Aluminium alloy 5251 is a medium-strength aluminium–magnesium alloy offering good ductility and excellent formability. It work-hardens rapidly, making it well suited to forming operations while still maintaining structural integrity. Alloy 5251 is readily weldable and provides high corrosion resistance, particularly in marine and coastal environments, making it a reliable choice for both structural and decorative applications. The mechanical properties listed below apply to the O (annealed) condition. Properties for other tempers are available separately.
Alloy 5251 is typically used in:
Alloy 5251-O
Spec: BS EN 573-3:2009
| Chemical Element | % Present |
|---|---|
| Manganese (Mn) | 0.10 – 0.50 |
| Iron (Fe) | 0.00 – 0.50 |
| Copper (Cu) | 0.00 – 0.15 |
| Magnesium (Mg) | 1.70 – 2.40 |
| Silicon (Si) | 0.00 – 0.40 |
| Zinc (Zn) | 0.00 – 0.15 |
| Chromium (Cr) | 0.00 – 0.15 |
| Aluminium (Al) | Balance |
| Property | Value |
|---|---|
| Density | 2.69 g/cm³ |
| Melting Point | 625 °C |
| Thermal Expansion | 25 × 10⁻⁶ /K |
| Modulus of Elasticity | 70 GPa |
| Thermal Conductivity | 134 W/m·K |
| Electrical Resistivity | 0.044 × 10⁻⁶ Ω·m |
Spec: BS EN 485-2:2008
| Property | Value |
|---|---|
| Proof Stress | ≥ 60 MPa |
| Tensile Strength | 160 – 200 MPa |
| Hardness (Brinell) | 44 HB |
Aluminium alloy 5251 corresponds to the following designations (not direct equivalents):
The most common tempers for aluminium alloy 5251 include:
Aluminium alloy 5251 is readily weldable. Recommended filler wire: 5356 when welding 5251 to itself, most 5XXX alloys, and 6XXX or 7XXX series alloys. 4043 when welding to 5005, 5020, 1XXX series, or 3XXX series alloys.
| Property | Rating |
|---|---|
| Weldability – Gas | Very Good |
| Weldability – Arc | Very Good |
| Weldability – Resistance | Very Good |
| Brazability | Poor |
| Property | Rating |
|---|---|
| Cold Workability | Very Good |
| Machinability | Average |
