Tried forge welding a billet of scrap rebar and got something totally unexpected

I had a pile of rebar from a job site in Detroit and figured I'd try to make a cheap billet for practice. Heated it up to welding temp, hit it with the hammer, and it just crumbled apart like old rust. Turns out some rebar has coatings or weird alloys that ruin the weld. Learned to check for mill markings first next time. Has anyone else had luck welding mystery steel from construction scraps?

3 comments

3 Comments

anna7174d ago

Oh man, that crumbly mess is exactly what happened to me the first time too! I read somewhere that rebar can have all sorts of junk mixed in depending on where it was made. @jennybailey is right about taking it slow, I've heard the trick with lower temps too. That epoxy coating stuff they use on bridge rebar is nasty, I saw a video where a guy tried it and his whole shop stank for days. Definitely worth the extra time to grind it clean first.

jennybailey4d ago

Ive had pretty good luck with scrap rebar actually. You gotta take it slow and get the heat just right if its mystery stuff. Maybe try a lower temp next time and see if that helps.

logan2714d ago

Took me three tries before I figured out the trick with rebar. You gotta grind off all the surface scale and any coatings first, like really get down to bare metal. Then wire brush it right before you put it back in the forge. The crumbly thing you saw happens when leftover mill scale or that weird rust converter coating they spray on some grades turns into slag at welding heat. I found that if you heat it to a dull red, let it soak for a few minutes so the junk bakes off, then wire brush and bring it up to welding temp, it sticks way better. Also stay away from the epoxy coated stuff they use for parking garages and bridges, that stuff is poison for forge welding and smells terrible when it burns off.