Letter to the Editor

Excerpt

The authors of the paper, discussed here, Freulon et al.,[1] have used two commercial composition ductile iron samples to evaluate composition profiles across ferrite/pearlite boundaries at room temperature. They also performed differential thermal analysis (DTA) to record eutectoid transformation temperatures during cooling at various rates after reaustenitization. They conclude that “composition profiles across ferrite/pearlite boundaries are smooth and similar to those issued from the solidification step” and also that “no trace of long-range diffusion of substitutional solutes could be detected.” As no similar reports for cast irons have been reported in the literature, the authors suggest that “showing smooth composition profiles must have been considered as not being worthy of publication.” They do mention in passing a report by Guo and Stefanescu[2] that disagrees with their conclusions, but they dismiss it summarily, stating that “Though not giving much detail, the authors indicate that some eutectic carbides were present in the as-cast material they investigated which may better explain the abrupt compositional changes they sometimes observed.” There is no mention of such carbides in Reference 2. However, such a sample is mentioned in some previous work by Guo and Stefanescu,[3] which does not appear in the reference list of the paper discussed here. This work also includes extensive details of the experimental method, to which Freulon et al. had access, as they mention the existence of carbides in a sample. The purpose of this discussion is to clarify the apparent discrepancies between the work of Freulon et al. and that of Guo and Stefanescu. …