This test consists of quenching a standardized specimen of steel that is the object of study.
It is first heated to the austenization temperature, subsequently cooled by a stream of water at a flow rate and at a specified temperature, which only cools its lower face.
This face acts as a quenchant surface and cools the specimen longitudinally towards its upper end only by conduction, appearing a cooling gradient (maximum speed at the quenched lower endand minimum at the upper end).