This group includes all steels that can be used for the manufacture of tools. However, in practice, the application of this term is limited to high quality special steels used in the manufacture of tools or tools intended to work materials by cutting, pressing or machining. There are various procedures which can be used to group tool steels. One of them is the hardening medium used: there are water-hardening steels, oil-hardening steels and air-hardening steels. Another is by the alloying elements. Finally, depending on their intended application, they are classified into high-speed steels and cold work steels.
