Hardness of Metals

Hardness of Metals:

Information extracted from Collier's Encyclopedia


Hardness of metals is usually determined by measuring the resistance to penetration of a ball or cone. The Brinell test on steel determines the resistance of indentation of a hardened steel ball 10 mm. in diameter under a load of 3,000 kg. (500 kg. for softer metals). The Brinell hardness scale is based on the ratio of the load in kilograms to the surface area of the indentation in square centimeters.


In the Rockwell method an indentation on a 1/16 in diameter steel ball is measured. Two superimposed impressions are made, first by applying a 10-kg. load and setting the gauge at zero, and then by increasing the load to 100 kg. and measuring the indentation recorded by the gauge. The instrument has a hardness scale called the B-scale.

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