Hardness of Metals
Hardness of Metals:
Information extracted from Collier's Encyclopedia
Brinell: 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.
Rockwell: 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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