What Are Aluminum Temper Designations?
When you specify aluminum products, the alloy number alone (e.g., 6061, 5052, 7075) is not enough. You also need the temper designation, which defines the mechanical treatment and resulting properties of the material.
Basic Temper Designations
| Code | Meaning | Description |
|---|---|---|
| O | Annealed | Fully annealed for lowest strength, highest ductility |
| F | As Fabricated | No special control of thermal or mechanical conditions |
| H | Strain Hardened | Strengthened by cold working |
| T | Thermally Treated | Produced by thermal treatment to stable tempers |
| W | Solution Heat Treated | Unstable temper for alloys that age at room temperature |
H Temper: Strain Hardened
First Digit: Base Treatment
- H1x: Strain hardened only
- H2x: Strain hardened then partially annealed
- H3x: Strain hardened then stabilized
Second Digit: Degree of Hardening
- Hx2: Half hard
- Hx4: Full hard
- Hx6: Between full hard and extra hard
- Hx8: Extra hard (maximum cold-worked)
T Temper: Thermally Treated
| Code | Process | Common Example |
|---|---|---|
| T1 | Cooled from hot forming + naturally aged | 6063-T1 (architectural) |
| T3 | Solution treated, cold worked, naturally aged | 2024-T3 (aerospace sheet) |
| T4 | Solution treated + naturally aged | 6061-T4 (general purpose) |
| T5 | Cooled from hot forming + artificially aged | 6063-T5 (extrusions) |
| T6 | Solution treated + artificially aged | 6061-T6 (structural benchmark) |
| T7 | Solution treated + overaged/stabilized | 7075-T73 (stress corrosion resistant) |
| T8 | Solution treated, cold worked, artificially aged | 2024-T851 (high-strength plate) |
How Temper Affects Properties (6061 Example)
| Temper | Tensile (MPa) | Yield (MPa) | Elongation (%) |
|---|---|---|---|
| 6061-O | 124 | 55 | 25 |
| 6061-T4 | 190 | 110 | 22 |
| 6061-T6 | 310 | 276 | 12 |
Application-Based Selection Guide
| Application | Recommended Alloy-Temper | Why |
|---|---|---|
| Architectural extrusions | 6063-T5 or T6 | Good surface finish, moderate strength |
| Aircraft structural parts | 2024-T3 or T4 | High strength-to-weight ratio |
| Marine structures | 5083-H321 | Excellent seawater corrosion resistance |
| Pressure vessels | 5052-H32 or H34 | Good formability and weldability |
| High-strength aerospace | 7075-T6 or T651 | Highest strength aluminum alloy |
Standards
- ANSI H35.1: Aluminum Alloy Sheet and Plate Temper Designations
- ASTM B209: Aluminum Alloy Sheet and Plate
- ASTM B221: Aluminum Alloy Extruded Profiles
- EN 515: Wrought aluminum alloys – Temper designations
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