Not only is aluminum the largest occurring metal on earth but also has several uses in different industries.
Understanding aluminum melting point is crucial in deciding the ideal application for it. Here is a closer look at the aluminum melting point.
What is the Melting Point of Pure Aluminum?
First, the melting point of aluminum refers to the point at which it changes from solid to liquid. In its purest form, aluminum has a melting point of 660°C which is equivalent to 1220°F.
This is relatively low as compared to other metals such as copper and steel. Notably, most aluminum applications use it in its alloy form.
Hence, factors such as the alloy composition in aluminum affect its melting point. In addition to that, since aluminum has a lower melting point, adding it to other metals decreases their melting points.
Melting Point of Aluminum Alloys and Grades
As mentioned earlier, most aluminum applications are from its alloy form. Aluminum alloys are made by combining pure aluminum with elements such as zinc, iron, copper, magnesium, and nickel.
That said, the aluminum alloy contains 4 digits with the first one signifying the purity or the alloy type.
The second digit specifies the alloy modifications. However, the third and fourth digits have different indications depending on the alloy.
In the 1xxx series, the third and fourth digits represent purity while in the other series, they represent alloys in the group.
Having understood that here are the different melting points of Aluminum alloys and grades.
| Aluminum Alloy and grades | Melting point (°C) | Melting Point (°F) |
| 1xxx, Pure Aluminum | 660 | 1220 |
| 2xxx, Aluminum-Copper | 548 | 1018 |
| 3xxx, Aluminum-Manganese | 640-655 | 1184-1211 |
| 4xxx, Aluminum –Silicon | 577 | 1070 |
| 5xxx, Aluminum-Magnesium | 605-650 | 1121-1202 |
| 6xxx, Aluminum-Magnesium-Silicon | 580-650 | 1076-1202 |
| 7xxx, Aluminum-Zinc | 475-635 | 887-1175 |
Factors Affecting Melting Temperature of Aluminum
Aluminum melting point is never constant and can be altered by different factors such as:
· Impurities
Impurities tend to have significant effects on aluminum melting point and metals in general. Impurities lower the melting point of aluminum since they interfere with molecule arrangement. As such, it becomes easier for it to change from solid to liquid state.
This explains why the addition of alloy in pure aluminum lowers the melting point of aluminum. You can otherwise refer to this process as melting point depression.
· Pressure
Normally, the more the pressure the higher the melting point. This is because more energy is required to heat aluminum to reach its melting point.
· Force of Attraction
A higher force of attraction results in a higher aluminum melting point. Owing to the strong polar bonds in aluminum, there is a decrease in volatility but a rise in both density and melting point.
· Molecule Composition
As earlier mentioned, aluminum has strong bonds. Meaning that it requires more energy to break the strong covalent bonds and this in turn increases its melting point.
· Molecule Weight
The higher the molecular weight the higher the melting point and vice versa. Large molecules create a bigger space for intermolecular interactions to take place. This results in an increased force of attraction between molecules and the melting point. Hence, this explains why aluminum melting point increases with an increase in molecule size.
· Alloy Composition
Alloying elements greatly impact the melting point of aluminum alloys in the sense that they have varying melting points. Some of the alloys added to pure aluminum include zinc, copper silicon, and magnesium.
Notably, the addition of the alloying elements to pure aluminum could alter some properties of the alloys.
Remember, alloy elements can either increase the strength and hardness of the alloy. Take for example aluminum alloy that contains high copper content. In this case, the melting point will be decreased while the strength of the alloy increases.
Comparing the Melting Point of Aluminum to Other Metals
Generally, Aluminum’s melting point is lower as compared to several other metals like copper and iron.
Adding some of the elements in the table below could either increase or decrease the aluminum melting point.
The table below shows a comparison of aluminum melting points with other common metals.
| Metal | Melting Point (°C) | Melting Point (°F) |
| Aluminum | 660 | 1220 |
| Brass melting point | 930 | 1710 |
| Copper melting point | 1084 | 1938 |
| Cast Iron melting point | 1204 | 2200 |
| Stainless Steel melting point | 1375-1530 | 2500-2785 |
| Potassium melting point | 63.3 | 146 |
| Sodium melting point | 97.83 | 208 |
| Zinc melting point | 420 | 787 |
| Tungsten melting point | 3400 | 6152 |
| Nickel melting point | 1453 | 2647 |
| Magnesium melting point | 670 | 1240 |
| Manganese melting point | 1260 | 2300 |
| Bronze melting point | 913 | 1675 |
| Chromium melting point | 1860 | 1983 |
| Lead melting point | 328 | 622 |
| Carbon steel melting point | 1425-1540 | 2597-2800 |
| Titanium melting point | 1670 | 3038 |
| Gold melting point | 1063 | 1945 |
| Silver melting point | 961 | 1762 |
| Chromium melting point | 1860 | 3380 |
| Tin melting point | 232 | 450 |
| Carbon melting point | 3600 | 6512 |
| Silicon melting point | 1420 | 2588 |
Best Way to Melt Aluminum
The best and most common way to melt aluminum is using a furnace. Ideally, a steel crucible is used to hold the aluminum in the furnace while it’s being heated.
First, position your founder in a safe and stable spot. This can be on a metal stand, sand, bare earth, or even gravel. The aim is to avoid any surface that could get damaged from the heated aluminum spillage.
Next, place your crucible inside the foundry. If your foundry uses charcoal, be sure to fill in some charcoal beneath and around your crucible ensuring all spaces are covered. Whether you’re using a propane-fueled foundry or a charcoal-fueled foundry fix the propane torch or the blower tube to the foundry.
Afterward, light the foundry and leave it to heat up for a few minutes (preferably 10 minutes). The crucible should turn orange for you to know that the foundry is hot enough.
Finally, you can place your aluminum inside the crucible to start the melting process.
Some important tools that you need for this aluminum melting process aluminum include:
- Hook and grill tongs for handling the crucible
- Shepherd’s hook
- Dross stick
- Adjustable pliers
Why the Knowledge of Aluminum Melting Temperature is Critical
Understanding the melting temperature of aluminum is important in determining the impurities present.
Also, the melting point of aluminum could be used to identify it in cases where the metal cannot be identified. In simpler terms, the melting point can be compared to other metals’ melting temperatures to determine whether or not it’s aluminum.
Not forgetting that the melting temperature range is also used to assess the purity of aluminum. The higher the melting range the lower the purity and vice versa.
This is one of the useful data in the manufacture of aluminum products.
Application of Aluminum based on Melting Temperature
Aluminum is the largest occurring metal on earth and so are its applications.
It is widely used in different industries and some of its uses are dependent on its melting temperature.
Bear in mind that most of the aluminum applications use aluminum alloys which affects its melting point. As such, different alloys are well suited for specific applications as illustrated below;
| Alloys | Melting Point (°C) | Melting Point (°F) | Applications |
| 2024 | 500-636 | 935-1180 | Aircraft parts, strong structural applications, cylinders, gears and shafts, Pistons |
| 3003 | 640-656 | 1190-1211 | Heat exchangers, pipes, cabinets, chemical apparatus, trailer parts, truck parts, fuel tanks |
| 5052 | 605-651 | 1125-1201 | Marine equipment, hydraulic tubes, pressure vessels, fencing accessories, appliances |
| 6061 | 580-650 | 1080-1204 | Building materials, pipes, Auto parts, railroad cars, furniture, and bicycle frames |
| 7075 | 475-635 | 890-1175 | Aircraft parts (wings & fuselages), worm gears, missile components, gears and shafts |
Conclusion
To sum it up, in as much as aluminum is the largest occurring metal on earth, most of its applications use its alloy form.
These alloys possess different melting points based on the alloying element thus affecting aluminum applications. Therefore, it’s important to carefully understand the melting point of the aluminum alloy you’re using and its compatibility with your desired application.
More Resources:
Gold Melting Point – Source: HM
Melting Point of Metals – Source: Metal Supermarket
Titanium Melting Point – Source: HM
Metals Melting Point – Source: Online Metals
Silver Melting Point – Source: HM
Aluminum Melting Temperature – Source: Kloeckner
Brass Melting Point – Source: HM
Copper Melting Point – Source HM