MICROHARDNESS (KNOOP / VICKERS)

Knoop & Vickers(Micro)/ASTM E384
These are the standard test methodsfor Microindentation Hardness of Materials. Knoop indenter has a rhombic-based pyramidal diamond with an included longitudinal angle of 172° 30´ and an included transverse angle of 130° 0´. The narrow, elongated indenter makes it ideal for testing materials with steep hardness gradients. Only the long diagonal of the indentation is measured for calculations. Knoop is widely used for microindentation hardness testing in USA. 
Vickers has a square-based pyramidal shaped indenter with face angles of 136°. Both the diagonals of the indentation are measured for calculations.