ABSTRACT
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Tool steels are very special steels used to shape, cut, and form an extremely wide variety of
metals and othermaterials under demanding conditions. The first known toolmade of iron date
back 60 centuries. The heat treatment to harden tool iron, consisting of heating and water
quenching,was known30 centuries ago.The earliest tool steelswere basedonplain carbon steel.
In the mid-19th century and early in the 20th century, highly alloyed tool steels were developed
to meet very stringent requirements for specific applications. This evolution was taking place in
parallel with the understanding of the benefit of the alloying elements such as manganese,
tungsten, molybdenum, vanadium, and chromium, and their availability. In parallel to this
evolution, steelmaking evolved toward more controlled conditions to improve the quality and
cleanliness of the tool steels. This advance in technology and knowledge allows designing
specialized tool steels for cold and hot working of metals, molding plastics, as well as for
many other special purposes. This chapter reviewsmanufacturing andheat treatment of various
types of tool steels to achieve the required properties for specific applications.