Hardness. This usually defined as a metals ability to resist indentation or abrasion. The measurement of hardness is usually based on a metals resistance to the indentation of either a hardened steel ball(the Brinell hardnees test) or a diamond (the Vickers or Rockwell hardness tests). Abrasion test are sometimes used, as in the shot-and sand-blasting industries, for example.
Hardness can be increased by deformation caused by cold working. This is known as work-hardening. In steels, carbon is the main hardening element, and in many ferrous alloys high levels of hardness can be obtained by heating the alloy to a high temperature followed by rapid cooling.
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