Abstract
The paper presents a solidification sequence of graphite eutectic cells of
A and D types, as well as globular and cementite eutectics. The morphology
of eutectic cells in cast iron, the equations for their growth and the
distances between the graphite precipitations in A and D eutectic types
were analyzed. It is observed a critical eutectic growth rate at which one
type of eutectic transformed into another. A mathematical formula was
derived that combined the maximum degree of undercooling, the cooling rate
of cast iron, eutectic cell count and the eutectic growth rate. One type
of eutectic structure turned smoothly into the other at a particular
transition rate, transformation temperature and transformational eutectic
cell count. Inoculation of cast iron increased the number of eutectic
cells with flake graphite and the graphite nodule count in ductile iron,
while reducing the undercooling. An increase in intensity of inoculation
caused a smooth transition from a cementite eutectic structure to a
mixture of cementite and D type eutectic structure, then to a mixture of D
and A types of eutectics up to the presence of only the A type of eutectic
structure. Moreover, the mechanism of inoculation of cast iron was studied.
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