Metallurgy

More Metallurgy Information

Aluminium Alloys

Aluminium Alloys

 

The following table describes some of the more important aluminum alloys of interest to home shop machinists and fabricators.

Note:

  • Aluminium alloys are grouped according to their primary alloying agents. These are listed in the column Alloy Group.
  • The machining reference for aluminum alloys is 2011. This has the best machining qualities of all the aluminum alloys and is assigned a rating of 100%.
  • When exposed to te air, pure aluminum rapidly forms a thin corrosion-resistant layer of aluminium oxide. The thickness of this layer can be increased through an electrolytic process called anodizing. Some aluminum alloys can be readily anodized to increase their corrosion resistance, while others cannot.

 

Some Important Aluminium Alloys
Type Alloy Group Description Available Forms Use
2XXX Copper
  • Strength and fatigue resistance: High
  • Corrosion Resistance: poor
  • Machinability: T-4 hardness very good; O hardness fair.

    Note: The T-4 designation indicates moderate hardness. The O designation means "annealed to the softest condition."

  • Weldable?: No
  • Heat Treatable?: Yes
  • Anodizable?: No
Sheet, plate, bar, rod Structural. 2024 is the most widely used alloy in this series.
3XXX Manganese
  • Strength and fatigue resistance: low
  • Corrosion Resistance: Good
  • Machinability: Poor
  • Weldable?: Yes
  • Heat Treatable?: No
  • Anodizable?: Yes
Sheet Complex shapes formed by bending; siding. 3003 is the most widely used alloy in this series.
5XXX Magnesium
  • Strength and fatigue resistance: Moderate
  • Corrosion Resistance: Good
  • Machinability: Fair
  • Weldable?: Yes
  • Heat Treatable?: No
  • Anodizable?: Yes
Sheet Complex shapes formed by bending; siding. 5052 is the most widely used alloy in this series.
6061 Silicon and Magnesium
  • Strength and fatigue resistance: High
  • Corrosion Resistance: Good
  • Machinability: Good
  • Weldable?: Yes
  • Heat Treatable?: Yes
  • Anodizable?: Yes
Sheet, plate, bar, rod Truck, marine, pipeline. 6061 is the most widely used alloy in this series and the most versatile of all aluminum alloys.
7XXX Zinc
  • Strength and fatigue resistance: Very high.

    Note: The 7XXX series alloys are the strongest aluminum alloys.

  • Corrosion Resistance: poor
  • Machinability: Good
  • Weldable?: No
  • Heat Treatable?: Yes, except for 7072.

    Note: Most of the 7XXX series alloys contain magnesium to allow hardability through heat treatment. 7072 contains only zinc, and is strain (work) hardenable only.

  • Anodizable?: No
Sheet, bar Aircraft. 7075 is the most widely used alloy in this series.