Effect of graphite morphology on tensile properties of flake graphite cast iron

Abstract

The mechanical properties of flake graphite cast iron were studied using normal cast and unidirectionally solidified (UDS) test pieces. Their chemical composition was cutectic, namely CE = 4.3%, differing only in sulfur content. To eliminate the influence of the discontinuity of graphite at the cutectic cell boundary, we used UDS samples. Fully annealed tensile test pieces were used to exclude the influence of the matrix. The experimental results are as follows: The tensile strength and elongation of normal and unidirectionally solidified cast iron are increased by the sulfur addition as the graphite morphology is modified. The tensile strength is improved by UDS. One of the reasons must be based on the continuity of the matrix. Neverthless, the tensile strength of the UDS samples is not as strong as that of spheroidal graphite cast iron because the fracture occurs at the graphite-terminated area in the aligned graphite samples.