ALUMINUM - Materials for Civil and Construction Engineers - page 147

T ABLE 4.3 Temper Designations for Aluminum Alloys

Symbol Meaning Comment

F as fabricated No special control over thermal conditions or strain

hardening is employed.

O annealed Wrought products—annealed to the lowest strength temper

Cast products—annealed to improve ductility and
dimensional stability. The “O” may be followed by a
digit other than zero, indicating a variation with special
characteristics.

H strain Wrought products only. Strength is increased by strain

hardened hardening, with or without supplemental thermal

treatments. The “H” is always followed by two or more
numerical digits. The first digit indicates a specific
combination of basic operations. The second digit
indicates the degree of strain hardening. (Codes for the
second digit are 2—quarter hard, 4—half hard, 8—full
hard, 9—extra hard.) When used, the third digit indicates
a variation of the two digit temper. The basic operations
identified by the first digit are as follows:
H1—strain hardening only. Applies to products that are
strain hardened to obtain the desired strength, without
supplementary thermal treatment.
H2—strain hardened and partial annealed. Applies to
products that are strain hardened more than the desired
final amount, and then reduced in strength to the desired
level by partial annealing.
H3—strain hardened and stabilized. Applies to products
that are strain hardened and whose mechanical properties
are stabilized either by a low temperature thermal
treatment or as a result of heat introduced during
fabrication. Stabilization usually improves ductility.

W solution heat An unstable temper applicable only to alloys that

treated spontaneously age at room temperature after solution heat

treatment. This designation is specific only when the
period of natural aging is indicated—for example, W 2 hr,

T thermally treated Applies to thermally treated products, with or without

to produce supplementary strain hardening to produce stable tempers.

stable tempers The “T” is always followed by one or two digits:

other than T1—cooled from an elevated temperature shaping process

F, O, or H and naturally aged to a substantially stable condition.

Products not cold worked after cooling from an elevated
temperature shaping process, or in which the effect of cold
working flattening or straightening may not be
recognized in mechanical property limits.
T2—cooled from an elevated temperature shaping process,
cold worked, and naturally aged to a substantially stable
condition. Products cold worked to improve strength after
cooling from an elevated temperature shaping process, or in
which the effect of cold work in flattening or straightening is
recognized in mechanical property limits.