Evidently, that’s a thing and that’s really cool.
I saw the video when it came out. Thought it was pretty damn interesting. Maybe one day I’ll get around to trying it myself.
CNC Plasma + TIG welding for a hardened Axe isn’t a bad first project. I’ll help if you’re interested.
If it can weld 135- ksi tubulars together, I could use it now.
I can’t give you advice, but normally you don’t want a “hardened” weld because it would crack.