Material Science and Technology for kids

Definitions

Back to Main page

More about the Jominy End Quench Test

Back to Case study
Back to definition
 The Jominy end quench test is a test used to determine the hardenability of a steel alloy.  The procedure for the test is to first heat a cylinder shape of the alloy to a very high temperature in which austenite is formed throughout.  One end of the specimen is then subjected to a jet of cold water, or water quenched, thus this end is cooled at the maximum rate.   The cooling process continues to flow through the length of the bar like water flows through a pipe.  Therefore, the rate of cooling diminishes along the remaining length of the specimen.  After the specimen has cooled to room temperature, hardness measurements can be made along the length of it.

 

The water-quenched end forms a martensitic structure and thus has the highest hardness values.  Since the cooling rate decreases with distance from the quenched end, carbon has more time for diffusion and the softer pearlite can form.  Therefore, the greater the distance from the quenched end, the lower the hardness values.