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Old September 22, 1999, 12:10 PM   #1
Jack Straw
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Somewhere along the way I came across a way to determine alloy hardness relative to pure lead. It required placing a steel bearing between a piece of pure lead and a piece of alloy and then squeezing them together in a vice. By measuring the indention on both samples and applying a mathematical formula to those measurements one could determine the alloy's hardness. Does anyone know that formula or any other "homemade" means of measuring alloy hardness?

Jack
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Old September 23, 1999, 05:54 PM   #2
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Jack, The only thing I'm aware of is in the Lyman handbook where they used a special fixture to hold a sample of lead in one of their reloading dies. An indenter was then pressed against a sample of lead with a certain amount of force that was measured. That is the key thing,you have to exert the same amount of measurable force on each sample in order to have an accurate measurement. My saeco tester does that. However, it's scale is not in Brinell and is only graduated in arbitrary numbers(1-10).

When I come across an alloy where I want to get an idea of it's hardness, I'll either drop it on a hard cement floor or hit it with a hammer while holding it. The duller the thud it makes the softer it is. Some harder alloys like linotype will actually "ring" when you hit them.

I'll check into my references for you. Sorry not to be of more help.

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Old September 23, 1999, 07:05 PM   #3
Quantrill
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I believe the article you are referring to is "Measuring the Hardness of Cast Bullets" in the booklet, "Cast Bullets" by Col. E.H. Harrison published by the NRA. It is on page 29. Quantrill
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Old September 23, 1999, 08:08 PM   #4
El Chimango Pete
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Most hardness testing, from steel to lead alloy, is done by indenting a sample under a standard load and then measuring the size of the dent. By indenting between a substance of known hardness (pure lead, Brinell Hardness Number - BHN = 5), the ratio of one t'other simplifies matters quite a lot. For soft materials a ball is usually used - in this case a steel bearing ball at 7/16" will do. Lyman uses a standard load of 100 lbs, presses ball between lead and sample for 3 secs. Measure dent in lead (diameter, any unit will do), then same in sample. Divede first by second. Square the result. Multiply by 5. You should have the BHN of the sample.
Some figures:

Pure lead , BHN = 5
Wheelweights, no heat treat, BHN = 9
Wheelweights, heat treated, BHN = 27
Linotype, BHN 21

(from Lymans Cast Bullet Handbook - but the physics checks out OK though the method is a little 'rule of thumb')

Banging a head against a brick wall, by the way, should not be considered a valid test for IQ. - regardless of the diameter of the dent
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Old September 24, 1999, 09:18 AM   #5
Jack Straw
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Elchimango,
That's the one I'm looking for! Thanks much.

My sweetie often questions my IQ and offers to verify her suspicions with the brick wall test; I'll see that she reads your message. The brick wall thanks you.

Jack

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Old September 29, 1999, 12:52 PM   #6
Cheapo
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Contender--

Is there any conversion chart for the Saeco tester to Brinnel hardness?

I have one of those things from a garage sale, but have no instructions for its use. It appears to use a vernier scale on the readout, right?

Thanks!
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