Differential Scanning Calorimetry and Microscopy Study of Transformations in Ductile Cast Irons: Part II. Continuous Cooling

摘要

The study of the cooling processes of ductile cast irons using the differential scanning calorimetry technique in the temperature range of 20-950 deg C 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.