2014 T6 Aluminum and 2014 T651 Aluminum
Both 2014-T6 and 2014-T651 aluminum alloys belong to the 2014 series and are heat-treated alloys, but they differ in their heat treatment processes and resulting mechanical properties.
The following table summarizes the differences between 2014-T6 and 2014-T651 aluminum:
| Characteristic | 2014-T6 Aluminum | 2014-T651 Aluminum |
| Stress Relief | There is no stress relief step. | After the stress relief step, the internal stress is reduced by stretching the metal. |
| Heat Treatment Process | Solution heat treatment + artificial aging | Solution heat treatment + stress relief + artificial aging |
| Dimensional Stability | May deform during machining. | More stable with reduced deformation due to stress-relief treatment. |
| Applications | Mainly used for applications requiring maximum strength, such as aerospace structural components. | Used for applications needing dimensional stability and reduced machining deformation, such as large aerospace parts. |
| Mechanical Properties | Provides high strength and good tensile strength. | Similar strength to T6, but with greater dimensional stability. |
2014-T6 Aluminum
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Heat Treatment Process: 2014-T6 aluminum alloy undergoes two main steps:
- Solution Heat Treatment: Aluminum is heated to a specific temperature to dissolve alloying elements into the solid solution.
- Artificial Aging: After solution heat treatment, the alloy is cooled and then artificially aged at a controlled temperature to enhance its strength.
- Mechanical Properties: The T6 temper provides a high strength-to-weight ratio, making it suitable for applications requiring excellent strength and durability, such as aerospace structures needing high tensile and yield strength.
- Common Applications: Aircraft structures, aerospace components, and high-performance applications where strength and fatigue resistance are essential.
2014-T651 Aluminum
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Heat Treatment Process: 2014-T651 aluminum alloy undergoes three steps:
- Solution Heat Treatment: Similar to T6, the alloy is heated to dissolve alloying elements.
- Stress Relief: After solution heat treatment, the alloy undergoes stress relief by stretching to reduce internal stresses introduced during manufacturing (such as rolling or forging).
- Artificial Aging: The alloy is then artificially aged to increase its strength.
- Mechanical Properties: Due to the stress-relief step, the mechanical properties in the T651 temper are more evenly distributed, with reduced risk of deformation or warping, making it ideal for large components and forgings requiring high precision.
- Common Applications: Structural components requiring high strength and resistance to deformation during machining or other processing, often used in aerospace applications like large, heavy components for wings and fuselage.
Material Properties of 2014 T6 and 2014 T651 Aluminum
| Physical Properties | Metric | English | Comments |
| Density | 2.8 g/cc | 0.101 lb/in³ | AA; Typical |
| Mechanical Properties | |||
| Hardness, Brinell | 135 | 135 | AA; Typical; 500 g load; 10 mm ball |
| Hardness, Knoop | 170 | 170 | Converted from Brinell Hardness Value |
| Hardness, Rockwell A | 50.5 | 50.5 | Converted from Rockwell B |
| Hardness, Rockwell B | 82 | 82 | - |
| Hardness, Vickers | 155 | 155 | Converted from Brinell Hardness Value |
| Ultimate Tensile Strength | 483 MPa | 70000 psi | AA; Typical |
| Tensile Yield Strength | 414 MPa | 60000 psi | AA; Typical |
| Elongation at Break | 13 % | 13 % | AA; Typical; 1/2 in. (12.7 mm) Diameter |
| Modulus of Elasticity | 72.4 GPa | 10500 ksi | In Tension |
| Modulus of Elasticity | 73.1 GPa | 10600 ksi | AA; Typical; Average of tension and compression. Compression modulus is about 2% greater than tensile modulus. |
| Compressive Modulus | 73.8 GPa | 10700 ksi | |
| Notched Tensile Strength | 414 MPa | 60000 psi | 2.5 cm width x 0.16 cm thick side-notched specimen, Kt = 17. |
| Ultimate Bearing Strength | 889 MPa | 129000 psi | Edge distance/pin diameter = 2.0 |
| Bearing Yield Strength | 662 MPa | 96000 psi | Edge distance/pin diameter = 2.0 |
| Poisson's Ratio | 0.33 | 0.33 | |
| Fatigue Strength | 124 MPa | 18000 psi | AA; 500,000,000 cycles completely reversed stress; RR Moore machine/specimen |
| Fracture Toughness | 19 MPa-m½ | 17.3 ksi-in½ | KIC; TL orientation. |
| Machinability | 70 % | 70 % | 0-100 Scale of Aluminum Alloys |
| Shear Modulus | 28 GPa | 4060 ksi | |
| Shear Strength | 290 MPa | 42000 psi | AA; Typical |
| Electrical Properties | |||
| Electrical Resistivity | 4.32e-006 ohm-cm | 4.32e-006 ohm-cm | AA; Typical at 68°F |
| Thermal Properties | |||
| CTE, linear 68°F | 23 µm/m-°C | 12.8 µin/in-°F | AA; Typical; Average over 68-212°F range. |
| CTE, linear 250°C | 24.4 µm/m-°C | 13.6 µin/in-°F | Average over the range 20-300ºC |
| Specific Heat Capacity | 0.88 J/g-°C | 0.21 BTU/lb-°F | Estimated from trends in similar Al alloys. |
| Thermal Conductivity | 154 W/m-K | 1070 BTU-in/hr-ft²-°F | AA; Typical at 77°F |
| Melting Point | 507 - 638 °C | 945 - 1180 °F | AA; Typical range based on typical composition for wrought products 1/4 inch thickness or greater. Eutectic melting is not eliminated by homogenization. |
| Solidus | 507 °C | 945 °F | AA; Typical |
| Liquidus | 638 °C | 1180 °F | AA; Typical |
| Processing Properties | |||
| Annealing Temperature | 413 °C | 775 °F | |
| Solution Temperature | 502 °C | 935 °F | |
| Aging Temperature | 160 °C | 320 °F | Sheet, plate, wire, rod, bar, shapes, tube; 18 hr at temperature |
| Aging Temperature | 171 °C | 340 °F | Forgings; 10 hr at temperature |