Tool steel refers to a variety of carbon steel and alloy steel that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures. As a result, tool steels are suited for use in the shaping of other materials.

Cold-work steels are further subdivided into:

• Air-hardening
• Medium-alloy cold-work steels
• High-carbon, high-chromium cold-work steels
• Oil-hardening cold-work steels

Hot work steels are subdivided into:

• Chromium
• Tungsten
• Molybdenum hot work steels

High-speed tool steels are divided into:

• Molybdenum
• Tungsten
• Intermediate high-speed steels

Other types of tool steels include:

• Water-hardening tool steels
• Shock-resistant tool steels
• Low-carbon tool steels
• Low-alloy special purpose tool steels.

=References=

• Wikipedia: Tool steel
• Tool Steel Classifications