There can be confusion
over what is meant by hardenability and hardness.
- a steel property which describes the
depth to which the steel may be hardened during quenching. It is important to note that hardenability is a material property,
dependent on chemical composition and grain size, but independent of
the quenchant or quenching system (cooling rate). However, the
structures obtained across a quenched section are a function of both
hardenability and the quenching process (severity of quench).
- a measure of the resistance of a material
to plastic deformation. This depends on the carbon content and
microstructure of the steel. Hence the same steel can exhibit
different hardness values depending upon its microstructure, which
itself may depend on how the sample was quenched, etc.
In order to select an appropriate heat treatable engineering steel
for a given application it is important to be able to measure its
hardenability. The most convenient way to do this is via Jominy
Hardenability (or End Quench) Test. The other
technique is to use transformation diagrams but
these are more time consuming to generate. However there are now many
in the literature that can be referred to.