What is aluminium 5251?
Aluminium 5251 is a medium strength magnesium manganese alloy best known for its good ductility and formability. It has high corrosion resistance, and as a result is commonly used in marine environments.
5251 is traditionally recognised as a general sheet metal working grade. It is not heat treatable to higher strength.
Similar or obsolete designations and trade names
- O – soft
- H22 – work hardened by rolling then annealed to quarter hard
- H24 – work hardened by rolling then annealed to half hard
- H26 – work hardened by rolling then annealed to three-quarter hard
Other designations include
- Al Mg2
- Al 2.0Mg 0.3Mn
- NS4
- EN AW 5251
- UNS A95251
- AA5251-H22
- Al5251-H22
Main attributes
- Good surface finish & aesthetic properties
- High corrosion resistance
- Very good weldability
- Low density
- Good anodising properties
- Good mechanical properties
- Medium strength
- High fatigue strength
5251 UK stock sizes
Here are the standard stock sizes/colours for 5251 in the UK.
Please note we do not supply stock material, the information provided is purely for design and research purposes.
5251 sheet
| Size | KG/Sheet |
| 2000mm x 1000mm x 1.0mm | 5.43 |
| 2500mm x 1250mm x 1.0mm | 8.49 |
| 2000mm x 1000mm x 1.2mm | 6.52 |
| 2500mm x 1250mm x 1.2mm | 10.19 |
| 2000mm x 1000mm x 1.5mm | 8.15 |
| 2500mm x 1250mm x 1.5mm | 12.74 |
| 3000mm x 1500mm x 1.5mm | 18.34 |
| 2000mm x 1000mm x 2.0mm | 10.87 |
| 2500mm x 1250mm x 2.0mm | 16.98 |
| 3000mm x 1500mm x 2.0mm | 24.45 |
| 2000mm x 1000mm x 2.5mm | 13.58 |
| 2500mm x 1250mm x 2.5mm | 21.23 |
| 2000mm x 1000mm x 3.0mm | 16.30 |
| 2500mm x 1250mm x 3.0mm | 25.47 |
| 3000mm x 1500mm x 3.0mm | 36.68 |
5251 technical properties
Physical properties
| Property | Value |
| Density | 2.69 g/cm³ |
| Melting Point | 625°C |
| Thermal Expansion | 25x10^-6 /K |
| Modulus of Elasticity | 70 GPa |
| Thermal Conductivity | 134 W/m.K |
| Electrical Resistivity | 0.044 x10^-6 Ω·m |
Sheet and plate – 0.2mm to 25mm – Spec: BS EN 485-2:2008
Mechanical properties
| Property | Value |
| Proof Stress | 120 Min MPa |
| Tensile Strength | 190 - 230 MPa |
| Hardness Brinell | 56 HB |
Typical 5251 chemical composition (weight %)
| Weight (%) | Manganese | Iron | Copper | Magnesium | Silicon | Zinc | Chromium | Titanium | Aluminium | Other (Each) | Others (Total) |
| min. | 0.10 | 0.00 | 0.00 | 1.70 | 0.00 | 0.00 | 0.00 | 0.00 | Bal | 0.00 | 0.00 |
| max. | 0.50 | 0.50 | 0.15 | 2.40 | 0.40 | 0.15 | 0.15 | 0.15 | Bal | 0.05 | 0.15 |
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