Guide to Aluminum Specifications and Classifications

Aluminum, the lightweight yet robust metal, originates from bauxite ore through an intricate two-stage refinement process:

The journey begins with converting bauxite into alumina (Al₂O₃) using sodium hydroxide under high pressure and temperature. Subsequent filtration, precipitation, and calcination yield high-purity alumina.

Alumina undergoes electrolysis in molten cryolite (Na₃AlF₆), decomposing into aluminum and oxygen. The molten aluminum collects at the electrolytic cell's base for periodic extraction.

Annual global aluminum demand reaches approximately 29 million metric tons, with 22 million from primary production and 7 million from recycling. Remarkably, recycled aluminum requires only 5% of the energy needed for primary production (14,000 kWh per ton) while maintaining identical quality standards.

Characterized by softness, ductility, corrosion resistance, and excellent conductivity, pure aluminum serves well in foil and cable production. However, its low strength necessitates alloying for demanding applications.

By incorporating various elements, aluminum alloys achieve superior strength-to-weight ratios exceeding steel. These customizable materials dominate aerospace, automotive, construction, and packaging industries.

• Copper (Cu): Enhances strength in 2XXX series alloys
• Zinc (Zn): Creates ultra-strong 7XXX series when combined with magnesium
• Magnesium (Mg): Improves corrosion resistance in 5XXX series
• Silicon (Si): Optimizes casting properties in 4XXX series
• Manganese (Mn): Strengthens 3XXX series alloys
• Lithium (Li): Reduces density in aerospace-grade 8XXX series

The first digit indicates primary alloying elements (e.g., 1XXX for pure aluminum). Subsequent digits specify modifications and purity levels.

Similar to wrought alloys but with additional digits denoting casting methods.

1. Lightweight (1/3 density of steel)
2. High strength (up to 690 MPa)
3. Superior corrosion resistance
4. Enhanced low-temperature performance
5. Excellent thermal/electrical conductivity
6. Full recyclability without quality loss

Key thermal processes include:

• Homogenization annealing
• Solution treatment
• Precipitation hardening

Temper designations (F, O, T, W, H) indicate specific treatment states.

3XXX, 4XXX, and 5XXX series alloys achieve strength through cold working rather than thermal processing.

The European EN standards now supersede British BS1470, maintaining chemical specifications while enhancing mechanical property documentation and dimensional tolerances.