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The Brinell hardness test measures the hardness of materials using a steel or carbide ball and a set amount of pressure. It was developed by Johan August Brinell in 1900 and is commonly used for metals and alloys. The test results are given in a standardized scale and include the type of ball used, diameter, force applied, and time.
The Brinell hardness test is used to determine the hardness of materials in relation to other materials along a consistent scale, so that scientists can both replicate the results and have a frame of reference for a material’s given hardness. During the test, a small steel or carbide ball is forced into the material of unknown hardness with a set amount of pressure. The area of the resulting indentation is measured and a mathematical formula is applied to obtain a Brinell hardness number. Brinell hardness is commonly used in reference to metals and alloys, although it can refer to other materials as well.
The test is named after Johan August Brinell, a Swedish engineer who lived from 1849 to 1925. His work with metals led to several discoveries including the Brinell hardness test. Its name is also related to brinelling, an engineering term referring to the point at which a metal breaks down under load and impact. He developed the Brinell hardness in 1900 and the discovery revolutionized the field of engineering as he created a standardized scale that could be easily referenced.
In a test for Brinell hardness, the ball used is typically about 4/10 of an inch (10 millimeters) in diameter. If the material is extremely hard, the ball will be tungsten or carbide, while for softer substances a simple steel ball is sufficient. The amount of pressure also varies depending on the material, but a standard amount of pressure for harder substances is 6,614 pounds (3,000 kilograms). The ball is forced into the material to be tested for thirty seconds and then removed so that reentry can be measured. The formula divides the force used by the surface area of the indentation.
When giving the Brinell hardness of a material, it is conventional to list the test conditions and metric measurements are used. The list begins with the Brinell hardness number, follows with the type of ball used, then lists the diameter of the ball, the amount of force applied, and the amount of time. For example, pine, an extremely soft wood, would be listed like this: 1.6 HBS 10/100/30. This means that the Brinell hardness of pine is 1.6 when impressed with a hardened steel ball that is 4/10 of an inch (10 millimeters) in diameter under a weight of 220 pounds (100 kilograms) for 30 seconds.
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