Grey Cast Iron is one of the most widely used types of cast
iron. Cast Iron is mainly manufactured by melting pig iron and
then pouring it into the cast or mould of desired shapes and
sizes. The widespread use of the Grey Cast Iron can mainly be
attributed to its cost efficiency and easy machinability. The
Grey Cast Iron is classified as grey due to the appearance of
the grey cracks on the surface of the finished cast iron, which
is caused by the presence of graphite content.
The Composition of Grey Cast Iron in terms of all its
constituent elements can be explained as follows:
Carbon (up to 4%): The carbon content of the grey cast
iron later on gets converted to graphite after going through a
series of chemical reactions. This graphite content is
responsible for providing strength and easy machinability
feature to the Grey Cast Iron.
Silicon (up to 3%): Silicon is mainly added for the
de-oxidation process so that the carbon content added does not
get oxidized to the iron carbides. Silicon acts as the
stabilizing element for the graphite in the Grey Cast Iron.
Manganese (0.8%): Manganese acts as a stabilizing element
that ensures that the Grey Cast Iron delivers high performance
even at high temperatures. This property increases the
toughening of the overall structure.
Sulfur (0.07%): It acts as a stabilizing element for
manganese and improves the toughness of the Grey Cast Iron at
Phosphorus (0.2%): Phosphorous has to be added in small
amounts to improve the fluidity, corrosion resistance and the
toughness of the Grey Cast Iron. Phosphorous, when added in
large amount, reduces the overall strength of the Grey Cast
Molybdenum (up to 0.75%): Molybdenum improves the
strength and elasticity of the Grey Cast Iron when added in
Chromium (0.35%): Chromium improves the temperature range
and hardness of Grey Cast Iron.
Vanadium (0.15 %): Vanadium improves the wear and tear
The composition of the Grey Cast Iron is very crucial for the
final set of properties that the finished Grey Cast Iron
acquires. Silicon and Carbon are very critical elements in terms
of the amount in which they are added for the production of Grey
Cast Iron. This is because the properties of Grey Cast Iron
depend to a great extent on the various reactions that these two
elements undergo during the production process.
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