Ductile Iron, which is also known as Nodular Cast Iron, is strong and tough. It is extensively used in factories and industries. Special properties in such iron make it good for welding. We will discover why they are unique, and three important tips to weld this type of metal right, especially when it comes to commercial use.
Nodular cast iron is not like typical cast iron; instead of flakes, it has small, rounded nodules. These nodules contribute to making the iron harder and less prone to breakage. However, when you are welding, keep in mind that nodular cast iron is very carbon rich. This makes it a little tricky to weld because it can crack if not done properly. And, this iron does not conduct heat as well as other materials, so we have to be cautious while welding.
And it is through certain steps that strong welding on nodular cast iron is achieved. The first thing is, we have got to preheat the iron before we start welding. Preheating helps by means of heating the temperature uniformly and minimizing the risk of cracking.
Another good idea is to use a different type of welding rod called a low-hydrogen rod. Hydrogen can introduce problems when welding, so using this type of rod can help prevent cracks. We need that welded piece to cool slowly too, so that it stays strong.
Nodular cast iron, when welded, sometimes will crack, but there are things you can do to possibly prevent it. One method is called peening. That translates to light hammer taps on the weld whilst it's still hot, to relieve stresses and prevent cracking.
Another type of bee used to prevent cracking is backstep welding. This requires welding in short intervals, moving back to dissipate heat. We can also employ a technique called buttering, wherein we apply a layer of material prior to the final weld to assist in achieving a good bond.
Ensure that your welding equipment is in a good state and properly cared for. This involves using the proper welding rod and temperature setting. Also do take care of cleaning the nodular cast iron surface before welding as dirt and other things will disturb the strength of the weld.