What Are the Guidelines For Welding Cast Iron
Welding cast iron calls for some special procedure. It is a challenging task and there can be no two opinions about that. Cast iron, unlike most other steels, has much greater carbon content at 2 to 4 percent. This causes most cast iron to be brittle making it difficult to weld. If the following procedure is followed, cast iron can be welded with relative ease:
Use either cooling or heating while welding cast iron as it is important to keep casting iron out of the 150- to 500-degree F range. Preheating is widely preferred, but there are times when cooling are also done. But stick to either cooling or heating and do not attempt to change in the middle of a weld.
Though preheating the cast ironing part should suffice, it is preferable to preheat the entire casting slowly and uniformly in the 500- to 1,200-degree F range. Be very careful to heat within the stated range as overheating may cause iron to crack. The casting should get hot just to the extent you can to touch it comfortably with your bare hand. If need be, make short welds intermittently to avoid overheating.
Occurrences of small cracks when welding cast ironing, is inevitable. You can apply some sealing compound to prevent leakages. If there are major cracks you must repair with studding. Studding is a complex process calling for a lot of skills. The first step is to drill and tap holes on the surface that has beveled. The next step is to put in steel studs and the studs should come out 5 to 6 mm above the surface and the studs should then be welded to remain in place.
Preheated welding can be easily done – particularly for small and manageable objects. While welding the cast iron without preheating, it is extremely essential the operator has good control over the welding gun and make the welds as small as possible.
Welding cast iron with an arc welder calls for different procedure. As a matter of fact, persons capable of welding cast iron with arc welder are few in number and there is a great demand for such skilled persons.
You may have to either purchase or hire a SMAW (shielded metal arc welding or stick electrode) welder depending how often you do cast ironing welding with arc welder. Plug your welder into a 220V outlet and then plug in your ground cord and welder electrode holder cord into the welder. Please know that to weld cast iron, you need a special electrode. You may buy a 770 stick electrode to weld cast iron.
First of all, clean the surface area to be welded with a wire brush. Clamp the grounding clamp cord from the welder onto the piece of cast iron that has to be welded. Thereafter, place an electrode into the welder electrode holder and position the electrode near where the weld has to begin.
Continue to tap the electrode on the cast ironing till an arc is created and begin to weave the electrode stick from side to side. Make it a point to keep the arc slightly away from the piece of steel you are welding. Wait for a few minutes for the weld to cool off gradually. Use the welding hammer to chip off the slag from the top of the weld.