If you are a machinist or engineer looking to use 2618 aluminum, you must first learn about its properties. With this knowledge, you can maximize 2618’s potential, therefore achieving optimal results from your job. Continue reading to learn about the workability of 2618 and its applications.
What is 2618 Aluminum
2618 is an aluminum alloy favored for its strength, machinability, and corrosion resistance. It is not pure aluminum. Alloying elements include copper, magnesium, zinc, nickel, iron, and titanium.
2618 is best suited for high-temperature environments such as aerospace and motorsports. Engineers have been using this metal for decades to produce aircraft engine parts and motor pistons. Since 2618 retains strength at extreme temperatures, it is one of the best options for these applications.
Additionally, 2618 is renowned for its exceptional fatigue resistance. This is why engineers use it for components that withstand repeated thermal and mechanical stress. For more details, you can check the guide on 2618 aluminum fatigue resistance.
Chemical Composition & Variants
2618 high-performance traces back to its unique composition. Find below the key alloying elements that contribute to the strength and versatility of this metal.
| Element | Percentage | Role |
| Copper | 1.9% – 2.7% | Enhances strength |
| Magnesium | 1.3% – 1.8% | Improves strength further |
| Nickel | 0.9% – 1.2% | Improves performance at high temperatures |
| Iron | 0.9% – 1.3% | Increases strength and hardness |
| Silicon | 0.10% – 0.25% | Enhances the metal’s machinability |
| Titanium | 0.04% – 0.10% | Adds strength while keeping the metal lightweight |
| Zinc | 0.10% | Improves the machinability of the metal |
| Aluminum | Rem | Base element |
2618 belongs to a group of high-strength aluminum alloys developed by Rolls-Royce before World War II. Early engineers wanted to use 2618 in aircraft compressor blocks. But it was later used as the primary structural component of the Concorde airline.
Additionally, these chemical values represent the composition of regular 2618 aluminum. 2618A or DTD 5014A is a high-strength alternative characterized by Copper (2%) and Magnesium (1.5%). These alloying elements ensure good machinability and moderate resistance against moisture, acids, or chemicals.
Thanks to 2618A’s mechanical properties, it is mostly used in aerospace. 2618A is also suitable for manufacturing racing car pistons and other high-performance parts.
Physical & Thermal Properties
The physical and thermal properties of aluminum 2618 are described below:
Density:
2618 is a lightweight alloy. It has a density of 2.75 to 2.76 g/cm. 2618 is lighter than stainless steel. And it does not add much weight compared to other common alloys. This quality makes it perfect for lightweight aircraft components.
Melting Point:
The melting range of 2618 is around 549 to 638 °C. This means it can handle high temperatures, such as in engines, without melting. Meanwhile, 2618’s heat capacity is 0.875 J/g-°C.
Thermal Conductivity:
The thermal conductivity of 2618 is 147 W/m·K; therefore, it moves heat really well. This property is essential for pistons because it reduces hotspots that could cause cracking or warping.
Thermal Expansion:
The linear thermal expansion of 2618 Aluminum is 22–24 μm/m‑K from 20 °C.
Mechanical Properties
Understanding the mechanical properties of 2618 Aluminum will help you know if it suits your application. These include:
Tensile Strength:
The tensile strength of 2618 is 372 MPa, while its ultimate tensile strength can climb to 441 MPa. These values mean it will resist stress deformation well, yet still retain a small amount of ductility.
2618’s elongation at break is around 10 percent, so it is not super stretchy. That’s okay, though, since the material is favored for toughness, not elasticity.
Fatigue Strength:
The fatigue strength of 2618 is around 124 MPa, making it suitable for components subjected to repeated and fluctuating stress. This characteristic is useful in high-stress components that need long-term reliability, such as pistons or turbine blades.
Unlike 7075, which loses its edge above 150 °C, 2618 maintains usable performance at temperatures approaching 300 °C.
Comparison with Other Alloys:
In terms of room temperature strength, 2618 outperforms 2014-T6. However, it is slightly inferior to 7075-T6, which offers the greatest strength at room temperature.
High-temperature capability:
You can treat and artificially age 2618 and 2618A to achieve optimal temperature properties. Notably, 2618 can be enhanced to a maximum of 300. However, it maintains its mechanical strength well to around 200 °C.
Fabrication & Machinability
2618 is known for its workability. If you want to modify the alloy’s mechanical properties to suit your project, consider these options:
Machinability:
2618 aluminum provides good CNC machining characteristics, particularly in heat-treated conditions. For instance, you can easily cut, drill, and shape 2618 or 2618A to tight tolerances.
2618 is also dimensionally stable in cast condition, offering superior machinability than other alloys.
Forming & Forging:
2618 offers impressive cold and hot formability. It is recommended to hot work the alloy at 350 °C and 372 °C. On the other hand, you can cold work 2618 right after heat treatment or annealing. Additionally, if you want to forge 2618, the recommended temperature range is 372 to 552 °C.
Welding:
We recommend you weld 2618 using resistance, friction stir, laser, or TIG/MIG welding processes. It is not suitable for conventional fusion welding because the high temperatures can damage this alloy. For more details, you can check the guide on TIG/MIG welding.
Heat Treatment Options:
- Solution treatment: The solution heat treatment process for 2618 forgings is simple. Bring the metal to 510 or 521 °C, then hold for a minimum of 6 hours. After that, you can quench your material in boiling water.
- Aging for T61: if you would like to age T61, simply bring the material to 182 or 187 °C for 20 hours.
- Alternative cycles: You can age 2618 using conventional aging processes. Simply bring the metal to 527 °C for 24 hours, then quench it in boiling water. For better results, you can repeat the aging process. This time bring the material to 199 for a minimum of 20 hours, then cool it in the air.
- Annealing: You can anneal your 2618 at 385 °C for a duration of 4 hours. You can then slowly cool it in the furnace.
Applications & Performance
Aluminum 2618 is highly sought after because it is strong and exhibits decent machinability. The demand for this metal will only continue to grow. Let’s now cover examples of 2618 products.
Aerospace:
If you work in the aerospace industry, you’ll interact with 2618 aluminum frequently. Due to its lightweight properties, 2618 is perfect for manufacturing aircraft components and compressor blades. Other aerospace applications include pistons, rotating parts, wings, and fuselages. For more details, check the guide on 2618 aluminum in aerospace manufacturing.
Automotive & Motorsport:
Grade 2618 Aluminum proves to be useful in the motorsports industry. With its strength and toughness, manufacturers use the metal to produce engine components that can endure high heat. These include engine blocks, automotive pistons, and rotating parts.
Other uses:
The thermal conductivity of 2618 makes it suitable for plastic mold applications. These include blow molding, compression molds, rotational molds, reaction injection molds, and resin transfer molds.
Historical relevance:
As you learned earlier, 2618 belongs to a group of alloys developed by Rolls-Royce before World War II. 2618 was originally meant to be used for jet engine compressor blades. But it was later selected as the main structural component of the Concorde supersonic airliner.
Grades & Variations
These are the main forms and grades of aluminum 2618.
Standard 2618:
2618 is most commonly sold as forgings, bars, and sheets. All variations are heat-treatable and designed for high-temperature environments.
2618A (DTD 5014A):
Another form of 2618 Aluminum is 2618A. It is characterized by copper (2%) and Magnesium (1.5%).
2618A offers acceptable machinability and fair resistance against atmospheric conditions. 2618A is also a strong aluminum alloy since it retains its strength up to temperatures of 300 °C.
Extruded round bars of 2618A are sold in sizes up to 650mm in diameter. The T6 and T5611 tempers correspond to the specifications below:
- DTD 5014A
- RRMS 34000
- MSRR 8018A
- AMS-STD-2154 Class A
2618A is also available in extruded bar, plate, round tube, and sheet form.
Zirconium-modified 2618
If you’re working with 2618, you might notice it is prone to hot cracking. Studies demonstrate that adding trace amounts of Zirconium to the metal may reduce cracking. Zirconium-modified 2618 has a high density and crack-free microstructure. For more details, you can check the guide on Zirconium Modified 2618.
Comparison Table
Understanding the performance differences between 2618 and aluminum alloys like 7075, 4032, and 6061 is crucial. Each alloy offers distinct properties that are best suited to different applications.
| Feature | 2618 Alloy | 7075 | 4032 | 6061 |
| Primary Alloys | Copper, Magnesium | Zinc, Copper, Magnesium | Copper, Magnesium, Silicon | Magnesium, Silicon |
| Density | 2.77 | 2.81 | 2.69 | 2.70 |
| Tensile Strength | ~441 MPa | ~570 MPa | 380 MPa | 310 MPa |
| Yield Strength | 370 | 505 | 315 | 275 |
| High-Temp Capability | Good up to ~300 °C | Moderate up to 120°C | Moderate up to 150°C | Good up to 150°C |
| Corrosion Resistance | Moderate | Fair | Fair | Excellent |
| Machinability | Excellent | Fair | Excellent | Moderate |
| Fatigue Resistance | Excellent | Excellent | Moderate | Moderate |
| Weldability | Fair | Poor | Poor | Exceptional |
| Key Strengths | Retains strength at extreme temperatures | Exceptional strength | Low thermal expansion, wear resistance | General engineering |
| Key Limitations | Limited corrosion resistance | Vulnerable to corrosion, poor weldability | Poor weldability | Inferior strength compared to 7075 |
Due to 2618’s temperature properties, it is commonly used to make aircraft and motorsports components. Parts like engine blocks and pistons are subjected to high heat and pressure. Therefore, manufacturers can produce reliable and long-lasting components when they select 2618.
7075, in contrast, offers the greatest strength of common aluminum alloys. It is best-suited for high-stress components, such as gears, missile parts, aircraft wings, and fuselages, among others.
Similar to 2618, 4032 is favored for engine parts since it has low thermal expansion and acceptable durability.
Lastly, 6061 is the most versatile of these alloys. It offers the best weldability and moderate corrosion resistance, so it is most commonly found in architectural applications. These range from bicycle frames to aircraft frames and yacht structures.
Conclusion
Selecting the optimal alloy is an important step in manufacturing. 2618 is a strong aluminum alloy, and its resistance to thermal fatigue makes it suitable for demanding applications. If you want to ensure the best settings for your projects, get in touch with JIEJIA CNC.
FAQs
How is 4032 aluminum different from 2618 aluminum?
The primary difference between 4032 and 2618 Aluminum lies in their chemical composition. 4032 is created with a high silicon content, often up to 12%.
The silicon content reduces the aluminum’s expansion rate and durability, making it a good choice for motor pistons. In contrast, the lower silicon content in 2618 makes it more malleable, which makes it better suited for high-load and high-stress applications.
2618 aluminum vs 6072 aluminum: what is the difference?
The difference between 2618 and 6061 aluminum is clear. 2618 has superior strength and durability, but it is not easily welded. 6061, in contrast, offers good weldability and corrosion resistance, making it best suited to general engineering applications.
How is 7075 aluminum different from 2618 aluminum?
Due to their high strength, 2618 and 7075 have quite similar applications. For instance, 2618 is known for its high temperature properties, making it the prime choice for engine parts.
Meanwhile, 7075 offers better strength but inferior temperature and corrosion resistance. This is why 7075 is widely used to create structural components in the automotive, aircraft, marine, and construction industries.
How much do 2618 pistons expand?
The lower silicon content affects the thermal expansion of 2618. Therefore, a 2618 piston will expand 15% more than its 4032 counterpart.
What is the material 2618t6?
To achieve the T6 temper, you can treat and artificially age 2618. Additionally, stretching of the material will produce the T6511 temper.
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