6061 aluminium alloy

6061 is a precipitation hardening aluminum 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 aluminum for general purpose use.

It is commonly available in pre-tempered grades such as 6061-O (solutionized) and tempered grades such as 6061-T6 (solutionized and artificially aged) and 6061-T651 (solutionized, stress-relieved stretched and artificially aged).

Basic properties

6061 has a density of 2.70 g/cm³ (0.0975 lb/in³).

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 Aluminum (95.85%-98.56%)

Mechanical properties

The mechanical properties of 6061 depend greatly on the temper, or heat treatment, of the material. Young's Modulus is 10x10^6 psi (69 GPa) irrespective of temper.

6061-O

Annealed 6061 (6061-O 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 %.

6061-T4

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%.

6061-T6

T6 temper 6061 has an ultimate tensile strength of at least 42,000 psi (300 MPa) and yield strength of at least 35,000 psi (241 MPa). More typical values are 45,000 psi (310 MPa) and 40,000 psi (275 MPa), respectively. 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. The typical value for thermal conductivity for 6061-T6 at 80°C is around 152 W/m K. A material data sheet defines the fatigue limit under cyclic load as 14,000 psi (100 MPa).

Uses

• 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 used in automotive parts, such as wheel spacers.

• 6061 is used in the manufacture of aluminum cans for the packaging of foodstuffs and beverages.

• 6061 is used in SCUBA tanks (post 1995)

• 6061 was the material used for the Pioneer plaques.

• 6061 T6 along with 7075 aluminium alloy is frequently used in the secondary chambers and baffle systems in firearm sound suppressors (primarily pistol suppressors for reduced weight and functionality), while the primary expansion chambers usually require 17-4PH or 303 stainless steel or titanium.

Welding

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-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. 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.