What kind of welding rod????

In any cast iron welding ,arc is far from the best choice .Most any arc wire contains some nickel to make it flow and mix with the base metal.nickel contracts at a much greater rate than does the cast , this creates internal stress that you cannot relieve completely by peening . manifolds are subject to much thermal cycling and each time it heats and cools stresses are at work in the repair .

I have much respect for steve and products , I also have had a powder torch for 30 years , great tooland it will do cast repair that arc will not , but most powder for cast repair contains some nickel , same problem with contraction as arc, but not quite as bad .

If the co that steve sells for had acetylene cast iron rod ,he would probably tell you there is no better way to repair cast . With rod and flux and some preheat you can repair many of the manifolds that arc weld or powder run off like water. If you have the patients , you can build ears or whole sides of manifolds successfuly .

george

I would agree that if you want to match the base material for color or chemistry.....you can't do better with anything else. Often times, it is best to match the filler metal to the base. Other times, not. The chemistry of the filler metal has a great deal of influence here. Russian metallurgists have successfully concluded that gas welding using cast iron based consumables can be improved by being held in the melting furnace crucible at a temp between 1400°C and 1580°C. The addition of copper, tin, and nickel to the cast iron further enhances the welding properties by creating an alloy that closely matched the cooling rate of the cast as you mention. The atomic structure of the rod must be closely controlled. If not, the heat of the welding process will burn off excessive amounts of carbon and silicon and the deposit will be remanufactured into an unacceptable form. The result is pin holes and cracking.

A study of ways to improve the properties of cast iron arc welding consumables showed that the addition of manganese to the flux, in combination with nickel..... produced a filler metal that also closely matches the coefficient of expansion and contraction of the weld deposit to the parent metal. From a scientific standpoint, there are many more ways to 'tweak', if you will, a flux coated electrode.

Having said that, I must also concede that everything has it's advantages and disadvantages. One advantage the Ni based material has is the fact that carbon is not soluble in nickel. The HAZ will be quite hard but the deposit can be drilled and tapped. It has also been my experience that a cast iron head cannot be successfuly repaired in the combustion chamber by using any other process than the powder welding torch.

It seems that much of the degree of success or the lack thereof is directly correlated to the skill level of the craftsman performing the task. Some people can make a silk purse out of a sows ear and others would not be able to make a good dog chew out of it. Heat control is key to successful cast iron welding. Many have failed by using the proper filler metal but using improper prep, pre or post heat techniques. You George, are in the category of one of the guys I learned so much from in my early days in the field. I have stood and watched the masters using those square cast rods and slaving over that fire box welding cast iron heads. It looked so easy. My hat is off to you sir.

Now apply a general preheat of at least 200°F not to exceed 300°F. If part of the area to be repaired is going to be drilled or tapped you should be using a 99% nickel electrode.

Run a stringer bead using a 3/32" electrode not exceeding 1/2" in length and utilize the backstep method. Back whip the electrode at the end of each deposit before breaking the arc. Stop and peen the area vigorously between deposits. Take care to maintain part temp in the 300°F to 500°F range. Continue with this procedure until welding is complete.

My personal favorite tool for repairing these manifolds is the powder welding torch. I would use the same prep procedure but when depositing the weld metal, I would start at one end of the joint and completely fill it to the opposite end w/o stopping. If the area to be repaired was quite large, I would knock out all the rotten metal before ever starting my repair. I have repaired holes in old manifolds the size of a silver dollar. Some of them couldn't be arc welded or brazed successfuly.

Now if you will forgive me, I can't resist the temptation to appeal to those gentleman who mentioned the Eutectic and Certanium alloys. Those are a very good product. As a direct competitor of specialty electrode suppliers such as Eutectic, Certanium, and so forth, the folks at U.S. Alloys back the quality of their comparable materials with a no questions asked money back guarantee. Regarding price, our product isn't cheap either, don't get me wrong, but it is less expensive than most.
Steve