From The Science and Engineering of Materials by Donald R. Askeland
Aluminum alloys can be divided into two major groups: wrought and casting alloys. These groups can be divided into two sub-groups: heat-treatable and non-heat-treatable alloys.
The temper designation (T or H) refers to heat-Treated or strain-Hardened. Other designations include annealed (O), solution-treated (W), or as-fabricated (F). The numbers following the T or H refer to the type of heat treatment or amount of strain hardening.
F: AS-FABRICATED (hot-worked, forged, cast, etc.)
O: ANNEALED (in the softest possible condition)
H1x–cold-worked only (x refers to the amount of cold work and strengthening.)
H12–cold work that gives a tensile strength midway between O and H14 tempers.
H14–cold work that gives a tensile strength midway between O and H18 tempers.
H16–cold work that gives a tensile strength midway between H14 and H18 tempers.
H18–cold work that gives about 75% reduction.
H19–cold work that gives a tensile strength greater than 2000 psi of that obtained by the H18 temper.
H2x–cold-worked and partially annealed.
H3x–cold-worked and stabilized at a low temperature to prevent age hardening of the structure.
T1–cooled from the fabrication temperature and naturally aged.
T2–cooled from the fabrication temperature, cold-worked, and naturally aged.
T3–solution-treated, cold-worked, and naturally aged.
T4–solution-treated and naturally aged.
T5–cooled from the fabrication temperature and artificially aged.
T6–solution-treated and artificially aged.
T7–solution-treated and stabilized by overaging.
T8–solution-treated, cold-worked, and artificially aged.
T9–solution-treated, artificially aged, and cold-worked.
T10–cooled from the fabrication temperature, cold-worked, and artificially aged.
And, thank you to @swertel for the excellent summary and reminder.
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