The ability of a ferrous alloy to form martensite when quenched from a temperature above the upper critical temperature.
A term applied to steels to describe the relative ease with which martensite can be formed in the steel. The lower the cooling rate at which a fully martensitic microstructure can be formed in the steel when it is cooled from austenitic condition the higher is the hardenability. Hardenability is commonly assessed by the Jominy end quench test.
The fundamental characteristic of a steel which determines the ease of preventing the transformation of austenite to anything else but martensite during the quench.