Brinell Hardness Testers

Brinell hardness testers are used widely with castings and forgings. The Brinell test method applies a predetermined test force to a carbide ball of fixed diameter that is held for a predetermined time and then removed. The diameter of the indentation width is measured twice, usually at right angles to each other and averaged. A formula or chart is then used to convert the averaged measurements to a Brinell hardness number. Test forces usually range from 500 to 3000 kilograms (occasionally down to 1 kg in less frequently used tests). Carbide Brinell indenters are 10 mm in diameter; however, there are less frequently used tests with light loads and smaller diameter indenters (from 5 mm to 1 mm). Generally, the Brinell tester load must be held for 10 - 15 seconds, although in practice, shorter dwell times may be used if they will not influence the test result. Typically, Brinell test measurements are made to the nearest 0.05 mm by using a standard 20X Brinell scope. Measurements from Brinell hardness testers are subject to operator influence.