5251 Aluminum Sheet Introduction
5251 aluminum sheet is a non-heat-treatable aluminum alloy sheet with better formability and higher mechanical strength compared to 1000 series aluminum alloys. The 5251 aluminum alloy contains 2% magnesium and 0.3% manganese, exhibiting higher ductility and better corrosion resistance. If higher strength is required, it can only be achieved through mechanical cold working. The 5251 aluminium sheet is an excellent option for applications involving sheet metal processing, shipbuilding structures, and aerospace components.
Characteristic of Aluminum 5251 Sheet
1.Moderate Mechanical Strength
Aluminum 5251 offers a tensile strength of approximately 240 MPa in the annealed (O) condition. Compared with commercially pure aluminum grades, it delivers noticeably higher strength while maintaining low weight. This balance makes it a practical choice for lightweight structural components that require reliable mechanical performance without adding excess mass.
2.Excellent Formability
With a controlled addition of magnesium, Tthe best al 5251 achieves outstanding ductility and cold forming performance. In the O temper, the material responds well to deep drawing, bending, and complex shaping operations. It maintains dimensional stability during processing, which reduces cracking risk in demanding forming applications.
3.Strong Corrosion Resistance
The presence of manganese enhances the alloy’s resistance to corrosive environments. Combined with its naturally forming oxide layer, aluminium 5251 performs well in marine and high-humidity conditions. It maintains structural integrity even when exposed to moisture, salt spray, or outdoor industrial environments.
4.Reliable Weldability
5251 aluminum supports common welding techniques such as MIG and TIG welding. It produces stable weld seams with low susceptibility to tearing or cracking when proper procedures are followed. This makes it suitable for fabricated assemblies that require consistent joint strength.
5.Excellent Surface Treatment Compatibility
The alloy responds well to anodizing and a wide range of surface finishing processes. It can achieve a clean, uniform appearance while improving surface durability. This makes 5251 suitable for applications where both aesthetics and long-term performance are important.
Specifications of 5251 Aluminum Sheet
| Alloy Grade |
5251 / EN AW-5251 |
| Temper |
O, H22, H24, H26, H32, H34, H321 |
| Thickness |
0.2 mm – 250 mm |
| Width |
900 mm – 3800 mm |
| Length |
≤ 6000 mm |
| MOQ |
2 TON |
| Standards |
ASTM B209 / EN 485 / EN 573 |
| Surface Treatment |
Mill Finish, Anodized, Brushed, Polished, Sand Blasted |
5251 Aluminum Composition
| Aluminum (Al) |
Balance |
| Magnesium (Mg) |
1.7 – 2.4 |
| Manganese (Mn) |
0.10 – 0.50 |
| Iron (Fe) |
≤ 0.50 |
| Silicon (Si) |
≤ 0.40 |
| Copper (Cu) |
≤ 0.15 |
| Zinc (Zn) |
≤ 0.15 |
| Chromium (Cr) |
≤ 0.15 |
| Titanium (Ti) |
≤ 0.15 |
| Others (each) |
≤ 0.05 |
| Others (total) |
≤ 0.15 |
Properties of 5251 Aluminum
| Temper |
Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) |
| O (Annealed) |
170 – 240 |
≥ 65 |
≥ 20 |
| H22 |
210 – 260 |
≥ 130 |
≥ 12 |
| H24 |
230 – 280 |
≥ 150 |
≥ 10 |
| H26 |
250 – 300 |
≥ 180 |
≥ 8 |
| H32 |
220 – 270 |
≥ 160 |
≥ 10 |
| H34 |
240 – 290 |
≥ 180 |
≥ 8 |
Physical Properties of 5251 Aluminum
| Density |
2.69 g/cm³ |
| Melting Point |
~ 605 – 650 °C |
| Thermal Conductivity |
134 W/m·K |
| Electrical Conductivity |
~ 34% IACS |
Application of 5251 Aluminium Sheet
Due to its lightweight nature, robust mechanical stability, and strong corrosion resistance, 5251 aluminum sheet is extensively utilized in various industries that demand dependable performance without increasing structural weight. Its excellent formability and weldability further expand its application range.
Marine Engineering
Al 5251 performs exceptionally well in moisture-rich and saltwater environments. It is commonly selected for small craft hull sections, interior and exterior marine trim, decking components, and floating platform structures. Its resistance to marine corrosion helps extend service life while reducing maintenance costs.
Transportation Industry
In the transportation sector, weight reduction is critical. The 5251 aluminum sheet is often used for automotive body panels, trailer assemblies, and decorative vehicle trim. The material offers a practical balance between strength and formability, allowing manufacturers to create durable yet lightweight components.
Building and Architectural Projects
Architects and fabricators value 5251 for its clean surface finish and adaptability. It is used for façade cladding, curtain wall systems, roofing panels, signage, and equipment cabinets. The alloy can also be anodized or surface-treated to enhance both durability and visual appeal.
Industrial Fabrication
Due to its structural reliability and ease of processing, 5251 is suitable for storage tanks, equipment casings, containers, furniture frames, and various light structural parts. It supports efficient fabrication processes such as bending, rolling, and welding without compromising integrity.
Aerospace and Precision Equipment
For applications where weight efficiency and dimensional stability are essential, 5251 aluminium sheet is used in selected aerospace components and light mechanical structures. Its strength-to-weight ratio makes it a practical solution for non-critical structural panels and general engineering assemblies.
