MACHINABILITY OF ALUMINUM

Aluminum is no doubt one of the most popular metals, shaping the capabilities of our modern world. Aluminum alloys make a wide range of in-demand products possible. HVAC, smart phones, automotive parts, and marine gear all require them. Scientists, architects, and designers prefer aluminum for many reasons including high strength-to-weight ratio, flexibility, and energy savings.


What Makes Aluminum So Popular?

After 1886—when the method for commercially producing aluminum was first introduced—aluminum has grown tremendously in popularity. This is in large part due to the needs of our modern lives and the versatility aluminum offers. Let’s use the automotive industry as a primary example.

The automotive industry is huge and revolves around the production of 95 million cars and trucks each year. At the same time, the desire for more efficient ground transportation is higher than ever. The need for lower vehicle weight, reduced emissions, and improved fuel economy has sparked intense interest in aluminum. Aluminum offers a one-two punch; it is lightweight without sacrificing strength. In fact, some aluminum alloys are as strong as structural steel.

List of Aluminum Alloys

This is a list of some important aluminum or aluminum alloys.

  • AA-8000: used for building wire per the National Electrical Code
  • Alclad: aluminum sheet made by bonding high-purity aluminum to a high strength core material
  • Al-Li (lithium, sometimes mercury)
  • Alnico (aluminum, nickel, copper)
  • Birmabright (aluminum, magnesium)
  • Duralumin (copper, aluminum)
  • Hindalium (aluminum, magnesium, manganese, silicon)
  • Magnalium (5% magnesium)
  • Magnox (magnesium oxide, aluminum)
  • Nambe (aluminum plus seven other unspecified metals)
  • Silumin (aluminum, silicon)
  • Titanal (aluminum, zinc, magnesium, copper, zirconium)
  • Zamak (zinc, aluminum, magnesium, copper)
  • Aluminum forms other complex alloys with magnesium, manganese, and platinum

Identifying Aluminum Alloys

Alloys have common names, but they may be identified using a four-digit number. The first digit of the number identifies the class or series of alloy.

1xxx - Commercially pure aluminum also has a four-digit numerical identifier. Series 1xxx alloys are made of 99 percent or higher purity aluminum.

2xxx - The principal alloying element in the 2xxx series is copper. Heat treating these alloys improves their strength. These alloys are strong and tough, but not as corrosion resistant as other aluminum alloys, so they are usually painted or coated for use. The most common aircraft alloy is 2024. Alloy 2024-T351 is among the hardest of the aluminum alloys.

3xxx - The main alloying element in this series is manganese, usually with a smaller amount of magnesium. The most popular alloy from this series is 3003, which is workable and moderately strong. 3003 is used to make cooking utensils. Alloy 3004 is one of the alloys used to make aluminum cans for beverages.

4xxx - Silicon is added to aluminum to make 4xxx alloys. This lowers the melting point of the metal without making it brittle. This series is used to make welding wire. Alloy 4043 is used to make filler alloys for welding cars and structural elements.

5xxx - The principal alloying element in the 5xxx series is magnesium. These alloys are strong, weldable, and resist marine corrosion. The 5xxx alloys are used to make pressure vessels and storage tanks and for various marine applications. Alloy 5182 is used to make the lid of aluminum beverage cans. So, aluminum cans actually consist of at least two alloys!

6xxx - Silicon and magnesium are present in 6xxx alloys. The elements combine to form magnesium silicide. These alloys are formable, weldable, and heat treatable. They have good corrosion resistance and moderate strength. The most common alloy in this series is 6061, which is used to make truck and boat frames. Extrusion products from the 6xxx series are used in architecture and to make the iPhone 6.

7xxx - Zinc is the principal alloying element in the series starting with the number 7. The resulting alloy is heat-treatable and very strong. Important alloys are 7050 and 7075, both used to construct aircraft.

8xxx - These are aluminum alloys made with other elements. Examples include 8500, 8510, and 8520.

9xxx - Presently, the series starting with the number 9 is unused.

What Is the Strongest Aluminum Alloy?

Manganese added to aluminum increases its strength and yields an alloy with excellent workability and corrosion resistance. The highest strength alloy in the non-heat-treatable grade is alloy 5052.

  • Workability/ formability
  • This factor relates to the mechanical deformation of aluminum parts into desired fashions. the workability of aluminum alloys from excellent to poor is as follows;

    Excellent workability

    Alloy 1100 and Alloy 3003

    Good workability

    Alloy 2011, Alloy 2024, Alloy 5052, Alloy 6061 and Alloy 6063

    Poor workability

    Alloy 7075

  • Weldability
  • Also known as joinability, it refers to the ability of aluminum to be welded depending on grades as follows;

    Excellent weldability

    Alloy 3003 and Alloy 1100

    Good weldability

    Alloy 5052, Alloy 6061, Alloy 6063, Alloy 6082

    Poor weldability

    Alloy 2021, Alloy 2024 and Alloy 7075

  • Machining
  • Aluminum is more machinable than other metals due to its easy to shape chips as follows:

    Excellent machinability

    Alloy 2011

    Good machinability

    Alloy 1100 (best in Hard temper), Alloy 3003, and Alloy 6061 (for T4 and T6)

    Fair machinability

    Alloy 2024 (best for annealed conditions), Alloy 5052 (best in Hard temper), Alloy 6063 and Alloy 7075 (best for annealed conditions)

  • Corrosion resistance
  • Aluminum alloys rank as follows about corrosion resistance.

    Excellent corrosion resistance

    Alloy 1100, Alloy 5052, and Alloy 6061

    Good corrosion resistance

    Alloy 3003, Alloy 6063, and Alloy 6082

    Average corrosion resistance

    Alloy 7075

    Poor corrosion resistance

    Alloy 2011, and Alloy 2024

  • Heat treatment
  • Aluminum can either be heat-treated or fail to respond to heat treatment as indicated below.

    Treated by heat

    Alloy 2011, Alloy 2024, Alloy 6061, Alloy 6063, and Alloy 7075

    Fails to respond to heat treatment

    Alloy 1100, Alloy 3003, and Alloy 5052

  • End-use of applications
  • Aluminum grades have different end-use applications as indicated below;

    Alloy 1100- for general fabrication works.
    Alloy 2011- general machining works.
    Alloy 2024- aerospace functions and applications.
    Alloy 3003- for general fabrication and in food and chemical appliances.
    Alloy 5052- used in marine applications such as ships and general fabrication.
    Alloy 6061- ideal for structural appliances and in general fabrication applications.
    Alloy 6063- ideal for architectural appliances.
    Alloy 7075- for aerospace appliances.

  • Strength of aluminum
  • Aluminum alloy haves varying strength ranging from high, high to medium and medium strength as follows.

    High mechanical strength

    Alloy 2011, Alloy 2024, and Alloy 7075

    Medium to high strength

    Alloy 5052, and Alloy 6061

    Medium strength

    Alloy 6063

    Not for high strength uses

    Alloy 1100