Aluminum Alloy Info
What is an Aluminum Alloy?
An Aluminum alloy is aluminum, combined with different alloying elements to increase certain characteristics that are desired, including strength, corrosion resistance, etc.
What do the numbers 2024, 3003 or 6061, etc mean?
The numbers describing the aluminum are the alloy number. The are a way of identifying the composition of the material.
Is it necessary to specify the alloy?
Only if there is some physical characteristic of the alloy that will have an impact on the application (such as corrosion resistance or strength) is it necessary to specify the actual alloy. Most of the time for general use, the alloy specification is not critical.
However, for critical applications you will need to consult an engineer to verify you have the correct alloy for the application.
What is temper?
Tempers describes it’s ability to spring back after it is flexed – in effect, the stiffness. A soft temper means that the piece can be easily bent and it will stay in that shape. A hard temper means that when it is bent, it springs back flat, and it takes a lot of force to put a kink into it. In aluminum the “O” temper is called annealed or “Dead Soft”, it is the most easily formed of all the aluminum tempers.
What are the letters and numbers T6, H14, or O after the Alloy number?
These are the temper designation of the material, they describe the temper (stiffness) of the aluminum, some alloys can be heat-treated to achieve a higher strength, some have to be cold worked to achieve the higher strength. A description of most common tempers are shown at the bottom of this page.
Alloy Numbers
These numbers refer to a specific chemical composition of the aluminum alloy . Pure aluminum is not used in very many applications, with it not being very machinable, low strength, etc. Pure aluminum must be combined with other elements to achieve the desired characteristics for each application. Some alloys provide high strength, some excellent corrosion resistance, etc.
1100
A low strength but very workable alloy with excellent corrosion resistance. It is not heat treatable. It is easily welded, however it is soft, and is like “chewing gum” when machined.
Tensile Strength: 14,000 to 24,000 psi
2011
A free machining, heat treatable alloy, with fair corrosion resistance, but not very easily welded.
Tensile Strength: 31,000 to 55,000 psi
2024
Heat treatable with high strength, good machinability and fair corrosion resistance. It welds very poorly.
Tensile Strength: 30,000 to 63,000 psi
3003
This alloy is not heat treatable but welds very well and has very good workability and excellent corrosion resistance. Like alloy 1100 it is somewhat soft and difficult to machine.
Tensile Strength: 17,000 to 30,000 psi
5052
Strong is not heat treatable, easily welded, with excellent corrosion characteristics. Typical uses fuel tanks, electronic mounting plates, panels, marine applications, etc.
Tensile Strength: 31,000 to 44,000 psi
5083
High Strength, with excellent welding and very high welding joint strength and excellent corroison resistance.
Tensile Strength: 40,000 to 59,000 psi
5086
Very strong, not heat treatable, with excellent corrosion resistance and good weldability.
Tensile Strength: 40,000 to 54,000 psi
6061
Heat treatable, easily welded, with very good corrosion resistance and finishing characteristics. Very commonly used for architectural and structural products.
Tensile Strength: 20,00 to 42,000 psi
6063
This heat treatable is specifically designed for extrusions, very popular for architectural shapes.
Low Strength, High corrosion resistance and excellent finishing qualities.
7050
High strength, excellent corrosion resistance, heat treatable, and weldable, but has poor workability.
7075
Heat treatable, this alloy is the strongest and hardest aluminum alloy. It has good machining characteristics but is not very easily welded nor is it very workable.
TEMPER LETTERS
The letters that appear after each alloy number refer to the “temper” of the alloy itself and are independent of the alloy. This means that a single alloy can be available in a variety of tempers and a variety of alloys can be available in the same temper.
F Temper (as fabricated tempers)
This letter indicates that there has been no effort to control the temper of the material.
O Temper (annealed temper)
Annealing is a process of heating up metal past a critical temperature whereby the material is relieved of the internal stresses from production or fabrication. It is the most easily bent temper available.
W Temper (solution heat treated temper)
This letter refers to metal that has undergone a specific procedure to produce a temper for a particular batch of metal in order to comply with some specific need of the customer.
H Temper (strain-hardened tempers)
This letter designates a process of stretching or compressing in order to impart a particular temper.
H_1 1/8 hard
H_2 1/4 hard
H_3 3/8 hard
H_4 1/2 hard
H_5 5/8 hard
H_6 3/4 hard
H_7 7/8 hard
H_8 Full hard
T Temper (thermally treated tempers)
These tempers are imparted by heating, quenching, or cooling in a controlled way.
T1 Cooled after being shaped to its final dimensions during a process involving high heat , then naturally aged to a stable condition.
T2 Cooled after being shaped to its final dimensions during a process involving high heat, then cold worked.
T3 Solution heat treated, cold worked and naturally aged to a stable condition.
T4 Solution heat treated and naturally aged to a stable condition
T5 Cooled after being shaped to its final dimensions during a process involving a lot of heat (such as extrusion), then artificially aged. T5 is T1 that has been artificially aged.
T6 Solution heat treated and artificially aged to a stable condition. T6 is T4 that has been artificially aged.
T7 Solution heat treated and naturally aged past the point of a stable condition. This process provides control of some special characteristics.
T8 Solution heat treated, cold worked and artificially aged. T8 is T3 that has been artificially aged.
T9 Solution heat treated, artificially aged and cold worked A stable temper T9 is T6 that has been cold worked.
T10 Cooled after being shaped to its final dimensions during a process involving a lot of heat (such as extrusion), then cold worked and artificially aged. T10 is T2 that has been artificially aged.