Aluminum Temper Meaning and Chart
When selecting aluminum materials, you often encounter designations like T6, O, or H14.
These designations are known as Tempers, which describe the mechanical and physical condition of the material after processing or heat treatment.
Understanding tempers helps you choose the right material for your application and avoid performance failures during use.
What Is Aluminum Temper?
Aluminum Temper refers to the condition of aluminum alloys after they have been strengthened through heat treatment, cold working, or a combination of processes.
Tempers are usually represented by a letter (F, O, H, W, T) followed by one or more numbers. For example:
T6: Solution heat-treated and artificially aged
H14: Strain hardened to half hard
O: Fully annealed for maximum softness
Each temper defines specific mechanical properties and is suitable for different applications.
Main Aluminum Temper Categories
O Temper — Annealed (Soft Condition)
What is O Temper?
O temper indicates aluminum that has been fully annealed to achieve maximum softness, ductility, and formability.
| Temper | Category | Description |
|---|---|---|
| O | Annealed | Fully annealed for maximum softness and ductility |
Key Characteristics
Lowest strength
Excellent formability
Easy to bend, deep draw, or spin
Not heat treated
Common Alloys & Applications
1100-O / 3003-O → Deep drawing, cookware, chemical tanks
5052-O → Fuel tanks, pressure vessels before forming
6061-O → Complex forming prior to heat treatment
H Temper — Strain-Hardened (Non-Heat-Treatable Alloys)
Applies mainly to non-heat-treatable alloys such as 1xxx, 3xxx, 5xxx series.
H Temper Coding Logic
H1X – Strain hardened only
H2X – Strain hardened + partially annealed
H3X – Strain hardened + stabilized (Mg-containing alloys)
| Temper | Description |
|---|---|
| H11 | Slightly strain hardened (~10%) |
| H12 | Quarter hard (~25%) |
| H14 | Half hard (~50%) |
| H16 | Three-quarter hard (~75%) |
| H18 | Full hard |
| H22 | Quarter hard, partially annealed |
| H24 | Half hard, partially annealed |
| H32 | Quarter hard, stabilized |
| H34 | Half hard, stabilized |
Key Characteristics
Strength increases with cold work
No heat treatment involved
Good corrosion resistance (especially 5xxx)
Strength cannot be restored once softened by heating
Common Alloys & Applications
3003-H14 → Roofing, insulation jacketing
5052-H32 / H34 → Marine panels, enclosures
5754-H22 → Automotive body panels
5083-H116 / H321 → Shipbuilding, offshore structures
T Temper — Heat-Treated (High Strength Alloys)
Applies to heat-treatable alloys such as 2xxx, 6xxx, 7xxx series.
Common T Temper Types
| Temper | Description | Typical Alloy |
|---|---|---|
| T3 | Solution treated, cold worked, naturally aged | 2024-T3 |
| T4 | Solution treated, naturally aged | 6061-T4 |
| T5 | Cooled from hot shaping, artificially aged | 6063-T5 |
| T6 | Solution treated & artificially aged (max strength) | 6061-T6, 7075-T6 |
| T651 | T6 + stress relieved by stretching | 6061-T651 |
| T7 | Overaged for stability | — |
| T73 | Overaged for corrosion resistance | 7075-T73 |
Key Characteristics
Highest strength levels
Heat treatment required
Lower formability than O or H tempers
Stress relief tempers improve dimensional stability
Common Alloys & Applications
2024-T3 → Aircraft skins, aerospace structures
6061-T6 / T651 → Structural components, CNC machining
6082-T6 → Bridges, transport structures
7075-T6 / T73 → Aerospace, high-stress mechanical parts
How to Choose the Right Aluminum Temper?
Aluminum Temper Selection by Application
| Application Field | Recommended Tempers | Why |
|---|---|---|
| Aerospace structural components | T6, T651, T73, T7351 | High strength, fatigue resistance, and improved corrosion performance |
| Automotive parts | T4, T6 | Good balance of formability, weldability, and post-forming strength |
| Molds and tooling | T6, T651 | High strength, excellent dimensional stability, suitable for CNC machining |
| Building facades and panels | H14, H24, O | Good formability, smooth surface finish, and ease of fabrication |
| Marine and offshore applications | H32, H116 | Excellent corrosion resistance in seawater environments |
| Pressure vessels and hydraulic parts | O, H112 | High ductility, good pressure resistance, and formability |
Quick Selection Guidelines (Optional, Strongly Recommended)
Complex forming or deep drawing → O, T4
Moderate strength with corrosion resistance → H32, H116
High-strength structural or load-bearing parts → T6, T651
Aerospace or fatigue-critical components → T3, T73, T7351
Precision machining and tooling → T651