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HOW TO WELD CAST IRON
All professional and amateur operators working in the welding field face daily challenges to work perfectly, supported by the continuous innovations developed by the research and development sector of the various manufacturers of welding generators.
However, welding cannot be defined as a perfect science, since in most cases the manual intervention of the operator is necessary to perform this process, unless we rely on a robotic support.
As mentioned above, the welding process cannot be defined as a perfect science, since human intervention is almost always necessary, it is also known as manual welding (MMA coated electrode, TIG) or semi-automatic welding (MIG/MAG, FLUX).
The most common welding process is certainly MMA welding with the aid of the coated electrode. This is because this particular process is easy to carry out, relatively inexpensive, does not require gas protection, and the operator can complete the processes independently and safely for a small fee of a few hundred euros. Moreover, thanks to the presence of a wide variety of coated electrodes on the market, you can work on any metal, you just have to get the correct consumables and, if necessary, comply with some special rules, for example when welding cast iron.
Our clients frequently ask if you can weld cast iron, or how to weld cast iron.
The answer is yes! It is possible to weld cast iron by following simple but fundamental rules. This particular iron alloy contains carbon or graphite with a content ranging from 2.06% to 6.67%. This element gives iron great resistance to heat (melting temperature 1150°), to wear and tear, and great mechanical strength. Cast iron is not subject to oxidation.
In the past, to weld cast iron, you had to melt it using a furnace, while nowadays, thanks to the use of inverter welding machines, you can weld cast iron and make repairs using a welding machine for MMA welding and the appropriate electrodes for welding cast iron.
HOW DO YOU WELD CAST IRON?
The first important step in welding cast iron is to make a chamfer, preferably U-shaped, on the two joints that you want to weld together, proportionate to the size of the object. This initial work facilitates the penetration of the welding pool, making cast iron welding easier and more effective.
The second step when welding cast iron is temperature control. This alloy is not stable in the temperature range from 65° to 260° and the risk of cracks and breaks during machining is very high. Consequently, the first step that must be followed to weld cast iron properly is to pre-heat it before welding, and to carry out controlled cooling of the joint at the end of the process. Professional welding machines, before proceeding to weld cast iron, pre-heat the two joints, bringing them to an intermediate temperature between 260° and 650° to make the two edges malleable. It is a good practice to slightly heat the entire cast iron object to maintain the necessary heat for the entire process.
Since it is difficult to work on this material, at the end of the cast iron welding process there may be cracks that can compromise the strength and integrity of the weld or repair.
How to weld cast iron and repair cracks?
If at the end of cast iron welding you can see cracks, even if they are from previous repairs, they must be removed. First, drill a hole at the ends of the crack to prevent its propagation during removal, and then remove the entire portion of the cast iron welding crack with a grinding wheel.
At the end of the operation, you have to carefully remove all impurities deposited during previous processes, especially cooling liquids or oils used during the cracking or drilling process.
Since during the preheating phase cast iron absorbs oily liquids which easily compromise the final result due to its porosity, the operator who welds cast iron must check that the joints are clean and free of external contamination.
Other factors that can cause cracks when welding cast iron may be:
- A low quality material that cannot withstand the stresses caused by cooling
- Excessive heat applied during cast iron welding that makes the thermally altered area too hard and therefore vulnerable to impact.
When professional operators weld cast iron or carry out large-scale repairs on this material, they use a technique known as "deep-drawing", which consists of covering the cast iron object with a specific substance that retains heat and slows down the cooling process, greatly reducing the possibility of cracks in the cast iron weld caused by fast cooling.
Below you can find a list of welding machines that are ideal for performing cast iron repairs and welds
- - Helvi Galileo 179
- - Esab Rogue ES 180i PRO
- - Deca I-ARC 318 LAB
- - GYS Progys 200A PFC
- - Lincoln Invertec 170S
You can also use wire welding for cast iron.
This filler material is widely used for the plating and coating of cast iron cylinders. The weld deposit has a rather high hardness, and it can be machined with special tools.
It is suggested to maintain an interpass temperature of at least 175°C to avoid the formation of cracks in the weld and in thermally altered areas.
This kind of wire is also used to repair cast iron and high phosphorus cast irons of high thickness.
Tuttosaldatura.it has a wide range of inverter welding machines to weld cast iron, available and with free shipping. If you need a customized offer or you are looking for a product that you can’t find in our list, contact us by phone or email, our team will be at your disposal.
