TIG welding cast iron

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Hi everyone,This is my first post in this forum!I've heard another welder in my city TIG weld cast iron cylinder heads. I'm pretty sure the only way to do it well is by metal spraying or furnace welding.Besides, I think the method he uses is wrong.He preheat the head up to 650F, then weld it with SMAW 99% nickel electrode removing the coating previously. I don't know the postheating, but let's assume he does it well.What do you think? Apparently it works, but I think both the preheating temperature and the "rod" are not the best choice.Regards from Argentina,Eric.
Reply:I use Ni-Rod Nickel 99 on cast iron but don't really do a lot of cast because the post heat is very important and should be done really with a digital oven even though guyshave success with Cat liter or blankets.....I tell the customer with the price of the Ni-Rod you might consider buying a new part if its available.......  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Certanium makes a great all purpose cast iron tig rod called 89T350f preheat and inter pass temps are recommended.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:could you use 309 stainless ?
Reply:I've heard of people using 309 to weld cast iron, but considering the heat and stresses that a cylinder head is subjected to, I would use nickel 99 myself.The method the OP describes is standard procedure and should be plenty strong if done correctly.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Arc welding a cast iron head in a combustion chamber will not work...Several years back a dude was selling this idea and some equipment to go with the process. After very limited success the couple of shops in neighboring towns have stopped arc welding heads (at least in the combustion chamber area.) The dudes process required pressurizing sealant into the leaky repairs. Not a durable repair.On the other hand, some other areas on heads can be welded with arc successfully.PeterEquipment:2  old paws2  eyes (that don't look so good)1  bad back
Reply:Originally Posted by castweldArc welding a cast iron head in a combustion chamber will not work...Several years back a dude was selling this idea and some equipment to go with the process. After very limited success the couple of shops in neighboring towns have stopped arc welding heads (at least in the combustion chamber area.) The dudes process required pressurizing sealant into the leaky repairs. Not a durable repair.On the other hand, some other areas on heads can be welded with arc successfully.Peter
Reply:There are a lot of ways to repair cast iron cylinder heads.  Some more info on the head in question would be helpful, what is the head for, where is the crack, how big is the crack and is it through into the water jacket yet?Cast iron heads can be repaired in a few ways, seat inserts for small cracks on the seating surface, "Lock-n-Stitch" pin repairs for external cracks and under the valve cover, spray welding, TIG weld/braze and O/A with cast iron or braze filler.  The amount of preheat and type of post heat depends on the location and size of the crack as well as the method of repair.For O/A a 900*F preheat then wrapped up in ceramic wool and welding blankets while repairing and then back into 900*F and a controlled cool down for about 12 hours.  O/A repairs on cast iron aren't as common now as they once were so finding an old timer that can do the repair or is willing to share their knowledge can be difficult.TIG repairs will usually get less of a preheat, 200*F to 600*F is normal and then either back into the oven for a controlled cool or wrapped up in blankets for a slow cool.  The amount of preheat and post heat depends on the size and location of the crack and is usually a judgement call based off experience.Here is a Chevy V8 head that I repaired last week.This is a core head for the shop It had a blown head gasket and combustion gasses torched the deck away.  After the repair it will head into storage.  The head was magnalfuxed to check for other cracks and make sure there is not a crack at the base of the torched area.Next the are was cleaned up with a carbide burr to remove any contaminated iron, wire brushed, cleaned with acetone and heated to 200*F then some localized heat from an O/A torch.TIG welded using 1/16 red and Chronatron 211T filler rod, peened and wire brushed between passes.The sides were ground to shape and the top was ground close then filed.After the repair it was wrapped up in blankets to cool.  When the head is needed it will get a valve job and be resurfaced with a CBN cutter.Hope this is helpful to you.~Alex
Reply:The reason for using 99 % nickel rod whether SMAW or GTAW is to create a soft filler that can be easily machined.  You can use fillers with less nickel but risk creating a hard deposit.  Interesting part of using high nickel is that the admixture of iron and nickel can create INVAR alloy which is a very low cooefficient of expansion and contraction thereby reducing shrinkage stresses.  900 F is your friend else you risk further cracking.