What process is commonly used to harden tool steels?

Quenching is a heat treatment process that involves heating the tool steel to a specified temperature where it becomes austenitic and then rapidly cooling it, usually in water or oil. This process transforms the microstructure of the steel, increasing its hardness significantly due to the formation of martensite. Tool steels are designed to maintain high hardness and wear resistance, which is why quenching is an essential step in preparing them for further use in tooling applications. This process is particularly relevant for tool steels that require high strength and edge retention, making it a common method in the industry.

While other processes like annealing and tempering are important in the overall heat treatment of steel, they serve different purposes. Annealing is used to relieve stresses and soften the material, making it easier to work with, and tempering is performed after quenching to reduce brittleness while retaining hardness. Forging, on the other hand, involves the physical shaping of metal and does not directly harden the material in the context of tool steel preparation.