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BASIC ENGINEERING
MATERIAL ED8E 11 | | |
 Wrought Iron
Wrought iron was the only form of iron available to man until displaced by steel in the late nineteenth
century.
Wrought iron is "
pig Iron
" which has been further refined in a "
puddling furnace
" from which it is removed in a
pasty condition and hammered and squeezed while hot to remove most of the slag and impurities. Some
slag
remains in the metal in the form of threads and this gives the metal a fibres character. The slag
content can be
further reduced by repeated hammering and squeezing operations. These operations result
in a stronger
wrought iron but production costs rise steeply.
Wrought iron is available in several grades and contains practically no carbon, usually somewhere around
0.4%
and is the purest form of iron available on a commercial scale, usually being 99.5% pure iron. Wrought
iron is
very malleable, ductile, and tough, and can easily be manipulated when hot or cold. these properties
make it a
very useful material where a lot of hammering, bending, twisting and forging has to be carried out,
such as
ornamental work, chain links, hooks, and couplings. The corrosion resistance of wrought iron is
superior to that
of steel and it turns an attractive matt black when corroded. This is made use of in decorative applications
such
as gates, fencing, and lamp brackets.
A further advantage of wrought iron is that it is very easily welded, even by hammering, when hot and
so it is a
popular material with blacksmiths, but, because of the high labor costs involved in its production,
it is a very
expensive material and so has been replaced in many of its earlier applications by Low carbon steel
(LCS or Mild
steel)
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