Age hardening

[duxnbux]

I'm new to the forum, been lurking for a few weeks and am impressed with the knowledge I've seen here.
I am smelting 50/50 lino and lead. #2? It tests about 15 bhn after a few days. When I cast it and test it, it's back up to about 20bhn like the lino was in the first place. The lead is mostly used plumbing pipe.
Apparently it is age hardening. The original smelt was about 30 to 45 days before the cast. I checked the boolits after 2 or 3 weeks and they are still at 20bhn. Will they "soften" over time?
I'm using the Lee 20# bottom pour with the Lee 6 banger molds. I'm casting 9mm,40, and 45 cals.

Thanks for you help.

[Fly]

duxnbux I'm new to this also & in saying that I,m not much help on this topic.But I can
tell you I have age harden & I don't see me soften any time soon.

[sagacious]

Your alloy ingots cool slowly, and can be expected to test softer than your cast bullets, which cool much more rapidly. Faster cooling increases hardness with the alloy you're using. Your bullets should not soften much over time-- I wouldn't waste any worry on it. Your listed calibers are not going to be affected by a miniscule drop in BHN anyway.

Other than that, your test results could be in error, but I think the above situation is likely. Good luck.

[John Boy]

Will they "soften" over time?

Dux - Nope! The antimony will stabilize in the alloy anywhere from 3 - 14 days, based on the percentage

My approach is mix and cast the ingots - take a Bhn reading every few days and when I get a constant Bhn for about a week ... that's what I mark on all the ingots and stack them by Bhn.

I'm a BPCR shooter and correct alloy is important. I learned the hard way - quick reading and wrong alloy for my BPCR bullets. So now, I let them 'age' and get the correct Bhn

[Fly]

John what kind of tester do you have.That is something down the line I would like to get.

[DLCTEX]

duxnbux I'm new to this also & in saying that I,m not much help on this topic.But I can
tell you I have age harden & I don't see me soften any time soon.

That age hardening is proving to be spotty, as some areas go in reverse.

[Bret4207]

Any age softening will occur over a long period of time- as in decades. I have some .451 boolits marked "7/78" IIRC and they measured 15 Bhn according to the box. I'm using a different tester but they are still at 14 Bhn. I think my tester (Cabine Tree) is pretty close to dead on.

[cajun shooter]

As far as testers go the Cabin Tree is the fastest and easy to use. If you are young and can mount the Lee tester into a solid mount then it is very accurate also.

[44man]

BHN testers and chronographs are toys to play with.
What counts is how the boolits shoot first, then see what you have for fun.

[armexman]

Darn I won't be able to use the Lee hardness tester (since I'm OLD). BUT i do have a SAECO and many here are correct. I let my boolits for the 41 age harden for 2 weeks and load; my boolits are cast so they stabilize at ~15 (Lyman #2). LLA and no leading with up to 19.5grns of H110. Which by the way is for real MEN, which I refrain to shoot much!

[45 2.1]

Dux - Nope! The antimony will stabilize in the alloy anywhere from 3 - 14 days, based on the percentage

My approach is mix and cast the ingots - take a Bhn reading every few days and when I get a constant Bhn for about a week ... that's what I mark on all the ingots and stack them by Bhn.

I'm a BPCR shooter and correct alloy is important. I learned the hard way - quick reading and wrong alloy for my BPCR bullets. So now, I let them 'age' and get the correct Bhn

Antimony in an alloy will cause the hardness to vary for a long time. It will not stabilize in 14 days........ more like 14 months is closer to reality. Hardness will grow slowly after about a month though. Test your marked ingots again and see what you get.

[cbrick]

I'm new to the forum, been lurking for a few weeks and am impressed with the knowledge I've seen here.
I am smelting 50/50 lino and lead. #2? It tests about 15 bhn after a few days. When I cast it and test it, it's back up to about 20bhn like the lino was in the first place. The lead is mostly used plumbing pipe.
Apparently it is age hardening. The original smelt was about 30 to 45 days before the cast. I checked the boolits after 2 or 3 weeks and they are still at 20bhn. Will they "soften" over time?
I'm using the Lee 20# bottom pour with the Lee 6 banger molds. I'm casting 9mm,40, and 45 cals. Thanks for you help.

Welcome to Castboolits duxnbux,

As was mentioned, the ingot and the boolit cast from that ingot will have different BHN readings and for the same reason that water quenching or oven heat treating increases the strength (BHN) of the alloy. The faster an antimony alloy cools the more it increases the strength. An ingot being much larger (more mass) will cool much slower than a boolit and give a softer reading.

As for your question "Will they soften over time"? Yes but very slowly. The harder they were made the faster they will age soften but again, very slowly. I discovered a couple of box's of oven heat treated WW alloy boolits that was dated 10 years old and 30 BHN, they tested 26 BHN. So yes, they age softened but not much and very slowly.

Water dropped or oven HT antimony boolits will gain "most" of their hardness "strength" in about two weeks and then continue to age harden very slowly for quite some time (1-2 years). After that they will very slowly age soften.

Here is an article on various BHN testers that may interest you.

http://www.lasc.us/Shay-BHN-Tester-Experiment.htm

An article on heat treating.

http://www.lasc.us/HeatTreat.htm

And an article on alloys.

http://www.lasc.us/CastBulletAlloy.htm

Hope this helps and again, welcome to Castboolits.

Rick

[duxnbux]

Thanks Rick
I'm using a Lee bhn tester. Like others have said, it's tricky to get used to but seems to work well after the learning curve has been completed.
Your info was very helpful regarding fluxing in order to not lose antinomy, etc. If I have a coffee can of "oatmeal" can I remelt it and flux the dickens out of it and recover a lot of it?

Thanks again for sharing.
Dux

[sagacious]

...
If I have a coffee can of "oatmeal" can I remelt it and flux the dickens out of it and recover a lot of it?

Thanks again for sharing.
Dux

Yes, no problem at all on recovery with generous fluxing. Good thing you saved it.

[cbrick]

If I have a coffee can of "oatmeal" can I remelt it and flux the dickens out of it and recover a lot of it? Dux

Should work but if you skimmed it off from say 10 pots of alloy don't dump it all back into one pot, spread it back out through 10 pots. I suggest saw dust for flux, it'll help reduce antimony and/or tin back into the alloy.

Rick

[44man]

Should work but if you skimmed it off from say 10 pots of alloy don't dump it all back into one pot, spread it back out through 10 pots. I suggest saw dust for flux, it'll help reduce antimony and/or tin back into the alloy.

Rick

Good suggestion.
I cut sprues in a coffee can and every now and then I dump them back in the pot, flux and skim. That really cuts down the dross.
Best to flux often when casting. Wax works best for me because it lights and cuts smoke in my garage and it smells better then the stink bugs I toss in the pot.