Brinellhårdhetstal

Brinellhårdhetstal is a measure of the resistance of a material to plastic deformation under indentation. It is determined by pressing a hardened steel or carbide ball of a specified diameter into the surface of the material to be tested under a specified load for a specified time. The diameter of the resulting indentation is then measured.

The Brinell hardness number (HB) is calculated by dividing the applied load by the surface area of the indentation. The formula is HB = (2 * F) / (π * D * (D - sqrt(D^2 - d^2))), where F is the applied load in kilograms-force, D is the diameter of the ball indenter in millimeters, and d is the average diameter of the indentation in millimeters.

The Brinell hardness test is widely used for testing the hardness of metals and alloys, particularly those with a coarse grain structure or those that are too soft to be tested with other hardness testing methods. The test is relatively simple and inexpensive to perform, and it provides a good indication of the material's tensile strength.

However, the Brinell hardness test has some limitations. It can only be used for materials that are not too hard, as the ball indenter can be deformed by very hard materials. The test can also be affected by the surface finish of the specimen, and it is important to ensure that the surface is clean and free from any defects.

The Brinell hardness scale is typically expressed in units of HB or HBW, with the "W" indicating that a tungsten carbide ball was used. Common ball diameters are 10 mm, and common loads are 500 kgf, 1500 kgf, and 3000 kgf, depending on the material being tested.