Spent two days trying to get a clean weld on a wrought iron repair

Had to fix an old gate hinge, and the wrought iron kept cracking right next to my bead. I was using my normal 7018 rod, but it just wouldn't fuse right. Finally dug into an old book and found out wrought iron has a lot of slag strings inside that mess with the weld pool. Switched to a 309 stainless rod at lower heat, and it worked on the first try. Anyone else run into this with antique ironwork?

3 comments

3 Comments

barnes.morgan26d ago

Start preheating the metal before you even strike an arc. @tarak17 mentioned the slag strings being fault lines, and he's right, but the real trick is getting the whole piece warm first. That old wrought iron holds heat different than modern steel, it soaks it up weird and then drops it fast. If you don't preheat, the weld zone cools way quicker than the rest and pulls all that stress right into the slag layers. I use a cheap propane torch for maybe 10 minutes on the whole hinge area before I touch a rod. It steadies the puddle and cuts down on the cracking by a lot. The 309 rod plus a good preheat makes antique ironwork almost easy.

tarak172mo ago

Old books are gold, like @emma684 said.

emma6842mo ago

Wrought iron is a total pain like that. Those slag strings act like little fault lines. Had a similar nightmare fixing an old fence post. The 309 rod trick is solid, it just seems to play nicer with the weird old metal. Good call digging into the old books, that's where the real fixes are.