Aluminum 6061 properties
Chemical Composition
Section titled “Chemical Composition”Aluminum 6061 contains 97.9% aluminum, with the main alloying elements consisting of 1.0% magnesium and 0.60% silicon. The typical nominal composition is detailed below.
| Element | Content (%) |
|---|---|
| Aluminum (Al) | 95.85 – 98.56 |
| Magnesium (Mg) | 0.80 – 1.20 |
| Silicon (Si) | 0.40 – 0.80 |
| Iron (Fe) | ≤ 0.70 |
| Copper (Cu) | 0.15 – 0.40 |
| Chromium (Cr) | 0.04 – 0.35 |
| Zinc (Zn) | ≤ 0.25 |
| Titanium (Ti) | ≤ 0.15 |
| Manganese (Mn) | ≤ 0.15 |
| Others (each) | ≤ 0.05 |
| Others (total) | ≤ 0.15 |
Physical Properties
Section titled “Physical Properties”The density of aluminum 6061 is 2.70 g/cm³ (0.0975 lb/in³) and its melting point is 585 °C (1085 °F). Other relevant physical properties are listed in the following table.
| Property | Metric value | Imperial value |
|---|---|---|
| Density | 2.70 g/cm³ | 0.0975 lb/in³ |
| Melting point | 585 °C | 1085 °F |
| Modulus of elasticity | 68.9 GPa | 10 000 ksi |
| Shear modulus (T6) | 26.2 GPa | 3.80 Msi |
| Poisson’s ratio | 0.33 | 0.33 |
Mechanical Properties by Temper
Section titled “Mechanical Properties by Temper”In the most common temper (T6), the tensile strength reaches 310 MPa (45 ksi) and the yield strength 276 MPa (40 ksi), with an elongation of 12–17%. The values vary significantly with heat treatment.
| Temper | Yield strength (Rp0.2) | Tensile strength (Rm) | Elongation (min.) | Brinell hardness (HBW) |
|---|---|---|---|---|
| O (annealed) | ≤ 110 MPa (16 ksi) | ≤ 150 MPa (22 ksi) | 16 % | 30 |
| T4 | ≥ 110 MPa (16 ksi) | 180 – 205 MPa (26 – 30 ksi) | 14 – 16 % | 58 – 65 |
| T6 | 240 – 276 MPa (35 – 40 ksi) | 290 – 310 MPa (42 – 45 ksi) | 4 – 10 %* | 80 – 95 |
* Elongation varies with thickness; for parts with thickness ≤ 6.35 mm the minimum is 8%, while for larger sections it reaches 10%.
Additional properties for T6 temper:
- Shear strength: 207 MPa (30 ksi).
- Fatigue strength (500 × 10⁶ cycles, fully reversed): 96.5 MPa (14 ksi).
Thermal Properties
Section titled “Thermal Properties”The thermal conductivity of aluminum 6061-T6 at room temperature (25 °C) is 167 W/(m·K), with a specific heat capacity of 897 J/(kg·K). The material maintains good thermal performance up to a maximum service temperature of 160 °C.
| Property | Metric value | Imperial value |
|---|---|---|
| Coefficient of thermal expansion (20–100 °C) | 23.2 × 10⁻⁶ /°C | 12.9 × 10⁻⁶ /°F |
| Thermal conductivity (25 °C) | 167 W/(m·K) | 1160 BTU·in/(h·ft²·°F) |
| Specific heat capacity (cₚ) | 897 J/(kg·K) | 0.214 BTU/(lb·°F) |
| Maximum service temperature | 160 °C | 320 °F |
Electrical Properties
Section titled “Electrical Properties”The volume electrical resistivity of 6061 is in the range of 32.5 – 39.2 nΩ·m, which corresponds to an electrical conductivity (IACS) of approximately 40% of standard annealed copper.
| Property | Metric value | Imperial (equivalent) value |
|---|---|---|
| Electrical resistivity | 32.5 – 39.2 nΩ·m | ≈ 2.05 – 2.47 μΩ·in |
| Electrical conductivity (% IACS) | ~ 40 % | – |
Heat Treatment
Section titled “Heat Treatment”The typical solution heat treatment for 6061 consists of heating to 533 °C (990 °F) followed by water quenching, and then artificial aging in two stages: 160 °C (320 °F) for 18 h followed by air cooling, and then 177 °C (350 °F) for 8 h also with air cooling. To obtain the annealed condition (O), the alloy is held at 415 °C for 2–3 hours with controlled cooling.
Welding
Section titled “Welding”Aluminum 6061 exhibits excellent weldability, especially in the T4 and T6 tempers, although the heat-affected zone loses some strength. Thin sections are preferably welded using the TIG (GTAW) process, while thicker sections use MIG (GMAW). Filler metal 4043 is recommended, although its use may affect the final mechanical properties of the T6 temper.
Machining and Forming
Section titled “Machining and Forming”Machinability of 6061 is considered good in the T4 and T6 tempers; in the annealed temper it can be machined but with a higher tendency to dulling. The alloy is easily formed in the O (annealed) condition and lends itself to operations such as bending, deep drawing, and spinning. Forging is performed in a temperature range of 233 to 483 °C (750 to 900 °F).
Applications by Industry
Section titled “Applications by Industry”6061 is the most widely used heat-treatable aluminum alloy, found in structural components requiring a good strength-to-weight ratio. By sector:
- Aerospace and defense: fittings, connectors, brackets, frames.
- Automotive: motorcycle chassis, suspension parts, racing radiators.
- Marine: masts, ladders, deck components.
- Machinery and tooling: blow molds, supports, precision machined parts.
- Sports and leisure: fishing reels, bicycle frames, airsoft components.
- Construction and furniture: profiles, joints, bolted connections.
Comparison with Similar Materials
Section titled “Comparison with Similar Materials”Compared to other aluminum alloys, 6061 offers an excellent balance of strength, toughness, and fabricability.
| Alloy | Temper | Tensile strength (MPa) | Yield strength (MPa) | Weldability | Machinability | Corrosion resistance |
|---|---|---|---|---|---|---|
| 6061 | T6 | 310 | 276 | Excellent | Good | Very good |
| 6063 | T6 | 240 | 215 | Excellent | Good | Very good |
| 6082 | T6 | 310 | 260 | Very good | Good | Very good |
| 7075 | T6 | 572 | 503 | Limited | Fair | Medium |
| 5052 | H32 | 228 | 193 | Excellent | Fair | Excellent (marine) |
6061 exceeds 6063 in strength but has slightly lower extrudability. 7075 offers much higher mechanical properties, although its weldability and corrosion resistance are lower. Compared to 5052 (non-heat-treatable), 6061 stands out in structural applications where subsequent heat treatment is required.
Equivalent Designations
Section titled “Equivalent Designations”Alloy 6061 is identified under multiple standards and designation systems.
| System | Designation |
|---|---|
| UNS | A96061 |
| AA / EN AW | 6061 |
| DIN (WNR) | 3.3211 (AlMg1SiCu) |
| SAE | J454 |
| ASTM standards | B209, B210, B211, B221, B241, B308, B429, etc. |
| AMS standards | 4117, 4025, 4026, 4027 |
| MIL standards | MIL-A-12545, MIL-W-23351, among others |
Frequently Asked Questions (FAQ)
Section titled “Frequently Asked Questions (FAQ)”What is the maximum tensile strength of aluminum 6061 in T6 temper?
Section titled “What is the maximum tensile strength of aluminum 6061 in T6 temper?”The maximum tensile strength can reach 310 MPa (45 ksi), and a minimum of 290 MPa (42 ksi) is guaranteed per standards.
What is the melting point of 6061?
Section titled “What is the melting point of 6061?”The melting temperature is 585 °C (1085 °F), although the full melting range extends approximately from 582 °C to 652 °C (1080 – 1205 °F).
What is the thermal conductivity of 6061-T6?
Section titled “What is the thermal conductivity of 6061-T6?”At 25 °C the thermal conductivity is 167 W/(m·K), equivalent to 1160 BTU·in/(h·ft²·°F).
What is the Brinell hardness of 6061-T6?
Section titled “What is the Brinell hardness of 6061-T6?”The typical Brinell hardness of 6061-T6 is 95 HBW, although it can vary between 80 and 95 HBW depending on the exact process.
What is the modulus of elasticity value for 6061?
Section titled “What is the modulus of elasticity value for 6061?”Young’s modulus is 68.9 GPa (10 000 ksi) regardless of temper or heat treatment.
What is the minimum elongation in T6 temper?
Section titled “What is the minimum elongation in T6 temper?”For thicknesses equal to or less than 6.35 mm (0.250 in) the minimum elongation is 8%, while in thicker sections it reaches 10%.
References
Section titled “References”- azom.com: https://www.azom.com/article.aspx?ArticleID=6636
- engineeringtoolbox.com: https://www.engineeringtoolbox.com/properties-aluminum-pipe-d_1340.html
- steelnumber.com: https://www.steelnumber.com/en/steel_alloy_composition_eu.php?name_id=1150