Welding cast iron can be challenging as it is less malleable and more brittle than wrought iron or mild steel. However, if you follow the correct approach, it is possible to weld cast iron with a wire feed welder. Cast iron is a combination of carbon, manganese, and silicon, and its chemical mixture makes it prone to cracking during welding.
Generally, you can weld a cast iron with a wire feed welder. But you must be careful and use a different approach than welding wrought iron. Otherwise, the cast iron will become brittle or might crack.
This article explains the process of welding cast iron with a wire feed welder, including identifying the type of alloy, cleaning and preheating the cast iron, selecting the correct filler material and welding technique, and post-welding treatments.
Is It Possible to Weld a Cast Iron with a Wire Feed Welder?
Sometimes, you might face a situation where you have to weld cast iron. And you might only have a wire feed welder.
It is entirely possible to weld cast iron with a wire feed welder. But you’ll have to follow a different approach than welding normal wrought iron or mild steel. I’ll teach you how to weld cast iron with a wire feed welder later in the article.
First, you should understand why welding cast iron with a wire feed welder is complicated. To understand this properly, you should learn three things.
- What Is Cast Iron?
- What Is Wire Feed Welding?
- Why is Welding Cast Iron Difficult?
What is Cast Iron?
Cast iron is a combination of carbon, manganese, and silicon. Also, cast iron contains a small amount of phosphorus and sulfur. But what is cast iron?
Simply cast iron is the iron that gets melted and molded. And as a result of this, the iron will get solidified.
On the other hand, wrought iron can be identified as iron that gets heated and worked with tools.
Info Bit: Most often, cast iron contains 2 to 4 percent of carbon, and other silicone and manganese amounts will vary depending on the type of cast iron.
What is Wire Feed Welding?
You now have a good idea about cast iron. But to understand the cast iron welding process properly, you should know about wire feed welding.
There are two main welding types; stick welding and wire feed welding.
Stick welding is old-fashioned compared to the wire feed welding technique. For instance, the stick welding process uses an electrode and electrode holder. The electrode melts, and it gets fed into the weld area.
You’ll have to use a welding gun when it comes to wire feed welding. You can use a standard gun or spool gun for this welding process. Either way, the electrode is housed inside the welding machine or the spool gun. The electrode is fed to the weld area using a cable. When you pull the trigger, the electrode melts and fills the weld area.
Note: Wire feed welding is mainly used in the MIG welding process. In truth, both of these processes are the same.
Why Welding Cast Iron Difficult?
Compared to wrought iron or steel, cast iron is less malleable. And when you weld an object, that object goes through heating and cooling cycles which are very important to the proper welding process. In other words, the metal object is exposed to expansion and contraction.
However, cast iron doesn’t deform or stretch like steel or wrought iron. Instead, it might crack during the welding process. That is why welding cast iron is so difficult. But that doesn’t mean it is impossible.
Why Does Cast Iron Crack Easily?
The main reason for these cracks while welding is the chemical mixture. The cast iron chemical mixture differs from the wrought iron and mild steel.
How to Weld Cast Iron without Cracking?
At this point in this article, you know why welding cast iron with a wire feed welder is so difficult. But as I said earlier, it is not impossible, and in this section, I’ll teach you how to weld cast iron without cracking.
Step 1 – Identify the Type of Alloy
First and foremost, identify the type of alloy that you are planning to weld. This is a very important step, and you shouldn’t ignore it. For instance, some alloy types are much easier to weld.
Grey Cast Iron
This is the most common type of cast iron that you could find. Grey cast iron is more weldable and durable than the other cast iron types.
White Cast Iron
White cast iron is different than gray cast iron. It has a different chemical mixture, and because of that, white cast iron is impossible to weld.
Ductile, Nodular, or Malleable Iron
This type of cast iron is less brittle because of its microstructure.
How to Identify Gray and White Cast Iron?
Checking the original specifications is the best way to correctly identify gray and white cast iron. However, checking specifications might not be possible. Hence, here are a few alternative ways to identify these two cast iron types.
White iron only shows white at a fracture point, and gray iron only shows gray. Hence, the fracture test is the best way to correctly identify gray and white cast iron.
Step 2 – Clean the Cast Iron Piece
It doesn’t matter which alloy type you are using; you should always prepare the cast iron piece for welding. Clean the cast iron piece first. Remove all surface materials from the cast iron piece, such as grease, paint, oil, and other material.
Step 3 – Preheat the Cast Iron
Preheating is one of the most important things you should do while welding cast iron. As you know, cast iron is highly vulnerable to cracks under this stress. Hence, heat control is necessary to avoid such a crack in the cast iron. There are 3 different stages for this preheating process.
- Low Heat Input
- Slow Cooling
It is always better to preheat the cast iron between 500-1200 ˚F. This is the ideal temperature for preheating cast iron before welding. Never preheat the cast iron over 1400˚F. If you go over 1400˚F, it will put the material in a critical state.
Step 4 – Complete the Welding Process
Finally, get your wire feed welder and complete the welding process.
What are the Advantages of Using Wire Feed Welder?
Using a wire feed welder comes with many benefits. In this section, I’ll briefly explain them.
Wire feed welders are excellent for any welding job. Because of that, they offer a much better welding profile and control over your welding. For instance, grind angle plays a major role in welding. And you’ll be able to control these angles better with a wire feed welder.
Most wire feed welders come with lots of controls for amperage. That means you can control the heat according to the type of material you are welding.
Wire feed welders are the best option if you are looking for a pure and neat welding job.
Also, using a wire feed welder comes with a few disadvantages too. For instance, mastering wire feed welding techniques is much harder than one might think. It will take some skill and time, without a doubt. You might also experience welder fatigue if you use wire feed welders regularly.
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