Aluminium 5083 vs 5251 – What’s the Difference

5083 Aluminium VS 5251 Aluminium

Metal fabrication is crucial in several industries worldwide, including the construction, automotive, and aerospace sectors. Aluminium is one of those versatile metals with several applications in such industries, thanks to its many benefits, such as being lightweight, corrosion-resistant, and durable. However, different types of aluminium alloys have different compositions and thus vary in several characteristics. This post explores the differences between two popular aluminium alloys – 5083 and 5251 – to help you determine the ideal alloy for your intended use.

What is Aluminium 5083?

Aluminium 5083 is a marine-grade alloy known for its exceptional strength and corrosion-resistant properties, making it a popular material choice for shipbuilding and other maritime applications. This alloy primarily comprises magnesium, manganese, and chromium, contributing to its high strength-to-weight ratio and overall durability.

What is Aluminium 5251?

Aluminium 5251 is an aluminium alloy with exceptional formability and high corrosion-resistant properties. It’s a popular choice in the manufacturing industry for various applications, including transportation, marine, and structural engineering. This alloy is often used for components in aeroplanes, boats, and other vehicles due to its lightweight yet durable nature.

Difference Between Aluminium 5083 and 5251

Aluminium 5083 and 5251 are two different kinds of aluminium that have various properties depending on the use. Aluminium 5083 is known for its excellent weldability and high resistance to corrosion, while 5251 is known for its moderate strength, good machinability, and ease of anodizing. Their main difference is their chemical compositions, with 5083 containing higher levels of magnesium than 5251; it’s also less resistant to stress corrosion cracking. Both alloys have useful applications in many industries, such as automotive, shipbuilding, electronics etc.

Chemical Composition

Both 5083 and 5251 belong to the aluminium-magnesium family of alloys. Aluminium 5083 has a higher magnesium content (4.0 – 4.9%) and a smaller amount of manganese, chromium, iron, and other elements. On the other hand, Aluminium 5251 comes with a lower magnesium content (2.2 – 2.8%) and some traces of iron, silicon, copper, and other elements. Ultimately, 5083 is stronger and more corrosion-resistant than 5251.

Mechanical Properties

The mechanical properties of an aluminium alloy determine its strength, flexibility, and toughness. For instance, 5083 has a yield strength of 240 MPa, an ultimate tensile strength of 330 MPa, and an elongation rate of 14%. In contrast, 5251 has a yield strength of 150 MPa, an ultimate tensile strength of 210 MPa, and an elongation rate of 10%. This means that 5083 is a better choice for high-stress applications that require a strong, durable material.


Weldability refers to the ability of an aluminium alloy to be welded or joined through various methods, such as TIG, MIG, or resistance welding. In this regard, 5083 is a highly weldable alloy with good weldability, crack resistance, and weld strength retention. Conversely, 5251 is less weldable and may require special welding procedures to avoid cracking and other issues.


Both 5083 and 5251 have several applications in different industries, depending on their specific characteristics. Aluminium 5083, for example, is ideal for marine and shipbuilding applications due to its excellent corrosion resistance, weldability, and strength. It also finds use in the construction, automotive, and aerospace sectors. In contrast, 5251 is a versatile alloy commonly used to manufacture coiled tubing, roofing, and cladding, among other applications.


The cost of an aluminium alloy depends on several factors, including availability, production, and demand. Although 5083 is generally more expensive than 5251, it is an investment worth making if your application calls for a robust and corrosion-resistant material that can withstand high-stress applications and harsh environments.


In conclusion, when choosing the ideal material for your fabrication project, it is vital to understand the differences between aluminium alloys, such as 5083 and 5251. While both alloys have their strengths and applications, 5083 is a superior choice for high-stress applications requiring strength, durability, and corrosion resistance. On the other hand, 5251 is a versatile alloy that is less expensive and commonly used in applications where strength is not paramount. With this information, you can make an informed decision and ensure optimal results for your project.



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