Water quenching cast bullets

[Reddot]

I have read that dropping your freshly cast bullets in a 5 gallon bucket of water will harden them significantly. However if you put them through a sizer this will decrease some of the hardness. Just what is being hardened in the quenching process? Just a thin outer layer of the bullet? I would think that the whole bullet would be hardened by this process.

[grumpy one]

Lead-antimony alloys with low to moderate amounts of antimony can be precipitation hardened. As they solidify the antimony becomes less soluble in lead, and precipitates out. Antimony precipitating into a matrix of solidified lead stresses the crystal matrix of the lead. The prestressed lead is harder than unstressed lead. Because lead is subject to creep, or stress-relaxation over time, the hardening process reverses itself very slowly.

When you size a bullet the alloy has to flow into a new shape of smaller diameter. Depending on the amount of sizing and the bullet design, some of this deformation happens close to the surface, especially through lead flowing into the lube grooves. However the bullet also becomes longer - a process which deforms the alloy all the way to the center. Deforming prestressed lead relaxes the prestress and makes the bullet soft wherever it was deformed. So, if you just size a heat treated bullet without lubing it first, the deformation is concentrated close to the driving bands, which deform into the lube grooves. If you lube the bullet first, the lube grooves become just about incompressible and the deformation reaches deeper into the bullet. Thus heat treatment benefit is largely lost if you size the bullet after it has hardened. (But remember it takes days to weeks for the precipitation to occur after quenching, so you can lube after quenching so long as you do it within say 2 to 4 hours.)

[Reddot]

Grumpy, thank you for that answer.

Does the hardening process start to reverse if you cast a bunch of bullets in the winter and don't use them for say a year? The reason I ask the question is I have access to a lot of lead now that may not be available in the future so I'm thinking that I should make hay while the sun shines so to speak.

[Ricochet]

They'll soften a bit, even in 6 months. Given enough time, they'd equilibrate at the same hardness as annealed boolits of the same alloy. But that'd take many years, I believe. I have a few quenched boolits I made in 2000 that are still quite hard.

[grumpy one]

Ricochet is right, as usual. Heat treated bullets harden fairly quickly for about two weeks, then continue to harden more slowly for additional weeks or months depending on the alloy. After perhaps a year they will be on their way toward softening, but this is a 'negatively accelerated exponential decay' process: even after quite a number of years they may still be measurably harder than annealed bullets made from the same alloy, though the softening will continue indefinitely.

There is no reason to delay buying alloy, or even to delay casting bullets, over this re-softening issue. Simply heat treat your bullets a couple of weeks up to say a year before you shoot them. You can heat treat ten or twenty year old castings as effectively as you can new castings.

[blackthorn]

Other than a bit of oxide, lead dont rot! so you can accumulate as much as you have room to store. It can be stored either outdoors or inside. Further, there is no reason you have to cast/heat treat/size up whatever you get until you are ready to use it. Collect away and have fun!!

[mold maker]

Lead is as cheap right now as it probably ever will be in the future. Beyond price the availability of lead may disappear in the not to distant future. More and more traditional uses for lead are being replaced either by other metals or plastics.
With the Left Coast, weenies , and political thinking, spreading, it would be wise not to pass on any that you find while you still can.
Even if you can't use all of your stash, it will trade for primer and powder to keep you shooting for a long time, kinda like a savings account for reloaders.

[454PB]

To answer your other question, I've hardness tested quenched boolits that were filed down 1/3 of their diameter, and they were just as hard inside as outside.

[Pat I.]

To answer your other question, I've hardness tested quenched boolits that were filed down 1/3 of their diameter, and they were just as hard inside as outside.

Me too with same results.

[NuJudge]

What hardens Lead when quenched is just that there are lots of incorrect Tin and perhaps Antimony atoms lost in the crystalographic latice of the Lead, plus some small islands of various precipitated compounds around the boundaries of or in Lead crystals. Both the incorrect atoms and the small islands of various Tin and Antimony compounds restrict deformation of the Lead lattice at room temperature. If quenched quickly, more of the incorrect atoms will be trapped in the lattice, and the islands will be small. The effect of aging on precipitates is for them to grow. My observation in the Lab 30 years ago was that over time, precipitate effect on resistance to deformation grew for a while until the precipitates reached an optimum size, then gradually fell off.

The effect of rapid freezing should be strongest at the edges, and lesser in the interior of a casting, but I don't know how you would get at the interior of a casting to determine what the property gradient was, because of the Recrystalization effect I mention below.

During the high temperature period of cooling right after freezing, those incorrect Tin and Antimony atoms migrate to Lead crystal boundaries. The incorrect Tin and Antimony atoms distort the Lead crystal lattice, and it is a lower energy state for them to be at the crystal boundaries.

All the metals I am familiar with have some Recrystalization temperature at which they spontaneously reorganize their crystalographic lattice in order to reduce stresses in it. For purposes of Cold Work and elimination of the effects of Cold Work by Recrystalization, Lead acts as if is at high temperatures. That temperature for all the metals I am familiar with is about one-half of the melting temperature, expressed in degrees absolute: degrees Rankin or Kelvin. Lead and its alloys are about at that temperature when at room temperature. That which fuels the recrystalization is the stresses in the lattice. Supply any Cold Work, and the recrystalization should take off, and you will lose most of the effect of improper atoms, plus precipitates, plus cold work.

There are other hardening mechanisms at work in many other metals when you quench them, such as in the Iron-Carbon system, but none of them are useful in Lead-Tin-Antimony.

[Pat I.]

Not bored but for sure lost. Could you give a Readers Digest version of what you just said in laymans terms?

[NuJudge]

Much is lost in doing so, but here's an effort at it.

Lead freezes into a closely packed 3-dimensional pattern.
Alloying elements, either through getting lost in the pattern or forming compounds, stress the pattern.
Stressed patterns bend/stretch/twist/compress less easily.
Metals patterns spontaneously reorganize at a temperature known as the Recrystallization temperature, and lose most stresses.
The Recrystalization temperature for most Lead alloys is about room temperature.
Cold Work of a metal at its Recrystalization temperature should make Recrystalization happen immediately.
Other metals have hardening mechanisms that do not happen with Lead.

[DLCTEX]

Basically, if you size hardened boolits you work soften the surface metal. this will only be the surface unless you are reducing the size a large amoumt. If you need hard surface boolits you must cast to size and water drop, or oven heat treat after sizing. The softening of the surface may not be as important as some think, considering that all the surface gets sized when fired. The internally hardened boolit stands up to the stresses of firing and even impacting the target, so all the benefits of hardening are not lost by sizing. You have to experiment and determine what process fits your needs. So far waterdropping, then sizing has met my needs

[mikenbarb]

Just store them in a smaller refrigerator and take out what you plan to use.LOL.
Just my guess on keeping them consistent for a long time.:confused:

[Bret4207]

Grumpy and NuJudge- OUTSTANDING POSTS!!! Thank you!

[MaxJon]

Any real world figures of BHN increase? My bullets are running at 16.5 BHN. Water quenching from the mold should increase this figure?

[greenjoytj]

It my understanding that water quenching will only harden bullets that contain antimony.
Also bullets cast with alloy containing antimony will swell bigger during the month after casting so the caster should wait a minimum of 1 month before sizing.

[44MAG#1]

Question like this is a fertile area for everything from scientific data to old wives tales on the subject.
Linotype, depending on how much it has been used will run 20-22 BHN. I had some that was either replenished back it was nearly new and it was HARD 22 BHN.
Now this is not scientific but Wheelweights, PROPERLY QUENCHED and PROPERLY QUENCHED is the keywords, will exceed Linotype by quite a bit, in the high 20's. But they will not be brittle like Linotype. One can take a PROPERLY QUENCHED wheelweight bullet base to base with replenished Linotype in a vise and the WW bullet will bust, burst, wreck the linotype bullet.
Put both on a hard surface and clobber both with a sleghammer and the Linotype bullet will fair poorly compared to a PROPERLY QUENCHED wheelweight bullet. Now if the wheelweight bullet is only "casehardened" how can it put extreme shame on a Linotype bullet?
Now, while I am not scientific, and cannot speak scientific lingo , some things don't need the scientific speak to get a proper grasp on it.
Lyman #2 runs 15 on the BHN number scale and is hard enough for most shooting purposes but, if one wanted to get a harder bullet for, lets say, an encounter with a big bear so penetration will be great due to lesser deformation I for one will water quench. Other than something like that , which will never happen for me, 15 BHN is great.
Also I have measured BHN too. So with that being said, lets say a 28 BHN WQWW bullet loses 40 percent over a long time it still will be 17 BHN so still all is good.
Not scientific but something to think about.

[Dusty Bannister]

The heat treated and quenched bullet is not "case hardened". That is a surface condition. The properly heat treated and quenched bullet is changed in structure throughout the bullet.

[Burnt Fingers]

Any real world figures of BHN increase? My bullets are running at 16.5 BHN. Water quenching from the mold should increase this figure?

Why are you seeking such hard bullets?

[popper]

As they solidify the antimony becomes less soluble in lead Partially correct. As the MIXTURE cools, layers of Sb rich/SB lean MIXTURES are created. Water dropping makes these layers very thin. Think of a block of sugar cubes (Pb). Lead 'moves' by sliding action between the cubes. Put a larger or smaller cube in the pile and force required for sliding increases. The 'alien' cube can be sulfur, arsenic, copper,antimony, calcium, zinc, tin and some others. When 'molton' the cubes move around. When cooling (or cold) they still move, just not as much. The alien cubes can accumulate in one spot (weaker/softer). There are a few ALLOYS that can form from the aliens, none are lead! Yea, tellurium, cadmium and some others will ALLOY with lead but we have no use for them. Contrary to popular belief, SbSn is NOT an end alloy - it may be formed during cooling but falls apart before solid is reached - except in special lab conditions. Sulfur and copper do stay in alloy but sulfur 'leaches' out on subsequent heating/cooling cycles. Of course lead oxide (as well as tin and Sb oxides) require FLUXING to remove the oxide - carbonation. Work SOFTENING of lead is a relatively slow process so sizing or shooting has minor effect. Hit you PB/Sn/Sb bullets hard with a heavy hammer. Gets hot but not deformed much. Let cool, next blow it will deform more (softer).

[Conditor22]

The hardness you get from quenching will depend on the alloy

antimony and arsenic have much to do with this.

[MaxJon]

I'm not really, just wondered if it will make them harder again.

[sutherpride59]

Lead-antimony alloys with low to moderate amounts of antimony can be precipitation hardened. As they solidify the antimony becomes less soluble in lead, and precipitates out. Antimony precipitating into a matrix of solidified lead stresses the crystal matrix of the lead. The prestressed lead is harder than unstressed lead. Because lead is subject to creep, or stress-relaxation over time, the hardening process reverses itself very slowly.

When you size a bullet the alloy has to flow into a new shape of smaller diameter. Depending on the amount of sizing and the bullet design, some of this deformation happens close to the surface, especially through lead flowing into the lube grooves. However the bullet also becomes longer - a process which deforms the alloy all the way to the center. Deforming prestressed lead relaxes the prestress and makes the bullet soft wherever it was deformed. So, if you just size a heat treated bullet without lubing it first, the deformation is concentrated close to the driving bands, which deform into the lube grooves. If you lube the bullet first, the lube grooves become just about incompressible and the deformation reaches deeper into the bullet. Thus heat treatment benefit is largely lost if you size the bullet after it has hardened. (But remember it takes days to weeks for the precipitation to occur after quenching, so you can lube after quenching so long as you do it within say 2 to 4 hours.)


Please believe I’m not saying you are wrong but if this is completely true then how is it that I can cast and heat treat hard bullets then the next day file the bullet and hit it with my lee tester and get a significant hardness such as 28bhn? Wouldn’t filing the bullet soften the metal that I am testing? Wouldn’t I be testing metal that isn’t impacted by the precipitation effect? Also if sizing sizes the surface of the metal wouldn’t it only be a super thin layer that wouldn’t even matter. If you size to 309 and your barrel is .308 then that metal that engages the rifling would be metal that hasn’t even been work softened yet.

[44MAG#1]

Water quenched bullets are not case hardened period. They are through hardened period. Scientific thought and eloquent speak is fine but one must understand that when the bullet is Quenched properly they are through hardened. And mighty hard they will become when PROPERLY QUENCHED and tough provided the Antimony content isn't too high.
Sized bullets will still crack, bust, burst or wreck a 22 BHN bullet provided the Wheelweight bullets are PROPERLY QUENCHED. A case hardened bullet would not do that. Also a hardness test on the center of the bullet will show through hardness.
This is a case where actual experience comes into play.


Please believe I’m not saying you are wrong but if this is completely true then how is it that I can cast and heat treat hard bullets then the next day file the bullet and hit it with my lee tester and get a significant hardness such as 28bhn? Wouldn’t filing the bullet soften the metal that I am testing? Wouldn’t I be testing metal that isn’t impacted by the precipitation effect? Also if sizing sizes the surface of the metal wouldn’t it only be a super thin layer that wouldn’t even matter. If you size to 309 and your barrel is .308 then that metal that engages the rifling would be metal that hasn’t even been work softened yet.

[Shiloh]

Wet boolits are cold bullets. Cold bullets don't burn you.

Shiloh

[MaxJon]

Water quenched bullets are not case hardened period. They are through hardened period. Scientific thought and eloquent speak is fine but one must understand that when the bullet is Quenched properly they are through hardened. And mighty hard they will become when PROPERLY QUENCHED and tough provided the Antimony content isn't too high.
Sized bullets will still crack, bust, burst or wreck a 22 BHN bullet provided the Wheelweight bullets are PROPERLY QUENCHED. A case hardened bullet would not do that. Also a hardness test on the center of the bullet will show through hardness.
This is a case where actual experience comes into play.

Agree 100%

[Texas by God]

Right or wrong, I never water quench my cast bullets. I have not found a need.

Sent from my SAMSUNG-SM-G930A using Tapatalk

[tazman]

Wet boolits are cold bullets. Cold bullets don't burn you.

Shiloh

This^^^^^^^^
The extra hardness is a nice side effect.

[44MAG#1]

Right or wrong, I never water quench my cast bullets. I have not found a need.

Sent from my SAMSUNG-SM-G930A using Tapatalk

You are neither wrong or right. You so what you want to do. Everyone else does the same.

[lotech]

It certainly hurts nothing to experiment with water quenching (and oven heat-treating). I used to do both some years ago, but realized I needed nothing harder than 12-13 BHN air-cooled wheelweight alloy for all my casting needs, rifle and handgun. We all have different requirements and water quenching may prove advantageous for some. Just be sure to do a side-by-side comparison using quenched and unquenched bullets to verify the benefit of the process.