Frequently asked Questions:
is an alloy?
An alloy is simply a mixture of metals
melted together to form a new metalwith characteristics distinct from
those of the metals from which it is made.
What is a steel alloy?
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 (chromium and
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
Why does Hot Rolled Steel have a rough,
blue-grey finish, while Cold Finished Steel has a smooth grey finish?
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 the 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.
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
Why are there so many shapes available
in Hot Rolled Steel and so few in Cold Finished Steel?
Steel is a very tough material when it is
cold. However, if it is heated past a particular temperature (usually a
red-heat) it immediately turns plastic and can be bent, formed, hammered, and squeezed very easily.
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 until it glowed a healthy cherry red color (about 1650
degrees Fahrenheit), 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 it's toughness and strength in that bent condition.
This means that the intricate profiles
apparent in, say, a Beam or Channel are formed fairly easily in the hot
condition, but would be impossible to produce in the cold condition,
and only flat, hex or round shapes that are relatively simple profiles
are available in Cold Finished Steels.
Can Hot Rolled Steels be chemically
colored or patinated?
The chemical coloring of metals relies on the action of the
chemicals with the metal itself. The only surface exposed on a Hot Rolled
Steel product is the blue oxide scale, which is virtually inert. In
order to color the metal, either the grey of the base metal must be
exposed by grinding and then can be colored, or pigmented lacquers or
paints must be used on the surface. Because the surface is rough, it
takes paints and lacquers very well.
Some Things to be aware of:
Hot Rolled Steel products are NOT a consistent
blueish color. This is particularly true with hot rolled
sheet, over the surface of which the color varies dramatically,
more blue at the edges, more grey in the center of the sheet.
The shapes available in hot rolled steels are available in 12ft,
20ft, and sometimes 40ft lengths, ask us, we can tell you what is available..
The blue scale finish on hot rolled products is incidental to
the process of producing the product, and so, is not controlled
in any way. This gives rise to fairly strong inconsistencies in
the finish, particularly in sheet and plate.
Again, the blue scale on the metal prevents any chemical coloring on
the surface of the metal unless the scale is removed, exposing the
bare metal beneath.
Most hot rolled products are very soft and bendable. This is really
only noticeable in the smaller bar sizes, but it can affect the final
product if you are relying on the product to take a lot of strain.
If you are looking for a stiffer
product, use Cold Finished Steel.
Hot rolled plate is a very rough product, and should be treated as
All hot rolled products weld, bend, drill, and form very easily,
and as well are the least expensive of the steels, giving
rise to the least expensive finished product of any of the
Nearly all metalwork involves welding or soldering the metal.
How those welds are addressed is often the difference between a
hack job and good craftsmanship. If hot rolled steel is welded,
either the un-dressed welds are left as a part of the aesthetic,
or they will have to be ground down by hand. Grinding and
dressing the welds, of course, removes the blue scale at the weld
zone while leaving the blue scale on the rest of the material. This
aesthetic difference must be addressed at every weld. It is
possible to return the color, but not the texture, of the blue scale
at the ground weld joint where the metal has been exposed by heating
up the joint red hot and allowing to cool.
A reminder - Pipe is specified by the inside diameter, Tubing is
specified by the outside diameter.
Hot rolled steel stock products mostly have a rounded appearance
at the corners and edges and relatively inexact dimensions,
whereas cold finished steels are much smoother and more precise.