heat treatment of aluminum

Heat Treatment of Aluminum and Aluminum alloys

Summary

Heat treatment is the process of heating or chilling, to an extreme temperature to achieve a desired shape through the hardening or softening of a material.

Heat treatment of aluminum and copper undergoes almost the same heat-treating process. but their result is different. The methods of annealing, homogenizing, and solution heat treatment on copper and aluminum give different results.

Since there are different applications made with aluminum, meeting the requirements of the items will require aluminum to undergo heat treatment. heat treatment will change the properties of aluminum in certain ways to meet a desired characteristic.

The heat treatment of aluminum and aluminum alloys includes annealing, homogenizing, solution heat treatment, natural aging, artificial aging, or precipitation hardening. Learn about the heat treatment of ferrous and nonferrous metals here!

https://studentlesson.com/heat-treatment-process-of-ferrous-and-non-ferrous-metals

Now, let’s go deep to explain the heat treatment of aluminum and aluminum alloys!

Contents

Heat treatment of aluminum & aluminum alloys

Heat treatment of aluminum and copper undergoes almost the same heat-treating process. but their result is different. The processes of annealing, homogenizing, and solution heat treatment on copper and aluminum give different results.

Just as explained, annealing is carried out in copper to soften the materials that have been hardened. It is done on aluminum to achieve strain-hardened material, unlike copper, which loses its hardening (strain hardening) when annealed. The same occurs with homogenizing.

Heat treatment of aluminum is carried out to increase the strength and hardness of a certain subset of aluminum alloys that are hardened by precipitation.

Different requirements for aluminum properties lead to various heat-treating processes. Below are the heat treatments for aluminum and aluminum alloys:

Annealing:

Aluminum alloys obtain strain hardening when subjected to work. It occurs when the material is plastically deformed, which causes the grain structure within the aluminum to slide against each other along the slip plane area.

The purpose of such aluminum alloys is to restore the crystalline grain structure and the slip plane. Helping the continuation of the shaping with low force. In other words, to relieve internal stresses that are developed during operation, such as cold forging or casting.

Annealing is achieved on aluminum alloys when the material is heated at about 570 to 770 degrees Fahrenheit, which is about 30 minutes to 3 hours. The temperature and time are determined by the composition of the alloys and the size of the material. The rate of cooling is not critical. That is, it has no effects after the annealing process is achieved.

Homogenizing:

Homogenizing is done to distribute the precipitation elements more evenly in an aluminum part. It is achieved by raising its temperature below its melting point, usually between 900 degrees Fahrenheit and 1000 degrees Fahrenheit. If the homogenizing temperature reaches 100 °C, the aluminum is allowed to slowly cool.

Solution heat treatment:

The purpose of solution heat treatment is to allow the metal part to easily work. It is performed by heating the aluminum part at a specific temperature, depending on the alloy composition in the aluminum. Specifically, at the range of 825 degrees Fahrenheit to 980 degrees Fahrenheit. If the exact temperature is not obtained, the operation will not be successful.

That is, if the temperature is too low, there will be strength lost, and when the temperature is too high, the part could melt, and end up being discolored. Or increased strain within the part. The part is soaked when it reaches the target temperature. This soaking time can range from 10 minutes for the materials to 12 hours for longer or thicker parts. The part is quenched at this point.

The quenching or rapid cooling helps to preserve the final distribution of dissolved elements in the alloy that was achieved. that is, to “freeze” the trapped elements in place, or to cool the aluminum part rapidly enough to keep the alloying element from precipitating out as the part cools. The part is commonly cooled with water.

heat treatment of aluminum

Natural aging:

Aluminum that undergoes solution heat treatment will precipitate out after some time, which will cause the grain to look into position, helping to increase the natural strength of the part. The natural aging or age-hardening process takes place at room temperature within four to five days, obtaining at least 90 percent of the hardening within the first day. For this reason, aluminum materials are shaped rather quickly after they undergo solution heat treatment.

Artificial aging (precipitation hardening):

Artificial hardening is done when an aluminum part needs maximum hardness, which is not achieved during natural aging, at room temperature. To achieve this, the dissolved elements need to be fully precipitated out, which is done by subjecting aluminum to heat in an alloy at a specific temperature. usually at 240 degrees Fahrenheit and 460 degrees Fahrenheit, respectively.

At this point, it is soaked for about six to twenty-four hours and then cooled to room temperature. the aluminum part will then increase in yield strength, show a slight increase in tensile strength, and decrease in ductility. Learn about the heat treatment of copper here!

Heat treatment of copper and copper alloys

That is all for this article, where I explained the heat treatment of aluminum and aluminum alloys. I hope you get a lot from this post; if so, kindly share it with other students. Thanks for reading, see you next time!


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