Effect of Silicon and Microstructure on Spheroidal Graphite Cast Iron Thermal Conductivity at Elevated Temperatures

Spheroidal graphite cast irons are materials that exhibit many possible microstructures and compositions, which in turn create a multitude of possible property combinations. Chemical composition and microstructure are some of the biggest influences on these material properties. This paper concentrates on the effect of silicon alloying in the range of 1–4% and varying ferrite–pearlite microstructures on thermal conductivity of spheroidal graphite cast irons from room temperature up to 400 °C. Results show that increasing silicon alloying levels decreases thermal conductivity, while a decreasing trend is also seen with increasing pearlite fraction, as composition and morphology act as hindrance to thermal conduction. Temperature dependence shows as an initial increase in thermal conductivity and a peak near 200–300 °C for the studied alloys. Based on the results, a model estimating thermal conductivity with silicon alloying, pearlite fraction and temperature is made to aid in the estimation of material properties for design use.