From olden times, heat has always been the best way to either improve or change the shape and properties of metals. Even today, with the existence of advanced techniques and methods, heat treatment processes are preferred while working with metals. In this article, we will go over the effects of heat on metals.
The Effects of Heat Treatment on Metals
When metals are exposed to intense heat, it expands, becomes resistance to electricity, and decreases its magnetism properties. That being said, the amount of change to its structure and properties highly depends on the temperature and the metal.

While the metal is hot, it ideally becomes softer, weaker, and more ductile, which is known as the allotropic phase transformation. It is during this phase that you can make changes to the structure of the metal, so much so that a sheet of metal can be stretched into a wire. When it comes to the increase in electrical resistance, heat causes the electrons in the metal to scatter, which makes it resistant to electrical currents.

Types of Heat Treatment Processes
As mentioned above, through heat treatment processes, metals change their microstructure and enhance their physical and mechanical characteristics making them more desirable and useful

Heat treatment is the process of heating and cooling metals to change their microstructure and to bring out the physical and mechanical characteristics that make metals more desirable.

The heat treatment processes generally include heating the metal to attain the desired change and then cooling the metal for it to retain the changes. Mentioned below are some of the common heat treatment processes:
Annealing

One of the most common and useful types of heat treatment processes, annealing is used to bring a metal closer to its equilibrium state. To carry out this process, the metal is heated using the above critical temperature that causes it to change its microstructure. This causes the metal to soften, making it more workable and increases its ductility. After the process is completed, the metal is cooled slowly.
Quenching

While quenching is less expensive than annealing, in quenching, you need to ensure you’re able to quickly cool the metal after it has been heated to the above critical temperature. Quenching is usually conducted with water, oil, or other sources, which hardens the steel at the same temperature accomplished through annealing.
Tempering

The most commonly used heat treatment process, tempering, is used to increase the hardness and toughness of the metal and reduce the brittleness. This process is most-effective for steel, as it creates a more ductile and stable structure for the metal. The aim of carrying out this process is to obtain the best combination of mechanical properties in the metal.
Normalizing

Normalizing is a form of heat treatment that eliminates impurities and improves strength and hardness by altering the grain size to be more uniform throughout the metal. This is achieved by cooling the metal by air after it has been heated to a precise temperature.

Regardless of advanced technology and techniques, heat treatment processes are always the best way to work with metals!