What is an alloy?
General Cold Finished Steel Information
|The 10 cold finished steel forms
available in the USA
An alloy is simply a mixture of metals melted together to form a new
metal with characteristics distinct from those of the metals from which
it is made.
What is a steel
A steel alloy is an alloy that is primarily iron, with small quantities
of other elements mixed in during the melting process which vary
the properties of the iron to maximize a particular characteristic of
the final alloy.
Some make the iron not rust (nickel), some make the iron possible to
harden with heat treatment (carbon), Some make the iron easy to machine
(lead), and so on. By varying the type and amount of the alloying
element, even in minute quantities, a huge range of steels is produced,
used for a myriad of industrial purposes.
Why does Cold
Finished Steel have a smooth grey finish, while Hot Rolled Steel has a
rough, blue-grey finish?
Cold Finished Steels
are just that - the final rolling is done when the steel is cold (room
temperature), the whole operation bathed in oil, so the finished
product is unoxidized, the grey of the actual steel, and as smooth as
the rollers that do the processing.
Hot Rolled Steels are just that - They are heated up red-hot and pushed
through rollers that squeeze the metal, literally squishing it into a
particular profile, depending on the shape of the rollers. The process
takes a long time, and because the steel is so hot for so long in th
open air of the steel mill, the surface of the metal has has a long
time to oxidize, producing a thick, tough oxide scale with the
characteristic blue grey finish of the final product.
Why are there so
few shapes available in Cold Finished Steel and so many in Hot Rolled
Steel is a very tough material when it is “cold” (meaning “room
temperature”). When it is bent, hammered (such as in cold forging), or
deformed in any way steel can actually harden in the area of distortion
and begin to crack or weaken. Only if it is heated past a particular
temperature (usually a red-heat) does it become plastic enough to be
bent, formed hammered, and squeezed with relative ease and without
damaging the metal. For example, few of us would be able to bend a bar
of 1” thick steel at room temperature no matter how hard we tried, but
if the middle of the bar were heated with a torch until it glowed a
healthy cherry red color, most of us would have very little trouble
bending the bar back upon itself until both ends touched. And when it
cooled it would regain its toughness and strength in that bent
condition and we would no longwr be able to bend it.
This means that the intricate profiles apparent in, say, a Hot Rolled
beam or channel is only possible to form if the steel is iin the
red-hot condition. If these types of profiles were attempted in the
cold condition both the metal and the equipment used to shape the metal
would be ruined.
This means that only relatively simple shapes like flats, hexagons or
rounds are available in Cold Finished Steels. However, one of the great
advantages of this process is that the
resulting products is a much finer surface (that is bare of oxidation)
and sharp corners to the profiles of Cold Finished products as opposed
to the rounded and rough finish of Hot
Steels be chemically colored or patinated?
Yes. Because the chemical coloring of metals relies on the action of
the chemicals with the metal itself and Cold Finished Steels do not
have any oxidation present on the surface, they are perfect for the
base metal fabrication that will eventually receive a secondary
coloring process. In addition, because the tolerances
and profiles of cold finished metals (some stainless steel products are
also produced with a cold finish process) are sharp and accurate the
final work fabricated from these products gives an overall aesthetic of
superior craftsmanship than working with Hot Rolled Steels.