BHN of 5% Sb alloy?

[Eutectic]

Does anyone have the BHN hardness of lead with 5% Antimony added? No tin... (This is a common "hard swage" alloy used by Hornady and others)

Thanks, Eutectic

[lylejb]

from rotometals web site

Basic Rules for Harding Lead-


For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.
For a simple equation,
Brinell = 8.60 + ( 0.29 * Tin ) + ( 0.92 * Antimony )

If this is right, it would be BHN 13

[sljacob]

from rotometals web site



If this is right, it would be BHN 13

how much more do you add for water dropped?

[Eutectic]

Thanks lylejb, that formula was what I was looking for.


Eutectic

[montana_charlie]

from rotometals web site

For a simple equation,
Brinell = 8.60 + ( 0.29 * Tin ) + ( 0.92 * Antimony )

Let's see how that formula works when there is no Tin or Antimony.

8.60 + (0.29 * 0) + (0.92 * 0) = BHN
Does anybody else get a hardness of 8.6 BHN for pure lead?

For every 1% additional tin, Brinell hardness increases 0.3.
For every 1% additional antimony, Brinell hardness increases 0.9.

It appears the formula is designed for calculating 'additions' to an alloy which is already at 8.6 BHN...but we don't know if that initial hardness comes from tin or antimony, or both.

If your alloy comes (say) from dental film, it is 7.8 BHN. The formula can't be right for your alloy, because you would have to throw in some uncounted additions just to bring it up to the '8.60' starting point.

CM

[lwknight]

That formula is where I get confused since pure lead is dead soft at about a 5 BNH
Where does the 8.6 come from in the first place?

[Eutectic]

It appears the formula is designed for calculating 'additions' to an alloy which is already at 8.6 BHN...but we don't know if that initial hardness comes from tin or antimony, or both.

If your alloy comes (say) from dental film, it is 7.8 BHN. The formula can't be right for your alloy, because you would have to throw in some uncounted additions just to bring it up to the '8.60' starting point.

CM

montana_charlie, I took the formula example as you ..... A known alloy with a BHN of 8.6 with amounts of additional tin and antimony added. Good point whether existing Sn and Sb amounts make a difference??

Pure lead is usually stated to have a BHN of 5. For my use on the binary alloy of 95% lead and 5% Antimony in my original question I used BHN of 5 for pure lead plus 4.5 for 5% Sb (0.9 x 5) for a BHN of 9.5. This seems close although I would have guessed between 10 and 11!

Eutectic

[runfiverun]

and yet 1 more % of antimony and 2% tin make it go to 16 bhn.
and a ww alloy of 1/2% tin and 3% antimony hit a bhn of 11?
seems antimony alone is not the great hardener it's been notched up to be.

[Barnowl]

Let's see how that formula works when there is no Tin or Antimony.

8.60 + (0.29 * 0) + (0.92 * 0) = BHN
Does anybody else get a hardness of 8.6 BHN for pure lead?


It appears the formula is designed for calculating 'additions' to an alloy which is already at 8.6 BHN...but we don't know if that initial hardness comes from tin or antimony, or both.

If your alloy comes (say) from dental film, it is 7.8 BHN. The formula can't be right for your alloy, because you would have to throw in some uncounted additions just to bring it up to the '8.60' starting point.

CM

See post #10 at the following link for comments on the "8.6" in the above formula:

http://castboolits.gunloads.com/show...ht=formula+bhn

And post #22 at the link below for an Excel spreadsheet for calculating alloys:

http://castboolits.gunloads.com/show...t=67401&page=2

Kevin

[lwknight]

The only thing that I can figure out about the 8.6 as a starting point is that any additive at all will make lead jump to 8.6. We all know that pure unadulterated lead ingots thud when dropped and even if there is as much as 1/2 % tin or antimony in it , suddenly they ring like a horseshoe when dropped.
Granted that the brilliance of the ring varies and I have never heard a kinda sorta ring. either it rings or it does not. No middle.

Evidently if anything at all is added, you start at 8.6 Strange physics to me but, it seems to be a fact.

[sqlbullet]

Alloying metals fundamentally alters certain properties. Using the linear logic many are trying to apply in this thread would never yield a melting point of 361.4°F for 63/37 since this is far below the melting point of BOTH constituent elements.

8.6 is a constant, and the formula applies ONLY to lead alloys. Pure lead is not an alloy, therefore the formula doesn't apply.