I will be presenting a series of articles on tool steels, tool-steel categorization, tool-steel heat treatments and heat treating of specific tool steels.

What are tool steels? Tool steels can be considered to be alloy steels that have been developed for specific applications and manufactured under very strict and controlled conditions.

Tool steels are classified by a very simple method designed by the American Iron & Steel Institute (AISI) or the Society of Automotive Engineers (SAE).

Tool steels contain most of the alloying elements that are generally found in the steels that are categorized as alloy steels. The alloying elements are added under very controlled conditions. The manufacture of the particular tool steel is also completed under very controlled conditions to ensure cleanliness of the resulting steel, which will be as free as possible from impurities, inclusions and gases.

Shown in Figure 1 is a “tree” of some of these alloying elements. In part 2, we’ll look at tool-steel specifics.