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:
| HX1 |
1/8 hard |
|
HX2
|
1/4 hard |
|
HX3
|
3/8 hard |
|
HX4
|
1/2 hard |
|
HX5
|
5/8 hard |
|
HX6
|
3/4 hard |
|
HX7
|
7/8 hard |
|
HX8
|
Full hard (approximately
75% reduction after a full anneal). |
|
HX9
|
Extra hard (limited
to certain alloys and/or product forms). |
|