Quenching, aging & hardness

[cohutt]

Great forum here guys, thanks for all the useful information I've already picked before getting around to this first post:

Using A-Neat's Lino & Pure lead formula 25:75, I had done a couple of practcie runs to get the cast mechanics familiar to me. Initially decided to go with Lee micro groove 6x molds and have cast some 240 swc in 44 and (more) 125 rn in 9mm.
after these test runs I sat down last night and cast about 400-450 of the 9mms. I set up a cardboard bullet chute that allowed me to drop the bullets out of the mold and directly into a coffee can full of water down on the floor. I was using a lee 20lb bottom pour pot and it took maybe 1 1/2 hours to do these even after a slow start. I ran the pot pretty hot (no thermometer, dialed 1 under max i think) for fast pouring and didn't get any frosting on the surface of the bullets. I am going to try and get away without sizing (as i don't have a sizer at this point) and roll them in liquid alox when time to lube.

An alloy calculator i downloaded suggests this combo of lead and linotype would be around 9.25 bnh. I assume this would be immediately after the cast cooled down with no quenching or heat treating. I mic'd a bunch of them and they all measured out a little bigger than the .356 spec that Lee has on them, by .0005 - .001.
I plan on shooting these through a S/A IMI UZI and possibly various 9mm Glocks (iIam aware of the Glock Barrel issues/concerns and will move slowly and consider various aftermarket barrels if i get there...) The UZI is tolerant of hot ammo, medium ammo, cold ammo, pretty much shoots anything.

OK, now the questions:

1- The quenching- as described above, what kind of bnh hardness would you estimate I moved up to by quenching?
and
2- Do quenched bullets of this alloy still stand to harden up some more if left alone for a couple weeks? I've seen posts here stating that a little time will help harden up most softer aloys. So do I get a double effect or does the quenching already do as much as I could expect?

Thanks ahead of time for your input and any comments/ advice/ warnings/ encuragement/ harrasment you care to toss into the thread. (To be kind, I left my fat-chick avatar back at GT for now)

[44man]

I never worked with that alloy but wonder if there is too much pure lead to gain much hardness. I'm curious too and will have to wait for someone else to sign in.

[BigSlick]

I just ordered a Cabin Tree tester. I'll be able to find out the tangible difference (with my alloy) in a couple of days.

I have been dropping a few lately, mainly .501-440's. First batch was air cooled and fairly soft. Tonight I dropped another 100 or so and ice-water quenched them. So far, one reject (maybe more to come upon closer inspection).

I did a vise check on the bullets from my first (AC) batch (about two weeks old) and the one from tonight (quenched). The difference is pretty amazing. I know the quenched bullets will harden over the next few days or weeks, but even with the ones dropped just tonight, the hardness of the quenched is (est) 25-30% greater.

I'll know Monday about noon or so if one or the other leads my barrel. I'm off tomorrow so I am going to drop 3-400 175TC's like the ones Yammer casts. I hope to have as good a result as he does.

'Slick
________
Lamborghini islero

[cohutt]

Slick I figured you were castng for years the way you ***** lead.
I finally got around to working on the 500 lbs of pure lead i picked up a couple months ago. A_Neat helped in a trade for some Lino to harden it up some an dsuggested the 3:1 blend I started with. If i can find a good mix for my casting needs with these I'll remain a "white glove" caster- only clean pure lead and linotype ingots, no wheel weights to mess with. (that is unless some fall in my lap)

[BigSlick]

I been whoring lead for a long time. I decided to wait until I got enough to make it worth it before getting started dropping bullets. Now I'm about half way there, I just need another few hundred pounds and that should last me until Hillary is out of office.
________
DEPAKOTE LAWYERS

[arkypete]

Cohutt
I'm a Wheel weight *****!
I have pure lead around but I use it for casting billets for swaging.
Wheel weights are the answer to a bullets casters fantasies. Your linotype will provide the bit of tin required to make perfect bullets using linotype.
Your alloy sounds pretty close to the NRA number two alloy which if fine for mid range pistol bullets.
I suggest getting some welders mitts and clean up some wheel weights. Cast your air cooled and water quinched and see the difference.
Jim

PS: Three or four tons of wheel weights are a good starting point, usually free for the asking.

[ANeat]

I never really worried about the age hardening thing untill I got a tester myself. I know my bullets that are 50/50 WW and pure lead do check quite a bit harder after a couple of weeks sitting around. Ill have to check them again and get you some hard numbers.

If you want it checked Cohutt just mail me a bullet and Ill let you know the BHN. Actually 500 or 1000 would be a better test but one is enough

I did luck into 600 lbs of WW a couple weeks ago
Adam

[454PB]

For heat treating, I've always used WWs as a base metal, I've never used linotype. In theory, since linotype and pure lead have no arsenic, it won't work.

Another point, if you water dropped them, they need to be sized quickly. If they are sized latter, they will resoften. It takes a while for that to happen, so shooting them up right away should be OK.

[cohutt]

Who am I kidding- I can hear the air tools of a decent sized tire store from my house. Gotta get the 600 buck tires i bought there rotated soon. I know i'll find a way to get WWs into the formula

Oh= and I do have welders gloves and a rawhide BBQ apron- look like a blacksmith down there, I figured out pretty early on this sh&t burns you really fast

[cohutt]

For heat treating, I've always used WWs as a base metal, I've never used linotype. In theory, since linotype and pure lead have no arsenic, it won't work.

Another point, if you water dropped them, they need to be sized quickly. If they are sized latter, they will resoften. It takes a while for that to happen, so shooting them up right away should be OK.

So arsenic in the key to heat treating / quenching adding the hardness.... thats what i was forgetting

[454PB]

I realized after I posted that you said you weren't going to size these, but if (and when) you decide to do that.....keep the sizing quickly in mind.

I've read that some guys use magnum shot to add arsenic to pure lead. I've never tried it, WWs are still fairly easy to find in my world.

[felix]

No, it is not arsenic per se, but any element considered to be a foreign matter to the rest of the elements in the mix. If a mix goes from liquid to solid in likity-split time, then it won't heat treat. Get the whole mix into having a slush stage between frozen and liquid, then that mix will heat treat. Wider the slush temp difference, the better the heat treat potential. Another indication of potiential is how long it takes after the heat treat to reach final hardness. Sometimes in 12 hours, sometimes in one month. Longer the slush stage, the longer the time it takes to reach max hardness. To hurry up the time to max hardness, put the finished boolits back into the oven at 200 degrees for a couple of hours. Then max hardness should be made in a much shorter time than left at room temperature to harden. ... felix

[454PB]

Here is a link to a site that explains the precipitation hardening of lead alloys. It is directed at battery plate hardening, but the principles are the same:

http://www.key-to-metals.com/Article88.htm


And another:

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


With a quote from the above site:

Heat Treating Tips

(From the pages of HandLoader Magazine)
The essential metals for heat treating are lead, antimony and arsenic. Tin is optional; although it may aid in an effort to cast more perfect bullets and contribute to ductility. To obtain maximum hardness, a minimum of one to two percent antimony is required in addition to a trace of arsenic. Arsenic is the catalyst. Heat-treating cannot work without it, regardless of the amount of antimony or other trace elements present.

Tin has the effect of reducing maximum hardness from heat treating as its ratio to other metals increases. Wheel-weights, one to two percent tin, can be heat-treated to a harder level than Lyman No. 2 with its five percent tin content. Linotype, 84/12/4 (lead-antimony-tin) has the lowest hardening potential when compared to other alloys commonly used to produce cast bullets.

[leftiye]

454- Years ago, I heat treated some Lee 250 grain .45 boolits, and with Blue Dot blew them out at 1250 fps with no leading. That was way before folks decided that you could run a .45 L.C. above 15000 psi. Nowadays my load is nothing special.

The method I used came from the NRA's E.H. Harrison book. It said that .5% tin and 5% Antimony heated to just below the slump temp for one hour and immediately dumped into water would harden to a Brinell hardness of 42. AND they WERE unbelieveably hard, though I still don't have a hardness tester. Couldn't EVEN make any effect with the ole thumbnail!

This is the first I've heard about arsenic being necessary. There weren't none in the aforementioned metal atall. The tin was only there to promote ease of casting, I suspect. Antimony is the crystalline structure forming agent. Heat treating to harden is all about heating and soaking to allow crystalline structure to form, and then freezing the alloy instantly in order to retain the crystalline structure. Otherwise the crystalline structure dissappears while the alloy cools. This may be the same for many metals, certainly also is true for steel.

I suspect that arsenic may well promote even harder (than 42?) crystalline formation. And I may be wrong, but this is the first I've seen it said to be the primary hardening agent in heat treating.

[Ricochet]

I've read that about arsenic being necessary, but it's definitely not true. I don't doubt it's helpful.

Alloys with only a little antimony in them will quench harden, not as hard as more highly alloyed ones. I suspect the lower the antimony concentration, the longer time needed to reach full hardness as the supersaturation of the solid solution is less.

[cbrick]

Taking from the above mentioned links, arsenic is not an absolute neccessity in heat treating, antimony is. However, a trace and only a trace of arsenic (1/4 of 1 percent) will dramatically increase the amount of hardness the alloy can acheive. See the article from "Key to Metals" as an industry perspective.

The cast bullet notes page mentioned by 454PB is my web site (lasc.us). The quote from HandLoaders is a bit off from newer info I have been able to learn. While arsenic is the catalyst it should read, "arsenic is the catalyst to greatly increased HT potential". The article by "Key to Metals" confirms this and is also on my site though there is no link to it yet while I am waiting for permission from them to reprint it.

I am also working on another page to be added to the 'Cast Bullet Notes" page. It will be some time yet but I have been keeping an accurate chart of all heat treating that I have done for nearly a year (and I HT a lot). The new page will be a chart listing alloy, starting BHN, convection oven temp (400, 410, 420, 430 etc), time in oven, water temp, time in water, BHN in 12 hours, 24 hours, 48 hours, 96 hours, 7 days and 14 days.

There have been some interesting results learned from keeping this chart. For one, alloy variations can be tracked more from the time it takes bullets to harden than from the final BHN. As WW alloy varies (I suspect less antimony) bullets are still acheiving the same final HT BHN but instead of 3 days its taking well over a week. From reading the article on "Key to Metals" they mention testing done with 2% - 4% - 6% - 8% antimony with 4% ideal for quickly acheiving quenched hardness so my theory of less antimony in my current lot of WW makes sense. In addition, pre HT BHN for several years was right at 11 with 3% tin added but currently its been 9 BHN. The current test underway for the chart is the WW + 3% tin with # 8 chilled shot (both antimony and arsenic) added to test for any possible difference and or how much shot is needed to gain an improvement.

Ricochet's post (while much shorter than this has turned out to be) is correct according to all of the testing I have done for many years. Heat treating the shiny goddess and group testing them has been the passion of my shooting for better than 15 years so I tend to get a little long winded.

Rick

[cbrick]

No, it is not arsenic per se, but any element considered to be a foreign matter to the rest of the elements in the mix. If a mix goes from liquid to solid in likity-split time, then it won't heat treat. Get the whole mix into having a slush stage between frozen and liquid, then that mix will heat treat. Wider the slush temp difference, the better the heat treat potential. Another indication of potiential is how long it takes after the heat treat to reach final hardness. Sometimes in 12 hours, sometimes in one month. Longer the slush stage, the longer the time it takes to reach max hardness. To hurry up the time to max hardness, put the finished boolits back into the oven at 200 degrees for a couple of hours. Then max hardness should be made in a much shorter time than left at room temperature to harden. ... felix

Interesting, somewhat different from everything I have tried myself or read about . . . but then that's why I'm here.

Linotype is eutectic (no slush stage) and can be heat treated because of its antimony but with its high tin content and lack of arsenic not to the dramatic results of WW.

I did a bunch of testing several years ago on the water temp with bullets HT in a conventional gas oven and found that the colder the water the faster they reached final hardness. They didn't get any harder with cold water but they got there faster. When I switched to the convection oven this difference seems to not apply or at least not nearly as much. Putting them back in the oven after HT would seem to be a method of annealing and would reduce the final amount of hardness acheived. Its a new concept to me but then again . . . that's why I'm here. I'll have to play with this and see what comes of it.

Rick

[ANeat]

Heres a little data that really suprised me, and I really cannot explain why but here it is. Bullets are H&G68 45acp 200gr SWC. The alloy is a mix I mix up 100lbs at a time. 48lbs of WW, 48lbs of pure lead, 2 lbs of tin. I always just water dropped them for convience and the little extra hardness is a side benifit. Checked right after quenching they check right at 10bhn. Well I had cast some back over the summer (6 months ago) and hadnt got around to sizing/loading them yet. I thought I would check a couple today and got a reading of 20.9bhn WOW. I pulled out about half a dozen more and they were all the same. Double checked the lead tester with a lead ingot that I had recieved from Cohutt and the tester (Lee) is right on the money.

Im not sure exactly why but the next batch I will reduce the WW %.


Adam

[cohutt]

Double checked the lead tester with a lead ingot that I had recieved from Cohutt and the tester (Lee) is right on the money.


Adam

You haven't melted the mega-ingot yet? Admit it, you keep it on the coffee table as conversation piece.

[454PB]

First, thank you cbrick for your fine web site. I use it as reference and point others to it frequently.

As I stated in my original reply, I've never tried heat treating linotype, so today I cast up some test boolits (Lee .44 300 RF) using 1 part linotype and 3 parts pure lead. These were quenched from the mould in cold water, as well as some that I dumped on a soft towel and air cooled. I then sized the quenched boolits in a Lee .430 push through within an hour of casting. They cast right close to .430 to .4305, so there was very little sizing actually done, but I ran them through anyway as a "control" measure for future testing. Incidentally, these same boolits cast in my normal 25% linotype and 75% WW measure .432 to .433.

I then did a preliminary hardness test for a baseline. The AC boolits tested 11 BHN. The quenched boolits tested 13.4 BHN measuring on the nose, and 14.3 BHN measuring on one of the driving bands after sizing.

My plan is to continue measuring these samples over the next few weeks. I learned long ago that the hardening (and resoftening) process takes months.

I also found this to be a rather bad alloy for quenching. The AC boolits were fine, but the quenched boolits where badly smeared and obviously so hot when they hit the water that they looked like they were covered with what appeared to be splashed solder. About 40% of them are unusable, but will serve as good test subjects.