6061 is a precipitation hardening aluminium alloy, containing magnesium and silicon as its major alloying elements. 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 (solutionized), 6061-T6 (solutionized and artificially aged), 6061-T651 (equivalent to T6 in rolled stock).
6061 has a density of 2.70 g/cm³ (0.0975 lb/in³).
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
The mechanical properties of 6061 depend greatly on the temper, or heat treatment, of the material.
Annealed 6061 (6061-0 temper) has maximum tensile strength no more than 18,000 psi (125 MPa), and maximum yield strength no more than 8,000 psi (55 MPa). The material has elongation (stretch before ultimate failure) of 25-30 %.
T4 temper 6061 has an ultimate tensile strength of at least 30,000 psi (207 MPa) and yield strength of at least 16,000 psi (110 MPa). It has elongation of 16%.
T6 temper 6061 has an ultimate tensile strength of at least 42,000 psi (290 MPa) and yield strength of at least 35,000 psi (241 MPa). In thicknesses of 0.250 inch (6.35 mm) or less, it has elongation of 8% or more; in thicker sections, it has elongation of 10%. T651 temper has similar mechanical properties. The famous Pioneer plaque was made of this particular alloy.
6061 is widely used for construction of aircraft structures, such as wings and fuselages, more commonly in homebuilt aircraft than commercial or military aircraft.
6061 is used for yacht construction, including small utility boats.
6061 is commonly used in the construction of bicycle frames and components.
6061 is highly weldable, for example using tungsten inert gas welding (TIG) or metal inert gas welding (MIG). Typically, after welding, the properties near the weld are those of 6061-0, a loss of strength of around 80%. The material can be re-heat-treated to restore -T4 or -T6 temper for the whole piece.
6061 is also an alloy used in the production of extrusions—long constant–cross-section structural shapes produced by pushing metal through a shaped die.
6061 is also an alloy that is commonly used in a 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.