Aluminum Tutorial
Courtesy of Aircraft Spruce
Aluminum - The Most Common Grades
1100 This grade is commercially pure aluminum. It is soft and ductile and
has excellent workability. It is ideal for applications involving intricate forming
because it work hardens more slowly than other alloys. It is the most weldable of aluminum
alloys, by any method. It is non heat-treatable. It has excellent resistance to corrosion
and is widely used in the chemical and food processing industries. It responds well to
decorative finishes which make it suitable for giftware.
2011 This is the most free-machining of the common aluminum alloys. It
also has excellent mechanical properties. Thus, it is widely used for automatic screw
machine products in parts requiring extensive machining.
2014 & 2017 The 2017 alloy combines excellent machinability and high
strength with the result that it is one of the most widely used alloys for automatic screw
machine work. It is a tough, ductile alloy suitable for heavy-duty structural parts. Its
strength is slightly less than that of 2014.
2024 This is one of the best known of the high strength aluminum alloys.
With its high strength and excellent fatigue resistance, it is used to advantage on
structures and parts where good strength-to-weight ratio is desired. It is readily
machined to a high finish. It is readily formed in the annealed condition and may be
subsequently heat treated. Arc or gas welding is generally not recommended, although this
alloy may be spot, seam or flash welded. Since corrosion resistance is relatively low,
2024 is commonly used with an anodized finish or in clad form ("Alclad") with a
thin surface layer of high purity aluminum. Applications: aircraft structural components,
aircraft fittings, hardware, truck wheels and parts for the transportation industry.
3003 This is the most widely used of all aluminum alloys. It is
essentially commercially pure aluminum with the addition of manganese which increases the
strength some 20% over the 1100 grade. Thus, it has all the excellent characteristics of
1100 with higher strength. It has excellent corrosion resistance. It has excellent
workability and it may be deep drawn or spun, welded or brazed. It is non heat treatable.
Applications: cooking utensils. decorative trim, awnings, siding, storage tanks, chemical
equipment.
5005 This alloy is generally considered to be an improved version of
3003. It has the same general mechanical properties as 3003 but appears to stand up better
in actual service. It is readily workable. It can be deep drawn or spun, welded or brazed.
It has excellent corrosion resistance. It is non heat-treatable. It is well suited for
anodizing and has less tendency to streak or discolor. Applications same as 3003.
5052 This is the highest strength alloy of the more common non
heat-treatable grades. Fatigue strength is higher than most aluminum alloys. In addition,
this grade has particularly good resistance to marine atmosphere and salt water corrosion.
It has excellent workability. It may be drawn or formed into intricate shapes and its
slightly greater strength in the annealed condition minimizes tearing that occurs in 1100
and 3003. Applications: Used in a wide variety of applications from aircraft components to
home appliances, marine and transportation industry parts, heavy duty cooking utensils and
equipment for bulk processing of food.
5083 & 5086 For many years there has been a need for aluminum sheet
and plate alloys that would offer, for high strength welded applications, several distinct
benefits over such alloys as 5052 and 6061. Some of the benefits fabricators have been
seeking are greater design efficiency, better welding characteristics, good forming
properties, excellent resistance to corrosion and the same economy as in other non
heat-treatable alloys. Metallurgical research has developed 5083 and 5086 as superior
weldable alloys which fill these needs. Both alloys have virtually the same
characteristics with 5083 having slightly higher mechanical properties due to the
increased manganese content over 5086. Applications: unfired pressure vessels, missile
containers, heavyduty truck and trailer assemblies, boat hulls and superstructures.
6061 This is the least expensive and most versatile of the heat-treatable
aluminum alloys. It has most of the good qualities of aluminum. It offers a range of good
mechanical properties and good corrosion resistance. It can be fabricated by most of the
commonly used techniques. In the annealed condition it has good workability. In the T4
condition fairly severe forming operations may be accomplished. The full T6 properties may
be obtained by artificial aging. It is welded by all methods and can be furnace brazed. It
is available in the clad form ('Alclad") with a thin surface layer of high purity
aluminum to improve both appearance and corrosion resistance. Applications: This grade is
used for a wide variety of products and applications from truck bodies and frames to screw
machine parts and structural components. 6061 is used where appearance and better
corrosion resistance with good strength are required.
6063 This grade is commonly referred to as the architectural alloy. It
was developed as an extrusion alloy with relatively high tensile properties, excellent
finishing characteristics and a high degree of resistance to corrosion. This alloy is most
often found in various interior and exterior architectural applications, such as windows,
doors, store fronts and assorted trim items. It is the alloy best suited for anodizing
applications - either plain or in a variety of colors.
7075 This is one of the highest strength aluminum alloys available Its
strength-to weight ratio is excellent and it is ideally used for highly stressed parts. It
may be formed in the annealed condition and subsequently heat treated. Spot or flash
welding can be used, although arc and gas welding are not recommended. It is available in
the clad ('Alclad") form to improve the corrosion resistance with the over-all high
strength being only moderately affected. Applications: Used where highest strength is
needed.
ALUMINUM ALLOY DESIGNATIONS
The aluminum industry uses a four-digit index system for the designation of its wrought
aluminum alloys.
As outlined below, the first digit indicates the alloy group according tothe major
alloying elements.
1xxx Series
In this group. minimum aluminum content is 99%. and there is no major alloying element.
The second digit indicates modifications in impurity limits. If the second digit is
zero, there is no special control on individual impurities. Digits 1 through 9,
which are assigned consecutively as needed, indicate special control of one or more
individual impurities. The last two digits indicate specific minimum aluminum content.
Although the absolute minimum aluminum content in this group is 99%, the minimum for
certain grades is higher than 99%, and the last two digits represent the hundredths of a
per cent over 99. Thus, 1030 would indicate 99.30% minimum aluminum. without special
control on individual impurities. The designations 1130, 1230, 1330, etc.. indicate the
same purity with special control on one or more impurities. Likewise. 1100 indicates
minimum aluminum content of 99.00% with individual impurity control.
2xxx through 9xxx Series
The major alloying elements are indicated by the first digit, as follows:
2xxx Copper
3xxx Manganese
4xxx Silicon
5xxx Magnesium
6xxx Magnesium and silicon
7xxx Zinc
8xxx Other element
9xxx Unused series
The second digit indicates alloy modification. If the second digit is zero. it indicates
the original alloy: digits 1 through 9, which are assigned consecutively, indicate alloy
modifications. The last two digits have no special significance, serving only to identify
the different alloys in the group.
Experimental Alloys
Experimental alloys are designated according to the four digit system, but they are
prefixed by the letter X. The prefix is dropped when the alloy becomes standard. During
development, and before they are designated as experimental, new alloys are identified by
serial numbers assigned by their originators. Use of the serial number is discontinued
when the X number is assigned.
ALUMINUM TEMPER DESIGNATIONS
Temper designations of wrought aluminum alloys
consist of suff ixes to the numeric alloy designations. For example, in 3003-Hl4, 3003
denotes the alloy and "Hl 4" denotes the temper, or degree of hardness. The
temper designation also reveals the method by which the hardness was obtained. Temper
designations differ between non heat-treatable alloys and heat-treatable alloys. and their
meanings are given below:
Non Heat-Treatable Alloys
The letter "H" is always followed by 2 or 3 digits. The first digit indicates
the particular method used to obtain the temper. as follows:
- H1 means strain hardened only.
- H2 means strain hardened, then partially annealed.
- H3 means strain hardened, then stabilized.
The temper is indicated by the second digit as follows:
2 1/4 hard
4 1/2 hard
6 3/4 hard
8 full hard
9 extra hard
Added digits indicate modification of standard practice.
Heat-Treatable Alloys
-F As fabricated
-O Annealed
-T Heat treated
The letter "T' is always followed oy one or more digits. These digits indicate the
meathod used to produce the stable tempers, as follows:
-T3 Solution heat treated, then
cold worked.
-T351 Solution heat treated, stress-relieved stretched,
then cold worked.
-T36 Solution heat treated, then cold
worked (controlled).
-T4 Solution heat treated, then
naturally aged.
-T451 Solution heat treated, then stress relieved
stretched.
-T5 Artificially aged only,
-T6 Solution heat treated, then
artificially aged.
-T61 Solution heat treated (boiling water
quench), then artificially aged.
-T651 Solution heat treated, stress-relieved stretched,
then artificially aged (precipitation heat treatment).
-T652 Solution heat treated, stress relieved by
compression. then artificially aged.
-T7 Solution heat treated, then
stabilized.
-T8 Solution heat treated, cold
worked, then artificially aged.
-T81 Solution heat treated, cold worked
(controlled), then artificially aged.
-T851 Solution heat treated, cold worked,
stress-relieved stretched, then artificially aged.
-T9 Solution heat treated,
artificially aged, then cold worked.
-TlO Artificially aged, then cold worked.
Added digits indicate modification of standard practice.
This article taken from the Aircraft
Spruce Catalog. Used by permission.