|The Jominy Test
involves heating a test piece from the steel (25mm diameter and
100mm long) to an austenitising temperature and quenching from one
end with a controlled and standardised jet of water.
Take a sample from the furnace and place it on the Jominy test
fixtures and observe the cooling pattern.
After quenching the hardness profile is measured at intervals from
the quenched end after the surface has been ground back to
remove any effects of decarburisation
(0.38mm is removed from the surface).
The hardness variation along the test surface is a result of
microstructural variation which arises since the cooling rate
decreases with distance from the quenched end. The cooling rate
along the Jominy test specimen varies from about 225 °C s-1
to 2 °C s-1.