Temper Designations for Aluminium

Aluminium alloys are supplied in a very wide range of tempers with two principal groups.

Non-heat Treatable Alloys

Alloys whose strength/mechanical properties are achieved by cold working (rolling, extruding, etc.). Sometimes called work hardening alloys, Temper is denoted by letter H.

Heat Treatable Alloys

Alloys whose strength/mechanical properties are achieved by heat treatment followed by cooling and natural or artificial ageing. Temper denoted by letter T.

Heat Treatable Alloys

Solution Heat Treating

The process of heating aluminium at prescribed temperature for a prescribed time and then cooling rapidly usually by quenching in water.

Natural Ageing (T1, T2, T3, T4)

The process which occurs spontaneously at ordinary temperature until the metal reaches a stable condition. This hardens the metal after solution heat treatment.

Artificial Ageing (T5, T6, T9)

The process of heating for a prescribed period (2-30 hours) at a prescribed low temperature (100-200ºC) until the metal reaches a stable condition. This hardens/increases strength after solution heat treating quicker than natural ageing and to a greater level.

Non Heat Treatable Alloys

Work Hardening (H14)

General term for processes which increase strength of aluminium and reduce the ductility, (e.g. rolling, drawing, pressing, stamping). Sometimes called strain-hardening.

Partial Annealing (H24)

A heating process which reduces strength and increases ductility of aluminium after work hardening. Sometimes called temper let- down.

Stabilising (H34)

A low temperature thermal treatment or heat introduced during manufacture which stabilises the mechanical properties. This process usually improves ductility and is only applied to those alloys which, unless stabilised, gradually age- soften at room temperature, (i.e. non-heat treatable range.) The purpose of stabilising is to relieve the residual internal stress in the metal. Mainly used for 5000 series alloys.

Non Heat Treatable Alloy Designations

Term Description

H1X

Work Hardened

H2X

Work Hardened and Partially Annealed

H3X

Work Hardened and Stabilized by Low Temperature Treatment

H4X

Work Hardened and Stoved

HX2

Quarter Hard

HX4

Half Hard

HX6

Three Quarter Hard

HX8

Fully Hardened

Temper Codes For Plates

Code Description

H111

Some work hardening imparted by shaping processes but less than required for H11 temper.

H112

Alloys that have some tempering from shaping but no special control over the amount of strain- hardening or thermal treatment. Some strength limits apply.

H321

Strain hardened less than required for a controlled H32 temper.

H323

A version of H32 that has been specially fabricated to provide acceptable resistance to stress corrosion cracking.

H34

Stabilised, Half Hard - A low temperature thermal treatment or heat introduced during manufacture which stabilises the mechanical properties and relieves residual internal stress, usually improves ductility. Only applied to alloys which, unless stabilised, gradually age-soften at room temperature.

H343

H34 specially fabricated to provide acceptable resistance to stress corrosion cracking.

H115

Armour plate.

H116

Special corrosion-resistant temper.

Full List of Temper Codes

Code Description

F

As fabricated (no property limits specified)

O

Fully Annealed, soft

H111

Some work hardening imparted by shaping processes but less than required for H11 temper.

H112

Alloys that have some tempering from shaping but no special control over the amount of strain- hardening or thermal treatment. Some strength limits apply.

H115

Armour plate.

H116

Special corrosion resistant temper.

H12

Work hardened to quarter hard, not annealed after rolling.

H14

Work hardened to half hard, not annealed after rolling.

H16

Work hardened to three-quarter hard, not annealed after rolling.

H18

Work hardened to fully hard, not annealed after rolling,

H19

Work hardened to Extra Hard, not annealed after rolling.

H24

Work hardened then partially annealed to half hard.

H26

Work hardened then partially annealed to half hard.

H28

Work hardened then partially annealed to fully hard.

H32

Work hardened then stabilised by low-temperature heat treatment to quarter hard.

H321

Strain hardened less than required for a controlled H32 temper.

H323

A version of H32 that has been specially fabricated to provide acceptable resistance to stress corrosion cracking.

H34

Stabilised, Half Hard - A low temperature thermal treatment or heat introduced during manufacture which stabilises the mechanical properties and relieves residual internal stress, usually improves ductility. Only applied to alloys which, unless stabilised, gradually age-soften at room temperature.

H343

H34 specially fabricated to provide acceptable resistance to stress corrosion cracking.

H36

Work hardened then stabilised by low-temperature heat treatment to three-quarter hard.

H38

Work hardened then stabilised by low-temperature heat treatment to fully hard.

T1

Cooled from an elevated temperature and naturally aged.

T2

Cooled from an elevated temperature, cold worked and naturally aged.

T3

Cooled from an elevated temperature, cold worked and naturally aged.

T351

Solution heat treated then stress relieved by stretching - Equivalent to T4 condition.

T352

Solution heat treated then stress relieved by stretching - Equivalent to T4 condition.

T3510

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T3511

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T36

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T361

Solution heat treated then stress relieved by stretching.

T4

Solution heat treated and naturally aged to a substantially stable condition.

T42

Solution heat treated and naturally aged to a substantially stable condition.

T451

Solution heat treated then stress relieved by stretching - Equivalent to T4.

T4510

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T4511

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T5

Solution heat treated and stress- relieved by stretching - Equivalent to T4 condition.

T6

Solution heat treated and artificially aged.

T62

Solution heat treated then artificially aged by the user.

T651

Solution heat treated, stress relieved by stretching then artificially aged.

T6510

Solution heat treated and stress- relieved by stretching then artificially aged with no straightening after aging - Equivalent to T4 condition.

T6511

Solution heat treated and stress- relieved by stretching then artificially aged with minor straightening after aging - Equivalent to T4 condition.

T7

Solution heat treated then stabilised.

T72

Solution heat treated then specially artificially aged for resistance to stress corrosion.

T73

Solution heat treated then specially artificially aged for resistance to stress corrosion.

T7351

Solution heat treatment then specially artificially aged for resistance to stress corrosion.

T8

Solution heat treated, cold worked then artificially aged.

T81

Solution heat treated, cold worked then artificially aged.

T851

Solution heat treated then stress relieved by stretching then artificially aged.

T8510

Solution heat treated, stress- relieved by stretching then artificially aged.

T8511

Solution heat treated, stress- relieved by stretching then artificially aged.

T9

Solution heat treated, artificially aged and cold worked.

T10

Cooled from an elevated temperature, artificially aged then cold worked

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