Rockwell number

noun Metallurgy.

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.

Origin of Rockwell number

1930–35, Americanism; named after Stanley P. Rockwell, 20th-century American metallurgist Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020