Effects of Sulfur and Manganese Contents on Decarburization Processing of Flake Graphite Cast Iron

The decarburization treatment for the generation of porosity effects in flake graphite cast iron are investigated from the view points of the amounts of two elements: one is sulfur which is known to give a large affection to the graphite morphology and the other one is manganese which is known to combine with sulfur to form MnS. The decarburization treatment for the generation of porosity effects were measured not only using the specimens produced by an ordinary sand mold casting but also using the specimens produced by a unidirectional solidification method in order to minimize the affection caused by the difference in the graphite morphology. The results obtained are as follows: The graphite morphology becomes finer as the amount of exceeded sulfur (the amount of free sulfur after formation of MnS) increases. The depth of pored layer increases as the sulfur content increases, and the velocity of the decarburization treatment for the formation of porosity decreases as the amount of exceeded sulfur increases. The affection of sulfur in the processing of the decarburization treatment for the formation of porosity is apparently larger than that in graphite morphology.