Temper Designation system for Aluminum Alloys


A temper designation system has been developed by the Aluminum Association and is published in the ANSI H35.1 standard. Basic temper designations for wrought aluminum alloys are: 

Basic Temper Designations for aluminum

F – as-fabricated: Applies to the products of shaping processes in which no special control over thermal conditions or strain hardening is employed. For wrought products, there are no mechanical property limits.
O – annealed: Applies to wrought products that are annealed to obtain the lowest strength temper, and to cast products that are annealed to improve ductility and dimensional stability. The O may be followed by a digit other than zero.
H – strain hardened (wrought products only): Applies to products that are strengthened by strain-hardening, with or without supplementary thermal treatments to produce some reduction in strength. The H is always followed by two or more digits.
W – solution heat-treated: An unstable temper applicable only to alloys that 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 1/2 hr.

T – thermally treated to produce stable tempers other than F, O, or H: Applies to products that are thermally treated, with or without supplementary strain hardening to produce stable tempers. The T is always followed by one or more digits.

Subdivision of H Tempers

Strain Hardened. The first digit following the H indicates the specific combination of basic operations as follows:

H1 – strain hardened only: Applies to products that are strain hardened to obtain the desired strength without supplementary thermal treatment. The number following this designation indicates the degree of strain hardening.

H2 – strain hardened and partially 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. For alloys that age soften at room temperature, the H2 tempers have the same minimum ultimate tensile strength as the corresponding H3 tempers. For other alloys, the H2 tempers

have the same minimum ultimate tensile strength as the corresponding H1 tempers and slightly higher elongation. The number following this designation indicates the degree of strain hardening remaining after the product has been partially annealed.

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. This designation is applicable only to those alloys that, unless stabilized, gradually ages often at room temperature. The number following this designation indicates the degree of strain hardening remaining after the stabilization treatment.

H4 – strain hardened and lacquered or painted: Applies to products which are strain hardened and which are subjected to some thermal operation during the subsequent painting or lacquering operation. The number following this designation indicates the degree of strain hardening remaining after the product has been thermally treated, as part of the painting/lacquering cure operation. The corresponding H2X or H3X mechanical property limits apply.

The digit following the designation H1, H2, H3, and H4 indicates the degree of strain hardening as identified by the minimum value of the ultimate tensile strength. Numeral 8 has been assigned to the hardest tempers normally produced. The third digit, when used, indicates a variation of the two-digit temper. It is used when the degree of control of temper or the mechanical properties or both differ from, but are close to, the two-digit H temper designation to which it is added, or when some other characteristic is significantly affected.

Subdivision of T Tempers

T1 – cooled from an elevated temperature-shaping process and naturally aged to a substantially stable condition: Applies to products that are not cold worked after cooling from an elevated temperature-shaping process or in which the effect of cold work in 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: Applies to products that are 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.

T3 – solution heat treated, cold worked, and naturally aged to a substantially stable condition: Applies to products that are cold worked to improve strength after solution heat treatment or in which the effect of cold work in flattening or straightening is recognized in mechanical property limits.\

T4 – solution heat treated and naturally aged to a substantially stable condition: Applies to products that are not cold worked after solution heat treatment or in which the effect of cold work in flattening or straightening may not be recognized in mechanical property limits.

T5 – cooled from an elevated temperature-shaping process and then artificially aged: Applies to products that are not cold worked after cooling from an elevated temperature-shaping process or in which the effect of cold work in flattening or straightening may not be recognized in mechanical property limits.

T6 – solution heat treated and then artificially aged: Applies to products that are not cold worked after solution heat treatment, or in which the effect of cold work in flattening or straightening may not be recognized in mechanical property limits.

T7 – solution heat treated and overaged/stabilized: Applies to wrought products that are artificially aged after solution heat treatment to carry them beyond a point of maximum strength to provide control of some significant characteristic. Applies to cast products that are artificially aged after solution heat treatment to improve strength and dimensional stability.

T8 – solution heat treated, cold worked, and then artificially aged: Applies to products that are cold worked to improve strength or in which the effect of cold work in flattening or straightening is recognized in mechanical property limits.

T9 – solution heat treated, artificially aged, and then cold worked: Applies to products that are cold worked to improve strength.

T10 – cooled from an elevated temperature-shaping process, cold worked, and then artificially aged: Applies to products that are cold worked to improve strength or in which the effect of cold work in flattening or straightening is recognized in mechanical property limits. Additional digits, the first of which shall not be zero, may be added to designations.

T1 through T10 to indicate a variation in treatment that significantly alters the product characteristics that would be obtained using the basic treatment. Additional information

regarding the temper designation system can be obtained from ANSI H35.1.

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