I guess I'd better hand in my metallurgy degree !
Some of the comments warrented snide remarks so that's what you got. So get me a list of types of rebar and chemical analysis.
I wasn't totally detailed in my responses. You can get purple in addition to green epoxy. For those who aren't cheap you even can get stainless steel rebar ! Of course normal barrel steels are typically 4140 . In any case we as kids years ago made "zip guns" for " 22" s from automobile antennas !! Real high tech stuff.That's enough for one night .