Hardness test methods
Knoop (DIN EN ISO 4545-1)
Principle:
A diamond indenter in form of a pyramid with rhombic base plane with fixed angles between mutually opposite planes is pressed into the surface of a sample, and the long diagonal d of the indent which remains on the test surface after the test force F has been removed, is measured.
Measurement equation:
F in N, d in mm
Test forces assigned to the hardness scales:
hardness scale | Test force, N |
HK 0.01 | 0.09807 |
HK 0.02 | 0.1961 |
HK 0.025 | 0.2452 |
HK 0.05 | 0.4903 |
HK 0.1 | 0.9807 |
HK 0.2 | 1.961 |
HK 0.3 | 2.942 |
HK 0.5 | 4.903 |
HK 1 | 9.807 |