What is the Most Common Aluminum Alloy for Machining?

Among all of the available grades of aluminum, 3003 is the most common aluminum alloy used for various general purpose applications due to its decent strength and good workability. With manganese as the primary alloying element, 3003 scores excellent in terms of formability and corrosion resistance as compared to other aluminum metals and tempers. However, when it comes to strength, 6061, another commonly used aluminum alloy, triumphs over 3003 with more yield strength, which is useful for designing structural applications.

It’s important to know which aluminum alloy will work best for your specific machining process. Below, we detail the properties of 3003 and 6061 aluminum and discuss the applications in which each alloy excels.

Understanding the 3003 Aluminum Alloy

3003 is an aluminum-manganese-copper alloy that is moderately strengthened by cold hardening. Manganese is the main alloying element in the 3003 alloys, with its percentage varying between 1% to 1.5%, depending on how the aluminum alloy is fabricated. The presence of copper and magnesium offers 20% additional strength than 1100 grade aluminum, yet it is labeled as a moderately strong material due to its low tensile and yield strengths.

The table below shows the typical strength of different 3003 tempers.

Apart from moderate strength, 3003 alloys display excellent resistance to corrosion, workability, and weldability. Thus, it is an ideal light structure material, globally acknowledged as the most common aluminum alloy or general use alloy. The most common applications of 3003 occur in the aerospace, food, and chemical industries.

Some popular applications include:

• Gutters.
• Folded sheets.
• Storage containers.
• Truck roofs.
• Radiators.
• Pressure vessels.
• Acoustic ceilings.
• Downspouts.

Despite all of these advantages, machining 3003 can prove challenging. Though 3003 tempers have fair machinability, they are less machinable than other harder alloys. They also are not heat treatable, which means, unlike heat-treated metals, they can not achieve a secondary phase of precipitation hardening required for improved strength.

As a cold-treated metal, 3003 alloys are also prone to hydrogen-induced porosity during welding. The best way to avoid this situation is to drop hydrogen pickup to a low level while welding. This is another major reason why 3003 cannot be used for extreme environment applications.

Understanding the 6061 Aluminum Alloy

Aluminum 6061 is an extremely versatile alloy, containing silicon and magnesium as major alloying elements. 6061 displays excellent corrosion resistance and a good strength-to-weight ratio, highly sought-after properties for building marine and aerospace structures. With good electrical and thermal conductivity, 6061 plates find broad applications in electrical fittings, connectors, and magneto parts as well.

6061 is a heat-treated alloy and thus is available in different tempers, such as F, O, W, and T. In this regard, the 6061-Tx variant has many applications. In 6061-Tx, the letter “T” represents temper, and “x”, usually represented as a digit, indicates whether the alloy has received any special treatment.

For instance, 6061-T6 alloy is solution heat-treated and artificially aged to offer good machinability and excellent weldability. However, it has poor formability. If you need good formability from a 6061 alloy, 6061-T4 would be a more ideal choice, as it is naturally aged to have good formability and excellent weldability. In short, different 6061 tempers can meet wide application requirements, unlike 3003 tempers.

6061 aluminum is commonly used in:

• Bicycle frames.
• Cans.
• Truck frames.
• Towers and pylons.
• Aircraft applications.
• Rail coaches.

The Most Common Aluminum Alloy for Machining: 6061 or 3003?

For a quick comparison, the table below lists the essential elements of 6061 and 3003.

In terms of formability, 3003 is a better choice over 6061, especially if the application requires good formability to meet design requirements. For example, 3003 is an excellent choice for outdoor decorative architecture that requires formability coupled with moderate strength for a good aesthetic appeal.

However, as a cold-treated alloy, it is not suitable for structural applications requiring heavy machining. A majority of aluminum production is intended for structural applications, such as body frames and parts, for the automobile and the aerospace industries to achieve an improved strength-to-weight ratio. In this regard, 6061 could be deemed the most common aluminum alloy that meets a wide range of application requirements.

Purchase Aluminum Alloys from a Trusted Metal Supplier and Recycler

Industrial Metal Service has been supplying metals to the San Francisco Bay Area and nationwide for more than two decades. Our extensive collection of aluminum stock includes 6061, 3003, 7075, 5080, MIC-6, and more. We not only supply new metals sourced straight from U.S. mills, but we also offer verified metal remnants, recycled from the production lines of manufacturers that have no further use of the scrap.