AL Barrel Nuts, Alloy Handguards and Heat

[grayfox]

One of my longer projects (in my past life) had to deal with an aluminum alloy that was supposed to be qualified for nuclear, not to mention, naval specs and QC. The trouble came in from the manufacturer not being as in control of the heat treating as was originally thought... and the upshot was over some time, that the aluminum leached away leaving a porous, leaky and weak metal lattice-architecture behind... that weeped, leaked, and even broke through a few times with just a pencil push. This came from corrosion occurring down at the grain-level and grain boundary level, and, like I said, alloy was qualified for safety-level systems in plants.

So now every time I read about this or that aluminum alloy with more reactive metals (think Li, Cu, etc etc)... even in small %s, I just get leery of all the promises, b/c the mfr in the case I dealt with, didn't know or didn't control or wasn't aware of the actual alloy-formations going on down at that inter-granular level, and they all swore that the heat treating etc was all gtg. I'm sure the guys who use these other alloys will swear that they are great and have no problems but I've had engineers, professionals and executives swear that also regarding this other alloy... and they all proved to be wrong. Got kind of expensive for them when they had to fix it.

Just a caveat. Maybe that couple of oz's you're looking to save aren't worth it after all.