toughness, not hardness?

[charger 1]

I could answer this myself on a ferrous issue but lead being a different animal I'd like input..How does one get a boolit to climb the toughness,resistance to deformation scale without getting more brittle?

[LET-CA]

I believe that brittleness sets in when the "hardness" gets too high. The harder your alloy, the more brittle it will become. Pure lead isn't brittle at all, but linotype, which is very hard - is also brittle. Mixing the two allows you to tailor your alloy to your specific requirements of velocity, etc. Lyman #2 has become the standard for most casters, but many add a little bird shot and then drop their freshly cast bullets into cold water to further harden them. The arsenic in the shot makes the water hardening possible.

[Bass Ackward]

How does one get a boolit to climb the toughness,resistance to deformation scale without getting more brittle?


Minimize the use of antimony and match the percentage of it with tin when you do. Then add a tinge of copper. Some folks say 5% is tops. I think that's way high and why the negative stereotypes about copper abound. Even around 1% makes a difference. Best way to do that is with some used Babbitt that already has a high, measured percentage in it.

[45 2.1]

The alloy constituents are the key to your question. Some, such as antimony, and hardness and brittleness. Others add heat treatable hardness without brittleness and others add toughness. Babbet is a good thing here as it aslready has the necessary materials that your looking for. Air cooled hardness versus Water dropped or oven heat treated hardness are different things also. It really depends on what you want to do with the boolit. I see a lot of people here useing the same alloy throughout the different pressure ranges from light pistol loads to high pressure rifle loads. That is the wrong approach. Match the alloy to the pressure range your going to use and the intended performance you want to have.

[Pepe Ray]

In one of the cast boolet hand books you'll see a section, illustrated with micron photos, and an explanation. Seems that our standard WW alloys are NOT alloys at all, but mixes. A true alloy must have atomic bonding which tin and lead can share. For some reason the antimony does not bond with either but remains in suspension like Cherioos in milk.
I suspect that that is why we're admonished to flux so much. Probably simply more stirring would suffice. That's one of the reasons that I pour from a dipper.
The "brittleness" comes about because of the MIX rather than the alloy, and of course ,too much will lead to ,too much.
The resident metallurgist should jump in here.
Pepe Ray

[felix]

This is entirely correct, Pepe. A true lead type alloy would exhibit zero slush between its liquid and solid phases. This kind of logic in the steel arena represents the situation where one barrel will outshoot another, with every other gun/shooter dimension exactly the same. However, this is the spice of life. ... felix

[Glen]

I beg to differ guys. Lead and tin do form true solid solutions, that much is right. Antimony IS soluble in lead, but only to a limited degree (and very temperature dependant; typically less than 1% at room teperature; this is why quenching can be so important in the microstructure of these bullets). Antimony and tin bond quite effectively with one another, and the intermetallic adduct is notably more soluble in lead alloys than is simple antimony, so you don't tend to get phase segregation in those alloys that have as much tin in them as antimony because you don't have any free antimony in those alloys.

As for the toughness vs. hardness question -- that is a very good point. There is an interesting discussion of that topic at:

http://www.lasc.us/AfricanHunt-CastBullets.htm

My own feeling is that hardness is the most important property in terms of good accuracy vs. engraving (i.e. in the barrel), and toughness is more important for impact behavior.

[felix]

Glen, it appears to me that you are not differing, but appending. It is practically impossible for us scroungers to obtain pure metals to create a true alloy by Pepe's/Lyman's definition. ... felix

[leftiye]

Plus one on glen's statement that hardness is about shooting, and toughness is about impacting. So, if hardness weren't required to get accuracy (accuracy was acceptable with softer alloys due to lower pressure loads, and etc.) and you wanted a better hunting boolit that would expand and not come apart you could/should concentrate on toughness.

Tin helps toughness out and copper may also. Both also increase hardness at the same time. Does anyone know how much hardness versus how much toughness these metals add proportionately?

[shotstring]

While not being much of a metallurgist myself, it would seem that the ideal fusion of hardness and toughness would be created by a boolit with a softer center (toughness) and a harder outer core created by heat treatment. That was the secret of the samurai sword being both tough and still able to take a razor edge.

[45 2.1]

While not being much of a metallurgist myself, it would seem that the ideal fusion of hardness and toughness would be created by a boolit with a softer center (toughness) and a harder outer core created by heat treatment. That was the secret of the samurai sword being both tough and still able to take a razor edge.

Everytime i've talked about heat treating boolits so that the outside is hard and the inside is softer, i've been told it doesn't work that way. Little do they know....................

[Ricochet]

That definition of "alloy" as being entirely a solid solution is incorrect. It would mean that no steel, for instance, is an alloy. They are all mixtures of different crystal structures of differing composition. (At room temperature.) Same with aluminum alloys, many of which are precipitation hardened like our lead alloys. Such heterogeneous mixtures of metals are commonly recognized as alloys. Their heterogenicity is what gives them their useful properties, in many cases.

And you don't HAVE to have arsenic to make a quenched, age hardening lead alloy. It's one of several elements that will do that, and is a helpful thing to have in your boolits if you want to quench them.

[Naphtali]

Would not creating two-alloy bullets be a worthwhile solution? At least two mold makers offer "soft-nose" casting molds with instructions. And several threads in these forums address the issue.

Having a hard, relatively brittle base two-thirds [bullet] joined with a much softer nose would appear to answer the question alluded to.

Were this method chosen, would this not also allow for a more aerodynamic nose -- since wound channel would be based upon nose expansion rather than metplat?

[Glen]

45 2.1 -- I would love to hear what you had to say on the matter of heat treating for a hard surface with a softer core. If not as a part of this thread, then feel free to PM me with your ideas/results...

[45 2.1]

45 2.1 -- I would love to hear what you had to say on the matter of heat treating for a hard surface with a softer core. If not as a part of this thread, then feel free to PM me with your ideas/results...

It works thusly:
Basically dilute WW alloy with very soft lead to a point where the antimony portion of the alloy is a small percentage. This usually works about 50 % each (depending on the age of the WW and the source of your soft lead). This percentage will work with less WW, but you will reach a point where it does not heat treat. You want any constiuents of the alloy to not have much of any hardening properties if you air cooled the alloy. Generally this will give a BHN of approx. 8 when air cooled and about 19 BHN when water dropped or oven heat treated. You do want alloy elements that heat treat though. Cast that alloy at approx. 680 to 720 degrees and water drop the boolits. The alloy will get hard on the outside and stay relatively soft on the inside. WE've done this in 30 caliber and above satisfactorly, under that it doesn't work as well due to the smaller girth of the boolit. Several of us do this and get XTP jacketed performance in 35 caliber boolits and soft jacketed performance in the 45 cal. rifles. Presently i've been working with the 4570 with a 300 gr. HP that I can get normal to SX type explosive expansion with light to medium level trapdoor loads.

[Marlin Junky]

Cast that alloy at approx. 680 to 720 degrees and water drop the boolits.

45 2.1,

How would you expect 780F to 800F ladle cast boolits in a 50/50 alloy that are air cooled, oven heat treated and quenched to turn out? My straight clip-on wheel weight metal boolits processed in this manner are approx. 20 BHN as far toward the center as I have checked which is nearly half way. I have oven heated at 425F and 450F for an hour+ and have noticed a small difference in hardness while testing with a Lee hardness tester.

MJ

[Glen]

Thanks 45 2.1. I assume that these bullets must be shot unsized to prevent work softening?

[45 2.1]

How would you expect 780F to 800F ladle cast boolits in a 50/50 alloy that are air cooled, oven heat treated and quenched to turn out? MJ

Part of the method is exactly as i've told. Make them hotter and more of the boolit towards the center will probably be harder. Quench temperature has a lot to do with this.


I assume that these bullets must be shot unsized to prevent work softening?

I size normally after about a week or two cureing time.

[Bass Ackward]

45 2.1,

How would you expect 780F to 800F ladle cast boolits in a 50/50 alloy that are air cooled, oven heat treated and quenched to turn out? My straight clip-on wheel weight metal boolits processed in this manner are approx. 20 BHN as far toward the center as I have checked which is nearly half way. I have oven heated at 425F and 450F for an hour+ and have noticed a small difference in hardness while testing with a Lee hardness tester.

MJ


MJ,

Realize that in different parts of the country, average WW is different percentages. If you are in an area that is running an average of 2% antimony, then 50/ 50 is a different percentage from someone that is running a 50/50 mix with a 4% base.

The goal for me seems to be a mixture that yields about 1.5 % antimony as I have some tin in my mix. That yields an 8 BHN bullet just after molding and air cools @ 10 BHN. Too much less than that, and it won't HT. Too much more and they are hard through and through. So if you are hard all the way, your percentage of antimony is still too high. Avoid tin and shoot for a mix that produces those hardness targets.

Once you get it, you will be good to go, but it can take time.

[Ricochet]

I think they harden through and through, but as the antimony goes down to very low levels the ultimate hardness is less and takes longer to reach. Most of my boolits are water quenched ones of very low (but unknown) levels of alloy. Easily thumbnail dentable when air cooled. Sometimes I blend in some wheelweights, but seldom more than 20%. Those end up nearly as hard as quenched wheelweights. The very soft ones, when quenched and aged, end up about as hard as air cooled wheelweights. Very malleable. I've seen nothing to make me think they have a hard shell and soft center, though, and I don't believe it's possible to achieve that with small arms bullets quenched in water. The heat path from the center to the outside is too short. Only takes a second or so for them to completely cool from eutectic temperature.

[shotstring]

You might both be right Richochet and 45 2.1. With such a small piece of lead metal, small amounts of arsenic, antimony or extra time quenching would probably all have very substantial effects on the final product I would think. While understanding that lead is very different than steel in its quenching attributes, there may be some things still to be learned from the steel quenching process.

In a samurai sword, you have a much larger metal base, thus a very long quenching window by comparison to a lead boolit. With the steel sword, the different cooling rates of the two metals actually causes the blade to curl upward. To achieve different cooling rates for such a small item as a boolit, it would seem that either a different medium other than water might be tried, along with different temperatures of the quenching bath. Has anyone tried quenching in hot or boiling water or just inserting the boolit with a tongs quickly into the water and then removing it? Thiers-Issard, one of the finest French manufactures of straight razors is the only manufacturer of razors that is licensed to do a "lead" quenching to achieve their superb tempering. While a lead bath wouldn't work for us, perhaps a hot oil bath would also slow down the tempering process, allowing for a slower cooling period and a softer center. Just thinking out loud here.

[leftiye]

These approaches may produce hardened boolits that may still expand, but I for one am very interested in the (original) issue of toughness. Softness may not shatter (unless it hits a hard object at high velocity - virtually identical to the brittle boolit) as readily, but pure lead fragments badly in expanding impact in game situations. Toughness is when they expand, but do not fragment. Anybody know if tin and copper affect this? Also how does 1% copper affect hardness?

[felix]

Copper is much tougher than tin. But, copper does not stay in solution as the boolit hardens, and will therefore migrate very quickly to where it is cooler, like to the outside of the boolit, or for that matter to the walls of the pot/ladle spout to clog them up. When this becomes obvious, drop the percentage of copper in the mix by half, and then retry for a boolit run. Of course, you can increase the temps all around first and see if that works. To make sure you have a good boolit lot, weigh the boolits. If the boolits are just as consistent as your normal lot without copper, then you are good to go. Copper is comparatively light enough to cause a strong imbalance within the boolits, and hopefully that will show up by having an equally strong weight variance. Cross your fingers. You can only tell for sure by shooting them, like anything else. Both tin and copper, together or not, will make the boolit harder, but that is not their forte. Antimony and bismuth are the elements of choice there. ... felix

[MLAKE]

heat treatment rather than alloy can make a hard boolit that is less brittle. I dont care for the antimony method of hardness save for varmints or the like where you would want the boolit to 'shatter'. As for a hard casing and soft center, perhaps you could put some copper plating on the outside of it with a battery charger, but it still would not be 'tough' as in solids, save for other materials like tungsten carbide or depleted uranium incorporated into the boolit

[BABore]

What 45 2.1 says about diluting the antimony content of WW's is dead on. I have been one of the few that has actually listened, tried, tested and proved to myself that it works. My typical alloy is 50/50 WW-Pb. It drops AC'd bullets at 8-9 Bhn and WD or OHT at 19-22 Bhn. Water dropped bullets do show more of an outside case hardening and ductile center over a full out oven heat treatment. Alloy temperature and casting rthymn dictate depth of hardness. The reason it works is the bullet/mold is "just" hot enough to harden the bullet when quenched. The inside of the bullet cools slower than the outside when dropped into water. Since you are just border-line hot enough to start with, the bullets core is already passing below the temperture threshold as it starts to cool rapidly from the quench. Alloy temperature, consistent mold temperature, and timing are key.You also have to learn to adjust and adapt when you change bullet size and configuration. Use of a small, high speed cooling fan helps achieve a consistent sprue freeze time and mold block temperature.

Another "Listener" has experimanted with how much you can water down WW's with Pb and still have enough hardening constituents available. It came out at approximately 35/65 WW-Pb. I have confirmed this with my alloy's and get about 16-18 Bhn with this mix once heat treated. The amount of PB used to dilute WW's can be varied to achieve the best accuracy for a particular gun/load. Some guns will shoot water dropped bullets better than oven heat treated and vise versa. I have found, through actual testing, that in many cases you can push a 22 Bhn bullet of WW-Pb alloy much faster and more accurately than a harder 28-35 straight OHT WW bullet. The grey wash (antimony) that occurs in a barrel at high velocity was totally eliminated when the alloy was diluted.

Below is a pic of a couple 458 caliber, 420 grain bullets cast from 50/50 WW-Pb and water dropped. They were shot into a 20 pine log at 50 yards. Velocity was 1,750 fps.

[felix]

BAB, thanks for describing that the way you did. I might add to what you said by stating that adding tin for a "better" mold fillout would be counter productive for the objective of having mushrooming boolits. Tin would almost eliminate the antimony gray-wash, and would be required for fillout when making smaller caliber boolits, like 22's especially. These smaller boolits tend to heat treat automatically, air cooled or water cooled, because they are too little to maintain soft centers. In reality, I think those of us who shoot small calibers prefer the boolit to completely disappear for safety reasons after impact with anything. There are always many folks around at the river/junkyard riding go-carts/four-wheelers, etc., where I shoot. ... felix

[357maximum]

FWIIW and FYI

Anybody that is interested in harvesting them there brown, antlered and tasty critters with one of their cast creations would be well served by going back and reading/re-reading 45 2.1's and BaBores writings on this subject until it sinks into the grey matter.

I have always been more of a "DOES IT WORK" and not a "WHY IT WORKS" kinda fellow. That being said the 50/50 WD'ed ww/pb is the best place to start when you are playing with the speed and pressures commonly encountered with 30 and 35 cal cast boolits launched at typical to hot 35 remington and 30/30 J-word velocities with goal of accuracy and killing ability. I am not really interested in the science of it all, but I can tell you first hand that a plus or minus 50/50 mix that is water dropped is the bees knees for accurately matching premium partition like bullets with boolits, and you do not have to burn your fingers to do it this way.

I have had alot of "good" hints delivered since i started casting for "full house" cast, and the "TRY SOME 50/50 WW/PB AND THEN WATER DROP THEM AND THEN WAIT A WEEK" has been THEEEEEEEEEE suggestion of all suggestions. You do not have to have the ratios exact either, as Babs has said the range it works is fairly broad, but you should try to match the alloys percentage somewhat to what you are doing pressure wise. BTW all of this has been posted before the bits and peices have been condensed above me in this thread for those who are interested in "listening".

These boolits would be what I would call "DUCTILE AND TOUGH" FOR THOSE WHO ARE INTERSTED.

On another note be really careful if you decide to add pure tin to help things along as there is a very fine line between making it mo-betta and totally tin poisoning your alloy. If you can "NOT add tin" you should not add tin, it will kick your **** if you let it...then you will end up with boolits that look like you drove over them on a dirt road, and they will also not perform as expected either...then you will have to dillute the mix with more 50/50 until the uglies go away............keep the tin for the softer mixes or for when you just want to impress people with your shiny boolits.

well my nickels spent, have fun fellas