A Guide to the Aluminum Alloy Numbering System

Aluminum is the most abundant mineral on Earth after oxygen and silicon and is the second most used metal globally after iron. It is widely used due to many of its versatile properties. Several properties that are attractive to its users include:

• Light weight
• Corrosion resistance
• Tensile strength
• Heat capacity
• Electrical and thermal conductivity
• Infinitely recyclable

In this article, we’re going to discuss various aluminum alloy numbering systems available so that you can more easily understand the properties of the aluminum alloy you’re looking for or attempting to purchase.

Applications

Aluminum can be alloyed with other elements to develop properties needed for various applications. Some of the typical alloying elements include copper, magnesium, manganese, silicon, tin, and zinc. The unique combinations of properties provided by aluminum and its alloys make aluminum one of the most cost-effective, useful metal materials for common applications like:

• Power lines
• Building structures
• Window frames
• Consumer electronics
• Industrial and household appliances
• Aircraft and Spacecraft components
• Ships
• Trains
• Automotive industry
• Construction of machine

When looking for aluminum alloys that satisfy your specific project and application, you will notice that not all aluminum suppliers use the same naming convention, especially for suppliers across different countries. To help you with the quoting and purchase process, we compiled the most popular aluminum designations around the world and highlighted the commonality between each naming system.

Naming Convention

Here’s a list of the most used designations used around the world:

ANSI/AA (The Aluminum Association)

The Aluminum Association created the ANSI/AA designation system and is the most accepted system in North America today. Each name begins with AA followed by four numbers: AA ####. The first number informs you of the aluminum’s main alloying element, which will be explained further in this article.

UNS (Unified Numbering System)

The UNS designation system is for metals and alloys and is also widely accepted in North America. This format begins with one letter A, followed by five numbers: A #####. The numbers could be similar to other pre-existing designations, like the ones from AA. On other occasions, the numbers could also provide information regarding its chemical composition.

EN (European Norm)

The European Union created the EN designation system in an attempt to unify all existing designations in some of their member states. This format starts with EN, followed by AC (cast alloys) or AW (wrought alloys) and a four-digit code, very similar to the ones from the AA system: EN AC/AW ####

ISO (International Organization for Standardization)

This is the one system that’s completely different. The naming convention for ISO is composed of the prefix AL, followed by the main alloying element percentages. With this naming system, you can easily identify the key metals that are mixed in the specific aluminum alloy.

Here’s an example of the same alloy designations across each of the four designation systems mentioned above.

ANSI/AA	UNS	EN	ISO
AA5083	A95083	EN AW-5083	Al-Mg4.5Mn
AA6063	A96063	EN AW-6063	Al-Mg0.5Si
AA2024	A92024	EN AW-2024	Al-Cu4Mg1
AA7075	A97075	EN  AW-7075	Al-Zn6MgCu

 

Alloy Classifications

There are two major alloy classifications: casting and wrought alloys. These can be further subdivided into heat-treatable and non-heat-treatable categories. The most accepted naming system created by the Aluminum Association (ANSI/AA) has two nomenclatures for these alloys and groups them into families based on the primary alloyed metal.

Wrought Alloys

A four-digit system is used to name wrought composition families. These are grouped based on their primary alloying elements.

1. 1xxx: This is the purest aluminum. This series is required to have at least 99.00% or higher aluminum purity. It’s characterized by low mechanical properties, excellent corrosion resistance, excellent workability, high thermal and electrical conductivities. You can find these primarily in the electrical and chemical industries. An example of a commonly used alloy in the 1xxx series is the 1100 aluminum plate for the power distribution industry.
2. 2xxx: is primarily alloyed with Copper alloys, often with magnesium as a secondary addition. Commonly used in aircraft and parts that require a high strength-to-weight ratio (yield strengths as high as 455 MPa, or 66 ksi). An example of a commonly used alloy in the 2xxx series is the 2024 aluminum.
3. 3xxx: is primarily alloyed with Manganese. It is used as general-purpose alloys and moderate-strength applications requiring good workability. You find them in cookware and other architectural applications. An example of the most used alloy in the 3xxx series is 3003.
4. 4xxx: is primarily alloyed with Silicon, creating a lower melting point which improves fluidity when molten. It is often used in welding rods and brazing sheet.
5. 5xxx: is primarily alloyed with Magnesium. It has high tensile strength and formability, and good resistance to corrosion in marine atmospheres. Hence, it’s commonly used in boat hulls, gangplanks, tanks, and bridges. An example of a commonly used alloy for armor plates in the 5xxx series is the 5083 aluminum.
6. 6xxx: is primarily alloyed with Magnesium and Silicon. Although not as strong as most 2xxx and 7xxx alloys, 6xxx series alloys have good formability, weldability, machinability, and corrosion resistance, with medium strength. It is commonly used for architectural extrusions and automotive components. An example of a commonly used alloy in the 6xxx series is 6061 aluminum for the semiconductor industry.
7. 7xxx: is primarily alloyed with Zinc. Although other elements, such as copper, magnesium, chromium, and zirconium, are often added in small quantities. The 7xxx series is the strongest aluminum alloys, with yield strengths ≥500 MPa (≥73 ksi) possible. It is commonly used in aircraft structural components, mobile equipment, and other high-strength applications. An example of the most used alloy in the 7xxx series is 7050 for aerospace applications. Another popular aluminum is the 7085 aluminum commonly used for military vehicles. While the 7085 alloy is quite popular in the defense industry, not many suppliers carry it. thyssenkrupp Materials NA is proud to be one of the very few selected distributors who stock 7085 aluminum.
8. 8xxx: Alloys characterized by miscellaneous compositions. The 8xxx series alloys may contain substantial amounts of iron, tin, and/ or lithium.
9. 9xxx: Reserved for future use

Cast Alloys

1. 1xx.x: is the unalloyed (pure) composition. It’s mainly used for rotor manufacture
2. 2xx.x: is primarily alloyed with Copper. Other alloying elements may be specified.
3. 3xx.x: is primarily alloyed with Silicon. Other alloying elements, such as copper and magnesium, are specified. This series covers nearly 90% of all shaped castings produced.
4. 4xx.x: is primarily alloyed with Silicon.
5. 5xx.x: is primarily alloyed with Magnesium.
6. 6xx.x: Unused
7. 7xx.x: is primarily alloyed with Zinc. Other alloying elements, such as copper and magnesium, may be added.
8. 8xx.x: is primarily alloyed with Tin.
9. 9xx.x: Unused

It’s important for engineers and purchasers to have a strong understanding of different aluminum, its many alloys, and properties when requesting a specific type for a project. As you can see, each alloy has its own property that may fit one application but not another.

If you’re unsure about which alloy best fits your needs and whether it’s interchangeable with other alloys, contact our team of experts today and we will be happy to help!

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For a list of available aluminum alloys, check our aluminum stock guide.