Rockwell number

American  

noun

Metallurgy.

1. a numerical expression of the hardness of a metal as determined by a test Rockwell test made by indenting a test piece with a Brale, or with a steel ball of specific diameter, under two successive loads and measuring the resulting permanent indentation.

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Etymology

Origin of Rockwell number

1930–35, named after Stanley P. Rockwell, 20th-century American metallurgist