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The designations for temper are used for all forms of magnesium and magnesium-alloy products except ingots. They are based on the sequence of basic treatments used to produce the various tempers. The temper designation follows the alloy designation, the two being separated by a dash.
Basic temper designation consists of letters. Subdivisions of the basic tempers, where required, are indicated by a digit or digits following the letter. These designate specific sequences of basic treatments, but only operations recognized as significantly influencing the characteristics of the product.
This article covers a system or designating the tempers of magnesium alloys, cast and wrought. The designations used in ASTM specifications are under the jurisdiction of committee B-7 for magnesium alloy castings and wrought products.
The designations for temper are used for all forms of magnesium and magnesium-alloy products except ingots. They are based on the sequence of basic treatments used to produce the various tempers. The temper designation follows the alloy designation, the two being separated by a dash.
Basic temper designation consists of letters. Subdivisions of the basic tempers, where required, are indicated by a digit or digits following the letter. These designate specific sequences of basic treatments, but only operations recognized as significantly influencing the characteristics of the product are indicated. Should some other variation of the same sequence of basic operations be applied to the same alloy, resulting in different characteristics, then additional digits are added to the designation.
The temper designations and the subdivisions are fully defined and explained in Table 1. A brief outline for quick reference is given in Table 2.
Table 1. Temper Designations
| F | As fabricated. Applies to products that acquire some temper from shaping processes not having special control over the amount of strain-hardening or thermal treatment. |
| O | Annealed, recrystallized (wrought products only). Applies to the softest temper of wrought products. |
| H | Strain-hardened (wrought products only). Applies to products that have their strength increased by strain-hardening with is without supplementary thermal treatment to produce partial softening. The H is always followed by two or more digits. |
| Subdivisions of the "H" Temper | |
| H1 | Strain-hardened only. Applies to products that are strain-hardened to obtain the desired mechanical properties without supplementary thermal treatment. The number following this designation indicates the final degree of strain-hardening. |
| H2 | Strain-hardened and then partially annealed. Applies to products that are strain hardened more than the desired and then reduced in strength to the desired final amount by partial annealing. The number following this designation indicates the final degree of strain-hardening remaining after the product has been partially annealed. |
| H3 | Strain-hardened and then stabilized. Applies to products that are strain hardened and then stabilized by a low temperature heating to slightly lower their strength and increase ductility. This designation applies only to alloys which, unless stabilized, gradually age soften at room temperature. The number following this designation indicates the degree of strain-hardening remaining after the product has been strain-hardened a specific amount and then stabilized. |
| Subdivisions of the "H1", "H2" and "H3" Tempers The digit following the designation H1, H2 and H3 indicates the final degree of strain-hardening. Tempers between 0 (annealed) and 8 (full hard) are designated by numerals 1 through 7. Material having a strength about midway between that of the 0 temper and that of the 8 temper is designated by the numeral 4 (half hard), between 0 and 4 by the numeral 2 (quarter hard), between 4 and 8 by the numeral 6 (three-quarter hard), etc. The third digit, when used, indicates a variation of a two-digit H temper. It is used when the degree of control of temper or the mechanical properties are different from but close to those for the two-digit H temper to which it is added. Numerals 1 through 9 may be arbitrarily assigned for an alloy and product to indicate a specific degree of control of temper or specified mechanical property limits. | |
| W | Solution heat-treated. An unstable temper applicable only to alloys which spontaneously age at room temperature after solution heat treatment. This designation is specific only when the period of natural aging is indicated: for example W1/2 hour. |
| 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 more digits. Numerals 1 through 10 have been assigned to indicate specific sequence of basic treatments as follows. |
| Subdivisions of the "T" Tempers | |
| T1 | Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition. Applies to products for which the rate of cooling from an elevated temperature shaping process, such as casting or extrusion, is such that their strength is increased by room temperature aging. |
| T2 | Annealed (cast products only). Applies to a type of annealing treatment used to improve ductility and increase stability of castings. |
| T3 | Solution heat treated and then cold worked. Applies to products that are cold worked to improve strength, or in which the effect of cold work in flattening and straightening is recognized in applicable mechanical properties. |
| T4 | Solution heat treated and natural 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 applicable mechanical properties. |
| T5 | Cold from an elevated-temperature shaping process and then artificially aged. Applies to products that are cooled from an elevated-temperature shaping process, such as casting or extrusion, and then artificially aged to improve mechanical properties or dimensional stability or both. |
| 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 applicable mechanical properties. |
| T7 | Solution heat treated and then stabilized. Applies to products that are stabilized to carry them beyond the point of maximum strength to provide control of some special characteristics. |
| 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 applicable mechanical properties. |
| 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, artificially aged, and then cold worked. Applies to products that are artificially aged after cooling from an elevated temperature shaping process, such as casting or extrusion, and then cold worked to further improve strength. |
| A period of natural aging at room temperature may occur between or after the operations listed for temper T3 throughout T10. Control of this period is exercised when it is metallurgically important.Additional digits may be added to designations T1 throughout T10 to indicate a variation in treatment that significantly alters the characteristics of the product. | |
Table 2. Basic Temper Designations and Subdivisions
| F | As fabricated |
| O | Annealed, recrystallized (wrought products only) |
| H | Strain-hardened |
| Subdivisions of the "H" Tempers: | |
| H1 | Plus one or more digits…. Strain-hardened only |
| H2 | Plus one or more digits…. Strain-hardened and then partially annealed |
| H3 | Plus one or more digits…. Strain-hardened and then stabilized |
| W | Solution heat-treated, unstable temper |
| T | Thermal treated to produce stable tempers other than F, O, or H |
| Subdivisions of the "T" Tempers: | |
| T1 | Cooled and naturally aged |
| T2 | Annealed (cast products only) |
| T3 | Solution heat-treated and then cold worked |
| T4 | Solution heat-treated |
| T5 | Cooled and artificially aged |
| T6 | Solution heat-treated and artificially aged |
| T7 | Solution heat-treated and stabilized |
| T8 | Solution heat-treated, cold worked and then artificially aged |
| T9 | Solution heat-treated, artificially aged and then cold worked |
| T10 | Cooled, artificially aged, and cold worked |