Aluminum Alloy Temper Designations
In the world of aluminum alloys, understanding temper designations is essential to selecting the right material for structural performance, machinability, surface treatment, or forming requirements. Temper codes define the specific processing and resulting mechanical properties of an aluminum product — from soft annealed tempers to high-strength heat-treated states.
At AMSpec, we specialize in manufacturing precision aluminum tubes and profiles with tightly controlled temper conditions to meet demanding aerospace, defense, industrial, and mobility…etc. applications.
What is an Aluminum Temper?
The temper of an aluminum alloy refers to the mechanical and thermal treatment applied after final shaping (such as extrusion or drawing), which significantly affects its hardness, strength, ductility, and corrosion resistance.
Temper designations appear after the alloy number — for example, 6061-T6 or 7075-T73 — and consist of a letter and one or more digits, indicating the type and degree of treatment.
Basic Temper Categories
The aluminum temper system is standardized under ANSI H35.1 and includes five primary categories:
Code | Description | Common Applications |
F | As Fabricated – No special thermal or strain-hardening treatment | Rough extrusions, general shaping |
O | Annealed – Fully softened condition for maximum ductility | Deep drawing, bending |
H | Strain Hardened – Cold worked to increase strength (non-heat-treatable alloys) | 1xxx, 3xxx, 5xxx series |
T | Thermally Treated – Heat-treated for strength (heat-treatable alloys) | 2xxx, 6xxx, 7xxx series |
W | Solution Heat Treated – Unstable state, aging occurs naturally over time | Intermediate or transition state |
“H” Temper: Strain-Hardened Aluminum
Applies to non-heat-treatable alloys, such as 1xxx, 3xxx, and 5xxx series.
The “H” temper is used for aluminum that has been cold worked to increase strength through strain hardening. Additional digits indicate the degree and method of strain hardening:
- H1X – Strain hardened only (e.g., H14)
- H2X – Strain hardened and partially annealed (e.g., H24)
- H3X – Strain hardened and stabilized (e.g., H34)
The second digit (1–9) represents the degree of strain hardening, where higher numbers mean higher strength.
“T” Temper: Heat-Treated Aluminum
Applies to heat-treatable alloys, such as 2xxx, 6xxx, and 7xxx series.
“T” tempers refer to material that has undergone solution heat treatment, quenching, and artificial aging to achieve desired mechanical properties. Common designations include:
- T4 – Solution heat-treated and naturally aged
- T5 – Cooled from shaping process and artificially aged
- T6 – Solution heat-treated and artificially aged (very common)
- T651 – Stress-relieved by stretching after T6
- T73 / T76 – Overaged tempers to improve stress corrosion resistance (used in 7075 and 7050 alloys)
At AMSpec, we offer precise in-house heat treatment for T6, T651, T73, and T76 tempers, delivering consistent high-strength solutions for aerospace, defense, and high-performance mechanical parts.
“O” and “F” Tempers: Soft or As-Fabricated
- O (Annealed) – Maximum ductility and lowest strength; suitable for deep drawing or complex forming.
- F (As Fabricated) – No special control over temper; used where properties are not critical.
Choosing the Right Temper for Your Application
Selecting the appropriate aluminum temper is just as important as choosing the right alloy. Temper designations affect:
- Mechanical strength
- Corrosion resistance
- Formability
- Machinability
- Thermal stability
At AMSpec, our team offers deep expertise in extrusion, cold drawing, and heat treatment, and can help guide you in selecting the best alloy and temper combination for your project.
Partner with AMSpec for Temper-Specific Aluminum Solutions
At AMSpec provides custom aluminum alloy solutions, whether you’re sourcing aerospace-grade tubing, structural profiles, or precision-drawn aluminum with specific mechanical properties, AMSpec can deliver solutions matched to your performance needs.
