The Aluminum Alloys Numbering Systemby Doug Zeug

Understanding the aluminum alloy numbering systems is key to selecting the right material for your application. With a wide range of alloys available, each designed for specific performance characteristics, knowing how they are classified can help you make informed decisions.

Aluminum is the second most widely used metal globally after iron, thanks to its exceptional versatility. Found abundantly in nature, aluminum offers a unique combination of properties that make it ideal for countless industries, including aerospace, automotive, construction, and manufacturing. Key advantages of aluminum include:

• Light weight, yet strong
• Naturally corrosion resistant
• High tensile strength
• Excellent heat capacity
• Superior electrical and thermal conductivity
• Infinitely recyclable

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. By understanding the number systems used for aluminum alloys, you can better assess their properties and determine the best fit for your needs.

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 it one of the most cost-effective, useful metal materials for common applications, including:

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

Aluminum Alloy Naming Conventions

Aluminum alloys are classified using several standardized designation systems worldwide, each developed to provide consistency in identifying alloy compositions and properties. Understanding these systems can help you quickly determine the key characteristics of an aluminum alloy and compare materials across different regions.

Here are the most widely used aluminum alloy designation systems:

1. 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.
2. 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.
3. 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 ####
4. 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.

Below is a comparison of how the same aluminum alloy is designated across the four systems:

Aluminum Alloy Classifications

Aluminum alloys are categorized into two major classifications: wrought alloys and casting alloys. The key differences are in how they are manufactured: 

• Wrought alloys are mechanically worked, through rolling, extrusion, or forging, which enhances their strength, ductility, and grain structure. 
• Casting alloys are melted and poured into molds, allowing for the creation of complex shapes. 

Each of these classifications is further divided into heat-treatable and non-heat-treatable alloys, depending on whether heat treatment can be applied to improve their mechanical properties.

The most widely accepted system for naming aluminum alloys is the ANSI/AA (Aluminum Association) designation system, which categorizes alloys into families based on their primary alloying element. This system is used across North America and is the standard followed by Copper and Brass Sales for classifying aluminum alloys.

Wrought Alloys

Wrought aluminum alloys are categorized using a four-digit designation system that groups them based on their primary alloying element. Each series (1xxx through 9xxx) has distinct characteristics that influence strength, corrosion resistance, formability, and other key properties. Understanding these classifications helps in selecting the right alloy for specific applications.

Here’s how the four-digit wrought alloy numbering system works:

• The first digit identifies the alloy series (1xxx–7xxx), which is based on the primary alloying element.
• The second digit is typically a modification indicator, meaning: 
  • If it is "0", the alloy is the original composition for that series.
  • If it is 1–9, it represents a variation of the original alloy.
• The last two digits (XX in 1XXX or XX in other series) have different meanings: 
  • For 1xxx series (pure aluminum): They indicate the minimum aluminum purity beyond 99.00%. For example, 1350 aluminum has 99.50% aluminum.
  • For all other series (2xxx–8xxx): These digits are simply identifiers for specific alloy compositions. They do not follow a strict numerical rule but are assigned sequentially.

Example for Clarity:

• 1100 Aluminum:
  • 1 (first digit): Part of the 1xxx series (pure aluminum).
  • 1 (second digit): A modification of the original 1000-series alloy.
  •  00 (last two digits): Identifies the specific alloy within this family.
• 6061 Aluminum:
  • 6 (first digit): Part of the 6000 series (magnesium & silicon alloy).
  • 0 (second digit): Original composition (not a variation).
  • 61 (last two digits): Distinguishes it from other 6000 alloys like 6063.

Here’s an overview of the wrought aluminum alloy families:

• 1xxx: Pure 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, and high thermal and electrical conductivities. 
  • Common applications: electrical and chemical industries. 
  • An example of a commonly used alloy in the 1000 series is the 1100 aluminum plate for the power distribution industry.
• 2xxx: Copper Alloys
  • 2000 series is primarily alloyed with copper alloys, often with magnesium as a secondary addition. These alloys offer high strength-to-weight ratios, making them ideal for aerospace applications.
  • Yield strengths as high as 455 MPa, or 66 ksi
  • Common applications: aircraft and aerospace components.
  • An example of a commonly used alloy in the 200 series is 2024 aluminum, a well-known aerospace alloy.
• 3xxx: Manganese Alloys
  • 3000 series is primarily alloyed with manganese offering moderate-strength applications requiring good workability. 
  • Common applications: cookware, roofing sheets, and other architectural applications. 
  • An example of the most used alloy in the 3000 series is 3003.
• 4xxx: Silicon Alloys
  • 4000 series is primarily alloyed with silicon, creating a lower melting point and improving fluidity when molten. 
  • Common applications: welding rods, brazing sheets, and automotive engine components.
• 5xxx: Magnesium Alloys
  • 5000 series is primarily alloyed with magnesium offering high tensile strength and formability, and good resistance to corrosion in marine environments. 
  • Common applications: boat hulls, gangplanks, tanks, and bridges. 
  •  An example of a commonly used alloy in the 5xxx series is 5083 aluminum, often used for armor plates.
• 6xxx: Magnesium and Silicon Alloys
  • 6000 series is primarily alloyed with magnesium and silicon, this aluminum alloy balances strength, weldability, machinability, and corrosion resistance. 
  • Common applications: architectural extrusions and automotive components. 
  • An example of a commonly used alloy in the 6xxx series is 6061 aluminum for the semiconductor industry.
• 7xxx: Zinc Alloys
  •  7000 series is primarily alloyed with zinc, although other elements, such as copper, magnesium, chromium, and zirconium are often added in small quantities. The strongest of the aluminum alloys are in this series, with yield strengths exceeding 500 MPa (≥73 ksi). 
  • Common applications: aircraft structural components, military vehicles, mobile equipment, and other high-strength applications. 
  • An example of the most commonly used alloy in the 7000 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. Through thyssenkrupp Materials NA, Copper and Brass Sales is proud to be one of the very few selected distributors who stock 7085 aluminum.
• 8xxx: Miscellaneous Alloys
  • 8000 series alloys are characterized by miscellaneous compositions. The 8xxx series alloys may contain substantial amounts of iron, tin, and/ or lithium.
• 9xxx: Reserved for future use.

Cast Alloys

While wrought aluminum alloys are mechanically worked into sheets, plates, and extrusions, cast aluminum alloys are produced by melting aluminum and pouring it into molds. This process allows for complex shapes and intricate designs, making cast alloys ideal for applications such as automotive components, machinery parts, and aerospace structures.

Cast aluminum alloys are classified using a four-digit numbering system, followed by a decimal point. The digit after the decimal point denotes the product form: "0" for casting and "1" or higher for ingot. Here’s an overview of the cast aluminum alloy families:

• 1xx.x: An unalloyed (pure) composition. It’s mainly used for rotor manufacture.
• 2xx.x: Primarily alloyed with copper. Other alloying elements may be specified.
• 3xx.x: Primarily alloyed with silicon. Other alloying elements, such as copper and magnesium, are specified. This series covers nearly 90% of all shaped castings produced due to high fluidity, wear resistance, and good mechanical properties.
• 4xx.x: Primarily alloyed with silicon.
• 5xx.x: Primarily alloyed with magnesium.
• 6xx.x: Unused.
• 7xx.x: Primarily alloyed with zinc. Other alloying elements, such as copper and magnesium, may be added.
• 8xx.x: primarily alloyed with tin.
• 9xx.x: Unused.

Factors to Consider When Choosing Aluminum Alloys

Selecting the right aluminum alloy depends on several factors:

• Application Requirements: Strength, corrosion resistance, and machinability vary significantly across alloy families. For example, marine applications require corrosion-resistant alloys like 5083, while aerospace applications demand high-strength alloys like 7075.
• Weight: Aluminum’s lightweight properties make it a natural choice for applications where reducing mass is critical, such as automotive and aerospace industries.
• Corrosion Resistance: Alloys in the 1000 and 5000 series are ideal for environments exposed to moisture or corrosive elements.
• Weldability and Machinability: The 6000 series offers excellent machinability and weldability, making it a go-to choice for structural components.
• Cost: Alloy cost depends on composition and processing requirements. Non-heat-treatable alloys are often more economical for general-purpose applications.

Sustainability of Aluminum

One of aluminum’s most notable features is its recyclability. Unlike many materials, aluminum can be recycled indefinitely without losing its properties. Recycling aluminum consumes only 5% of the energy required to produce primary aluminum, making it a highly sustainable choice for industries seeking to reduce their environmental impact.

Manufacturers increasingly prioritize aluminum for eco-conscious projects, from green building designs to lightweight electric vehicles. The metal’s sustainability aligns with modern demands for environmentally friendly materials.

Why Choose Copper and Brass Sales as your Aluminum Supplier

Choosing the right aluminum alloy supplier is crucial for project success. Copper and Brass Sales offers:

• Expert Guidance: Our knowledgeable team helps you navigate alloy options to ensure you select the best fit for your project.
• Comprehensive Inventory: We stock a wide range of aluminum alloys to support demanding industries, including:
  • Aerospace & Defense: 2024, 7050, 7075, 6013 – known for their high strength and fatigue resistance. 
  • Marine & Corrosion-Resistant Applications: 5083, 5086 – ideal for saltwater and harsh environments. 
  • Electrical & Automotive: 6101, 6063, 6020 – selected for conductivity and formability. 
  • Precision Machining & Manufacturing: 2011, 6262, CASTMIC6, CAST5000 – designed for exceptional machinability and stability.
• Seamless Online Ordering: Easily quote, compare, and order aluminum alloys through our user-friendly website.
• High-Quality Ready-to-Use Materials: With precision cutting and processing capabilities, we supply aluminum sheets, plates, and extrusions that meet tight tolerances and industry standards.

Understanding aluminum alloys and their properties is essential when selecting the right material for your project. Each alloy offers distinct advantages, from lightweight strength in aerospace to corrosion resistance in marine environments.

If you’re unsure about which alloy best fits your needs and whether an alternative alloy could work for your project, our experts are here to help! Contact us today for personalized guidance, and explore our aluminum stock guide for a complete list of alloys that we stock or can source for you.

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