Interesting read from a 1924 publication, thanks for sharing, John.
Predated aluminum though.
"Brinell's Test. -- In this method, a hardened steel ball is pressed into the smooth surface of the metal so as to make an indentation of a size such as can be conveniently measured under the microscope. The spherical area of the indentation being calculated and the pressure being known, the stress per unit of area when the ball comes to rest is calculated, and the hardness number obtained. Within certain limits, the value obtained is independent of the size of the ball and of the amount of pressure."
Still learning on my end.
PG (poor George).
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Just a blind squirrel looking for a nut.
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