So much fallacious within the prior reply. It's the Aluminum association (AA) that developed the total numbering method for aluminum alloys and the tempers. The American Society for testing and materials (ASTM) and the Society for automotive Engineers (SAE) both publish standards that then define the distinctive limits for composition, manufacture process, first-class manipulate, etc. The ASTM spec is frequently regarded as business/industrial excellent even as the SAE spec is considered aerospace first-rate. US military specs are additionally almost always regarded as aerospace quality. For instance, extruded aluminum alloy 6061-T6 could be ordered both per ASTM B221 or SAE AMS4150. The FAA doesn't most commonly certify the substances used however Boeing certain does. Boeing will accept material produced to SAE AMS specs, but now not ASTM specs. 6061-T6 is a medium force alloy that's used widely in commercial applications, equivalent to a welded aluminum tanker trailer. It is also used on aerospace functions, just no longer within the high stress areas. Per the Aluminum organization process, 4xxx alloys use silicon as the important alloying aspect, and 6xxx alloys use magnesium and silicon. 2xxx alloys use copper, and 7xxx alloys makes use of zinc. 2024-T3 or -T4 and 7075-T7351 or 7050-T7451 are primarily high strength. You do not "temper" aluminum alloys, you "solution deal with" it at a given temperature for a period of time. You then quench (rapidly cool) it. For the T6 condition, then you definately additionally "age harden" it. See AMS2772 for small print.