On Thermal Expansion and Density of CGI and SGI Cast Irons

Abstract

The thermal expansion and density of Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were measured in the temperature range of 25–500 °C using push-rod type dilatometer. The coefficient of the thermal expansion (CTE) of cast iron can be expressed by the following equation: CTE = 1.38 × 10−5 + 5.38 × 10−8 N − 5.85 × 10−7 G + 1.85 × 10−8 T − 2.41 × 10−6 RP/F − 1.28 × 10−8 NG − 2.97 × 10−7 GRP/F + 4.65 × 10−9 TRP/F + 1.08 × 10−7 G2 − 4.80 × 10−11 T2 (N: Nodularity, G: Area fraction of graphite (%), T: Temperature (°C), RP/F: Pearlite/Ferrite ratio in the matrix).