PDA

View Full Version : Heat treating alloy questions



offshore44
02-04-2014, 04:49 PM
I started monkeying around with heat treating a 94-3-3 alloy for a couple of rifles. My results are not what I expected.

The first try was with some stuff that was under the bench. 16-1 range lead and pewter with enough Lyman #2 from Rotometals to get to the 94-3-3 that was wanted. Water dropping these produced a nice boolit that went to about 28 bhn in a week. Fair enough, that was what I was looking for.

I then carefully mixed some 94-3-3 out of West Coast Shot (#8 Magnum shot) and more of the 16-1 plus a bit of pewter. I water dropped these and got about 14 bhn after a few days. We'll see what they do in a week or so.

Then I took the same alloy and oven tempered and quenched them at 420 and 460 degrees. The write up on the LASC site seems to be telling me that I should expect some difference in bhn in a few days; we'll see.

The thing that has me a little concerned is that the boolits made from Lyman #2 etc. got much harder much faster than what I am seeing from the magnum shot concoction. The magnum shot is supposed to have about 4% antimony in it. And arsenic. That's what I've used in the alloy calculations anyway.

Should I not worry and just be happy? Is this the correct direction to head? This worked out once, but the new 94-3-3 alloy from different source components is acting differently this time around.

What have all you water droppers and heat treaters experienced?

The alloy is usable for other things, so nothing is going to waste. Should I get another bag of shot and add enough pewter to get to about 1-2% tin and try that? That should be about 94-4-2 alloy, theoretically anyway.

The end result that I'm looking for is a hard alloy for the StG-58 (308) and higher pressure 8mm Mauser loads for punching paper. The StG-58 needs it to keep the boolits from getting mangled during the feeding cycle. The Mauser is just because it seemed like an interesting thing to try.

popper
02-04-2014, 11:39 PM
I'm using 3% Sn 1% Cu, PCd & WD in AR-10 clone, works fine. I do add the shot. #2/pure 50/50 isn't too weak.

offshore44
02-05-2014, 02:26 PM
I tested the oven heat treated boolits again after 24 hours and the 460 degree ones have gone to a bhn of 20, the 420 degree one's have gone to a bhn of 19. Things appear to be working the way they should at this stage. The water dropped ones are in the same range, but there is a lot more variation in the bhn. The few that were tested went from 18.5 to 21 bhn. The results are mirroring what the testers on the LASC site observed. A couple of the water dropped ones must have hit the water pretty cold though, not much of a change in hardness yet.

Thanks popper...95-2.5-2.5 + copper. That's in the ballpark of where this stuff is at. The English pewter that I use for a tin source starts out with 1.5% copper. By the time it's all mixed together, it's probably more of a contaminate than an alloy. The spreadsheet says 0.05% copper.