Aluminium Alloys are engineered materials created by alloying aluminium with controlled additions of elements such as magnesium (Mg), silicon (Si), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), and titanium (Ti).
These alloying elements significantly improve strength, hardness, corrosion resistance, fatigue life, and machinability while retaining aluminium’s lightweight nature. Unlike pure aluminium, aluminium alloys can be heat-treated or work-hardened, offering a wide range of mechanical properties.
Fundamental Advantages
✔ High strength-to-weight ratio
✔ Excellent corrosion resistance
✔ Low density (≈ one-third of steel)
✔ Good thermal & electrical conductivity
✔ 100% recyclable
✔ Wide fabrication flexibility
✔ Attractive surface finishes
Physical & Mechanical Properties
| Property | Typical Range |
|---|---|
| Density | 2.6 – 2.9 g/cm³ |
| Tensile Strength | 150 – 750 MPa |
| Yield Strength | 50 – 600 MPa |
| Hardness | 25 – 150 HB |
| Elastic Modulus | ~69 GPa |
| Melting Point | 555 – 660 °C |
| Fatigue Resistance | Moderate to Excellent |
| Corrosion Resistance | Excellent |
Classification of Aluminium Alloys
Aluminium alloys are classified into series (1xxx–8xxx) based on the principal alloying element.
Heat Treatment & Tempers
Non-Heat Treatable Alloys:
✔ Strengthened by cold working
✔ Series: 1xxx, 3xxx, 5xxx
Heat Treatable Alloys:
✔ Strengthened by solution heat treatment and aging
✔ Series: 2xxx, 6xxx, 7xxx
Common Tempers:
O – Annealed
H – Strain hardened
T4 – Solution treated & naturally aged
T6 – Solution treated & artificially aged
T651 – Stress relieved
Fabrication Characteristics
Forming: Excellent for rolling, bending, stamping
Machining: Good machinability; free-cutting grades available
Welding: Excellent (1xxx, 3xxx, 5xxx, 6xxx); limited (2xxx, 7xxx)
Surface Finishing: Anodizing, powder coating, polishing, painting
Available Forms
✔ Sheets & plates
✔ Coils
✔ Extrusions (custom profiles)
✔ Bars, rods & wires
✔ Pipes & tubes
✔ Foils
✔ Castings
✔ Forgings
✔ Billets & ingots
Industry Applications
✔ Construction & architecture
✔ Automotive & transportation
✔ Aerospace & defense
✔ Marine & offshore
✔ Electrical & power systems
✔ Packaging industry
✔ Machinery & industrial equipment
✔ Consumer goods
Limitations
⚠ Lower stiffness than steel
⚠ Reduced wear resistance unless treated
⚠ High-strength grades may require surface protection
⚠ Welding restrictions for 2xxx & 7xxx series
Aluminium Alloys provide an unmatched balance of lightweight performance, strength, corrosion resistance, and versatility. They are essential to modern engineering, transportation, infrastructure, and sustainable manufacturing worldwide.