|Density (?)||2.70 g/cm3|
|Young's modulus (E)||68.9 GPa (9,990 ksi)|
|Tensile strength (?t)||124-290 MPa (18.0-42.1 ksi)|
|Elongation (?) at break||12-25%|
|Poisson's ratio (?)||0.33|
|Melting temperature (Tm)||585 °C (1,085 °F)|
|Thermal conductivity (k)||151-202 W/(m·K)|
|Linear thermal expansion coefficient (?)||2.32×10-5 K-1|
|Specific heat capacity (c)||897 J/(kg·K)|
|Volume resistivity (?)||32.5-39.2 nOhm·m|
6061 is a precipitation-hardened aluminum alloy, containing magnesium and silicon as its major alloying elements. Originally called "Alloy 61S", it was developed in 1935. It has good mechanical properties, exhibits good weldability, and is very commonly extruded (second in popularity only to 6063). 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 (annealed), tempered grades such as 6061-T6 (solutionized and artificially aged) and 6061-T651 (solutionized, stress-relieved stretched and artificially aged).
The alloy composition of 6061 is:
Annealed 6061 (6061-O temper) has maximum tensile strength no more than 120 MPa (18,000 psi), and maximum yield strength no more than 55 MPa (8,000 psi). The material has elongation (stretch before ultimate failure) of 25-30%.
T4 temper 6061 has an ultimate tensile strength of at least 210 MPa (30,000 psi) and yield strength of at least 110 MPa (16,000 psi). It has elongation of 16%.
T6 temper 6061 has an ultimate tensile strength of at least 290 MPa (42,000 psi) and yield strength of at least 240 MPa (35,000 psi). More typical values are 310 MPa (45 ksi) and 270 MPa (39 ksi), respectively. In thicknesses of 6.35 mm (0.250 in) 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 25 °C (77 °F) is around 152 W/m K. A material data sheet  defines the fatigue limit under cyclic load as 97 MPa (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.
6061 is commonly used for the following:
6061-T6 is used for:
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-T4, a loss of strength of around 40%. The material can be re-heat-treated to restore near -T6 temper for the whole piece. After welding, the material can naturally age and restore some of its strength as well. Most strength is recovered in the first few days to a few weeks. Nevertheless, the Aluminum Design Manual (Aluminum Association) recommends the design strength of the material adjacent to the weld to be taken as 165 MPa/24000 PSI without proper heat treatment after the welding. Typical filler material is 4043 or 5356.
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. This particular alloy is suitable for open die forgings. Automotive parts, ATV parts, and industrial parts are just some of the uses as a forging. Aluminum 6061 can be forged into flat or round bars, rings, blocks, discs and blanks, hollows, and spindles. 6061 can be forged into special and custom shapes.
Different forms and tempers of 6061 aluminum alloy are discussed in the following standards: