What is malleable cast iron?
Malleable cast iron is produced from white
cast iron, which is made from hot liquid iron with certain chemical
components. The white cast iron needs to be treated by malleablizing,
such as graphitizing or oxidation and decarbonization, then its
metallographic structures or chemical components will be changed, so
can become into malleable cast iron.
Comparing with the gray cast iron,
malleable cast iron has better strength and ductility, especially
better impact resistance in low temperatures.
Comparing with cast steel,
malleable cast iron has better abrasive resistance and shock
Comparing with the ductile iron,
both of them have good strength and ductility, but malleable iron
has better impact resistance, but ductile iron has better abrasive
There are several types of malleable cast iron.
Black heart malleable cast iron is mainly used to produce the
iron casting parts with
impact, shake or torsion functions. Normally used to produce rear
axle housing castings, spring bracket, low pressure valve body,
pipe fittings, tools
and wrenches. Black heart malleable cast iron is also called as
ferritic malleable cast iron.
Pearlite malleable cast iron has higher strength,
abrasive resistance. So, it is mainly used to produce the abrasion
resistant parts for motive power machinery and agricultural
White heart malleable cast iron is seldom used because of its long
The good physical properties of malleable cast iron is because of
its microstructures. Its inside graphite is existed as the regiment
floe, so the graphite has lower tearing function to the iron body.
The following is the metallographical photo to the micro structures
of graphite in malleable cast iron.
In the past, many foundries produced
malleable iron castings, however, with the development of ductile
iron, most of malleable iron casting parts could be replaced by
ductile iron. So, only few iron
foundries in China are still producing this material.