What is the Aluminum Temper Designation? There are four main types of aluminum tempers. The type is indicated by a letter preceding the number. The four letter designations are:
T: heat treatment
H: strain hardening
O: annealed
F: Free machining state
The letters of the aluminum temper designations are followed by numbers. These numbers illustrate exactly how the tempering method performs. For example, both T5 and T6 are heat treated, however, T5 indicates that the aluminum alloy is cooled from a high temperature forming process and artificially aged, while T6 is solution heat treated and then artificially aged. Differences in numbers in the designation of aluminum tempers can inform buyers of aluminum alloys about subtle differences that can have a significant impact on the alloy's mechanical properties.
While many number variants are available, the "T" number variant is probably the most commonly used and most important to understand. Here are descriptions of some of the "T" model variants:
T1: Natural aging after cooling at high temperature during the forming process
T2: High temperature forming process cooling, cold working, then natural aging
T3: Solution heat treatment, cold working, then natural aging
T4: natural aging after solution heat treatment
T5: artificial aging after high temperature cooling in the forming process
T6: artificial aging after solution heat treatment and cooling
T7: Solution heat treatment followed by overaging
T8: Solution heat treatment, cold working, then artificial aging
T9: Solution heat treatment, artificial aging, then cold working
T10: High temperature forming process cooling, cold working, then artificial aging
For the meaning of the numbers following the letter temper designations such as "O", "H" and "F", it is best to obtain the technical data sheet for the aluminum alloy in question to determine exactly what the temper designation means.
