Temper Designation System

The heat treatment (temper) designation system of EN is used for all forms of wrought aluminium and aluminium alloys. Property (mechanical or physical) limits apply to individual alloy-temper-product combinations.

• Basic temper designations consist of letters (F, O, H, W, T).

• One or more digits following the letter, where required, indicate sub-divisions of the basic tempers. These designate specific sequences of basic treatments.

• Additional digits are added to the designation, if some variation of the same sequence of basic thermo-mechanical operations should be applied to the same alloy, resulting in substantially different characteristics.

For the purpose of the standard temper designations, the following definitions are applied.

Cold working: Plastic deformation of metal at such temperature and rate that strain hardening occurs.

Strain-hardening: Modification of a metal structure by cold working resulting in an increase in strength and hardness with loss of ductility.

Solution heat-treating: A thermal treatment which consists of heating the products to a suitable temperature, holding at that temperature long enough to allow constituents to enter solid solution and cooling rapidly enough to hold the constituents in solution.

Ageing: Precipitation from supersaturated solid solution resulting in a change in properties of an alloy, usually occurring slowly at room temperature (natural ageing) and more rapidly at elevated temperatures (artificial ageing).

Annealing: A thermal treatment to soften metal by removal of strain-hardening or by coalescing precipitates from solid solution.

Basic Tempers

F Temper - As fabricated

• no mechanical property limits specified.

O Temper - Annealed

• to obtain the lowest strength temper.

H Temper - Strain-hardened

• cold worked after annealing (or after hot forming) or in combination with partial annealing or stabilizing

W Temper - Solution heat treated

• unstable temper, only with indication of ageing time at RT

T Temper - Thermally treated to produce stable tempers other than F, O, or H

• solution heat treated and aged at room or intermediate temperatures with or without supplementary strain-hardening

H-Tempers for strain-hardening wrought alloys (EN 515)

The designations (below) give a brief survey over the various temper designations for non heat-treatable wrought aluminium and aluminium alloys.

Fist Digit
H1	Strain-hardened only
H2	Strain-hardened and partially annealed
H3	Strain-hardened and stabilized by temperature treatment
H4	Strain-hardened and subjected to paint bake cycle
Second Digit
HX2	Quarter hard
HX4	Half hard
HX6	Three quarter hard
HX8	Full hard
Third Digit
e.g. HX11	Products with are slightly strain-hardened between O and HX11
e.g. H112	Hot worked products with mechanical property limits
e.g. HXX5	Welded tubes with prop'ty limits deviating from HXX temper of strip

T-Tempers for heat-treatable wrought alloys (EN 515)

The designations (below) give a brief survey over the various temper designations for heat treatable wrought aluminium and aluminium alloys.

First Digit
T4	Solution heat treated and naturally aged to a stable condition
T6	Solution heat treated and artificially aged to maximum strength
T7	Solution heat treated and artificially overaged
T8	Solution heat treated, cold worked and artificially aged
T9	Solution heat treated, cold worked and artificially aged
Second Digit
TX1, 3 to 9	Variations of basic temper, usually indicating lower strenght
T42, T62	Solution heat treated from O to F temper and aged
T61, T63,T65	Increasingly, but not fully, artificially good aged for improved formability
T79...T73	Increasingly overaged for improved corrosion resist and toughness
T66	6XXX alloys; better properties than T6 by special process control
T4+	6XXX alloys; better properties than T4 by special process control

Temper designation system for castings (EN 1706)

The conditions of thermal treatment of castings as defined by EN 1706 are as follows:

F	As-cast
O	Annealed
T1	Controlled cooling from casting and naturally aged
T4	Solution heat treated and naturally aged
T5	Controlled cooling from casting and artificially aged or overaged
T6	Solution heat treated and fully artificially aged
T64	Solution heat treated and artificially under aged
T7	Solution heat treated and artificially overaged