Cast iron classification and properties
Generally, iron castings occupied more
than 50% of weight of the machine equipments, so they are very
important for the industry of one country.
The classifications of the cast iron
1. White cast iron
The carbon is on the surface of ferrites with small fraction and is
in the form of Fe3c, the section of white cast iron is in sliver
white color, its features is hard and fragile, it is difficult to be
processed with machine and little used to produce parts. The main
usage: it is used as the raw materials to make steel, also can be
deal to malleable irons.
2. Gray cast iron
The carbon is on the surface of ferrites with small fraction and all
is in the form of graphite, the section is in grey color. It is used
widely actually, it occupies 80% of the cast iron. Their features
are soft, fragile, poor intensity and small gravity. It includes
common gray cast iron, malleable cast iron, ductile cast iron and
vermicular graphite cast iron.
3. Mottled cast iron
It is belonged to the transition tissue between the white cast iron
and gray cast iron. Because its property is not very good so it is
4. Ductile Iron
Ductile iron is also called as spheroidal graphite cast iron or sg
iron. Because of the nodular agent, the graphite form is shown as
the spherodal, so this iron will have larger elongation and higher
tensile and yield strength.
The factors which affect the micro-structure and property
1. The contents of carbon
When C=0.8%, it is pearlitic grey iron, the graphite piece is small
and intensity is high, so it used to produce important parts. When
C<0.8% they are pearlites and ferrite gray pig iron they have high
hardness and the property is good, so it suits to the common machine
2. The degree of graphitization
The chemical component of cast irons, the cooling speed of cast
irons crystallizes, the superheating of iron water and quiescence in
high temperature all affect the graphitization.
The development of cast iron
After China joining in WTO, the cast iron foundries meet great
opportunities and challenges. China has great market potential in
domestic and overseas. The advanced technology has a great effect on
the traditional industries, the use of artificial intelligence and
net technology can improve the control system guarantee the quality
of the products.