HARDNESS TESTING

The Brinell hardness test is a test that can provide useful information about metallic materials. This information may correlate to tensile strength, wear resistance, ductility, or other physical characteristics of metallic materials. This test may also be useful in quality control and selection of materials. Brinell hardness testing at a specific location on a part may not represent the physical characteristics of the whole part or end product. The Brinell Hardness Test consists of applying a constant load or force, usually between 500 and 3000 Kgf, for a specified time (from 10 – 30 seconds) using a 5 or 10 mm diameter tungsten carbide ball. The load time period is required to ensure that plastic flow of the metal has ceased.

Lower forces and smaller diameter balls are sometimes used in specific applications. Similar to Knoop and Vickers testing, the Brinell test applies only a single test force. After removal of the load, the resultant recovered round impression is measured across diagonals at right angles and is usually recorded millimeters using a low-power microscope or an automatic measuring device. The Brinell hardness test method as used to determine Brinell hardness, is defined in ASTM E10. Most commonly it is used to test materials that have a structure that is too coarse or that have a surface that is too rough to be tested using another test method, e.g., castings and forgings. Brinell testing often use a very high test load (3000 kgf) and a 10mm wide indenter so that the resulting indentation averages out most surface and sub-surface inconsistencies.