Aluminum Tempers
Aluminum alloy is a light metal alloy based on aluminum with a particular number of other alloying elements, such as Al-Mn alloy, Al-Cu-Mg hard aluminum alloy, and so on. Aluminum alloy has the general properties of aluminum, but it also has some better physical and mechanical properties than pure aluminum due to the different types and amounts of alloying elements added, such as good casting properties and plastic processing properties, good electrical and thermal conductivity, good corrosion resistance, good weldability, high strength (σb of 110–650 MPa), specific strength similar to high-alloy steel, specific stiffness greater than steel, and in some cases higher specific stiffness than steel. There are several uses in aviation, transportation, building, mechanical and electrical, light chemical, and daily necessities.
According to its composition and manufacturing method, aluminum alloy is further classified as deformed aluminum alloy and cast aluminum alloy. The deformed aluminum alloy is first melted and cast into a billet, then plastic deformation processing is used to create a variety of plastic processing products by rolling, extrusion, stretching, forging, and other ways. Casting aluminum alloy is created by melting the materials and directly casting them into various sections using a sand mold, an iron mold, a fusion mold, or the die-casting process.
The most common processing methods are hot processing, cold processing, solution heat treatment, age therapy, annealing treatment, and others. In addition to a wide range of materials, each aluminum alloy material has multiple tempers, and each temper serves a specific purpose, which we must thoroughly comprehend.
The following summarizes the temper of processed aluminum products according to different processing methods：
| Temper | Meaning | Description |
| F | As fabricated |
It is appropriate for products that do not require any particular work-hardening or heat treatment conditions during the molding process, and the mechanical qualities of goods in this state are not defined. |
| O | Annealed |
It is appropriate for totally annealed processed products with the lowest strength. |
| H | Strain-hardened |
It pertains to products that have been hardened by machining to improve strength and have been treated with an additional heat treatment that diminishes strength after hardening. The H designation must be followed by two or three digits. |
| W | Solution heat treated |
It is an unstable condition that only applies to the alloy after solution heat treatment and natural aging at room temperature; the state code merely shows that the product is in the natural aging stage. |
| T | Thermally treated to produce stable tempers other than F, O, or H |
It is applicable to products that have attained a stable state following heat treatment, with or without work hardening. |
Subdivisions of the Basic Tempers
The following is a concise explanation of temper designations:
The Basic H Tempers:
The H designation is usually followed by two digits, and the first digit indicates the method of processing and hardening treatment.
| Temper | Meaning | Description |
| H1 | Strain-hardened only |
It is appropriate for the temper in which the requisite strength is acquired solely by work hardening and without the use of extra heat treatment. |
| H2 | Strain-hardened and partially annealed |
It is appropriate for products whose strength is reduced to the prescribed index by incomplete annealing after the degree of work hardening exceeds the finished product's defined standards. |
| H3 | Strain-hardened and stabilized |
It is appropriate for products with stable mechanical qualities following process hardening by low-temperature heat treatment or due to heat action during processing. |
| H4 | Strain-hardened and lacquered or painted |
It is appropriate for products that have been partially annealed as a result of the paint treatment following process hardening. |
The second digit indicates the degree of hardening achieved by the material; the higher the number, the higher the hardness.
| Temper | Description |
| HX1 | 1/8 Hard |
| HX2 | 1/4 Hard |
| HX3 | 3/8 Hard |
| HX4 | 1/2 Hard |
| HX5 | 5/8 Hard |
| HX6 | 3/4 Hard |
| HX7 | 7/8 Hard |
| HX8 | Full Hard |
| HX9 | Extra Hard |
Sometimes the H designation is followed by three digits, but this is not often the case.
| Temper | Description |
| H111 |
It indicates that the final annealing has been followed by a moderate amount of hardening. |
| H112 | It is suitable for products that are formed by hot processing. |
| H116 | It is suitable for products made of 5000 series alloy with magnesium content ≥ 4.0%. |
The Basic O Tempers:
| Temper | Description |
| O1 |
Following processing, the material is retained and heated for an equal period of time at the same temperature as the solution heat treatment before being cooled progressively to ambient temperature. |
| O2 |
It is a deformation treatment temper used in superplastic processing to increase the material's molding qualities. |
| O3 |
It is the temper following homogenization therapy. |
The Basic T Tempers:
Our common heat-treated enhanced aluminum alloy's temper designation is generally presented as follows: After the T designation, the first digit 0–10 indicates the heat treatment technique for the product, where the first digit must not be 0 and T0 is used as a separate temper.
| Temper | Meaning | Description |
| T0 | After solution heat treatment, by natural aging and then by cold working condition | It is appropriate for cold-worked products with increased strength. |
| T1 | Cooled from elevated temperature shaping process and naturally aged to a substantially stable condition |
It is appropriate for high-temperature-forming products that have been cooled and are no longer cold-worked (can be straightened and leveled without affecting the mechanical property limits). |
| T2 | Cooled from an elevated temperature shaping process, cold worked, and naturally aged to a substantially stable condition |
It is appropriate for products that have been cooled by the high-temperature forming process and then cold-worked, straightened, or leveled to increase strength. |
| T3 | Solution heat treated, cold worked and naturally aged to a substantially stable condition |
It is appropriate for cold-worked products that have been straightened or leveled to improve strength after solution heat treatment. |
| T4 | Solution heat treated and naturally aged to a substantially stable condition |
It is appropriate for products that can no longer be cold worked (straightened and leveled without altering mechanical property limits) following solution heat treatment. |
| T5 | Cooled from an elevated temperature shaping process, then artificially aged |
It is appropriate for products that have been artificially aged after cooling from the high-temperature forming process but have not been cold-worked (straightening and leveling can be performed without affecting the mechanical property limits). |
| T6 | Solution treated, then artificially aged |
It is appropriate for products that can no longer be cold worked (straightened and leveled without altering mechanical property limits) following solution heat treatment. |
| T7 | Solution heat treated and overaged/stabilized |
It is used on products whose strength crosses the maximum peak point on the aging curve during artificial aging after solution heat treatment to get certain critical properties. |
| T8 | Solution heat treated, cold worked, then artificially aged |
It is appropriate for products that have been cold-worked, straightened, or leveled to increase strength. |
| T9 | Solution heat treated, artificially aged, then cold worked |
It is appropriate for cold-worked materials that have been strengthened. |
| T10 | Cooled from an elevated temperature shaping process, cold worked, then artificially aged |
It is appropriate for products that have been cold-worked, straightened, or leveled to increase their strength. |
As stated in the table below, after the TX temper, add a digit (called TXX temper) or two digits (called TXXX temper), indicating the temper of a specific process that has considerably affected the characteristics of the product (such as mechanical qualities, corrosion resistance, etc.).
| Temper | Description |
| T42 |
It is appropriate for products that have reached the complete stable condition by natural aging following solution heat treatment in the O or F temper, as well as products whose mechanical properties have reached the T42 temper following demand-side heat treatment of processed products in any temper. |
| T62 |
It applies to products that undergo artificial aging following solution heat treatment in the O or F temper, as well as products whose mechanical qualities have reached the T62 temper after heat treatment of processed products in any temper by the demand side. |
| T73 |
It applies to products that have been aged after solution heat treatment to achieve the specified mechanical qualities and stress corrosion resistance index. |
| T74 |
It is the same as the temper definition in T73. This temper has a higher tensile strength than T73 but a lower tensile strength than T76. |
| T76 |
It is the same as the T73 temper definition. This temper has a higher tensile strength than T73 and T74 tempers, respectively, and a lower stress corrosion fracture resistance than T73 and T74 tempers, but it still has a stronger anti-spalling corrosion performance. |
| T7X2 |
Since O or F temper and artificial aging treatment are used, it is suited for products with mechanical qualities and corrosion resistance up to T7X temper after solution heat treatment. |
| T81 |
It is appropriate for products that have been cold worked and distorted by around 1% after solution heat treatment to improve strength, and then artificially aged. |
| T87 |
It is appropriate for products that have been cold-worked and distorted by approximately 7% to improve strength following solution heat treatment and then artificially aged. |
To indicate the stress-relieving state of the aluminum alloy, add "51," "510," "511," "52," and "54" following TX, TXX, and TXXX tempers, as shown in the table below:
| Temper | Description |
|
TX51 TXX51 TXXX51 |
It applies to thick plates, rolled or cold-finished bars, and die-forged, forged, or rolled rings that have been stretched in prescribed amounts after solid solution heat treatment or cooling from the high-temperature forming process and are no longer straightened after stretching. |
|
TX510 TXX510 TXXX510 |
It applies to extruded bars, profiles, and tubes that have been stretched by a specified amount following solid solution heat treatment or cooling after a high-temperature forming process, as well as drawn tubes that have been stretched and are no longer straightened. Extruded bars, profiles, and tubes have a permanent deformation of 1%–3%; drawn tubes have a persistent deformation of 1.5%–3%. |
|
TX52 TXX52 TXXX52 |
It is suitable for products that have been stress relieved by compression after a solution heat treatment or a high temperature forming process, resulting in a 1%-5% permanent deformation. |
|
TX54 TXX54 TXXX54 |
It is appropriate for die-forged items that have been stress-relieved through cold shaping in the final forging die. |
