Common Aluminum alloys grades.

2024 – Typically used in aircraft skins, cowls, aircraft structures. Also used for repair and restoration.

3003 – This aluminum sheet is widely used for cowls and baffle plating.

5052 – Commonly used to make fuel tanks. 5052 has excellent corrosion resistance (particularly in marine applications).

6061 – Typically used for aircraft landing mats and many other non-aviation structural end-uses.

7075 – Commonly used to strengthen aircraft structures. 7075 is a high-strength alloy and is one of the most common grades used in the aviation industry (next to 2024).

Heat Treatment for Aluminium alloys.

The four digit designation of aluminum alloys is usually accompanied by any of the following four letters: F, O, W, and T.

The extension F stands for as fabricated (forgings and castings prior to heat treatment),O for annealed, W for solution heat treated, and T for heat treated to stable temper conditions other than O or F. The following temper designations are commonly used:

• T3 - solution heat treated,cold worked and naturally aged.
• T4 - solution heat treated and naturally aged.
• T6 - solution heat treated and artificially aged.
• T7 - solution heat treated and overaged.
• T8 - solution heat treated, cold worked and artificially aged.

In addition to these heat treatments, a heat treat condition number can have additional numerical information like T7xx, where the xx describes either a stress relieving treatment done to the alloy or the extent of aging.

Some examples of aluminum heat treatment and alloy designations:

• 2024 - T3 is an Aluminum-Copper alloy,which is solution heat treated, cold worked and naturally aged.
• 7075 - T7351 is an Aluminum-Zinc alloy that has been overaged and stress relieved by stretching