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Aluminum Alloy Properties
Wrought Aluminum Alloys
Pure aluminum is soft and ductile. However, most
commercial uses require greater strength than
pure aluminum affords. This strength is achieved
by the addition of other elements to produce alloys
which singly, or in combination, impart strength to
the metal. These alloys have been classified into
seven categories according to their chemical
composition, and have been given numerical
designations for each series of alloys of 1000
through 7000 by the Aluminum Assoc. In addition
to alloying the pure aluminum, further strengthening
is possible by heat treating.
Heat-Treatable Alloys
The initial strength of
alloys in this group is enhanced by the addition of
such alloying elements as copper, magnesium, zinc
and silicon, and are designated as 2000, 6000, and
7000 series. Since these alloys singly, or in
various combinations, show increasing solid
solubility in aluminum with increasing temperature,
it is possible to subject them to thermal treatments
which will impart pronounced strengthening.
Non-Heat-Treatable Alloys
The initial strength
of alloys in this group depends upon the hardening
effect of elements such as manganese, silicon, iron
and magnesium, singly or in various combinations.
The non-heat treatable alloys are designated as
1000, 3000, 4000, and 5000 series. As these
alloys are work harden-able, further strengthening
is made possible by various degrees of cold working,
denoted by the “H” series of tempers. Alloys
containing appreciable amounts of magnesium
when supplied in strain-hardened tempers are
usually given a final elevated temperature
“stabilizing” to insure stability of properties.
The International Alloy Designation System is the most widely accepted naming scheme for wrought alloys. Each alloy is given a four digit number, where the first digit indicates the major alloying elements.
1000 series Aluminum
• 1000 series are essenitally pure aluminium with a minimum 99% aluminium content by weight and can be work hardened.
1000 Series Finishing charateristics:
Most common: 1000 series finishes to a Bronze-grey in color at .002 inch, alloy is soft and not particularly good for machining. Maximum practical coating thickness .0025 inch.
2000 series aluminum
2000 series are alloyed with copper, can be precipitation hardened to strengths comparable to steel. Formerly referred to as duralumin, they were once the most common aerospace alloys, but were susceptible to stress corrosion cracking and are increasingly replaced by 7000 series in new designs.
2000 Series Finishing charateristics:
Most common: 2014, 2017, 2024, 2618 (forgings). Avoid sharp corners on 2011 and 2017; Finishes to a grey-black at .002 inch to blue-grey at .002 inch. Excellent machining characteristics, Maximum practical coating .002 inch; .0025 inch possible for salvage though not as hard as less heavy coats.
3000 series aluminum
3000 series are alloyed with manganese, and can be work hardened
3000 Series Finishing charateristics:
3000 series aluminum is good for dye work and machining. Finishes to a Grey-black in color with a recommended maximum coating of .002 inch.
4000 series aluminum
4000 series are alloyed with silicon. They are also known as silumin
4000 Series Finishing charateristics:
4000 series should be avoided due to the high silicon content, which forms a heavy black smut when anodized. 4000 series aluminum finishes to a dark gray at .001 inch.
5000 series aluminum
5000 series are alloyed with magnesium, derive most of their strength from solution hardening, and can also be work hardened to strengths comparable to steel.
5000 Series Finishing charateristics:
5000 series aluminum alloys are great for dye 5052 not good for die work, except black. Both have good machining characteristics, Maximum practical coating .002 inch. 5052 has excellent dielectric properties when coated to .002 inch.
6000 series aluminum
6000 series are alloyed with magnesium and silicon, are easy to machine, and can be precipitation hardened, but not to the high strengths that 2000, 5000 and 7000 can reach.
6000 series finishing characteristics:
6000 series aluminum forms an excellent hardcoat for grinding, lapping or honing. Excellent dimensional stability. 6063 used for extrusions. Maximum practical coating .0025 inch.
7000 series aluminum
7000 series are alloyed with zinc, and can be precipitation hardened to the highest strengths of any aluminium alloy.
7000 Series finishing characteristics:
7000 series forms an excellent hardcoat that is machinable, and has a great deal of dimensional stability. Maximum recommended coating thickness is .002 inch.
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Aluminum Alloy Composition Sheet
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