Elevated temperature thermal conductivities of some as-cast and austempered cast irons

The aim of this study was to provide insight on thermal conductivity of three cast iron groups, namely lamellar, compacted and spheroidal graphite irons at elevated temperatures up to 673 K (400°C) in as-cast and austempered states. Austempering treatments increased mechanical properties of all the studied materials while decreasing thermal conductivity across the line. The effects of austempering on conductivity were lower for grey and compacted graphite iron than for spheroidal graphite irons. The results indicate that heat treating can be a viable option in increasing cast iron performance in thermally stressed applications. One ferritic low-silicon spheroidal graphite iron surpassed lamellar graphite iron in conductivity at elevated temperatures, while high-silicon spheroidal graphite irons exhibited low conductivities.