Temper of aluminum foil refers to its hardness, ductility, and mechanical properties, determined by cold rolling and annealing (heat treatment). It directly impacts flexibility, formability, and application suitability. Temper is usually designated by letters and sometimes numbers, following standards like ASTM or EN.
Common Temper Designations & Properties
| Temper | State | Key Characteristics | Typical Applications |
|---|---|---|---|
| O | Fully annealed (softest) | Highest ductility, very flexible, low hardness | Food/medical packaging, insulation, general wrapping |
| H18 | Full hard (no annealing) | Highest strength, rigid, brittle, low elongation | Rigid containers, cable shielding, structural foils |
| H22 / H24 | Semi-hard (strain-hardened + partial anneal) | Balanced strength & flexibility | Foil containers, lids, formed packaging |
| H14 / H16 | Work-hardened (no annealing) | Moderate hardness, good flatness | HVAC fins, industrial liners, formed parts |
How Temper Is Produced
- O-temper: Heated to 300–400°C in inert atmosphere, slow-cooled to relieve stress and recrystallize.
- H-series: Cold-rolled to desired thickness; H1x = no annealing; H2x = partial annealing after rolling.
Key Property Differences
- Elongation: O ≈ 15–25%; H18 ≈ 1–3%.
- Formability: O > H22/H24 > H14/H16 > H18.
- Rigidity: H18 > H16 > H14 > H24 > H22 > O.