F as fabricated. Denotes metal that has been fabricated to ordered dimensions without any attempt on the part of the producer to control the results of either strain-hardening operations or thermal treatments. There are no mechanical property limits, and the strength levels may vary from lot to lot and from shipment to shipment.
O annealed. Applies to wrought products that have undergone a thermal treatment to reduce their mechanical property levels to their minimums. Often described as "dead soft" metal.
W solution heat-treated. An unstable temper applying to certain of the heat-treatable alloys that, after heat treatment, spontaneously age harden at room temperature. Only when the period of natural aging is indicated (W 1 hr for example) is this a specific and complete designation.
H strain- hardened. Applies to those wrought products which have had an increase in strength by reduction through strain-hardening, or cold working, operations. The "H" is always followed by two or more digits.
T thermally treated to produce tempers other than F, O or H. Applies to those products which have had an increase in strength due to thermal treatments, with or without supplementary strain-hardening operations. The "T" is always followed by one or more digits.
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