Aluminium
There are two main types of alloyed aluminium; wrought and cast. Wrought
alloys (rolled, extruded or forged) are strengthened either by
work–hardening or by heat treatment, with different alloying elements
being added to achieve the required strength. Cast alloys are usually
very different in their composition to their wrought counterparts, as
suitable composition is required for the production of effective casting
materials.
The wrought alloys are also divided into two groups:
heat-treatable and non heat-treatable alloys. Heat-treatable alloys are
produced in the main for their strength and durability while the non
heat-treatable alloys for their ductility, weldability and corrosion
resistance.
Alloy Specifications
All alloys are given a specification number and a combination of letters
and numbers that are placed after this specification number to indicate
the strengthening process undergone by the metal. For example, the alloy
specification 6082 often carries the definition T6 – this indicates that
it is solution treated and artificially aged (also known as “fully heat
treated”), while alloy 2011 often carries the T3 definition, indicating
it has been solution heat treated, cold worked and naturally aged to a
substantially stable condition.
Other common designations are:
F as manufactured, with no heat treatment and without regard to work
hardening.
O the product is annealed, soft.
T4 solution heat treated and naturally aged to a substantially stable
condition.
T5 cooled from elevated temperature shaping process and artificially
aged.
H12 strain hardened to ¼ hard.
H14 strain hardened to ½ hard.
H16 strain hardened to ¾ hard.
H18 hard condition.
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