Finally got a straight weld on a rusty railroad spike knife

I tried preheating the spike in my little propane forge (nothing fancy, just a Mr. Volcano) before hammering and it actually held together at the anvil (which never happens for me with rusty metal). What's your go-to trick for old, pitted scrap?

2 comments

2 Comments

grace4191mo ago

So there I was last weekend with an old rusty spike from a railroad salvage yard (you know the type, all flaky and pitted). I tried preheating it in my propane forge too and it actually stuck together on the anvil, which shocked me honestly. @nathan_barnes I totally get your worry about the scale, but I found that if you heat it slow and gentle, the rust kinda burns off before you start hammering (it's like the heat helps it fall away). My go-to trick for old pitted scrap is to give it a quick wire brush after the first heat, then hit it again hot. That way you get rid of the loose crud but the good layers underneath still weld up tight. It's definitely not perfect every time, but I've had way better luck with that method than grinding all the rust off first (which just leaves more weak spots in my experience).

nathan_barnes1mo ago

Ain't preheating just gonna make the scale worse and splatter more when you hit it? I usually grind off as much rust as I can first, old pitted stuff just never seems to hold together for me no matter what I do.