What Is 6061 Aluminum?
6061 aluminum is one of the key alloys in the 6000 series. Its primary alloying elements are magnesium and silicon, forming what is known as an aluminum-magnesium-silicon alloy. These elements give the 6000 series excellent overall performance, including high strength, outstanding corrosion resistance, and strong weldability.
6061 aluminum offers notable advantages such as high strength, strong corrosion resistance, an exceptional strength-to-weight ratio, good electrical and thermal conductivity, and reliable weldability. Because of these properties, it is widely used in the automotive sector, aerospace components, building materials, machinery manufacturing, and many other fields.
Overview of 6061-T6 Aluminum Properties
Chemical Composition of 6061 Aluminum
| Element | Percentage (%) |
|---|---|
| Aluminum (Al) | 95.85 – 98.56 |
| Magnesium (Mg) | 0.80 – 1.20 |
| Silicon (Si) | 0.40 – 0.80 |
| Iron (Fe) | 0 – 0.70 |
| Copper (Cu) | 0.15 – 0.40 |
| Chromium (Cr) | Up to 0.04 |
What Does "T6" Mean?
T6 is one of the standard tempers available for 6061 aluminum. Common 6061 tempers include:
6061-O: Fully annealed for maximum softness and formability.
6061-T4: Solution heat-treated and naturally aged, offering moderate strength.
6061-T6: Solution heat-treated and artificially aged for high strength.
6061-T651: Similar to T6 but stress-relieved by stretching to reduce residual stress after processing.
Physical Properties of 6061 Aluminum Alloy
Color: Silver-gray
Luster: Metallic
Malleability: High; easily shaped and formed
Ductility: Good; can be stretched or drawn into wire
Electrical Conductivity: High
Thermal Expansion: 23.6 × 10⁻⁶ K⁻¹ (at 25°C)
Crystal Structure: Face-centered cubic (FCC)
Reflectivity: Strong reflection of visible and infrared light
Surface Texture: Smooth and generally free of impurities
Introduction to the Properties of 6061-T6 Aluminum
6061 aluminum is a heat-treatable alloy featuring good plasticity, reliable weldability, excellent machinability, and medium-level strength. Even after annealing, it retains solid processing performance.
Magnesium and silicon are the main alloying elements, giving 6061 medium strength, excellent corrosion resistance, good weldability, and an effective anodizing response.
A small amount of copper is also included, increasing strength relative to 6063, but also making 6061 more sensitive to quenching. As a result, it cannot be air-quenched directly after extrusion; instead, it requires re-solution treatment followed by quenching and artificial aging to achieve maximum strength.
Yield Strength of 6061 Aluminum
For the 6061-T6 temper:
Ultimate tensile strength: ≥ 42,000 psi (290 MPa)
Yield strength: ≥ 35,000 psi (241 MPa)
Mechanical Properties of 6061-T6
| Property | Value |
|---|---|
| Ultimate tensile strength | 45,000 psi |
| Yield strength | 40,000 psi |
| Shear strength | 30,000 psi |
| Brinell hardness |
95 |
Physical Properties
| Property | Value |
|---|---|
| Density | 0.0975 lb/in³ |
| Melting point | 1,080–1,205 °F |
| Modulus of elasticity | 10,000 ksi |
| Poisson's ratio | 0.33 |
Thermal Properties
| Property | Value |
|---|---|
| Specific heat capacity | 0.214 BTU/lb-°F |
| Thermal conductivity | 1,160 BTU-in/hr-ft²-°F |
| Thermal expansion coefficient | 13.1 µin/in-°F |
6061-T6 Aluminum Density
The density of 6061-T6 aluminum is approximately 2.70 g/cm³, which is the widely accepted standard value.
As one of the most commonly used heat-treatable aluminum alloys, 6061-T6 combines good mechanical properties, strong corrosion resistance, and excellent weldability. The T6 temper indicates that the alloy has been solution heat-treated and artificially aged to reach peak strength.
