Aluminum plates are classified into five main temper states—F, O, H, T, and W—each representing a unique processing method. Choosing the correct aluminum plate temper can significantly impact mechanical strength, formability, heat resistance, and cost-efficiency.
What Are Aluminum Plate Tempers?
Tempering refers to the mechanical or thermal treatment process applied to aluminum plates to achieve specific material characteristics. Below is a detailed breakdown of each temper and how it affects performance.
1. F State — As-Fabricated Condition
Definition:
The F state (Fabricated) indicates that the aluminum plate is produced without any specific mechanical or thermal treatment. It’s typically used when post-processing is expected by the customer.
Key Characteristics:
- No defined mechanical properties
- Ideal for custom post-treatment (e.g., heat treatment or work hardening)
Use Cases:
- CNC machining parts
- Specialized engineering components
2. O State — Annealed (Soft) Condition
Definition:
The O state is fully annealed, meaning the aluminum is softened through a controlled thermal process to maximize ductility and minimize strength.
Key Benefits:
- Excellent formability
- Easy to bend, roll, and shape
- No subcategories (unlike other states)
Common Applications:
- Kitchenware
- Automotive body panels
- Aerospace forming parts
3. H State — Strain-Hardened (Cold Worked)
Definition:
The H state refers to aluminum that has undergone strain-hardening (cold working) to increase its strength without additional heat treatment.
Sub-Temper Codes:
- H1x – Strain-hardened only
- H2x – Strain-hardened, partially annealed
- H3x – Strain-hardened and stabilized
Strength Indicator:
The second digit (e.g., in H14 or H18) represents strength level, ranging from 1 (low strength) to 8 (full hard).
Ideal For:
- Roofing and facade panels
- Electrical enclosures
- Marine fittings
4. T State — Thermally Treated and Stable
Definition:
The T state indicates that the aluminum has been heat-treated to reach a stable condition after fabrication, typically to achieve maximum strength and dimensional stability.
Common Sub-Tempers:
- T5 – Cooled from shaping process and artificially aged
- T6 – Solution heat-treated and artificially aged
- T651 – T6 + stress-relief through stretching
Applications:
- Aerospace frames
- Structural components
- Heavy-duty machinery
5. W State — Solution Heat-Treated (Unstable)
Definition:
The W state is a transitional temper, meaning the aluminum plate has been solution heat-treated but is still undergoing natural aging at room temperature. It is unstable and temporary.
Important Notes:
- Rarely sold in this condition
- Mostly used internally in manufacturing processes
- Eventually transitions to T-temper if artificially aged
How to Choose the Right Aluminum Plate Temper?
| Temper | Strength | Ductility | Process | Typical Use |
|---|---|---|---|---|
| F | Varies | Varies | As-Fabricated | Custom processing |
| O | Low | High | Fully annealed | Forming, bending |
| H | Medium–High | Medium | Strain-hardened | Construction, cladding |
| T | High | Medium | Heat-treated | Aerospace, machinery |
| W | Unstable | — | Natural aging | Transition only |
🧠 Expert Tip:
If your application involves precision parts, aerospace performance, or marine corrosion resistance, always consult material engineers or certified suppliers to match the correct temper.
FAQ: Aluminum Tempering Explained
Q1: Is T6 aluminum stronger than H18?
A: Yes. T6 is heat-treated for high strength, while H18 is strain-hardened. T6 usually offers better balance between strength and machinability.
Q2: Can O-temper aluminum be anodized?
A: Yes, but since O-state is soft, the surface may be less resistant to mechanical damage compared to H or T tempers.
Q3: What is the difference between T5 and T6 aluminum?
A: T5 is cooled from a shaping process and artificially aged, while T6 undergoes full solution heat treatment and aging, resulting in higher strength.
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