Designation of Aluminum Alloys

Major Alloy Groups
Aluminum employs a four-digit system. The first digit indicates the alloy group. The last two digits identity the alloy or, in the instance of the 1000 Series, the purity. The second digit indicates a modification of the alloy. The alloy groups are these:
1XXX	Aluminum - 99% and greater	6XXX	Magnesium & Silicon - Major alloying element
2XXX	Copper - Major alloying element	7XXX	Zinc - Major alloying elements
3XXX	Manganese - Major alloying element	8XXX	Other elements
4XXX	Silicon - Major alloying element	9XXX	Unused to date
5XXX	Magnesium - Major alloying element

Temper Systems
The temper designation follows and is separated from the alloy designation by a dash, i.e. 3003-H14 or 6061-T6 It indicates mechanical or thermal treatment. Additional digits to the right indicate variations in basic treatment.
Basic Tempers
-F	As fabricated. No special control over thermal conditions or strain hardening. No mechanical property limits
-O	Annealed Applies to wrought products which are annealed to obtain the lowest strength temper.
-H	Strain-hardened (cold worked). Applies to products which have their strength increased by strain-hardening, with or without supplementary thermal treatments to produce some reduction in strength. The H is always followed by two or more digits.
-W	Solution heat-treated. An unstable temper applicable only to alloys which spontaneously age at room temperature after solution heat treatment.
-T	Thermally treated to produce stable tempers other than O or H. Applies to products which are thermally treated with or without supplementary strain-hardening, to produce stable tempers. The T is always followed by one or more digits.

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Non-Heat Treatable Alloy Tempers 1000, 3000 and 5000 Series		Heat Treatable Alloy Tempers 2000, 6000 and 7000 Series
-O	Annealed and recrystallized.	-O	Annealed and recrystallized (Solution Annealed.
-H1	Work or strain hardened.	-T1	Naturally aged only (certain extrusions).
-H2	Strain hardened and partially annealed.	-T3	Solution heat treated then cold worked and naturally aged
-H3	Strain hardened, then stabilized. A digit to the right of -H1, -H2 or -H3 above indicate the degree of hardness: 1 is the least degree of strain-hardness 2 is 1/4 hard 4 is 1/2 hard 6 is 3/4 hard 8 is full hard	-T4	Solution heat treated then naturally aged
		-T42	Solution heat treated by the user, and then naturally aged.
		-T5	Artificially aged only (certain extrusions)
		-T6	Solution heat treated, then artificially aged.
		-T62	Solution heat treated by the user, then artificially aged.
-H111	Strain-hardened less than required for controlled H11 temper	-T8	Solution heat treated, cold worked then artificially aged.
-H112	Equivalent to F temper except that mechanical property limits have been set or mechanical listing is required.	-T9	Solution heat treated, artificially aged and, then cold worked.
-H116	Work or strain hardened and when tested by the user is required to pass the exfoliation corrosion resistance test (asset method)	-T3511	Solution heat treated and cold worked (stress relieved by stretching to produce a permanent set of 1 1/2 to 3%). minor straightening after stretching.
		-T4511	Solution heat treated (stress-relieved by stretching to produce a permanent set of 11/2 to 3%) minor straightening after stretching.
		-T651	Solution heat treated (stress-relieved by stretching to produce a permanent set of 11/2 to 3%), with no further straightening.
		-T6511	Solution heat treated (stress-relieved by stretching to produce a permanent set of 11/2 to 3%) and artificially aged, minor straightening after stretching.

The information and data presented herein are typical or average values and are not a guarantee of maximum or minimum values. Applications specifically suggested for material described herein are made solely for the purpose of illustration to enable the reader to make his own evaluation and are not intended as warranties, either express or implied, of fitness for these or other purposes.

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