Wrought Aluminum and Aluminum Alloy Designation
System
A system for designating wrought aluminum and
wrought aluminum alloys was established by the Aluminum Association.
Specific limits for chemical composition to which conformance is required
are provided by applicable product standards.
A system of four-digit numerical designations
is used to identify wrought aluminum and wrought aluminum
alloys.
The first digit indicates the alloy group as
follows:
| 1XXX |
Aluminum, 99.00% minimum and
greater |
Pure
Aluminum
In the 1XXX group for
minimum aluminum purities of 99.00 percent and greater, the last two of
the four digits in the designation indicate the minimum aluminum
percentage. These digits are the same as the last two digits to the right
of the decimal point in the minimum aluminum percentage when it is
expressed to the nearest 0.01 percent. The second digit in the designation
indicates modifications in impurity limits. If the second digit is zero,
it indicates unalloyed aluminum having natural impurity limits; integers 1
through 9, which are assigned consecutively as needed, indicate special
control of the of more individual impurities or alloying
elements.
Aluminum alloys grouped by major alloying
elements
| 2XXX |
Copper (Cu). |
| 3XXX |
Manganese
(Mn) |
| 4XXX |
Silicon
(Si) |
| 5XXX |
Magnesium
(Mg) |
| 6XXX |
Magnesium and
Silicon (Mg and Si) |
| 7XXX |
Zinc
(Zn) |
| 8XXX |
Other
elements |
| 9XXX |
Unused
series |
Aluminum
Alloys
In the 2XXX through 8XXX alloy
groups the last two of the four digits in the designation have no special
significance but serve only to identify the different aluminum alloys in
group. The second digit in the alloy designation indicates alloy
modifications. If the second digit is zero, it indicates the original
alloy; integers 1 through 9, which are assigned consecutively, indicate
alloy modifications.
Temper Designation System
The temper designation system is used for
all forms of wrought and cast aluminum and aluminum alloys except ingot.
It is based on the sequence of basic treatments used to produce various
tempers. The temper designation follows the alloy designation with the two
separated by a hyphen. Basic designations consist of a letter while
subdivisions of those basic tempers, where required, are indicated by one
or more digits following those letters. The system is designed to set down
specific sequences of fabrication processes, but only those operations
that are recognized as significantly influencing the characteristics of
the product involved. Should some other variation of the same sequence of
basic operations be applied to the same alloy, resulting in different
characteristics, the additional digits will be added to the numerical
designation.
Basic Temper Designations
|
F |
As fabricated.
Denotes metal that has been fabricated to ordered dimensions without
any attempt on the part of the producer to control the results of
either strain-hardening operations or thermal treatments. There are
no mechanical property limits, and the strength levels may vary form
lot to lot and from shipment to shipment. |
|
O |
Annealed. Applies
to wrought products that have undergone a thermal treatment to
reduce their mechanical property levels to their minimums. Often
described as "dead soft" metal. |
|
W |
Solution
heat-treated. An unstable temper applying to certain of the (7XXX)
heat-treatable alloys that, after heat treatment, spontaneously age
harden at room temperature. Only when the period of natural aging is
indicated (W 1hr. for example) is this a specific and complete
designation. |
|
H |
Strain-hardened.
Applies to those wrought products which have had an increase in
strength by reduction through strain-hardening or cold working
operations. The "H" is always followed by two or more
digits. |
|
T |
Thermally treated
to produce tempers other than F, O or H. Applies to those products
which have had an increase in strength due to thermal treatments,
with or without supplementary strain-hardening operations. The "T"
is always followed by one or more
digits. |
Subdivisions of "T" Temper-Heat-Treatable
Alloys
| T1 |
cooled from an
elevated temperature shaping process and naturally aged to a
substantially stable condition. Usually associated with extruded
products and limited to the 6XXX series alloys. |
|
T2 |
cooled from an
elevated temperature shaping process, cold worked, and naturally
aged to a substantially stable condition. Usually associated with
cast products. |
|
T3 |
solution
heat-treated, cold worked, and naturally aged to a substantially
stable condition. (T4+cold work) |
|
T4 |
solution
heat-treated, and naturally aged to a substantially stable
condition. |
|
T5 |
cooled from an
elevated temperature shaping process and artificially aged. Usually
associated with extruded products in the 6XXX series alloys.
(T1+artificial age) |
|
T6 |
solution
heat-treated, and artificially aged. (T4+artificial
age) |
|
T7 |
solution
heat-treated, and overaged/stabilized. Applies to alloy products
which are thermally overaged after solution heat-treatment to carry
them beyond the point of maximum strength to provide control of some
special characteristic. |
|
T8 |
solution
heat-treated, cold worked, and artificially aged. (T3+artificial
age) |
|
T9 |
solution
heat-treated, artificially aged and cold worked. (T6+artificial
age) |
|
T10 |
cooled from an
elevated temperature shaping process, cold worked, and artificially
aged. Usually associated with cast products.(T2+artificial
age) |
The following
specific digits have been assigned for stress-relieved tempers of
wrought products:
|
T_51 |
Applies to cold
finished rod or bar when stress-relieved by stretching 1 to 3 %
permanent set. Stretching is performed after solution heat treatment
or after cooling from an elevated temperature shaping process. No
straightening takes place after stretching. |
|
T_510 |
Applies to
extruded products and to drawn tube when stress-relieved by
stretching 1 to 3 % permanent set. Stretching is performed after
solution heat treatment or after cooling from an elevated
temperature shaping process. No straightening takes place after
stretching 1 to 3 % permanent set. |
|
T_511 |
Applies to
extruded products and to drawn tube when stress-relieved by
stretching 1 to 3 % permanent set. Stretching is performed after
solution heat treatment or after cooling from an elevated
temperature shaping process. These products may receive minor
straightening after stretching to comply with standard
tolerances. |
Subdivisions of "H" Temper-Non-Heat-Treatable
Alloys
|
H1 |
Strain-hardened
only. Applies to products which are strain-hardened or cold worked
to obtain the desired strength level without supplementary thermal
treatments. The number following this designation indicates the
degree of strain-hardening. |
|
H2 |
Strain-hardened
partially annealed. Applies to products strain-hardened or cold
worked more than the desired level by partial annealing. The number
following this designation indicates the degree of strain hardening
remaining after the partial annealing process. |
|
H3 |
Strain-hardened
and stabilized. Applies to products in the magnesium-aluminum class
which will age-soften at room temperature after strain-hardening.
These products are strain-hardened to the desired amount and then
subjected to a low temperature thermal operation which results in a
improved ductility. The number following this designation indicates
the degree of strain-hardening remaining after the stabilization
treatment. |
The digit following the designation H1, H2 or H3 indicates the
degree of strain-hardening as
follows:
| H1 |
1/8
hard |
|
H2 |
1/4
hard |
|
H3 |
3/8
hard |
|
H4 |
1/2
hard |
|
H5 |
5/8
hard |
|
H6 |
3/4
hard |
|
H7 |
7/8
hard |
|
H8 |
full hard
(approximately 75% reduction after a full
anneal). |
|
H9 |
extra hard
(limited to certain alloys and/or product
forms). |
|