Hardness is the measure of a material’s resistance to localized permanent deformation. Permanent deformation is also called plastic deformation. While elastic deformation means that a material changes its shape only during the application of force, a resulting plastic deformation means that the material will not return to its original shape.
The three types of hardness are scratch, rebound, and indentation hardness. Measuring each type of hardness requires a different set of tools.
The commonly used units for hardness measurement we have are:
⦁ Brinell Hardness Number (HB) (Upto 3000 kgf)
⦁ Vickers hardness number (HV) (10 g to 1000 g)
⦁ Rockwell hardness number (HRA, HRB, HRC)
⦁ Leeb hardness value (HLD, HLS, HLE)