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119
Non-ferrous metals are metals and alloys the main component of which is
not iron but some other element such as copper (Cu), aluminium (AT) and oth-
ers. Copper, aluminiun and some other metals are referred to as non-ferrous
metals. The properties of ferrous metals:
a) all metals can be easily known by their specific metallic
lustre;
b) metals can be forged;
c) metals can be pulled;
d) all metals, except mercury, are hard substances. However,
hard metals can be reduced to liquid by heating;
e) being fusible metals can be melted;
i) in general, metals are good conductors of electricity.
These characteristics are possessed by all the metals, but the metals them-
selves differ from one another.
Steel and cast iron are referred to the group of ferrous metals. They are al-
loys of iron (Fe) with carbon (C), manganese (Mb), Silicon (Si) and other com-
ponents. By the content of carbon in metals we distinguish cast iron, white cast
iron, grey cast iron and wrought iron. The carbon content ranges from 0 to 4 per cent.
Cast iron is the cheapest of the ferrous metals. Cast iron contains 1.7 per
cent carbon.
White cast iron is used in those machines which require some resistance
to abrasion. The tensile strength of white cast iron is about 30,000 pounds per
square inch, its hardness is about 400 to 500 Brinell.
Grey cast iron is an alloy of iron, and carbon in which some of the iron
carbide is dissociated to form graphite carbon. Grey, cast iron has its term be-
cause of surecial colour of its fracture.
It is quite necessary to regulate the proportion of silicon in the melt and to
control the temperature after the grey cast iron has been poured.
Wrought iron is a mixture of very pure iron and silicate slag. Properties of
wrought iron such as strength, toughness, ductility have more advantages than
cast iron. Wrought iron is quite ductile and can be easily rolled, drawn, forged
and welded.
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