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Mig welding cast iron?

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  • Mig welding cast iron?

    Well more than one person have said it's possible so I got curious myself. I got this cracked top plate from a wood fired stove that belongs to my uncle, I offered to try and fix it as a last ditch effort:

    It was in bad shape, the fins on the bottom tells that it's probably nearly worn out anyway. I cut the whole thing in two since I could see no other way to clean out the crack and correct the springback which had occured.

    I fitted the parts and tacked them together (this was difficult, the tacks cracked or did not take, eventually I got it) and I welded it up, went a lot easier when the metal was hot. I placed it on insulating firebricks so the welding table would not cool them down.

    After grinding the top welds

    I'm planning to do some more work yet, fill some of the undercuts but I think I will tig braze that.Why not tig braze the whole thing? That's beyond my skill level. I could've done the top but the bottom with the fins, no way I could've gotten in there with a tig torch, I got problems going straight on a plane... Gas brazing would have worked but I don't have such a setup yet. Nickle rod would probably have been easiest though but I do not have any.

    I am thinking I'll do a finish pass of the weld with the mill with some carbide tooling to get it looking nicer.

  • #2
    I’m impressed-I’ve used mig on cast iron and long thin section presumably infused with carbon, strikes me as “worst case”.


    • #3
      Nice job, it will be interesting to see how it holds up to a few heat and cool cycles on the stove. I have no idea if that's actually even a real concern but it seems to me the only potential risk.
      I like it when someone just tries something like this that they have never done before. Even if it doesn't work out, you have certainly gained a bit of experience that will make it work better next time.
      Thanks for posting and please report back the final results once this goes into service.


      • #4
        there HAS to be a reason.


        • #5
          Reason for what? That's not the wire I used, it's regular mig welding wire, 0.8mm or .030"

          I swapped it out last night for .6mm or .024" wire though, also regular wire. To test how it differs on sheet metal.


          • #6
            ER70S6 ??

            Okay. Let us know how it lasts. I do not mean that sarcastically. I genuinely would love to see a follow up after a few weeks/months of use.

            I would have guessed stainless wire if I didn't have any special wire or rod for cast iron. I do have a little nickle rod I bought when a local store was specially out one brand of welding stock/supplies/equipment for another.
            *** I always wanted a welding stinger that looked like the north end of a south bound chicken. Often my welds look like somebody pointed the wrong end of a chicken at the joint and squeezed until something came out. Might as well look the part.


            • #7
              The reason Crown makes a specific wire for cast is because 70S6 doesn’t have the nickel content needed.
              Stainless is better but still not the recommended filler.


              • #8
                I know itäs not recommended in the slightest, but it was an experiment