You think that manufacturers start with galvanized stock? I thought it would be wound, and fabricated, then galvanized.
I work with RR spikes a lot, and yes I have also read that HC stamped would only rate as a mid carbon for knives, but is really good for flex and tensile. And really unless you doing a super hard super strong tactical military knife I find that they hold a decent edge. Also some of the old RR spikes are made of puddle steel, so carbon tracings show up when you grind and polish.
As I said I got the idea from a TV show I saw couple years ago, the guy on the show welded a big pile of barbed wire, to make the top plate of a garden gate.
Trying to experiment with pattern welding various things, to see if I can come up with a unique product.