Hardness

The resistance of that metal to penetration or scratching. In a hardness test an indenter of known shape and size is pushed/forced into the metal surface with a known pre-established pushing load. The size of the penetration or resistance to penetration is measured. This resistance to penetration is reported as a number dependent on the type of indicator and the load causing the indention. One of the first and simplest hardness tests was the “scratch scale”. In the “Scratch Scale of Hardness” the materials that were the most scratch resistant were above (harder than) those with lesser resistance to scratching.