Metallurgical question

[PeteH]

This came up on another list I subscribe to.

Someone asked about using 12L14 for a blackpowder cannon. One of the responses said that the lead in the alloy might be present in small particles, which would weaken the barrel.

I'd been planning on doing the same thing. I know 12L14 rusts like blazes, but it machines so nicely... and I just got a couple of nice golfball-mortar-sized billets of it.

From at least one source, it seems the tensile strength of hot-rolled 12L14 is just a bit less than that of 1018, which I've read is OK.

Any comments ?

Thanks...

[Bobby Bailey]

Several of the best makers of custom muzzle loader barrels use 12L14.
Bobby

[jpfalt]

I use a lot of 12L14 and it should be fine. More important is the direction of grain structure. I machined some thin washers from 12L14 by parting them off cold finished rounds and when loaded they fractured into pie segments. What I took from that is that 12L14 is more brittle across the grain than along the grain length. I would avoid thin wall sections in your barrel, but if you stay thick walled, you should be fine. Cold finished stress proof is even worse and 1018 cold roll is pretty much an unknown for strength across the grain as the material is pretty much remelt scrap and the chemistry is really loose.

On one project I considered 41L40 instead of 12L14, but after research I was surprised to find that annealed 41L40 is actually weaker than 12L14 cold drawn.