My first alloy melt and...what happened?

[zampilot]

OK, I decided to try to make an alloy, 7.2 lbs lead and 5 lbs Linotype. Melted it on a propane stove in a cast iron fry pan, poured into a Lyman ingot mold. I fluxed and skimmed away the black stuff. The metal was completely melted and I poured the mix, the first pour of four came out nice and shiny, the next four slightly frosted, the last eight were frosted. OK...we'll see what the Lee BHN says tomorrow.
Today I'm surprised: I used a hammer to flatten an area to measure on each ingot tested, the first four ingots were a Lee BHN of 20.9, so were the second four. The last eight were Lee BHN 12.7......
What happened?
Aside from that, my 13 yr old daughter has taken a liking to the idea of melting metal...

[Boerrancher]

Hmmm, It sounds to me like you didn't quite flux and mix well enough, and all of your hardening agents, were floating at or near the top. When I make an alloy for ingots I melt it in a deep pot, and use a ladle to stir and scoop out my mixture to pour in the ingot moulds. This keeps everything nice and uniform. I hope this helps some.

Best wishes from the Boer Ranch,

Joe

[docone31]

Yeah, ditto that.
When I melt, I use a dee pot. I stir before each time I dip my ladle to make an ingot. I flux like crazy untill I get that shiney melt. The wife hates it, I love the smell.
I also make thin long ingots. One ladle dip worth for each one.
When I melt for the pour, I take the ingots which I put into seperate piles and kinda blend them so they all melt and pour the same.
It is approximate, one from here, two from there, but my alloy works for me.
Kinda like by gosh, and by golly alloying after melting off the original crud.
Hey, its fun.

[zampilot]

OK, guys thanks for the info. I think the propane may be to erratic temp wise also.

[garandsrus]

Zampilot,

Welcome aboard :)

I would think that hammering a flat spot on the ingot could/would change it's harness value in that spot. If you had a pot full of metal, all of the ingots should be the same. Filing a flat spot may not change the hardness as much, I really don't know for sure.

Give the ingots a week or two and I would bet that they will all be very similar. They will continue to harder during that time.

The frosty appearance of the ingots show that the mix got pretty hot as it sat on the burner waiting it's turn to get poured out. Once the alloy is liquid, it doesn't take much to keep it there. You can turn down the gas quite a bit while waiting for the ingots to solidify. A thermometer is a big help here!

I am not sure what you are going to cast, but your ratio's make a pretty hard boolit!

John

[zampilot]

Thanks John,
Your points are well taken, and I came up with some of the same conclusions as the others, but the important thing was.......I wanted to pour some metal!!
I found those bell shaped duck weights to be a bhn of 9....

[870TC]

Not sure about the Lee BHN tester, but the instructions for my LBT tester say not to test ingots only bullets. Also says to file a flat spot, as others have mentioned. The duck weights make fine bullets, you may want to mix a little lino in for higher velocities.

[454PB]

I agree with garandsrus. The ingot mould got hotter with each fill, and just as with a mould, as the heat increases, the ingots get frosty. Wait a few days, file a flat rather than hammering it, and do another hardness test.

[leftiye]

Banging on lead (or swaging it - anything that breaks down the crystalline structure) creates a hardness equal to soft lead on the area where the lead was moved. I'm surprised that they all didn't measure 5 or 6. My take on the last one being softer is that the first two pours quenched against the cool ingot mold and were hardened. The last cooled slowly, and didn't harden. This is borne out by the progression of the frosting.

[JIMinPHX]

I'm on the bandwagon with Leftiye & some of the others.

It sounds to me like you poured into a cold ingot mold the first time & that quenched the alloy & hardened it. After that, the mold was hot & subsequent pours did not get the chill effect, so those ingots came out softer.

the instructions with the Lee gizmo say to file a flat spot, not hammer it. Hammering metals (lead or otherwise) changes hardnesses.

The hardness of the boolits that you cast will likely be a little different from the hardnesses that you measure in the ingots since the boolits cool faster due to their size & surface area to mass ratio.

[madsenshooter]

Unlike brass or steel alloys that with work harden, lead alloys soften with working. The hammering is a part of it, and I imagine the quenching effect of the ingot mold has a bit to do with it too. That's one reason for filing, to remove some top surface hardness that comes from quenching in the mold. Though it's nice that your daughter has an interest in what you're doing, keep an eye on her, the pretty silvery flow really burns, as in scarred for life! My dad worked in an aluminum plant for 30 years and I recall a nasty burn on his foot he got from molten metal, not pretty at all.

[zampilot]

Yup, I filed a spot on each ingot and they are all 13.5 via Lee BHT, a rookie "excitement mistake" in the hammering, please excuse me!
As for my daughter, make no mistake I've told her about steam explosions (I produced one when I was about 11 or 12 making lead soldiers). She's more into RenFest baubles anyway.

[garandsrus]

Zampilot,

It's good to hear that you got things figured out....

John