What is heat treatment?
All of the typical processes performed on metals produce heat, whether it’s welding or cutting, and any time you heat metal, you change the metallurgical structure and properties of it. Inversely, you can also use heat treatment to restore metals to its original form.
Heat treatment is the process of heating metal without letting it reach its molten, or melting, stage, and then cooling the metal in a controlled way to select desired mechanical properties. Heat treatment is used to either make metal stronger or more malleable, more resistant to abrasion or more ductile.
Whatever your desired properties, it’s a given that you’ll never be able to get everything you want. If you harden a metal, you also make it brittle. If you soften a metal, you reduce its strength. While you improve some properties, you worsen others and can make decisions based on the metal’s end-use.
All heat treatments involve heating and cooling metals, but there are three main differences in process: the heating temperatures, the cooling rates, and the quenching types that are used to land on the properties you want. In a future blog post, we’ll cover the different types of heat treatment for ferrous metals, or metal with iron, which consist of annealing, normalizing, hardening, and/or tempering.
To heat treat metal, you’ll need the proper equipment so that you can closely control all of the factors around heating, cooling, and quenching. For example, the furnace must be the proper size and type to control temperature, including the gas mixture in the heating chamber, and you need the appropriate quenching media to cool metal correctly.