The hardness of forged steel, cast steel, cast iron, nonferrous
and nonmetallic materials is usually measured by
force loading Brinell hardness testers. Namely, under some
experimental conditions, engineers and technicians apply
a normal force load F on the surface of measured material,
after a force holding time, unloading the material, they use
the average stress of the indentation spherical surface area
as the Brinell hardness value of the measured material. The
ideal Brinell hardness measurement principle can be described