Aluminum Alloy Temper Designation System
Explanation of Temper Designations (Basic Symbols)
| Symbol | Definition | Examples & Detailed Explanation |
|---|---|---|
| F | As Fabricated | Applies to products of shaping processes in which no special control over thermal conditions or strain-hardening is employed. |
| O | Annealed | Applies to wrought products which are annealed to obtain the lowest strength temper, and to cast products which are annealed to improve ductility and dimensional stability. |
| H | Strain-Hardened | Applies to products which have their strength increased by strain-hardening, with or without supplementary thermal treatments to produce some reduction in strength. |
| T | Thermally Treated | Applies to products which are thermally treated, with or without supplementary strain-hardening, to produce stable tempers other than F, O, or H. |
1. Sub-divisions of H Temper (Strain Hardened)
The digits following the H indicate the specific combination of basic operations.
- H1: Strain-hardened only.
- H2: Strain-hardened and partially annealed.
- H3: Strain-hardened and stabilized.
- [Note] The second digit indicates the degree of strain-hardening (e.g., H18 is full hard, H14 is 1/2 hard).
2. Sub-divisions of T Temper (Heat Treated)
The digits following the T indicate specific sequences of basic treatments.
| Symbol | Explanation | Details |
|---|---|---|
| T1 | Cooled from elevated temperature and naturally aged | Cooled after processes like extrusion and stabilized at room temperature. |
| T2 | Cooled from elevated temperature, cold worked, and naturally aged | Strength increased by cold working followed by natural aging. |
| T3 | Solution heat treated, cold worked, and naturally aged | Cold worked to increase strength after solution heat treatment. |
| T4 | Solution heat treated and naturally aged | Stabilized at room temperature without cold working after solution heat treatment. |
| T5 | Cooled from elevated temperature and artificially aged | Strength increased by low-temperature heating after cooling. |
| T6 | Solution heat treated and artificially aged | High strength obtained by artificial aging without cold working after solution heat treatment. |
| T7 | Solution heat treated and overaged | Aged past peak strength to improve resistance to stress-corrosion cracking. |
| T8 | Solution heat treated, cold worked, and artificially aged | Reinforced by cold working and then artificially aged. |
| T9 | Solution heat treated, artificially aged, and cold worked | Cold worked after artificial aging to further increase strength. |
| T10 | Cooled from elevated temperature, cold worked, and artificially aged | Combined strain-hardening and artificial aging for maximum strength. |
3. Additional Sub-divisions (TX, TXX, etc.)
Additional digits are used for specific treatments such as stress relieving.
- T31, T351, T651, etc.: Indicates stress-relieved by stretching.
- T62, T42: Applies to products heat-treated by the user.
- T73: Applies to products specially overaged to improve resistance to stress-corrosion cracking.