mikroomhärdhetstestet

The mikroomhärdhetstestet, or microhardness test, is a method used to measure the hardness of a material on a very small scale. This technique is particularly useful for testing materials that are too thin or too delicate to be tested using standard macrohardness methods, or for assessing the hardness variation across a surface. The test involves indenting the material's surface with a precisely shaped indenter under a specific load.

The most common type of microhardness test is the Vickers test. In this method, a diamond pyramid indenter with a square base and an apex angle of 136 degrees is pressed into the material's surface. The load applied is typically very light, ranging from 10 grams-force (gf) to 1 kilogram-force (kgf). After the load is removed, the length of the diagonals of the resulting indentation is measured using a microscope. The Vickers hardness number (HV) is calculated based on the applied load and the average length of the diagonals.

Other types of microhardness tests exist, such as Knoop and Rockwell superficial tests, each employing different indenter geometries and load ranges suitable for specific applications. The microhardness test is invaluable in fields like metallurgy, materials science, and failure analysis. It allows for the evaluation of surface treatments, coatings, and the uniformity of hardness within a material. Due to the small indentation size, sample preparation is critical to ensure accurate and repeatable results.