Any good tips for Welding Cast to mild steel

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I've done some searches and can't come up with any satisfying results... I have been welding a few gates now and have been tacking the cast iron decorative collars and picket dressings in place with no real problems. I have a few larger heavier rosettes I am putting in some gates for me (finally get to make my own ) and I'm having some trouble with them. Welds look like bird poop and I am having trouble getting good penetration. I am kicking the heat up but it it then causes a funky burn into the cast piece. I was told that cast has a really high carbon count and I need to use a different wire than the ER70S-6 I've been using. Most of the info I can find deals with cast to cast.... Any tips?KevMiller 210 and 140 MigsBernard Q-Torches on bothMiller Syncrowave 200Spoolmate 3035 for sale, excellent condtion- PM for detailsThermal Dynamics 38XLShop OutFitters 20/20 Bending SystemLots of other cheap and not so cheap tools Still have LOTS to learn, but got some nice stuff to learn on!
Reply:Honestly I have never had any luck welding Cast with a mig.  Others here may have had luck, and be more suited to answer, but I don't think cast and migs go together.  All of the cast I have welded were done with a stick using a 55% or 99% Nickel rods, or even a 309 stainless rod.  If I was going to attempt to weld cast with a mig I would run a 309 stainless wire or possibly silicone bronze.  Brazing is another option?  Also, are you preheating before you weld?I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......
Reply:I have done it with .035 stainless wire and preheat to near red hot.  No problems the few times I have done it.  Nickel rod is the best way that I know.Lots of toys.
Reply:I use the same wire you use for cast iron to mild steel.  However, I only use it to weld collars, shoes and caps.  For items more critical ( thing that do not slip on ) I use stick welding.  I do not preheat relatively light stuff like scroll work or mailbox castings.  I peen the weld with a chipping hammer immediately-until it cools.  If you plan to grind, then you must vee the material, otherwise the material will thin and definately crack.I would say a rosette would be critical, because of the movement of the gate and the shock of shutting  and the fact the weld are the only thing holding it in place.  HTP sells a mig wire for welding cast.  Fourney sells nomacast a cheap nonmachineable cast iron welding rod.
Reply:Another method is just TIG it with 309L stainless filler.I'm guessing 309 MIG wire would also work but a roll of that is pricey.Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.
Reply:I don't have a stick welder, jumped straight in to MIG. I do have a 2lb spool of stainless wire, so I'll have to give that a shot. Do you use the tri-mix gas on it or 75/25?Miller 210 and 140 MigsBernard Q-Torches on bothMiller Syncrowave 200Spoolmate 3035 for sale, excellent condtion- PM for detailsThermal Dynamics 38XLShop OutFitters 20/20 Bending SystemLots of other cheap and not so cheap tools Still have LOTS to learn, but got some nice stuff to learn on!
Reply:Since you aren't needing to preserve the non-rusting aspect of it, feel free to use the C-25 gas.
Reply:I have done some recently on some old pot kettlesI preheated close to red... used 92% argon 8% co2tried to use the spray arc technique using 35 wire.I really had no problems..    not sure if the gas mixture and the  spray xtransfer meathod was key or not.... I just know it worked better w/ mig than before.Im interested too what others might comment using migI tried the nickle rod as filler with flux cleaned off but my tig is just not strong enough. weld it like you own it
Reply:Kev I do alot of wrought iron and if you a talking about the cast iron  spear heads for picketts . Ya its hard to weld that cast to mild steal but for the spear heads (dont laugh it works) I fill them with liquid nail stick them on the pickett let that dry then weld around the bottom. and they wont move. If i just weld them and you bump them the wrong way they come lose. I sure wish they made pressed steal ones!! I know this sounds half A**ed but you cant tell and its all decrotive  and it works.
Reply:I've never had a spear head come off.  I weld two sides of the spear head at right angles to each other to prevent a hinge/lever moment on the brittle weld.Seems he didn't have a problem with the spear heads though, but something heavier that attached differently.
Reply:Ah  sorry didnt read to well you are not talking about the spear heads, the cast decrotive incerts i get have these little 1/2 x1" long steal tabs imbeded in the cast. sorry manBrian
Reply:I get the weldable tabs on the cast aluminum stuff, but not the cast steel.  To which are you referring?
Reply:The Rosettes I have are cast iron, no weld tabs. About 18 inches in diameter and heavy. I rolled a 3/16 HR flat bar piece in the diameter of the rosette and ran some heavy and hot welds and it seems OK. I didn't have any Stainless wire. Need to get some and give that method a try.Wledingfireman- I like the liquid nails approach!!  (sorry couldn't resist)KevMiller 210 and 140 MigsBernard Q-Torches on bothMiller Syncrowave 200Spoolmate 3035 for sale, excellent condtion- PM for detailsThermal Dynamics 38XLShop OutFitters 20/20 Bending SystemLots of other cheap and not so cheap tools Still have LOTS to learn, but got some nice stuff to learn on!
Reply:ive welded cast exhaust parts on bulldozers and machinery , just heat it up then weld it in , my dads been doing it for years with success
Reply:Originally Posted by DkevdogThe Rosettes I have are cast iron, no weld tabs. About 18 inches in diameter and heavy. ...
Reply:Another idea popped into my head -- why not braze them.  You can OA or TIG braze them.Maybe also try silicon bronze MIG wire if you want to MIG them.  They don't need to be super strong (of course) so brazing should be plenty strong.Favorite right now is a Miller Syncro 200.Tons of tools and I blame at least one of them when things don't go right.