Ladies and Gentlemen,
I apologise in advance for the lack of brevity.
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Lets us not accept the "Asterisk" like mark as a hardness test !
The Germans were and are very advanced in the art of Materials Testing would never have applied a complex figure as a hardness testing penetrator form !
Several things will forever dispense of this false assumption that they used complex shapes for their their penetrators in hardness testing.
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The Hardness test is based upon the depth of penetration of a shape that is easily described mathematically, and is progressive in its displacement of material with increased depth of penetration .
Various attempts were made with points of spherical, conical and diamond shaped penetrators of various angles and with a variety of controlled bluntness applied to the extreme point.
It was found that the majority of tests could best performed with the spherical forms of the Brinell type tests and the Ball and Cone shapes of the Rockwell tests.
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I quote from The 16 th Edition of Machinery's
Handbook as follows;
"Rockwell Hardness Test-- The Rockwell hardness tester is essentially a machine that measures hardness by determining the depth of penetration of a penetrator into a specimen under certain fixed conditions of test. The penetrator may be either a steel ball or a diamond sphero-conical penetrator. The hardness number is related to the depth of indentation and the number is higher the harder the material."
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The Vickers test is similar in application however the penetrator is a Square Based 135 deg
diamond pyramid shape.
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Brinell tests are performed with a ball type penetrator and are determined by the following Formula, (a simple Example of the Formula)
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load on indenting tool in kilograms
-------------------------------------- = Brinell Hardness Number
surface area of indentation in sq. mm.
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As can be seen the Rockwell test is a measure of controlled penetration and the Brinell test is a measure of the area of a controlled indentation.
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As can easily be seen by the nature of the formula, the penetrator point must be easily described mathematically, in both cases, or the calculation becomes overwhelming in complexity and therefor useless for production inspection!
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In general These tests will appear as from 1 -3 penetrations in a small area, Brinell tests would most likely never appear on WW-1 and WW-2 weapons.
The most likely test would be the Rockwell type tests of from 1 -3 conical indentations taken within a 1/4" diameter area.
And then seldom appearing on any but a very rare few possibly one in a hundred or more parts at the discretion of the inspection department.
Thank you for your patience!
ViggoG
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