What is the difference between 2024 T3 and 2024 T81?
The heat treatment processes of 2024 T3 and 2024 T81 aluminum are different, resulting in differences in their mechanical properties.
2024 T3 and 2024 T81 Key Differences
Here is a table summarizing the Key Differences between 2024-T3 and 2024-T81 aluminum based on specific properties:
| Property | Key Difference |
| Tensile Strength: Ultimate (UTS) | 2024-T81 has higher UTS |
| Tensile Strength: Yield (Proof) | 2024-T81 has higher yield strength |
| Elongation at Break | 2024-T3 has higher elongation at break |
| Fatigue Strength | 2024-T3 has higher fatigue strength |
| Shear Strength | 2024-T81 has slightly higher shear strength |
- 2024 T81 improves fatigue strength and toughness through a more stringent aging process, making it more suitable for high-strength applications subjected to long-term alternating loads, such as aircraft landing gear.
- 2024 T3 is suitable for structural components that require high strength but do not need extreme fatigue resistance.
2024 T3 and 2024 T81 are two common states of 2024 aluminum alloy, both belonging to the heat treatment and processing forms of 2024 aluminum. Although they share the same alloy composition (mainly aluminum, copper, magnesium, and manganese), their differences in processing and heat treatment result in variations in mechanical properties, performance, and application fields.
Differences between 2024 T3 and T81
T3 and T81 are two different heat treatment and processing states of 2024 aluminum alloy. The main difference lies in the aging process.
Below is a table showing the main differences between 2024 T3 and 2024 T81 aluminum:
| Characteristics | 2024 T3 Aluminum | 2024 T81 Aluminum |
| Aging Process | Shorter aging process, with a shorter treatment time | Longer aging process, with a longer time and lower temperature |
| Mechanical Properties | High tensile strength, relatively low ductility | Better fatigue resistance and toughness |
| Applicability | Suitable for high-strength environments but not extreme load conditions | Suitable for high-fatigue-strength environments subjected to long-term alternating loads |
| Main Applications | Aircraft structural components, wing skins, etc. | Aircraft landing gear, structural frames, and other high-fatigue-strength components |
The table clearly shows the differences between 2024 T3 and 2024 T81: 2024 T3 aluminum is suitable for environments requiring high strength, while 2024 T81 aluminum has advantages in fatigue resistance and long-term stability, making it ideal for higher load and longer-duration environments.
2024 T3 Aluminum
Heat Treatment State: T3 indicates that the aluminum alloy has undergone solution treatment, followed by cold working (usually cold rolling or drawing), and then artificial aging for hardening.
Hardening Process:
- Solution Treatment: The aluminum alloy is heated to the solution temperature and held for a period to achieve uniform distribution of the alloying elements.
- Cold Working: The material is cold rolled or drawn to increase its strength.
- Aging Treatment: The material is heated to a certain temperature (usually lower than the solution temperature) to allow the precipitates to gradually form and enhance strength.
Mechanical Properties:
Strength: 2024 aluminum alloy in T3 condition has high yield strength and tensile strength, but relatively low ductility.
Applicability: T3 state is suitable for applications requiring high strength and strong tensile capabilities, commonly used in aerospace structural components.
Typical Applications: Aircraft structures, wing skins, and components for aerospace vehicles, etc.
2024 T81 Aluminum
Heat Treatment State: T81 is a more stringent aging process based on the T3 condition of 2024 aluminum alloy, usually involving a longer aging or low-temperature annealing treatment.
Hardening Process:
- Solution Treatment: Similar to T3, the alloy is first subjected to solution treatment.
- Cold Working: Typically similar to T3, but the cold working in T81 may focus more on optimizing the microstructure.
- Aging Treatment: Compared to T3, the aging treatment in T81 is usually longer and at a lower temperature, allowing for more uniform precipitation and sometimes improved aging strength.
Mechanical Properties:
Strength: The aluminum alloy in T81 condition has higher strength, particularly improved fatigue resistance, making it suitable for environments subjected to alternating loads.
Toughness: Compared to T3, T81 exhibits better toughness and ductility, making it more ideal for certain applications, especially those requiring fatigue resistance.
Typical Applications: T81 aluminum alloy is often used in applications that require higher fatigue strength and longer service life, such as structural frames of aircraft, landing gear, and other components exposed to high-frequency alternating loads.
2024 T3 and 2024 T81 Mechanical Properties
Tensile Strength and Yield Strength
In general, T81 condition will have higher tensile and yield strength than T3, making it suitable for applications requiring higher strength.
Ductility and Toughness
T3 condition typically offers better ductility and toughness, making it suitable for applications that require shaping and forming.
T81 condition may have lower ductility, making it more suitable for applications that do not require deep forming.
| Property | 2024-T3 Aluminum | 2024-T81 Aluminum |
| Elastic (Young's, Tensile) Modulus, x 10⁶ psi | 10 | 10 |
| Elongation at Break, % | 15 | 5.4 |
| Fatigue Strength, x 10³ psi | 20 | 19 |
| Poisson's Ratio | 0.33 | 0.33 |
| Shear Modulus, x 10⁶ psi | 3.9 | 3.9 |
| Shear Strength, x 10³ psi | 41 | 43 |
| Tensile Strength: Ultimate (UTS), x 10³ psi | 69 | 75 |
| Tensile Strength: Yield (Proof), x 10³ psi | 47 | 65 |
2024 T3 and 2024 T81 Thermal Properties
| Property | 2024-T3 Aluminum | 2024-T81 Aluminum |
| Latent Heat of Fusion, J/g | 390 | 390 |
| Maximum Temperature: Mechanical, °F | 390 | 390 |
| Melting Completion (Liquidus), °F | 1180 | 1180 |
| Melting Onset (Solidus), °F | 930 | 930 |
| Specific Heat Capacity, BTU/lb-°F | 0.21 | 0.21 |
| Thermal Conductivity, BTU/h-ft-°F | 70 | 70 |
| Thermal Expansion, µm/m-K | 23 | 23 |
Electrical Properties
| Property | 2024-T3 Aluminum | 2024-T81 Aluminum |
| Electrical Conductivity: Equal Volume, % IACS | 30 | 30 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 90 | 90 |
Otherwise Unclassified Properties
| Property | 2024-T3 Aluminum | 2024-T81 Aluminum |
| Base Metal Price, % relative | 11 | 11 |
| Calomel Potential, mV | -600 | -600 |
| Density, lb/ft³ | 190 | 190 |
| Embodied Carbon, kg CO₂/kg material | 8.3 | 8.3 |
| Embodied Energy, x 10³ BTU/lb | 65 | 65 |
| Embodied Water, gal/lb | 140 | 140 |
