Common grades of aluminium and their uses
Aluminium is prized for its low density, high strength-to-weight ratio, corrosion resistance, and ease of fabrication. Unlike steels, aluminium grades are not classified by a single standard but by a four-digit alloy designation system set by the Aluminum Association. The first digit indicates the primary alloying element, which governs the material's properties and typical applications. Aluminium alloys are broadly divided into two categories: wrought alloys (shaped by mechanical working) and casting alloys (shaped by casting). Wrought alloys are further divided into heat-treatable and non-heat-treatable types. Below is a breakdown of common grades, their composition, properties, and typical uses.
1xxx Series: Pure Aluminium (99% or higher)
Example: 1050, 1100
Key properties: Excellent corrosion resistance, high thermal and electrical conductivity, good workability, but low strength.
Typical uses: Electrical conductors, chemical equipment, food and beverage containers, reflective surfaces.
Note: Not suitable for structural applications due to low strength.
2xxx Series: Aluminium–Copper Alloys
Example: 2024
Key properties: High strength and fatigue resistance, lower corrosion resistance, poor weldability.
Heat-treatable: Yes
Typical uses: Aerospace structures, automotive components, high-performance sporting equipment.
Note: Typically clad with pure aluminium (Alclad) to improve corrosion resistance.
3xxx Series: Aluminium–Manganese Alloys
Example: 3003
Key properties: Good corrosion resistance, moderate strength, excellent workability.
Heat-treatable: No
Typical uses: Roofing, siding, cooking utensils, storage tanks.
Note: One of the most widely used non-heat-treatable grades.
4xxx Series: Aluminium–Silicon Alloys
Example: 4045, 4032
Key properties: Good wear resistance, reduced thermal expansion, high corrosion resistance.
Heat-treatable: Some are; varies by specific alloy
Typical uses: Heat exchangers, engine components, cladding materials.
Note: Some grades are used as brazing sheets due to their thermal characteristics.
5xxx Series: Aluminium–Magnesium Alloys
Example: 5052, 5083
Key properties: Excellent corrosion resistance, especially in marine environments; good weldability and moderate-to-high strength.
Heat-treatable: No
Typical uses: Marine hulls, pressure vessels, truck trailers, and architectural applications.
Note: 5083 has among the highest strength of non-heat-treatable alloys and is often used in shipbuilding.
6xxx Series: Aluminium–Magnesium–Silicon Alloys
Example: 6061, 6063
Key properties: Good strength, corrosion resistance, weldability, and machinability; widely used and highly versatile.
Heat-treatable: Yes
Typical uses:
6061: Structural components, pipelines, aerospace frames, bicycle frames.
6063: Architectural extrusions, window frames, railings.
Note: Among the most common grades due to balanced properties and ease of extrusion.
7xxx Series: Aluminium–Zinc Alloys
Example: 7075
Key properties: Very high strength, poor corrosion resistance unless protected, more difficult to weld.
Heat-treatable: Yes
Typical uses: Aircraft structures, aerospace fasteners, sporting goods, military equipment.
Note: 7075-T6 is one of the strongest aluminium alloys available.
| Series | Main Alloying Element | Heat Treatable | Key Properties | Typical Uses |
|---|---|---|---|---|
| 1xxx | None (Pure Al) | No | High ductility, corrosion resistance | Electrical, chemical, food |
| 2xxx | Copper | Yes | High strength, low corrosion resistance | Aerospace, transport |
| 3xxx | Manganese | No | Moderate strength, good corrosion resistance | Roofing, cookware |
| 4xxx | Silicon | Varies | Thermal resistance, wear | Engine parts, brazing |
| 5xxx | Magnesium | No | High corrosion resistance, weldability | Marine, transport |
| 6xxx | Mg + Si | Yes | Versatile, balanced strength/corrosion | Structural, architectural |
| 7xxx | Zinc | Yes | Very high strength | Aerospace, performance applications |
Final Notes
When selecting an aluminium alloy, trade-offs must be made between strength, corrosion resistance, formability, weldability, and cost. For structural applications, 6xxx and 7xxx series dominate. For corrosion resistance, especially in marine or chemical environments, 5xxx series is preferred. The choice of alloy depends not only on static properties but also on environmental exposure, fabrication methods, and regulatory requirements.