Hardness Testing 

HRDHardness Testing is the measurement of a material’s resistance to penetration. HRD is used to assess a material’s resistance to abrasives, resistance to plastic deformation, its strength and brittleness or lack of ductility. Hardness is not a fundamental property of a material and is defined by the measurement technique applied. HRD can show if a component material is changing properties during operation.

In the laboratory, HRD is commonly performed using a Vickers or Rockwell hardness tester. Laboratory testers rely on measuring the relationship between load and the indentation in the surface produced by a ball, cone or pyramid applied to the surface (see Figure).
Techniques for portable HRD testers have been developed. One such technique uses the measurement of the velocity of a body before and after hitting the component surface to calculate a hardness value. Another approach uses the change in resonant frequency of a body when it is
embedded in the material. Portable HRD equipment gives an LCD readout of the hardness value.
For more information on HRD see:

What the hec?! articles are not intended to be the definitive account on the topic or acronym in question. Readers’ comments and contributions are welcomed. Email: