Brinelltest

The Brinell hardness test, also known as the Brinell test, is a method for determining the hardness of materials by indenting their surface with a hard spherical indenter. It was developed by Johan August Brinell in 1900 and is widely used for metals and some other materials. The test uses a ball-shaped indenter made of steel or carbide, with common diameters of 5, 10, or 2.5 millimeters, depending on the material being tested and the expected hardness.

During the procedure, the indenter is pressed into the material surface with a specified load for a short dwell time, typically 10 to 15 seconds. After unloading, the diameter of the resulting impression is measured, usually with a microscope. The Brinell hardness number (BHN or HB) is calculated from the applied load, the ball diameter, and the impression diameter using the standard formula HB = 2P / (π D (D - sqrt(D^2 - d^2))), where P is the load in kilograms-force, D is the ball diameter in millimeters, and d is the impression diameter in millimeters. The resulting hardness value is expressed in HB, often in kilograms-force per square millimeter.

Standards and applications: The Brinell test is standardized in organizations such as ISO 6506 and ASTM E10. It is particularly suited for metals with coarse or uneven structures, weld regions, and larger samples where precise surface finishing is challenging. Limitations include relatively large indentation size, which can be problematic for thin sections, coatings, or materials with very high hardness. For such cases, other hardness tests like Vickers or Rockwell may be preferred.