WARNING: Machine tools present a safety hazard. Improper operation can result in severe injury. These topics are for non-laboratory study only and are not to be used in conjunction with the operation of any tool or machine described herein. Never use a machine tool without the supervision of a qualified instructor.
In metallurgy, hardness is the characteristic of a solid material expressing its resistance to permanent deformation. Hardness can be measured using a Rockwell C scale tesitng instrument. Hard materials are tool steels and daimonds.