Technical rust in joint?

I had to stop welding in my toe board and I had not completed all of the welds around it. I ***ume there is rust on the edge of the metal now. Can I mig weld and burn it off or do I need to derust it with something or did I really F up?

Thanks,

Mike

 

Pic? How rusty? If it's just light flash rust it's probably fine to jump back in where you started. But you can't really "burn off" rust with a weld, you're just going to introduce a contaminant to the weld, and if it's heavy enough, you'll cause porosity, which looks like a MIG weld with the gas turned off.

Show us what it looks like. But even if you can't, it's never a bad idea to clean up the weld area as clean as you can get it.

 

Wire wheel it or brush it as best as you can then go for it.

 

Would phosphoric acid wash be ok? In addition to wire brushing?

 

That's what I try to do. Clean the rust up as best I can and then treat it with a little ospho. Especially if you can't get at all of it, like a seam. Always seemed like a good idea. I've never had any issues with it later on, although I've seen some threads where people have different opinions.

 

With MIG, cleanliness isn't just next to godliness it really IS godliness. Won't be that hard to clean it up bit. Don't get crazy with a steel wire brush on a drill or die grinder. The tips will deposit carbon steel waste where you least want it. Hand brush or chemical is best.