Tig welding cast

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Hello All, I am having some issues welding cast iron. I do not know the material make other then cast iron. Iam using 2% red tung. argon gas 18/20 psi Dc current. Cast is cracking along welded area spatter is jumping on tungsten hard to establish a arc.material is very clean and recleand. Any help please thank you. Wrong polarity?Miller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:DC electrode neg I would assume? Send a pic of what you got bud, that will help!I hate being bi-polar it's awsomeMy Heroes Have Always Been Cowboys
Reply:How is the casting flowing? Is it dirty, how is it reacting to your filler choice?Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:If the polarity is wrong your tungsten will immediately suck back and burn up.  Some cast is just nasty. I'm all about tig welding unless it's cast, in that case I much prefer to braze with a torch. Much easier and forgiving in my experience.
Reply:powerThere are numerous types of cast-iron, which vary in weldability from good - to not at all.I have experienced all of your problems in a single pass;and I have welded cast that ran like bronze. Aside from spark testing, what the object is or does, generally correlates to its weldability.Is your casting from a CAT, or a old wood stove part?Opus
Reply:Are you using nickle filler (Ni-99)?
Reply:Real honest to god true cast iron will not Tig well....if at all. On top of that cast iron likes to be treated gently and slowly. Pre and post heating are a must if you care about the part. The only real way to weld the material, is with actual cast iron filler, slightly doped with extra silicon, a suitable flux, pre and post heating, and a torch. In restoration work I have done, I have spent more time re-doing some nickel based arc brazing/welding that was done by the previous "welder" than I care to think of. The only reason those nickel based poor excuses for electrodes were ever developed, was as a hack artists way to a quick and dirty(maybe temporary) fix without having to take a machine down. And for that they work ok. Now modern "cast iron" is more like a cast steel, and is much more forgiving of the rapid cooling of an arc process. So what you pick, depends on what you have. If its quite old....stick to true welding, or brazing.
Reply:Thank you all for the advice. All is very interesting and a lot to consider. I always write notes on what I weld and what is suggested from you guys (other welders) for future ref. The fix to the issue I was having was to warm the material up a bit by placing a heater under the diff for a few hrs thanks Zap! I gave it a try again and welded very well. The casting material Iam not sure of? The diff is off a john deere front axle. I used 3/32 red tungsten 18-25 gas flow 309l stainless filler dc electrode neg. Attached ImagesMiller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:before pictures. Wrong order oops Attached ImagesMiller 250DX HTP 221 DV AC/DCHenrob O-A Miller 180 MigMiller 150 Inverter   Hobart 10,000 Welder-Generator   Have a good day!!!
Reply:Originally Posted by powerbefore pictures. Wrong order oops
Reply:Why 309ss filler? I would say 625 inconel because of more nickel would be better but I would've brazed as I said before instead of tig. Jmo
Reply:Originally Posted by Showdog75If the polarity is wrong your tungsten will immediately suck back and burn up.  Some cast is just nasty. I'm all about tig welding unless it's cast, in that case I much prefer to braze with a torch. Much easier and forgiving in my experience.