Help finding lead-copper alloy. high lead,

[fastline12]

We are primarily needing a lead alloyed with copper and or other elements to harden the material and improve the machinability to run in a lathe. We also need the improved strength and would prefer non-ferrous alloying but have considered other alloys.

I am not a metallurgist so I am trying to learn from you guys about the molecular bonds of these alloys. I cannot seem to find too many lead alloys that have an appreciable amount of copper. I found one called C98840 but cannot find it available anywhere or familiar with it.

We will need to machine .500 and .750" rods of this in a lathe. We have milled pure lead but turning will be a different story because the deflection of the rod in the lathe becomes an issue.

 

[fastline12]

oh, ideally, we would like to see about 75% Lead and 25% Cu. I know Antimony is also a very common alloy material here. We just need to maintain a high density and ductility near lead.

 

[btrueblood]

Lead and copper don't form an alloy, the lead is too different in melting point, so what you have is lead puddles in copper matrix, or vice versa. I think copper is not the way to go for finding a harder lead alloy.

Lead and antimony is the standard mix for bird shot. A few % of Sb gives much harder shot than pure lead. You can also alloy small amounts of tin and smaller yet amounts of calcium to get even better strengths (but calcium might be tough to control due to its reactivity). From my good old materials notebook, values are tensile strength, elongation (of chill cast material, extruded material is much better), and density in lbs. per cubic inch:

Chemical lead (pure): 2.4 ksi, 45%, .41 lb/cu. in.
Pb-1Sb: 3.0 ksi, 7%, .406
Pb-4Sb: 4.0 ksi, 10%, .398
Pb-6Sb: 4.2 ksi, 12%, .393
Pb-8Sb: 4.6 ksi, 13%, .388
Pb-9Sb: 4.7 ksi, 15%, .385

also:

Pb-.08Ca: 5.5 ksi, 9%, .41
Pb-.08Ca/1Sn: 9.0 ksi, 17%, .41

 

[fastline12]

Thanks so much for the reply. I wondered if the dissimilar properties of CU and Pb would create a poor alloy. Tin could possible work for our needs if in high enough %.

Let me better explain what we need. We need to simply improve the strength of a Pb allow. We are working on a custom firearm round where we need to machine the sug instead of cast it. It has been proven in the industry that Pb/Sb alloys for casting will vaporize at high firing pressures. We need to reduce the deformation. We can machine a solid copper slug but at the cost of weight. jackets slugs are common as dirt but they can suffer from balance issues.

It would be best to have an extruded alloy that has a much more consistent density and machine from solid.

 

[unclesyd]

You might want to look at Bearium Metal B-10. It is about 20% Pb in Copper.

http://www.metaltek.com/divisions/bearium-metals.html

http://www.matweb.com/search/datasheettext.aspx?matguid=65

a7df2aacc44465bf6b84ff75cb2f68

 

[fastline12]

Thank you. HOwever, I think we are headed in the opposite direction by starting with a pure lead product and alloying to improve tensile, etc without hugely affecting the density. Obviously the more alloying, the lower the density in this case.

I had heard that Cu made for a very poor alloy in Pb so I have to wonder why it is being done. I have my nose in the books right now to determine if there is an alloy out there that will help.

Also, I would like to ask about possible material property improvements with extrusions? Being somewhat outside my area of expertise here. We primarily machine Al. Could the extrusion process in itself drastically improve properties by machining from solid rather than casting when working with Pb? Obviously is far superior in aerospace Al applications so I have to ask the question.

 

[TVP]

Have you considered tungsten-based alloys, such as Densimet? They have very high density (higher than Pb) and are machinable.

http://www.plansee.com/tungsten-densimet.htm

 

[fastline12]

I think the ultimate goal for the immediate is considering all Lead based alloys and their corresponding strengths. I have yet to find any supplier or metallurgist in the net that can help us find a suitable material. I also want to explore possible form methods , cold rolled, extruded, etc, to improve the properties of the alloy.


Can anyone recommend a facility to contact regarding assistance with these questions? I seem to be running into places that just sell the stuff but have no idea about alloy properties, etc and I am well out of my element with Lead.

I don't think we can used Tungsten for this just because the price will be just out of sight for such an application.

 

[btrueblood]

I'd certainly be talking to the powder metal folks, Bearium like Unclesyd suggests is one of those. HIP'ing (hot isostatic press) of the powder forms greatly improves density, as does infiltration.

Pb/Sb alloys "vaporizing" - you mean the bullet fragments, or does it truly melt and vaporize? At some fairly high speed, yes, you need a jacketed round or a different alloy I think, because the lead is smearing and melting where it contacts the barrel wall. Pb and Sb have similar melting points, so I don't think you will get much better there. Can you use a sabot?

 

[fastline12]

The main reason to target a machined solid projectile is there will need to b weight and shape changes and that can get very pricey with mass production techniques.

I called several places and they either do not call back or know nothing. I would sure think there is a way to improve the strength of Pb but this may be just an effort to remake an impossible wheel.

 

[unclesyd]

Antimony-Selenium Lead, Calcium Lead would be two alloys to checkout, especially the Antimony/Selenium.

http://www.alloysinternational.com/search/node/lead calcium alloy?page=1

 

[arunmrao]

Have you tried contacting the officers at international Lead Zinc Research Organization. They could be of help.

http://www.ila-lead.org/

http://www.ilzro.org/

_____________________________________
"The richer we have become materially, the poorer we have become morally and spiritually." Martin Luther King Jr

 

[bruv]

@ btrueblood:

I always thought Bearium was a centrifugally cast alloy - I've never seen it as a powder alloy, although it wouldn't surprise me if it was.

More info here:

http://www.metaltek.com/alloy-guide/non-ferrous/bearing-bronze/

 

[btrueblood]

bruv,

You could well be right, I had PM on the brain.