1. Test Principle, Computational Formula
The basic principle of the Webster Hardness Tester is that press a certain shape chilled indenter into the surface of specimen under the action of a standard spring test force. It is defined that every 0.01mm indentation depth is one Webster hardness unit. The hardness of material and the indentation depth are in inverse proportion. The smaller the indentation depth is, the higher the hardness value is, while the bigger the indentation depth is, the smaller the hardness value is.
In the formula:
HW— The Webster hardness symbol
L— Extension length of the indenter, that is the indentation depth pressed into the specimen /mm
0.01—— Defined value/mm
Indication of hardness value: If the indentation depth of indenter is 0.05mm, the dial head will point at 15 scale. It is indicated that HW=20-5=15 unit hardness value. Write it before hardness symbol, that is 15HW.