H32 H34 H36 H38 0 H12 H14 H16 H18

0 20 40 60 80 Percent cold work

FIGURE 9.1 Effect of cold work on yield strength.

0 20 40 60 80 Percent cold work

FIGURE 9.1 Effect of cold work on yield strength.

designation, the two being separated by a hyphen (e.g., 5052-H32). Basic temper designations are letters. Subdivisions of the basic tempers are given by one or more numbers following the letter.

The basic temper designations are:

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 0 may be followed by a number other than zero.

H Strain hardened. (wrought products only). Applies to products that have their strength increased by strain-hardening, with or without supplementary thermal treatments to produce some reduction in strength. The H is always followed by two or more numbers.

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, h.

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 numbers.

For strain-hardened tempers, the first digit of the number following the H denotes:

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. Example: 1100-H14.

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 strain hardening remaining after the product has been partially annealed. Example: 3005-H25.

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 age soften at room temperature. The number following this designation indicates the degree of strain-hardening remaining after the stabilization has occurred. Example: 5005-H34.

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

The digit following the designation H1, H2, H3, or H4 indicates the degree of strain-hardening. Number 8 is for the tempers with the highest ultimate tensile strength normally produced. Number 4 is for tempers whose ultimate strength is approximately midway between that of the O temper and the HX8 temper. Number 2 is for tempers whose ultimate strength is approximately midway between that of the O temper and the HX4 temper. Number 6 is for tempers whose ultimate strength is approximately midway between that of the HX4 temper and the HX8 temper. Numbers 1, 3, 5, and 7 similarly designate intermediate tempers between those defined above. Number 9 designates tempers whose minimum ultimate tensile strength exceeds that of the HX8 tempers by 2 ksi (15 MPa) or more.

The third digit, when used, indicates a variation in the degree of temper or the mechanical properties of a two-digit temper. An example is pattern or embossed sheet made from the H12, H22, or H32 tempers; these are assigned

H124, H224, or H324 tempers, respectively, since the additional strain-hardening from embossing causes a slight change in the mechanical properties.

For heat-treated tempers, the number 1 through 10 following the T denotes:

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. Example: 6005-T1 extrusions.

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. Example: 2024-T3 sheet.

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. Example: 2014-T4 sheet.

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. Example: 6063-T5 extrusions.

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. Example: 6063-T6 extrusions.

T7 Solution heat treated and then 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 provide dimensional and strength stability. Example: 7050-T7 rivet and cold heading wire and rod.

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. Example: 2024-T81 sheet.

T9 Solution heat treated, artificially aged, and then cold worked. Applies to products that are cold worked to improve strength after artificial aging. Example: 6262-T9 nuts.

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 may be added to designations T1 through T10 for variations in treatment. Stress-relieved tempers follow the format T_5, which may be followed by additional numbers.

Typical heat treatments for wrought alloys are given in Table 9.8 Heat treatments for cast alloys are given in Table 9.9.

TABLE 9.8 Typical Heat Treatments for Aluminum Alloy Mill Products©
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