Aluminum 2618

Aging Procedure

The aging heat treatment (T 61) is accomplished by first solutioning at 980 F for up to 24 hours (depending on section size) followed by quench in boiling water and then aging at 390 F for up to 20 hours (minimum of 5 hours again dependent upon section size) and air cooled.

Annealing Procedure

Annealing, which may be required as a result of cold work, may be done at 725 F for 4 hours followed by slow cooling (typically furnace cooling).

Applications

Commonly used in the manufacture of aircraft engines.

Cold Workability

The alloy has good formability and is readily cold worked in either the solution heat treated or annealed condition.

Forgeability

Hot forging is done in the range of 970 down to 700 F, starting with the material preheated to 970 F.

Formability

Formability, both hot and cold, is good.

Hardening Procedure

Hardens by cold working and aging heat treatment for T 61 condition. See "Aging".

Heat Treatability

Solution heat treatment is done at 985 F for a period of time that will permit thorough heating and solutioning. This may be as long as 24 hours for heavy sections. A water quench follows this heating. Annealing and age hardening heat treatments are also possible - see "Annealing" and "Aging".

Hot Workability

This alloy may readily be hot worked in the temperature range of 660 to 700 F.

Machinability

AL 2618 has excellent machining characteristics. The heat treated (aged) condition will allow machining to a smoother finish than is the case for annealed or water quenched conditions.

Other Mechanical Properties

Shear strength for the T 61 (aged) material is 40 ksi.

Other Physical Properties

Electrical conductivity 36% of copper.

Principle Design Features

This alloy containing copper and magnesium is age hardenable for good strength in applications that involve exposure to heat up to 575 F.

Tempering Procedure

Not applicable to this alloy.

Weldability

Resistance welding may be done satisfactorily. The amount of heat input by other welding means may be harmful to this alloy and thus conventional fusion welding methods should NOT be used.