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TIG welding cast iron??

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  • TIG welding cast iron??

    Today one of the machinist messed up and needed some help. Needed to build up the bottom of a 2 inch hole he had machined too deep. So I gave it to one of my guys and he used silcon bronze rod and it flowed in well and looked great. The problem was when he went to machine it back out he burned up several inserts getting it done. So my question is what would have been a better choice of rod for an applcation where the weld needed machined after welding??? We have nickel 99 stick welding rod but in this case TIG was a better choice because of splatter.Any suggestions? Thanks

  • #2
    A 99 nickel rod will produce a machineable weld. A 55 nickel rod may possibly be machined after several passes. In your situation, I would have knocked the flux off of the 99 rod and used it as a tig rod.

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    • #3
      I wouldn't recommend TIG for cast iron unless you're willing to put in a lot of preheat. Cast needs preheat anyway but even more if you're going to electrically weld it rather than with a gas torch. The heat of a TIG torch is far too focused and localised. You'll end up cracking it. If you go ahead with TIG do yourself a favour and don't use a rosebud for your preheat; use a tiger torch. Same reasons.


      • #4
        I would have migged it with Crown Alloys Royal 44-30 cast iron mig wire. Nice easy to machine weld when done. Just my thoughts...Bob
        Bob Wright

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        • #5
          We used to machine the steering head bores on motorcycle frames that were filled in with Silicon Bronze to correct non concentric bores for the steering head bearings. We flooded it with a strong stream of coolant (to cool it and to clear the chips). We never have a problem going through bits. Did they flood it with coolant while machining?


          • #6
            Techalloy makes a product called, Techalloy 99 for welding cast iron. It is easy to machine and comes in Tig or Mig. Talk to your LWS they can usually buy it from the manf.


            • #7

              Yes it should have been tiged for sure. You can use stainless on case iron aswell


              • #8
                TIG welding cast iron??

                stainless contain a lot of chrome,, not a good choice to match cast iron ...


                • #9
                  TIG welding cast iron??

                  100 percent nickel stick rod works great


                  • #10
                    I collect antique farm equipment and old tools. I have done a fair share of repairs on cast. I have been able to tig smaller pieces (with nickle or low carbon steel filler) that I could fit into a forge to preheat and slowly cool down after the weld. Tig welding without preheat is bad. There will be carbon concentrated in the weld zone and the weld shrinks to fast. Toe or underbead cracks will soon follow. I have used Nickle rods on larger castings but often needed to drill holes at the ends of a crack, preheat casting, and peen the weld while still red hot. Some castings (usually the ones that are really gray) due to very high carbon content are nearly impossible to weld and need to be braised. Some very gray castings I have repaired with a oxy/fuel torch and a nickle rod. The truth is that there are so many variations of cast that it is hard to tell what will happen until you go through with the repair. I try to look for clues in the break, such as the size of the grain and the color. If you don't understand what I am talking about then read up on cast iron. There is much more to it than I could post here. Ultimately if you can get the weld to fuse to the cast, post-heat (glowing red hot) allows the carbon concentrated along the edges of the weld to spread back out into the surrounding metal and a combination of preheating the metal along with post-heat and slow cooling helps to even out the contraction of the weld with the surrounding metal to reduce stress cracks.
                    Last edited by WELD81; 11-16-2012, 07:38 PM.