Knoop Hardness Test

A hardness testing method in which the microhardness of a specimen is determined by forcing a rhombohedral-shaped diamond indenter into a test specimen at a load ranging between 1 gram and 1,000 grams and measuring the long axis created by the rhombohedral-shaped diamond tip indenter. This value is then converted to a Knoop Hardness Number, abbreviated KHN or HK.