The process of heating and cooling metals in order to change their microstructure and also to bring out the physical characteristics that make the metals more desirable is called heat treatment.
The temperatures that metals get heated to and the rate of them cooling after the treatment can significantly change the metal’s properties.
Some of the most common reasons that metals will undergo heat treatment are to improve their hardness, strength, toughness, ductility and corrosion resistance. Below we have a few examples of common heat treatments:
Annealing is a form of heat treatment which brings a metal closer to its equilibrium state. This type of heat treatment softens the metal which makes it more workable providing a greater ductility. In the annealing process, metal is heated above its upper critical temperature in order to change its microstructure. Thereafter, the metal will be slow-cooled.
What Is Quench Hardening?
Quench hardening is less expensive than annealing, it is a heat treatment method that quickly returns the metal to room temperature after its been heated above its upper critical temperature. This quench hardening process stops the cooling process from altering the metal’s microstructure.
Quench hardening, which can be done with oil, water and other media, will harden steel at the same temperature that full annealing does.
The Precipitation Hardening Process
Precipitation hardening, often referred to as age hardening, is a heat treatment process which creates uniformity in a metal’s grain structure.
This process will make the material stronger.
This process involves heating a solution treatment to very high temperatures after a fast cooling process. Precipitation hardening is most commonly executed in an inert atmosphere at temperatures that range from 900 to 1150 degrees Fahrenheit. It could take anywhere from 1 to 4 hours to carry out this process, it just depends on the thickness of the metal and similar factors.
Why Are Metals Tempered?
Tempering is most commonly used in steelmaking, it is a heat treatment used to improvise the hardness and toughness in steel, it also reduces brittleness. This process can create a much more ductile and stable structure. The point of tempering is to achieve the very best combination of mechanical properties in metals.
At Viking Foundry, we specialize in a wide range of heat treatments. For more information, visit our website on www.vfdy.co.za.