile Iron

Spheroidal graphite was obtained by direct quenching iron melt atfter spheroidization and inoculation procedures. The morphology and the effects of trace elements on the formation of spheroidal graphite were investigated by scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy. Results indicate that all the graphite fixed by quenching, is nearly spheroidal with a diameter of approximately 20 mu m. In addition, the SEM image of graphite morphology confirms the screwed growth model of spheroidal graphite. The linear distribution of trace elements shows that the nucleus of spheroidal graphite consists of antimony, cerium, magnesium and sulfur element. Meanwhile, trace elements, such as antimony, cerium and magnesium, enrich around graphite nodule, which facilitates the formation of spheroidal graphite.