The melting point of aluminum is a crucial physical property with which it is possible to create the ideal aluminum metal. The temperature at which a substance goes from solid to liquid directly influences its handling and application.
In this case, aluminum has a melting point that approaches 1220°F (660°C). Unlike other metals, in the case of aluminum it is almost double the melting point of zinc and half the temperature of the stainless steel melting process.
It is important to mention that the melting point of aluminum varies according to the composition of the alloy. This data is vital to know the time and temperature it will take to manufacture aluminum parts.
Elements of the aluminum melting process
In almost all metal manufacturing processes, these are usually required to be heated to their melting temperature. In this case, casting, fusion welding, and molding require the metals to be practically liquid in order to be created.
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Aluminum and alloys can be melted and remelted as needed. This process also includes melting, such as for the casting of ingots and billets, as well as for subsequent manufacturing processes such as rolling, forging, and recycling.
How is premium quality aluminum produced?
It is important to note that a quality aluminum is produced in a different way. Aluminum always presents as a compound, never in a pure form, as its properties are altered and quality cannot be guaranteed.
Pure forms of the metal must first be chemically refined into alumina or aluminum oxide. Then it must be melted into aluminum through an electrolytic reduction process, commonly called the Hall-Héroult, primary production process.
Did you know that according to the Aluminum Association the primary production process has become more efficient? Improving by 20% in the last 20 years.
How is aluminum obtained?
Obtaining aluminum begins with the extraction of a basic raw material called bauxite. This raw material is used to produce aluminum, and then impurities are removed from the bauxite through sedimentation and filtration.
This chemical process also produces alumina, but for it to work the bauxite must be crushed and mixed with a sodium hydroxide solution. In the end, it is heated with steam under pressure to dissolve the alumina and obtain the aluminum metal.
The melting point of aluminum
The melting point of aluminum oxide is higher than that of aluminum, in fact it must be done at about 3,762°F (2072.22°C). That's why the extraction of aluminum from aluminum oxide is done through a process called electrolysis before melting the metal.
Electrolysis is a separation technique that works to divide chemical elements. It is usually used in pots or reduction cells in a reductive process plant. This process removes the oxygen from the alumina and thus pure aluminum is obtained.
Factors affecting the melting point of aluminum
As in any chemical process, there are factors that affect the melting point of aluminum and it is important to know them so that we can obtain pure and premium quality aluminum for the necessary processes.
Alloy compound
We mentioned a moment ago that the type of aluminum alloys is an important factor in knowing how to handle the metal. Melting temperatures vary slightly depending on the alloy.
Some melting ranges for some alloys described by ASM International are:
- Alloy 1100: from 1190 (643.33°C) to 1215°F (657.22°C)
- Alloy 2024: from 935 (501.66°C) to 1180°F (637.77°C)
- Alloy 3003: from 1190 (643.33°C) to 1210°F (654.44°C)
- Alloy 5052: from 1125 (607.22°C) to 1200°F (648.88°C)
- Alloy 5456: from 1055 (568.33°C) to 1180°F (637.77°C)
- Alloy 6061: from 1080 (582°C) to 1205°F (651.66°C)
- Alloy 7075: from 890 (476.66°C) to 1175°F (635°C)
Chemical impurities in aluminum
Chemical impurities are common in metallurgical refining processes. In the case of aluminum and its alloys, they inevitably always contain impurities. An impurity is described as a chemical element that should not be in the composition of the alloy.
Chemical impurities will change the melting point temperature, so when the melting point varies by more than 41°F (5°C) it is called: melting point depression and this is a sign that there are impurities.
Impurities usually appear at different parts of the melting process. In fact, there can be contamination of the charge during melting and casting. Or it can occur during interaction with the metal coating and fluxes and even dissolution of elements from the casting equipment and casting tool.
Even impurities can enter during the remelting of aluminum waste in secondary production.
The composition of the molecules
There are characteristics that must be altered one way or another for the melting process to work. Molecules with strong bonds require more energy to break, in this case, aluminum has covalent bonds that lead to a higher melting point.
Also, the tensile strength of aluminum is important. This metal has strong polar bonds that lead to low volatility, high melting points, boiling points, and high density.
Finally, the application of pressure during the heating process can alter melting points as when the melting point starts to decrease above a certain critical pressure it can induce a reentrant heating.
At Ulbrinox we know the importance of knowing the melting point of aluminum in different industries. That's why we are one of the leading distributors of this metal in Mexico and Latin America.
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