What Is Aluminum Alloy Heat Treatment Temper Designation

The physical properties exhibited by aluminum alloys are significantly influenced by the treatment of the sample. A standardized system has been developed to designate these treatments. The aluminum alloy data sheets in MatWeb will generally have a temper designation connected with them to indicate the treatment used to produce the properties listed.

Basic Aluminum Heat Treatment Designations

• F As Fabricated - No special control has been performed to the heat treatment or strain hardening after the shaping process such as casting, hot working, or cold working.
• O Annealed - This is the lowest strength, highest ductility temper
• H Strain Hardened - (applied to wrought products only) Used for products that have been strengthened by strain hardening, with or without subsequent heat treatment. The designation is followed by two or more numbers as discussed below.
• W Solution Heat Treated - This is seldom encountered because it is an unstable temper that applies only to alloys that spontaneously age at ambient temperature after heat treatment.
• T Solution Heat Treated - Used for products that have been strengthened by heat treatment, with or without subsequent strain hardening. The designation is followed by one or more numbers as discussed below.

Heat Treating T Temper Codes

• T1 - Cooled from an elevated temperature shaping process and naturally aged to a substantially stable condition.
• T2 - Cooled from an elevated temperature shaping process, cold worked, and naturally aged to a substantially stable condition.
• T3 - Solution heat treated, cold worked, and naturally aged to a substantially stable condition.
• T4 - Solution heat treated, and naturally aged to a substantially stable condition.
• T5 - Cooled from an elevated temperature shaping process then artificially aged.
• T6 - Solution heat treated then artificially aged.
• T7 - Solution heat treated then overaged/stabilized.
• T8 - Solution heat treated, cold worked, then artificially aged.
• T9 - Solution heat treated, artificially aged, then cold worked.
• T10 - Cooled from an elevated temperature shaping process, cold worked, then artificially aged.

Additional digits may be used after the first T temper digit to indicate subsequent stress relieving by processes such as stretching, compressing, or a combination.

H Temper Strain Hardening Codes

• H1 - Strain hardened only
• H2 - Strain hardened and partially annealed
• H3 - Strain hardened and stabilized
• H4 - Strain hardened and lacquered or painted. This assumes that thermal affects from the coating process affect the strain hardening; seldom encountered.

The second digits (required) after the first H temper digit indicates the level of strain hardening and is based on the minimum ultimate tensile strength obtained. The third digit (optional) is a variation of the two digit temper.