Jominy testing - hardenability testing 

The hardenability of an alloy is measured by a Jominy End Quench Test, also called a Jominy Hardenability Test or Jominy Test. Hardenability refers to the test specimens ability to be hardened to a particular depth under a particular set of conditions. The jominy end quench test provides information needed for selecting the proper combination of alloy steel and heat treatment to minimize thermal stresses and distortion when manufacturing components of various sizes. The test is conducted by first heating the specimen, then quenching and finally grinding a flat surface before taking hardness measurements along the sample.

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The Jominy test provides a measure of the ability of a steel to harden by transforming into martensite under set conditions, i.e., a measure of the hardenability of the steel. A standardised bar, 25.4 mm diameter and 102 mm long, is heated to the austenitising temperature and then placed on a rig in which one end of the rod is quenched by a standard jet of water. This results in a progressive decrease in the rate of cooling along the bar from the quenched end. The depth from the quenched end, over which martensite is obtained, is then the measure of hardenability.