What kind of heat treatment does steel hardening belong to?
The hardening of steel is a type of heat treatment. Specifically, it is the quenching process in heat treatment. Hardening is the process of changing the crystal structure of steel by heating it to the appropriate temperature and then cooling it rapidly, thereby increasing its hardness and wear resistance.
The hardening process usually involves the following steps:
1. Heating (austenitizing treatment): First, the steel is heated to the appropriate temperature, usually above its critical temperature. This process transforms the steel's structure into an austenitic structure, a crystalline structure with the potential for high hardness.
2. Rapid cooling (quenching): Once the steel reaches the required temperature, it is rapidly cooled, usually by immersion in water, oil, or other cooling media. This rapid cooling process makes the steel's crystal structure very hard, but it also makes it brittle.
Hardening is a common heat treatment method often used to manufacture tools, parts and components that require high hardness and wear resistance, such as cutters, gears, bearings and molds, etc. However, hardened steel is usually very brittle, so subsequent tempering is often required to increase toughness and achieve the desired balance of properties. This treatment, called tempering after quenching, adjusts the trade-off between hardness and toughness.