{"id":2498,"date":"2021-06-01T02:38:00","date_gmt":"2021-06-01T02:38:00","guid":{"rendered":"https:\/\/sybridge.com\/?p=2498"},"modified":"2023-08-10T10:19:55","modified_gmt":"2023-08-10T15:19:55","slug":"decoding-aluminum-alloy-numbering","status":"publish","type":"post","link":"https:\/\/sybridge.com\/decoding-aluminum-alloy-numbering\/","title":{"rendered":"Decoding the Aluminum Alloy Numbering System"},"content":{"rendered":"\n

Originally published on fastradius.com on June 1, 2021<\/em><\/p>\n\n\n\n

Aluminum is a lightweight yet incredibly strong metal, making it an excellent choice for many applications in the\u00a0automotive,\u00a0aerospace, and electronics industry. Along with its durability and physical lightness, aluminum is\u00a0corrosion-resistant<\/a>\u00a0due to a strong layer of oxide film covering its surface.<\/p>\n\n\n\n

Since aluminum easily forms compounds with other chemical elements, a large number of aluminum alloys have been developed over the years. To create an aluminum alloy and improve certain qualities of base aluminum, you must add a chemical element to pure aluminum. This requires a thorough mixing of these elements \u2014 such as magnesium, silicon, zinc, or copper \u2014 with aluminum while the metal is molten. These elements can increase aluminum\u2019s strength, density, workability, electrical conductivity, and more.<\/p>\n\n\n\n

Aluminum alloys can vary significantly depending on their composition and tempering. To prevent confusion, aluminum alloys are named and categorized according to an aluminum alloy numbering system. These systems help designers and engineers familiarize themselves with various alloys, their characteristics, and common applications. This helps product teams choose the right aluminum alloy and manufacturing method for a particular part.<\/p>\n\n\n\n

Wrought Aluminum Series Numbers<\/h2>\n\n\n\n

The Aluminum Association established the wrought alloy description system in 1954. When the system was first implemented, it listed 75 chemical compositions \u2014 today, there are more than 530 registered active chemical elements, and this number continues to grow.<\/p>\n\n\n\n

The wrought aluminum series names elements with four numerical digits where the first digit represents the principal alloying element, the second digit indicates a modification of a specific alloy, and the third and fourth digits are arbitrary numbers assigned to specific alloys in the series.<\/p>\n\n\n\n

Here are the primary alloying agents in the wrought aluminum series:<\/p>\n\n\n\n

1xxx \u2014 99.000 Minimum Aluminum<\/h3>\n\n\n\n

It\u2019s impossible for aluminum to be 100% pure, but aluminum in this wrought series category contains at least 99% aluminum. For all intents and purposes, 1xxx alloys are considered pure aluminum. Notably, this alloy is the exception to the wrought series naming rule \u2014 in 1xxx alloy names, the last two digits stand for the minimum percentage of aluminum above 99. For example, Alloy 1350 consists of at least 99.50% aluminum.<\/p>\n\n\n\n

Pure aluminum has great corrosion resistance and workability, plus high electrical and thermal conductivity. For this reason, this alloy is often used for electrical and chemical applications. Pure aluminum is not very strong and is seldom used for structural applications, but strain hardening can moderately increase material strength.<\/p>\n\n\n\n

2xxx \u2014 Copper<\/h3>\n\n\n\n

This wrought series alloy offers high strength and performance over a wide range of temperatures and is regularly used in aerospace applications. One well-known aircraft aluminum alloy is Alloy 2024. However, some copper aluminum alloys are susceptible to heat and stress corrosion cracking and are considered non-weldable, whereas other 2xxx alloys can be welded using the right methods. 2xxx decreases the elongation and tensile strength of aluminum and doesn\u2019t offer as good corrosion resistance as other alloys in the wrought series.<\/p>\n\n\n\n

3xxx \u2014 Manganese<\/h3>\n\n\n\n

3xxx aluminum alloys were first used only in pots and pans, but are now widely used in heat exchanger components for vehicles and power plants. With good temperature stability and corrosion resistance, alloys in this category are suitable for use in extreme conditions. 3xxx also allows for good formability and workability. 3003 is a popular manganese alloy used for moderate strength applications that require complex shapes.<\/p>\n\n\n\n

4xxx \u2014 Silicon<\/h3>\n\n\n\n

Silicon reduces aluminum\u2019s melting point and improves its fluidity when molten. For this reason, 4xxx alloys are often used in fusion welding wire and as brazing alloys. Silicon on its own is non-heat-treatable, but a number of 4xxx alloys respond well to heat treatments thanks to added copper or magnesium.<\/p>\n\n\n\n

5xxx \u2014 Magnesium<\/h3>\n\n\n\n

Aluminum alloys in this category are easily weldable and widely used for applications in shipbuilding, transportation, bridge building, and construction. 5xxx alloys offer good corrosion resistance in marine environments and have the highest strength of all non-heat-treatable alloys. However, 5xxx alloys with more than 3 to 3.5% magnesium are not recommended for elevated temperature service above 65.6\u00b0C (150\u00b0F) due to the possibility of stress corrosion cracking.<\/p>\n\n\n\n

6xxx \u2014 Magnesium and Silicon<\/h3>\n\n\n\n

6xxx alloys usually consist of around 1.0% magnesium and silicon each, which produces magnesium-silicide. Magnesium-silicide can support solution heat treatments that improve strength, formability, and corrosion resistance. This wrought series number is used throughout the welding fabrication industry, primarily incorporated into structural components and extrusions.<\/p>\n\n\n\n

These alloys are sensitive to solidification cracks, which means they should not be welded without filler materials \u2014 oftentimes, 6xxx is welded with 4xxx or 5xxx filler materials to increase weldability. A major magnesium-silicide alloy is 6061, which is one of the most versatile heat treatable aluminum alloys.<\/p>\n\n\n\n

7xxx \u2014 Zinc<\/h3>\n\n\n\n

This wrought series number contains some of the highest strength aluminum alloys that are best-suited for high-performance applications in competitive sporting equipment or the aircraft and aerospace industries. Zinc additions range from 0.8 to 12% in 7xxx alloys and can be coupled with smaller percentages of magnesium, copper, and chromium for heat treatability.<\/p>\n\n\n\n

Like 2xxx, 7xxx contains alloys both suitable and non-suitable for welding \u2014 one commonly welded alloy is 7005, which is primarily used with 5xxx alloy fillers. One of the highest-strength aluminum alloys available is 7075, which is often used in air-frame structures and for other high-stress applications.<\/p>\n\n\n\n

Considerations for the Wrought Aluminum Series<\/h2>\n\n\n\n
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Aluminum alloys can vary significantly depending on their composition and tempering.<\/em><\/figcaption><\/figure>\n\n\n\n

It\u2019s important to note which aluminum alloys are heat treatable and which are non-heat-treatable. This will help product teams determine appropriate applications for specific aluminum alloys, and protect components from high temperatures when necessary.<\/p>\n\n\n\n