Tin vs Antimony

[dieguy59]

If I was wanting to raise the hardness of an alloy, what are the 'pros' and 'cons' of using tin instead of antimoy? If this has already been asked in a previous thread, please re-direct me and save everyones time.

Thanks in advance for the info.

[Muddy Creek Sam]

Antimony makes it harder, Tin makes it tougher. Depends on your use.

Sam :D

[white eagle]

antimony can be further hardened by water quenching tin can not

[badbob454]

tin makes it hard ,tough and flexable .. antimony makes it brittle and hard , antimony hardens more inexpensively than tin , antimony age hardens , tin age softens . i reccomend tin to aid fillout ,2% ... and antimony 6-8% to harden ......
wheel weights also have .05% arsenic also a hardener great for water quenching to harden

[AndyC]

From Rotometals:


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 )

[badbob454]

check out this article it is exellent
http://www.lasc.us/heattreat.htm

and this one
http://www.lasc.us/WiljenArsenic.htm

[dieguy59]

As always, you guys come through with the answers. Much appreciated!

[sqlbullet]

From Rotometals:


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 )



Keep in mind this reaches a point of diminishing return. Going from 16:1 (6.25% tin) to 10:1 (10% tin) only buys you about a .5 increase in hardness.

Same goes for antimony.

I tend to look to tin to add toughness, as Sam said, and to antimony for hardness. Tin makes lead harder without having a big effect on its tensile strenght/plasticity. Antimony makes it harder at the expense of tensile strength.

[Larry Gibson]

"Raise the Hardness" for what use and what velocity range?

Lead/tin alloys are very useful up to a point. So are lead/antimony alloys. Those are both binery alloys. The better alloy will be a ternary alloy of lead/tin/antimony. In correst proportions it has "toughness" and "hardness".

Larry Gibson

[white eagle]

"Raise the Hardness" for what use and what velocity range?

Lead/tin alloys are very useful up to a point. So are lead/antimony alloys. Those are both binery alloys. The better alloy will be a ternary alloy of lead/tin/antimony. In correst proportions it has "toughness" and "hardness".

Larry Gibson
oooh .......the way you talk [smilie=w:

[Sonnypie]

I like Lyman #2. (For my rifle) 90/5/5
It has proportions I can depend on. The last tested out at BHN 16
And oddly enough, it is what other alloys were derived from.
A base by which others were judged.
I'm not out to reinvent the wheel.

And after collecting and refining some wheel weight metal, I came to the conclusion there is no telling what the ratio is, other than it melts and casts. :confused:

Martha sez, "If it works, don't fix it!"

YMMV

[geargnasher]

No one has mentioned another, very important factor of the lead/antimony/tin ternary alloy called the intermetallic compound Sb/Sn. In liquid solution the antimony (Sb), and tin (Sn) will combine in approximately equal parts by weight to form a compound within the solution that behaves like a pure element. Lyman #2 actually behaves like a binary alloy composed of 90% Pb and 10% Sb/Sn. This intermetallic compound has a characteristic toughness that exceeds the sum of Sb and Sn individually.

A ternary alloy with different proportions of Sb and Sn (like WW metal) will behave like a molten solution of Pb, Sb, and Sb/Sn. There will be no free tin in the mix unless the tin quantity present exceeds the antimony present, a condition we call "overtinning". It's generally undesireable to have more tin than antimony present because it is unnecessary and leaves free tin nodules throughout the finished boolits. These nodules are soft spots and can contribute to "leading" at high velocity/high pressure.

Another thing to consider when alloying boolit metal is the melt and freeze point of each constituent, and how the proportions of each affect overall melt, slush, and freeze points, and also which constituent freezes first. In an "overtinned" alloy, the free tin freezes last, that's why it forms nodules. In WW metal, the free Sb freezes first (IIRC), followed by Pb, and Sb/Sn, since any tin present will have combined in an ~equal amout with Sb. Lyman #2 has Pb on the primary phase of crystallization, followed by Sb/Sn, at which point it's solid since the Sb/Sn in equal proportions freeze at one temperature.

Gear

[Sonnypie]

That's good to know, Gear. Thanks for posting that.
I am currently very nearly out of my Lyman #2 alloy (It's all in 1000+ free boolits, and loads.)
I was entertaining the idea of trying some Magnum shot and adding Lead-Free solder to tin it up. (Pb, 4-6% Sb)
Your post explains to not over tin the alloy. (Not that I would, that stuff is costly.)


So in conclusion, the only place we want chunky is in our soup bowl. Not in our barrels. :D

[atr]

anitmony = hardness
tin= more flowable

[MBTcustom]

Be careful adding to much tin. As the tin content goes up the closer it gets to solder and will lead the heck out of your barrel. The tin aids fill out and improves toughness but it can only do so much by itself. Just like antimony can only do so much by itself. I like to think of the two as an epoxy compound in the metal. They need to be of approximately equal portions to give you the best performance. They go hand in hand.

[USSR]

While the aversion to "overtinning" may be all well and good for you guys who cast solids, I regularly "overtin" my alloys for HP's, and have found no evidence of soft spots or leading in .45 Colt loads at 1000 - 1100fps. My normal alloy consists of 1.0 - 1.5% Sb and 4.0 - 5.0% Sn.

Don

[MBTcustom]

I was referring to an alloy that is closer to 20% Sn being driven to 2000 FPS. It will lead the barrel easier than you might think. Ask me how I know.

[imashooter2]

A handy chart:

http://home.comcast.net/~imashooter2/pictures/fig8-sm.JPG

[dieguy59]

Wow, homework! That is quite a chart. Thanks for posting. The reason for the original question was a chance to spend some money on either some mono type or solder dripping. I was trying to figure which would be the better investment. I went with 90-100lbs of mono. I've appreciated all the input.

[sabrecross03]

Now I see. All this time I was trying to get an 8-digit grid coordinate from the chart... :)