"Shelf hardening" is a term we use to describe the natural hardening of aluminum extrusions over time.
This is news to me, that alu extrusions harden over time? What is going on, oxydation below the surface level? Does this mean that old masts are suspect as they stiffen and hence become more brittle?
I've heard of "age hardening" (precipitation hardening) but that term is a bit of a misnomer - it's a heat treatment process...I've never heard that aluminum extrusions gradually harden over time...or maybe "age hardening" is a quick way to do what might naturally take place over a large period of time?
