Jominy test

a method for determining the hardenability of steel. The Jominy test is covered by BS 4437:1987. A standard test piece 25 mm x 100 mm is heated to a pre-determined temperature and quenched by a jet of water sprayed onto one end. When the specimen is cold, hardness measurements are made at intervals along the test piece from the quenched end and the results are plotted on a standard chart from which is derived the hardenability curve. BS 970 contains hardenability curves for many of the steels in the Standard. Properly carried out, this test will illustrate the effect of mass upon a chosen steel when heat treated and indicate if the steel is of a shallow, medium or deep hardening type.