Differential scanning calorimetry and microscopy study of transformations in ductile cast irons: Part II. Continuous cooling

The study of the cooling processes of ductile cast irons using the differential scanning calorimetry technique in the temperature range of 20-950degreesC shows three thermal effects. They are due to three transformations: the restoration of magnetic properties (T(Cc)), austenite-->pearlite transformation (T(Pc)), and austenite to ferrite plus graphite transformation (T(Fc)). The data allow studying the kinetics of the transformations at different testing conditions, cast iron composition and as-cast microstructure. During cooling the temperature sequence at which the transformations occur is T(Fc)>T(Cc)>T(Pc). The increase in cooling rate changes the intensity and temperatures of the different transformations in different ways. This results in the overlapping of the thermal effects.