impurity limits. The last two digits designate the
67--Indicates the year the specification was
minimum aluminum percentage. The following is an
issued or last revised.
example of a 1xxx group aluminum metal and is broken
down into its component parts:
Aluminum and Aluminum
Alloy Classification
1040--Is a pure aluminum. The second digit
(0) indicates that there is no special control on
Aluminum is supplied in literally hundreds of
impurities. The last two digits (40) indicate
different alloys. Making the most practical choice of
that it is 99.40 percent pure.
aluminum to serve your needs depends largely on
Aluminum Alloys.--In the 2xxx through 8xxx
y o u r knowledge and understanding of the
groups, the last two of the four digits in the designation
identification and coding system. Aluminum alloys
have no special significance on the percentage of
are broadly classed as castings or wrought alloys.
aluminum. Instead, the last two digits indicate the alloy
Generally, you will not work much with aluminum
modifications. The second digit, as in the lxxx group,
castings; therefore, this section will only talk about
wrought aluminum (plates, sheets, and shapes) and
indicates the control on impurities. The following is an
aluminum alloys.
example of a 2xxx group aluminum metal and is broken
down into its component parts:
NUMERICAL CLASSIFICATION SYSTEM.--
A 4-digit numerical designation system is used to identify
2117--Is an aluminum alloy with copper as the
aluminum and aluminum alloys. The first digit indicates
major alloying element. The second digit (1)
the alloy group as follows:
indicates that there is some control on
impurities and the last two digits (17) indicate
1xxx--Aluminum, 99.00% minimum purity,
that it is the 17th alloy of the 2xxx group.
no alloying element
NOTE: For complete chemical composition,
2xxx--Copper
s p e c i f i c identification numbers must be
cross-referenced. These numbers can be found in most
3xxx--Manganese
metal handbooks.
TEMPER AND HARDENING DESIGNA-
4xxx--Silicon
TIONS.--In addition to the 4- digit alloy designation,
a letter or letter/number combination is included as a
5xxx--Magnesium
temper/hardness designation. The temper/hardness of
an aluminum alloy is one of the major factors governing
6xxx--Magnesium and silicon
also need to have an understanding of the
7xxx--Zinc
temper/hardness designation as it relates to mechanical
and physical properties.
8xxx--Other elements
Temper Designations.--Some aluminum alloys
The second digit indicates modifications of the
are hardened and strengthened by cold working or
original alloy or impurity limits. The last two
strain hardening. Tempering is accomplished by cold
digits identify the aluminum alloy or indicate the
rolling, drawing, stretching, or coining. Other
aluminum purity. Pure aluminum and aluminum
aluminum alloys are heat treatable and their
alloys are classified in this manner and will be
properties can be improved by thermal treatment
looked at further.
methods. The following temper designations denote
the condition of aluminum alloys and the method
Pure Aluminum.--Pure aluminum is any
used to obtain that condition.
aluminum product that is 99.00 percent aluminum and
greater and classified in the 1xxx classification group.
If there is a second digit after the 1, it will designate the
F--As fabricated
control on impurities. These controls on individual
Q--Annealed and recrystallized (wrought
impurities will be designated with the digits 1 through
9. If the second number is 0, it indicates natural
only)
13-17
