The Knoop hardness testing procedure is also referred to as a microhardness test method. It is commonly used for lean sections, case depth work and tiny parts. The Knoop resulting notch is not as balanced as Vickers indentions, focusing on different variations of the resulting hardness assessments when testing to Knoop scales notably lower than 200gf. Knoop hardness is not distinctively being used to identify bulk hardness; however the Knoop hardness test method, ASTM stipulates a scope of light loads using a diamond indenter to formulate an indentation quantified and translated to a hardness rate. It comes in handy when testing a broad category of materials so long as the tests are prepared carefully.
The Knoop hardness tester
The Knoop diamond indenter is created with a significant disparity between the short and long Knoop diagonals, which is regularly better suited for establishing variations of hardness over very short distances than the Vickers indenter. The Knoop indentation’s perimeter is capable of offering further decree for measurement, and the indentation is also less profound. Contrasting the Vickers test where the indentation length on the erect and parallel axes are calculated and standardized, the Knoop method uses the extensive centre line: the dimension is transfigured to a Knoop hardness numeral using a graphic representation. Sectioning in Knoop hardness testing is crucial to provide a small but enough sample to fit into the tester. The test preparation process’s achievement in removing preparation-induced spoil can and will sway the test outcome; this hitch becomes more vital as the test force drops off.