The hardenability of a steel is an important indicator of the suitability of the steel and the manner in which it may be processed by heat treatment to provide the desired or designed properties in the product or component. The Jominy end quench test is a popular method of providing a measure of the hardenability of steels. Implicit in the specified procedures for the test (e.g. under BS 4437:1969 or ASTM A 255-67) is that the hardness profiles of the steels will be the same whatever the depth of the flats that are ground on the opposite sides of the Jominy specimens, provided that they are beyond 0.4 mm. The validity of this assumption is explored systematically in this paper. Investigations were carried out on two shallow-hardening steels as these were the most liable to give different hardnesses for different depths of flats. It is found that, provided sufficiently long austenitising times are used, different depths ground off the Jominy specimens produce only minor differences in the Jominy hardness profiles. However, if the austenitising times are inadequate, significant differences in the hardness profiles result.
