The most commonly used method for determining harden ability is the
end quench test developed by Jominy & Boegehold.
In this test a normalized 25 mm diameter & 100 mm length test sample
of steel to be evaluated is heated uniformly to its austenitizing temperature. The specimen is then removed from the furnace & placed in the end
quench test apparatus & immediately end quenched by a jet of room temperature water.
After end quenching, longitudinal flat surfaces are ground on opposite
sides of the test piece as per dimensions. This grinding is very important
for correct positioning of the sample in the fixture and also for accurate
repeatable and reliable test results.
Jominy Test Fixture is to be positioned on the main screw of the hardness
tester for checking hardness of the test sample. Hardness at equal intervals
(1 mm or 1/16') to be checked and noted. Plot the resulting
graph paper with hardness value as ordinate (Y axis) and
from the quenched end as abscissa (X axis). By comparing
resulting from end quench tests of different grades of steels, their relative
harden ability can be established. Thus the flatter the curve, the greater
the harden ability.
The details of the test are covered in IS : 3848-1981 & ASTM : A 255.