Vickers hardness test
The Vickers hardness test was developed in the early 1920s and uses a pyramid-shaped indenter made of diamond. It is based on the principle that impressions made by this indenter are geometrically similar regardless of load. Accordingly, loads of various size are applied, depending on the hardness of the material to be measured. The Vickers Hardness (HV) is then determined from the formula
HV = (1.854 F / D^2)
where F= applied load, kg; and D= the diagonal of the impression made by the indenter, mm, as indicated in the figure. The Vickers test can be used for all metals and has one of the widest scales among hardness tests.