alloys are a mixture of aluminum and a variety of other metals. Different
metals, when added to the base aluminum impart enhanced properties to the
aluminum, such as enhanced corrosion resistance, better formability, greater
strength, and/or other beneficial properties, in a wide range of permutations
are dozens of aluminum alloys in fairly common use in the
alloying elements include silicone, manganese, magnesium, copper, zinc, nickel
chromium, and titanium. In a few instances, one can find the use of lead,
bismuth, vanadium, chromium, zirconium, iron, and/or boron. Each will change not
only the various properties of the aluminum compound, but its density, as well.
The 1000 series of
alloys are generally considered “soft alloys”. They are probably most
commonly used in electrical and chemical applications, but can be found in tube,
pipe, extrusions, rod, wire, foil, and other applications.
They contain a minimum
of 99% aluminum, and usually only a trace of any other metals, with one of the
few exceptions being 1100, which contains 0.12% copper. Otherwise, the main
impurities are iron and silicone.
Because of the high aluminum content, they have low mechanical properties, giving them good workability. They have very good corrosion resistance and both thermal and electrical conductivity.
The 2000 series of
alloys are a set of “hard alloys”. They are probably most commonly used in
aircraft and military types of applications. Other 2000 series uses include sheet and plate,
armor plate, wire, rod, bar, extrusions, tube, and forgings.
Copper is the primary alloying element of this group, but many contain noticeable quantities of silicone, manganese, magnesium, nickel, and/or titanium.
tend towards high strength, but require solution heat treating to achieve their
maximum properties and/or artificial aging. After heat treating, they may
approach the properties of mild steel. Good machinability is a benefit offered
in this series, but it doesn’t offer the best of corrosion resistance. 2024 is
probably the widest used and best known aircraft alloy.
The 3000 series of alloys are another set of “soft alloys”. Manganese is the primary alloying element. Copper and magnesium are also often included. 3003 offers fairly good strengths and good workability, and the series is generally fairly corrosion resistant, though generally not favored for its machinability. Their uses include sheet, plate, and tube and pipe.
The 4000 series of alloys contain quite high silicon contents, and are typically not used for extrusion purposes. They are popular for a variety of welding wire and brazing wire applications. Their uses include sheet, forgings and welding and brazing products.
The 5000 series of
alloys are another set of “hard alloys”. They contain comparatively high
percentages of magnesium, and have manganese, chromium and titanium as their
other primary alloying elements.
They offer very good
marine corrosion resistance, making them popular for maritime applications.
Their uses include sheet, plate, wire, tubes, conductors, forging stock, armor,
welding rods and electrodes and foil.
5000 series alloys have low to moderate strength, but, like the 4000 series alloys, have good welding characteristics. They are not very friendly to cold working applications, and elevated temperatures can lead to stress corrosion.
They account for the
vast majority of the tonnage of aluminum extrusions produced. Many of these
alloys are comparatively cheap, readily available, and durable. They finish
well, and are the “work horses” of the extruded products industry. They
offer good corrosion resistance, machinability, weldability, formability, and at
least medium strength. They are also heat treatable. They can be solution heat
treated and artificially aged. Up to a T-6 temper.
Some of the more common 6000 series alloys are discussed below in a narrative sequence for easy and logical reading, rather than in series number order.
The 6063 alloy is the
most commonly used extrusion alloy in the
It also anodizes well,
including most common and specialty colors, and is a good strata for painting
(as are most alloys). 6063 is used in countless applications, including most
window – patio door – curtainwall – storefront – skylight architectural
applications, many automotive and a few aircraft applications, some boating,
sporting goods, and you – name - it other uses. It is found in wire, rod, bar,
extrusions, structural shapes, tubing, pipe, etc.
It’s the work horse of the industry. It’s not as strong as many of its more expensive brethren, but strong enough for most uses. Like most aluminum, it’s comparatively corrosion resistant, but yields a bit in this area to its only slightly more expensive close relative, 6061. Some mills will only extrude the 6063 alloy, and no others.
This alloy is probably
the second most commonly used aluminum alloy in the US today, and by our
guesses, probably accounts for around 10% - 15% (by weight) of all aluminum
extrusions produced. The remaining balance (5% - 15%) is probably somewhat close
to the total for all other alloys.
It is more corrosion
resistant than 6063, and alloyed slightly differently, in a way that makes it
somewhat harder and easier to machine. It is preferred by most machinists over
6063, if there’s a lot of machining to be done, as it tends to provide better
chip break away, and gums up less.
Like 6063, it achieves
its maximum extruded form strength in a T-6 temper. In order for it to achieve
that temper, however, it must be cooled (or quenched) quickly after it comes out
of the press, requiring a water spray system. A number of mills do not have this
capability This often pushes them away from producing extrusions with it.
It tends to be slightly
more difficult to extrude than 6063, due to its harder characteristics. Although
we do not agree with the use of the terms, it is referred to by some as an
“Aircraft alloy”, or a “Marine alloy”. This is probably because it is
often used in the aircraft industry for non-structural, non-critical
applications, and is more corrosion resistant than 6063 and yet close in price,
making it quite popular in the marine field.
Certainly the former
term gives it a bit more credit than it is really due, not to take away from the
fact that it is a good alloy to use in many applications.
It is found in sheet
and plate, wire, rod, bar, extrusions, structural shapes, tubing, pipe,
forgings, foil, etc.
The structural and
machining properties of 6005 alloy are quite similar those of 6061, but water
quenching is not required to achieve the properties of the T-6 temper.
Accordingly, it is not uncommon for mills which do not offer 6061 (and some
others) to offer 6005. It is generally considered virtually interchangeable with
6061 in most respects.
It is found in wire,
rod, bar, extrusions, structural shapes, tubing, etc.
This alloy is generally
similar to 6063 with regard to its physical properties, though it is generally
slightly more expensive. It is, however slightly more friendly with regard to
the anodizing processes. While 6063 is very good for most anodizing processes
and finishes, it does not “bright dip” well.
6463, on the other hand
accepts a “bright dip” finish well, providing a lustrous, bright mirror
finish (assuming the extrusion die has been well polished to minimize “die
lines”, and/or the extrusions have been mechanically polished before anodizing
to remove them.) 6463 is not commonly used other than for its special finishing
It can, however often be found in automotive trim, shower and mirror door, mirror and bathroom trim and other areas where the “chrome look” is aesthetically pleasing and desired. It is also found in wire, rod, bar, extrusions, tubing, etc.
7000 series of alloys contain comparatively high percentages of zinc as their
primary alloying element. Silicon, nickel, manganese are not commonly found in
They offer high
strength, good machinability and are heat treatable, but have poor corrosion
resistance. They are another set of “hard alloys”. They are also probably
most commonly used in aircraft and military applications. They are found in
sheet and plate, wire, rod, bar, extrusions, structural shapes, tubing,
7075 is among the highest strength aluminum alloys available, and is, especially, often used in aircraft structural applications.