Alloy designations

Wrought and cast aluminium alloys use different identification systems. Wrought aluminium is identified with a four digit number which identifies the alloying elements.

Cast aluminium alloys use a four to five digit number with a decimal point. The digit in the hundreds place indicates the alloying elements, while the digit after the decimal point indicates the form (cast shape or ingot).

Temper designation

The temper designation follows the cast or wrought designation number with a dash, a letter, and potentially a one to three digit number, e.g. 6061-T6. The definitions for the tempers are:

-F : As fabricated
-H : Strain hardened (cold worked) with or without thermal treatment

-H1 : Strain hardened without thermal treatment-H2 : Strain hardened and partially annealed-H3 : Strain hardened and stabilized by low temperature heatingSecond digit : A second digit denotes the degree of hardness-HX2 = 1/4 hard-HX4 = 1/2 hard-HX6 = 3/4 hard-HX8 = full hard-HX9 = extra hard

-O : Full soft (annealed)
-T : Heat treated to produce stable tempers

-T1 : Cooled from hot working and naturally aged (at room temperature)-T2 : Cooled from hot working, cold-worked, and naturally aged-T3 : Solution heat treated and cold worked-T4 : Solution heat treated and naturally aged-T5 : Cooled from hot working and artificially aged (at elevated temperature)-T51 : Stress relieved by stretching-T510 : No further straightening after stretching-T511 : Minor straightening after stretching-T52 : Stress relieved by thermal treatment-T6 : Solution heat treated and artificially aged-T7 : Solution heat treated and stabilized-T8 : Solution heat treated, cold worked, and artificially aged-T9 : Solution heat treated, artificially aged, and cold worked-T10 : Cooled from hot working, cold-worked, and artificially aged

-W : Solution heat treated only

Note: -W is a relatively soft intermediary designation that applies after heat treat and before aging is completed. The -W condition can be extended at extremely low temperatures but not indefinitely and depending on the material will typically last no longer than 15 minutes at ambient temperatures.

Wrought alloys

The International Alloy Designation System is the most widely accepted naming scheme for wrought alloys. Each alloy is given a four-digit number, where the first digit indicates the major alloying elements, the second   if different from 0   indicates a variation of the alloy, and the third and fourth digits identify the specific alloy in the series. For example, in alloy 3105, the number 3 indicates the alloy is in the manganese series, 1 indicates the first modification of alloy 3005, and finally 05 identifies it in the 3000 series.

1000 series (essentially pure)

1000 series are essentially pure aluminium with a minimum 99% aluminium content by weight and can be work hardened.