Effect of microstructure on the hardness of ASTM A48 class 20 flaked graphite cast iron

ABSTRACT In foundries, it becomes necessary to minimise the machining allowance for economic reasons. It will save resources and costs by reducing the energy and expenses incurred on re-melting, machining and tooling. A deeper understanding of the complicated microstructures developed within about 3.5 mm of the mould-metal interface is necessary. The current research work uses a unique experimental design that involves performing surface and subsurface microscopy and spectroscopy at 0.5 mm intervals from the as-cast surface to a depth of up to 3.5 mm for three samples. The objective is on evaluating microstructure for determining graphite flake size, distribution, grouping, pearlite and ferrite percentage, and different elements. All three samples were subjected to a hardness test, which is a measure of machinability. The relationship between hardness as a single response to percentage presence of elements, graphite distribution and pearlite has been established using statistical analysis.