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Tempers of heat-treatable aluminium alloys



Condition of metal of aluminium or aluminium alloy produced by mechanical and/or thermal processing. Typically characterized by a certain macro or micro metallurgical structure and specified properties. These properties may be mechanical, corrosion, electrical or xxxxx.

Solution heat treatment

Heating an alloy to a suitable temperature for sufficient time to allow one or more soluble constituent to enter into solid solution, where they are retained in supersaturated state after quenching.


Cooling a metal from an elevated temperature by contact with a solid, a liquid or a gas, at a rate rapid enough to retain most or all of the soluble constituents in solid solution


Treatment of a metal aiming at a change in its properties by precipitation of intermetallic phases from supersaturated solid solution.


Thermal treatment to soften metal:

Non-heat Treatable Alloys

Alloys whose strength/mechanical properties are achieved by cold working (rolling, extruding, etc.). Sometimes called work hardening alloys or strain hardening alloys. Tempers are denoted by first letter H. The example is 5052-H24.

Heat Treatable Alloys

Alloys whose strength/mechanical properties are achieved by heat treatment followed by cooling and natural or artificial ageing. Tempers are denoted by first letter T. The example is 6060-T66.

Heat treatment of aluminium alloys

The complete heat-treatment consists of:

Unlike steel, aluminium alloys are not hard immediately after quenching. To get the highest strength values it is important to keep the material at the correct solution heat temperature for enough time and to follow the correct quenching procedure. Depending on the alloy, this may be carried out using water or air.

Heat-treatable alloys are produced in many tempers. The basic tempers for heat-treatable alloys are shown below. Each of these basic tempers can have several pieces and even dozens of options for more specific tempers for various types of aluminum products.

 Basis tempers for heat-treatable aluminium alloys

Table 1 – Various uses of the second digit after letter T [3]


Fig. 1 – The relationships for some T7X temper proprties [3]

Fig. 2 – Relative position of the variations of T6 and T7 tempers [3]

The tempers of extrusion 6xxx series aluminium alloys

For extrusion 6xxx series aluminium alloys only a limited number of tempers is important. Below are listed the tempers that are used in the European standard EN 755-2 which specifies the requirements for the mechanical properties of extruded aluminum products.

The tempers of 6xxx series extruded aluminium alloys

The relationships between the tempers of 6063 aluminium alloy

Fig. 3 – The relationships of tempers with various variations of ageing [4]

Fig. 4 – The SUPPOSED relationships of various tempers of extruded products from 6063 aluminium alloys. Modified from [5].

Annex A

Table A1 – The examples of uses of the tempers for extruded 6000 aluminium alloys products in EN 755-2 [3]


  1. Global Advisory Group GAG – Guidance “Terms and Definitions” – 2011
  2. Introduction to Aluminum Alloys and Tempers – J. Gilbert Kaufman
  3. EN 755-2:2017
  4. Design of aluminium structures Introduction to Eurocode 9 with worked examples – European Aluminium – 2020
  5.  Extrusion of Aluminium Alloys / T. Sheppard


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