Rant: stop telling new smiths to start on scrap rebar, mild steel bar stock is the right call
Every time a new person asks what to learn on, the top reply is always some version of "grab free rebar off a job site and beat on that." I get the appeal, it costs nothing, but it sets people up to fail and I wish the old guard would quit pushing it. Rebar is mystery alloy, often high carbon or who knows what, it work hardens under the hammer, and it cracks at the edges when you try to forge a taper. I watched a guy at the shop in Akron burn three weekends on a rebar knife and it snapped on the first chop test, then he almost quit the craft entirely. A 20 dollar stick of 1/4 inch or 3/8 inch 1018 from the local supplier moves like butter, welds fine, and lets a beginner actually learn hammer control instead of fighting the metal. The scrap pile has its place later, once you can read color and feel how a piece wants to move. If you learned on rebar and it worked out, what did you do different, because I have never seen it go smooth for a total beginner.
My grandpa had a coffee can of old railroad spikes he'd hand to anyone who wanted to try forging. Same deal though, mystery steel, hard as hell to move, guys would get frustrated and quit. He finally switched to plain old bar stock and suddenly everyone stuck with it. Funny how the free stuff is always the thing that costs you the most in the end.