6061 is a precipitation hardening aluminium alloy, containing magnesium and silicon as
its major alloying elements. Originally called "Alloy 61S," it was developed in 1935. It
has good mechanical properties and exhibits good weldability. It is one of the most common
alloys of aluminium for general purpose use. It is commonly available in pre-tempered grades
such as 6061-O and tempered grades such as 6061-T6 and 6061-T651.
Basic properties 6061 has a density of 2.70 g/cm³.
Chemical composition The alloy composition of 6061 is:
Silicon minimum 0.4%, maximum 0.8% by weight Iron no minimum, maximum 0.7%
Copper minimum 0.15%, maximum 0.40% Manganese no minimum, maximum 0.15%
Magnesium minimum 0.8%, maximum 1.2% Chromium minimum 0.04%, maximum 0.35%
Zinc no minimum, maximum 0.25% Titanium no minimum, maximum 0.15%
Other elements no more than 0.05% each, 0.15% total
Remainder Aluminium Mechanical properties
The mechanical properties of 6061 depend greatly on the temper, or heat treatment, of the material.
Young's Modulus is 10×106 psi regardless of temper.
6061-O Annealed 6061 has maximum tensile strength
no more than 18,000 psi, and maximum yield strength no more than 8,000 psi. The material
has elongation of 25–30%. 6061-T4
T4 temper 6061 has an ultimate tensile strength of at least 30,000 psi and yield strength
of at least 16,000 psi. It has elongation of 16%.
6061-T6 T6 temper 6061 has an ultimate tensile strength
of at least 42,000 psi and yield strength of at least 35,000 psi. More typical values
are 45,000 psi and 40,000 psi, respectively. In thicknesses of 0.250 inch or less, it
has elongation of 8% or more; in thicker sections, it has elongation of 10%. T651 temper has
similar mechanical properties. The typical value for thermal conductivity for 6061-T6
at 77°F is around 152 W/m K. A material data sheet defines the fatigue limit under cyclic
load as 14,000 psi for 500,000,000 completely reversed cycles using a standard RR Moore
test machine and specimen. Note that aluminum does not exhibit a well defined "knee" on
its S-n graph, so there is some debate as to how many cycles equates to "infinite life".
Also note the actual value of fatigue limit for an application can be dramatically affected
by the conventional de-rating factors of loading, gradient, and surface finish.
Uses 6061 is commonly used for the following:
construction of aircraft structures, such as wings and fuselages, more commonly in homebuilt
aircraft than commercial or military aircraft. 2024 alloy is somewhat stronger, but 6061
is more easily worked and remains resistant to corrosion even when the surface is abraded,
which is not the case for 2024, which is usually used with a thin Alclad coating for corrosion
resistance. yacht construction, including small utility
boats. automotive parts, such as wheel spacers.
the manufacture of aluminium cans for the packaging of foodstuffs and beverages.
SCUBA tanks 6061-T6 is used for:
the construction of bicycle frames and components. many fly fishing reels.
The famous Pioneer plaque was made of this particular alloy.
the secondary chambers and baffle systems in firearm sound suppressors, while the primary
expansion chambers usually require 17-4PH or 303 stainless steel or titanium.
The upper and lower receivers of many AR-15 variants.
Many aluminum docks and gangways are constructed with 6061-T6 extrusions, and welded into place.
Material used in some Ultra-high vacuum chambers Welding
6061 is highly weldable, for example using tungsten inert gas welding or metal inert
gas welding. Typically, after welding, the properties near the weld are those of 6061-O,
a loss of strength of around 80%. The material can be re-heat-treated to restore -T4 or -T6
temper for the whole piece. After welding, the material can naturally age and restore
some of its strength as well. Nevertheless, the Alcoa Structural Handbook recommends the
design strength of the material adjacent to the weld to be taken as 11,000 psi without
proper heat treatment after the weld. Typical filler material is 4043 or 5356.
Extrusions 6061 is an alloy used in the production of
extrusions—long constant–cross-section structural shapes produced by pushing metal
through a shaped die. Forgings
6061 is an alloy that is suitable for hot forging. The billet is heated through an induction
furnace and forged using a closed die process. Automotive parts, ATV parts, and industrial
parts are just some of the uses as a forging. References
Further reading "Properties of Wrought Aluminum and Aluminum
Alloys: 6061 Alclad 6061", Properties and Selection: Nonferrous Alloys and Special-Purpose
Materials, Vol 2, ASM Handbook, ASM International, 1990, p. 102-103.