Cast iron can be welded, but the technique and equipment used depends on the type of cast iron. Cast iron is a very strong and durable material; however, this very strength makes it somewhat difficult to work with when welding because it expands and contracts at different rates due to high thermal expansion of its alloys.
Cast iron welding
Cast iron is an alloy that is made up of more than 2% carbon, and often contains other elements as well. Cast iron is not malleable, and therefore cannot be forged. It can be cast (melted into a mold), but most people who have experience in welding prefer to use ductile cast iron.
In most cases, cast iron repairs can only be welded using special rods that have been designed to melt at the temperature of the casting material found in the cast iron piece. These rods will usually contain nickel alloy and other metals which complement the composition of the casting material.
The fact is that without high quality equipment and training, you are unlikely to make a successful repair on your own. If you decide to try anyway, you could end up burning yourself or others, destroying valuable property, or even creating a fire hazard in your home or business.
Which cast iron can be welded?
In most cases, grey cast iron can be welded. However, the weld strength is typically very low (around 10% of the base metal). It is not uncommon for grey cast iron to fracture after welding. To increase its weldability, a small amount of carbon and silicon is added during casting.
Which cast iron cannot be welded?
White cast iron cannot be welded because it contains carbon in the form of cementite (Fe3C). This makes white cast iron brittle.
Why cast iron cannot be forged?
The high melting point combined with poor heat conductivity makes it hard to reach forging temperatures with just forge fires. In fact, if you try to forge cast iron without using appropriate heating methods, it will crack and break instead of flowing into the desired shape.
Cast iron cannot be forged because it does not have a grain structure, so therefore it will crack whilst you are forging it.
Why must cast iron weld metal be ductile?
Cast Iron Weld Metal Ductility is important for most of the welding processes, but it is particularly important in the case of welding wrought iron or steel to gray or malleable iron, where the shrinkage stresses in the weld metal are usually large enough to cause cracking of the joint in alloys which do not have high ductility.
Who weld cast iron?
A welder who has experience with these types of metals may be able to weld them for you. If you do choose to hire someone, make sure they know what type of material your project requires before starting work on it so there are no surprises down the road!
A stick electrode that has a classification of E70XX or E80XX is the best choice for this application. A lower-hydrogen stick electrode such as EXX18 will provide a more consistent weld deposit when welding cast iron to steel, and will help to minimize cracking in the weld joint area.
Will JB Weld work on cast iron?
It depends on what kind of repair you need to do and how much time you have available. If it’s just a small crack in your cast iron cookware then yes – jb weld will probably do fine but if you’re trying not to buy new pots/pans then maybe not so much…
JB Weld can be used as an alternative to brazing/welding in non-structural applications where appreciable loads are not present or expected. JB Weld can withstand high temperatures; however, continuous exposure to temperatures above 650 degrees F should be avoided.