Hardness number which does not depend on the ductility of metal:
KNOOP HARDNESS TEST (KHN)
A diamond indenting tool is used. Knoop hardness values is independent of the ductility of the material and values for both exceedingly hard and soft materials can be obtained from this test. The Knoop and Vickers tests are classified as microhardness tests. The Brinell and Rockwell tests are classified as macrohardness tests.
Mannapalli 3rd ed page no 17
KHN
VHN
RHN
BHN