Abstract
Graphitic cast steels are in the hypereutectoid range and have spheroidal graphites in the as-cast state. This research can be summarized as follows:
(1) Gray cast irons with the strongest graphitizing tendency have oxygen and sulfur contents in the ranges of 20∼30 and 150∼300 ppm, respectively. It can be assumed that their contents of the graphitic cast steels are equal to those of gray cast irons having the strongest graphitizing tendency.
(2) Use of carbide slag before and after melting down of raw iron materials effectively decreases oxygen contents of these steels and improves their behaviour of graphitization; that is, the form of graphite is more spheroidal, nodules are increased and sizes become smaller than those when carbide slag is not used.
(3) Concerning the fading phenomena after inoculation, there is almost no degradation in the spheroidal form of graphite, and the size of graphite becomes smaller with the lapse of time.
