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

Abstract

The study of the cooling processes of ductile cast irons using the differential scanning calorimetry technique in the temperature range of 20-950°C shows three thermal effects. They are due to three transformations: the restoration of magnetic properties (TCc), austenite→pearlite transformation (TPc), and austenite to ferrite plus graphite transformation (TFc). 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 TFc>TCc>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.