The term
hardened steel is often used for a
medium or high carbon steel that has been given the heat treatments of
quenching followed by
tempering. The quenching results in the formation of metastable
martensite, the fraction of which is reduced to the desired amount during tempering. This is the most common state for finished articles such as tools and machine parts. In contrast, the same steel composition in
annealed state will be softer as required for forming and
machining.