Why this alloy water quench hard??

[kens]

I cast a brief session getting ready for muzzleloader deer season. I cast boolits for front-loader's using sabots in twist of 1:48 twist and 1:28 twist.
My molds of choice were:
Lee 452-200RF
Lee 452-230TC
Lee 452-255RF
My alloy was 8lbs soft lead with 4oz of smelted pewter.
I always water drop right from the mold when casting WW, this time I use water anyway b'cause soft lead and tin do not get hard by quenching, right??
I find it just easier to water drop than to mess with towels to air drop boolits on.

But, I found that these boolits today did react to quench. How is that to be?
Soft lead and tin are not supposed to respond to water drop??
But they did.
Why is this?

[bangerjim]

That is the problem with using "pewter". You do not know what is in it. I could have had a bit of Sb in there? Only way to know is get an x-ray gun shoot.

Pewter can vary in Sn content, and depending on where is comes from and how old, it may have some Sb for hardness from what I have heard.

Using pure Sn or solder of known % mix is the really only way to know what is actually in there.

And what is your source of "pure soft" Pb? Soft is a relative term. Could it have Sb in it for a bit of stiffness as some shielding and other sheeting can have?

Lots of unknown sources of Sb could be there.

banger

[Tenbender]

I use plain soft lead for black powder. Using a sabot no need for hard boolits.

[JWFilips]

Why water quench a ML boolit?

[kens]

Why water quench a ML boolit?
I find dropping in a water bucket easier than fiddling with a air cool soft blanket.
Soft lead isn't suppose to respond to water quench, so it isn't suppose to change anything.
It not supposed to matter

[303Guy]

How hard is the allow if you air drop? If I remember correctly, tin alloy does water quench harden but it softens up in time. Recheck yours from time to time and see if there is any change.

Pewter has some copper in it too. I'd guess there is some Sb, some Cu and who knows what else, possibly a little As?

[bobthenailer]

A mix of 50/50 ww and soft lead will WD harden to about 15 bhn.

[bigjake]

I don't understand how any lead regardless of alloy can get harder water quenched. I know how it works on steel, with the carbon and all but cant understand how it works with lead.
Can anyone explain to us folks that want to know?

[bangerjim]

I don't understand how any lead regardless of alloy can get harder water quenched. I know how it works on steel, with the carbon and all but cant understand how it works with lead.
Can anyone explain to us folks that want to know?

Well, I covered things like that in a year of metallurgy engineering back in college. Hard to explain it on a forum in a thread with a single post.

I would suggest inquiring minds use the amazing tool called google to do some word searches around metallurgy of Pb/Sn/Sb/As on the net. It is a tad different than the martensitic and austenitic steel alloy transformation you referenced.

But Sb and As do bestow various hardness properties to Pb alloys when cooled rapidly.

[303Guy]

Briefly (and crudely), the alloys often harden (or soften) over time as the atoms migrate and crystals grow. Sudden cooling locks the crystals as they first form on freezing. Crystals continue to change at room temperature. Some alloying constituents do interesting things to the crystal growth (grain refining) and sometimes alloys will achieve water quench hardness in a few days anyway. Heating the alloy to some point below melting point will result in the grain altering over time (an hour or so) which when allowed to cool slowly, leaves the alloy at its softest. Quenching it takes it to its hardest form which may soften some over time. Well, that wasn't too brief but is pretty crude. :roll:

[triggerhappy243]

I water quench (muzzleloader boolets) because I want to inspect them quick and also do not want to damage them when they drop out of the mould. My only reason.

[303Guy]

That's my logic too although for me the hardening is a bonus. It really is so convenient to simply water drop them. No hot boolits lying around, no damage on dropping and of course, hardened boolits without having to wait for them to age harden. Mind you, some folks have to wait for them to age anyway.

[Yodogsandman]

I don't understand how any lead regardless of alloy can get harder water quenched. I know how it works on steel, with the carbon and all but cant understand how it works with lead.
Can anyone explain to us folks that want to know?

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

[Larry Gibson]

I don't understand how any lead regardless of alloy can get harder water quenched. I know how it works on steel, with the carbon and all but cant understand how it works with lead.
Can anyone explain to us folks that want to know?

Also try reading the chapters on metallurgy in Lyman's #3 and #4 CBHs.

Obviously there was some Sb (antimony) in the "soft lead" and/or the pewter the OP was using. BTW, just because lead is "soft" does not mean it is pure. As mentioned who knows what was in the pewter(?).

Larry Gibson

[kens]

So I assume that pewter is 90% tin at least, so whatever else is in there is only trace amounts when measured against my soft lead.
If my pewter is 32:1 to start with, and the other 'stuff' is less than 10% of the pewter, then it gets clear that lead will quench hard with only trace amounts of antimony.
I am now assuming that you could an alloy like Lyman #2 and cut it down 75/25 with pure and still get hard BHN boolits.
So, how little of 'trace' element like antimony is enough to make alloy harden?

[bangerjim]

I do not know of any formula that can give exact answers with one of the variables being "a trace amount" of Sb or As.

Bottom line is.......why does it even matter? Just don't water drop if you are concerned about hardness increase due to an undetermined amount of "stuff". I mix my alloys for air hardness, even though I drop castings in water just to cool them for handling. after PC baking, all that goes away.

Since you are using unknown alloys, your hardness will be unpredictable.

[RogerDat]

Pewter is commonly 6% antimony, the OP stated mix of 4 oz. to 8 lbs. would be better than 9 BHN just on the alloys, close to 3% on tin. Lot harder than plain. Not a very high percentage of antimony at less than 1% assuming the plain was true plain rather than having a bit of "something" in it. Even a tiny amount of arsenic (common to help lead form) will act as a catalyst for the water quench reaction. Sn/Sb/As in even small amounts can change the crystal structure and matrix during a water quench out of proportion to their amounts.

BHN of 9 from the added tin and antimony seems like it would be sufficient for ML sabot use. Don't water drop unknown alloy because as Jim said you won't get predictable results. Or if you do then make a large enough batch of alloy that being "predictable" for the next 100 lbs. is good enough, 8 lbs. is not a batch size that works well for assorted scrap and predictable results.

[bigjake]

Thanks to the ones that explained the water quenching for hardness.

[Nose Dive]

Yep.... Pewter is a 'grab bag' of constituents. Or, there is no 'legal' blend that folks have to adhere to. Generally, 'good' foundry folks leave out the lead so mugs, jugs and bowls won't poison folks. BUT,,, i bought a box full of 'broken' pewter pieces at a garage sale from a guy fresh out of Angola and with out testing, i would swear it had lead in the mix. Or, 'pay your money, take your chance'.
That said, I use a lot of pewter items in my smelt pots. And there is plenty of prose on this site about doing it. Some shows zinc, some doesn't. Unless you can really 'test it' accurately, your relegated to do what we do when standing beside your smelt pot. (keep the pot 'cool', scrap dross mix often, flux,,,flux...flux...'keep your fingers crossed!' and pay attention to the smelt)

I got a really 'good' mix from a guy in a print shop once. It was made in Great Britain and believe their product safety laws are much better than in Angola. And, I have had to resmelt some boolits made from smelt with lead, WW's, trash and corruption and a few pewter mugs due to hi zinc content. Or, three days of work down the drain. So, what did I say above? 'Pay your money, take your chances".

You can also go to PEWTERTANKARD web site and see how to alloy with it. "FROM INGOT TO TARGET" is also good. If you get some good pewter pieces, it really help the alloy pour and fill out the mold. And, if you do as I do, 'water drop EVERYTHING', regardless of final use, (mussle loader, pistol, rifle, cannon), it helps the boolit retain it's hardness longer. 'things soften over time'.

Stay safe on your smelting!

Nose Dive

Cheap, Fast, Good. Kindly pick two.