Carbon
steel,
also called plain
carbon steel, is
steel where the
main alloying constituent
is carbon. The AISI
defines carbon steel
as: "Steel
is considered to
be carbon steel
when no minimum
content is specified
or required for
chromium, cobalt,
columbium [niobium],
molybdenum, nickel,
titanium, tungsten,
vanadium or zirconium,
or any other element
to be added to obtain
a desired alloying
effect; when the
specified minimum
for copper does
not exceed 0.40
per cent; or when
the maximum content
specified for any
of the following
elements does not
exceed the percentages
noted: manganese
1.65, silicon 0.60,
copper 0.60."[1]
The
term "carbon
steel" may
also be used in
reference to steel
which is not stainless
steel; in this use
carbon steel may
include alloy steels.
Steel
with a low carbon
content has properties
similar to iron.
As the carbon content
rises, the metal
becomes harder and
stronger but less
ductile and more
difficult to weld.
In general, higher
carbon content lowers
the melting point
and its temperature
resistance. Carbon
content influences
the yield strength
of steel because
carbon atoms fit
into the interstitial
crystal lattice
sites of the body-centered
cubic (BCC) arrangement
of the iron atoms.
The interstitial
carbon reduces the
mobility of dislocations,
which in turn has
a hardening effect
on the iron. To
get dislocations
to move, a high
enough stress level
must be applied
in order for the
dislocations to
"break away".
This is because
the interstitial
carbon atoms cause
some of the iron
BCC lattice cells
to distort.
85%
of all steel used
in the U.S. is carbon
steel.[1]
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AS PER THE NATIONAL
& INTERNATIONAL
STANDARD &
SPECIFICATIONS
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