Cast iron is famous among welders due to its high utility in the user’s community. No one will say that cast iron is easy to weld, rather the opposite is true!
Different types of welding rods suit gray cast iron, malleable cast iron, white cast iron & ductile cast iron, etc. It depends on what you intend to use.
In this article, I tried to cover all the areas relevant to the welding rod & the welding rod itself in detail. So that it becomes like A B C D for you & you know what kind of welding rod to use on cast iron. Stay tuned!
Different types of welding rods
Despite so many welding rods, you can use very limited rods for welding cast iron. Not only that, but they also vary in different types of parameters like direct welding ability, machinability, ductility, strength & toughness, etc.
In the below part, I will talk about some of them…
ENiFe-CI
ENiFe-CI is a specially made electrode that does an excellent job for cast iron welding. This road is consist of around 55% nickel, 0.90% carbon, 2.10% Silicon, 40% iron, and other elements.
In addition to that, the weld metal of this rod is machinable if you can use it properly care & ensure no deep fusion into casting. Because a deeper fusion will lead to an increase in the amount of carbon with electrodes iron. As a result, carbide can form easily.
And, the forming of carbide will increase the probability of cracking in the weld metal due to its chemical bonding.
So let’s see why it is one of the best rods you can pick for welding cast iron in the following:
First of all, using this you can smoothly work on thick plus heavy cast iron sections. Plus they are appropriate for castings that became weak due to a long time of service under extreme conditions.
Along with that, this amazing rod is designed perfectly for the job of welding gray iron casting with another one. Likewise, it is also used for jointing cast iron with mild steel, nickel alloys plus stainless steel, etc.
In terms of price, the ENiFe-CI rod comes at a much cheaper price. Also, it comes with more hardness which gives strength & has higher ductility compared to other rods.
Furthermore, they are extremely beneficial for castings that have a significant portion of impurities like phosphorus. Finally, for highly complicated joints, this tool will play well and will stay under extreme pressure.
ENi-CI
This welding rod literally fully consists of nickel with an amount varies from 90-99% nickel. Because of nickel’s carbon absorption nature, the weld metal will be soft plus machineable.
However, this is the most expensive category of welding rod for cast iron. You can use this welding rod for repairing a thin piece of cast iron. Also, you can use ENi-CI for gray cast iron stuff like engine gearbox & machining tools, etc.
Furthermore, for the main task which is to join cast iron the ENi-CI welding rod is an unparallel choice without any doubt.
Steel Rods
These are the cheapest welding rod you can buy for casting iron. The best thing about this welding rod is that it can produce welded metal that has the same color as cast iron along with similar types of mechanical properties and compositions.
However, the weld metal of this electrode is hard that needs additional grinding for the smooth finishing & not machinable. Also, the welded metal sadly has a good chance of cracking.
Because of its nature, they will make a very good welding rod for fixing minor repairs like small cracks. Keep in mind that they are not appropriate for working on complex joints.
ENiCu
This electrode has mostly nickel plus copper, low portion carbon, iron, silicon, and varieties of alloying components. Due to the lower tensile strength & high sensitivity to carbon absorption of this rod, it can lead to cracks after welding.
So, maintain a lower dilution by maintaining lower amperage along with faster travel speed you can do a standard weld.
You will find two categories of ENiCu welding rods in the market. One is ENiCu-A that’s made of 55% nickel & 40% copper.
Another one is known as ENiCu-B which is consist of 65% NIckel & 30% copper.
SMAW
Another type of welding rod you can use for the welding of cast iron. Both terms of price & efficiency, this electrode is superb.
The structure of cast iron welding rods is that they come with a flux cover system that swallows penetration so that it can reduce the hardening of the cast iron heat-affected zone(HAZ).
Plus, the flux material will add more components to the weld metal for machining cast irons characteristics. In addition to that, it ensures the cleaning of the weld metal from different types of impurities.
Moreover, you will get an advantage due to the flux layer of the rod which will decrease the probability of weld metal shrinkage. Not only that, it will make it close to the shrinkage rate of cast iron. So, there will be no extra uneven stress on the joints.
Stick welding comes with a variety of versions of rods for cast iron. Nickel rods are the best quality rod for cast iron due to some specific reasons and these are:
First of all, they don’t absorb any carbon component from the casting. As a result, welded metal doesn’t become hard & stays elastic. Secondly, it’s very easily machinable due to its softness.
Third, Drilling plus cutting is easy to do. Fourth, due to the high ductility which excellently resists shrinkage forces after the bead is already cooled down. Makes it a perfect thing for welding restraint joints.
The final one is that you can use it as no preheating is required and is perfect for superficial casting or small casting.
Oxyfuel welding rods for cast iron
The oxyfuel process requires rods having varieties of shapes like round, hexagonal and square, etc. They contain both a high amount of carbon & silicon like cast iron.
You can easily do welding of gray cast iron using the RCI rod. Besides, you can use an RCI-A rod for welding high-strength gray cast iron.
This process requires a long time plus high temperature preheating. It’s an appropriate flux material for cast iron. Flux will prevent oxidation & clean the weld metal from impurities.
Comparison of different types of rods
Based on different types of factors each welding rod has its attributes. Let’s have a look at them…
| Electrode type | Tensile strength | Ductility | Preheating | Machinability | Cracking sensitivity |
| ENi-CI | 70,000 | Medium-high | Lowest | Top-notch | Low |
| ENiFe-CI | 90,000 | High | Low | Pretty Good | Lowest |
| ESt | 70,000 | Missing | High | Not possible | High |
| ENiFeMn-CI | 100,000 | High | Low | Pretty Good | Lowest |
| ENiCu-A | 70,000 | High | Medium | Pretty Good | Low – medium |
How to store cast iron welding rods?
Not a very hard thing to do, you just make sure they are not exposed to moisture. Because moisture gets mixed with the flux cover and leads to welding problems.
If you want to reap the maximum benefit then use it the moment before welding. You can store the leftover rod by storing them inside a rod even with a temperature of 250 degrees F.
In case your unused weld rods become in contact with moisture then bake them for 1 hour inside a rod oven and maintain 480 degrees F.
What is cast iron?
Your depth of knowledge about cast iron is very important. Because the more you have an idea about it your approach for welding or casting iron would be better.
Chemistry of Cast Iron
A significant amount of people do not know that cast iron is one kind of alloy. The process of making cast iron is the mixing of melting pig iron with different types of scrap materials & alloys like chromium, copper, titanium, molybdenum & vanadium.
After that, this liquid mixture is thrown into the mold and let cool down to become solid. Finally, you will get cast iron which has high-level carbon content.
Mechanical attributes of cast iron
In the following I will explain some characteristics of cast iron in brief.
- Cast iron itself is pretty hard. You can make it harder by either heating them or by suddenly cooling them. Both these temperature shifts increase the durability of the cast iron.
- The toughness of the cast iron is low.
- Malleability of cast iron is low too.
- Tensile strength of cast iron is weak so no bending or stretching is possible.
- Melting point for the cast iron is low and around 12000 degrees celsius.
- Working on cast iron is easy due to the presence of an additional amount of carbon in the cast iron.
- Cast iron has high machinability and great strength.
- The durability of cast iron is unparalleled.
- The compression strength of cast iron is many times higher than steel.
What to look for when selecting a cast iron rod?
The very first thing you have to ensure is that your cast iron is suitable for welding. If you don’t know the type of cast iron type then select the ENiFe-CI rod.
Weld metal’s machinability is extremely crucial. Which determines the easiness of cutting and drilling it. If your cast iron comes with high machinability then it would be best to select the Eni-CI rod.
Price is a big factor when buying a cast iron rod. Though nickel cast iron rods are considered to be the top-notch rod for welding cast iron. However, if you have a budget issue then you can go for ESt.
Depending on what type of welding you are going to do you need to pick the rod. For single pass weld, you should choose the Eni-CI rod.
If you want to work on any project which is exposed to corrosive materials and needs repair then the ENiCu rod. Because when you will use them for welding they will perform better because of their corrosion resistance.
Cast Iron Types
When it comes to classification, cast iron is divided into four types. Let’s have a look at them…
Gray Cast Iron
You will notice that this cast iron is used frequently in the welding community. Though they are not strong like steel it has close enough compressive strength like steel. In this cast iron graphites are present like interconnected flakes. They are machinable & come with excellent resistance to wear.
White cast iron
Comes with high compressive strength plus hardness. They don’t have any free graphite and are not weldable at all.
Ductile cast iron
While the gray cast iron is under the process of furnace melting then the addition of a little amount of magnesium plus cesium makes the ductile cast iron.
The graphite inside the cast iron become like nodules making them immobile. Besides, it also increases the strength and ductility of the cast iron. They are pretty easy to weld however, they require some special procedures.
Malleable cast iron
When white cast iron goes through heat treatment then a new metal forms with higher ductility. However, it does not lose its original characteristics. This specific cast iron is called malleable cast iron. They are not directly weldable until some areas are turned into gray cast iron.
Pre Welding Preparation & Post Welding Process
Something you need to ensure proper welding of cast iron while others required after the welding. Without the perfect preparation, there’s a high chance of an unsuccessful weld.
Cleaning the casting
Irrespective of the amount of alloy present in the cast iron, you must clean the cast iron before starting the welding project. In simple words, there should be no contamination like grease and paint, etc on the surface layer of cast iron.
In addition to that, post-cleaning should be followed by moderate heating for a few minutes. This heating will let the trapped gas move out from the opened pores of both metal plus alloy. Even a small amount of impurities on the surface of cast iron can lead to the weld becoming brittle.
Preheat
The nature of cast iron is to crack during high-level stress. You need to preheat the weld zone & its surrounding area to prevent cracking due to thermal expansion. So, 250 degrees F preheat of the cast iron is recommended.
Welding
Keeping the low heat setting during welding is best. Focus your arc on the weld pool mostly compared to the base metal.
Cooling process
Just like preheating, the cast iron post cooling is crucial to avoid any kind of cracking. Any uneven colling of the metal will lead to a crack.
So, you can add insulating material, which will slow down the cooling process. Following the peening method is beneficial for preventing cracking.
Frequently Asked Questions
Can you weld cast iron with stainless steel rods?
Despite being a good choice for welding with versatile metals stainless steel is not a good pick for welding cast iron. Because at welding time iron and chromium in the filler metal come into contact with the carbon from the casting iron. Which leads to brittle carbides that increase the risk of cracking.
There is one method you can follow is to join the surface using a piece of ENi-CI electrode. In the conventional welding community, it’s called buttering. It will help keep away the carbon of the casting from mixing with the chromium & iron of the electrode.
Then finally, you can easily weld the gap using a stainless steel rod-like E309.
What are the main features of the best-cast iron rod for welding?
The best-cast iron rod for welding must have a high amount of nickels. As they don’t absorb carbon from the cast iron so provide an excellent welding result.
Can you weld cast iron using an E6011 rod?
No, you should not use an E6011 rod for welding cast iron. Because an E6011 rod will provide an aggressive arc that will heat up the casting rapidly. Which will lead to rapid expansion and finally there will be a crack.
In addition to that, the thin slag covering & you will see the bead will cool down extremely fast. Due to the absorption of carbon, the weld metal will become prone to crack.
Which welding rod is best for cast iron?
In my opinion, the best welding rod for cast iron is the ENIFe-CI due to its flux covering material which helps a lot in welding.
Final Words
Even passionate welders will agree that welding is not an easy job. The cast iron having a significant amount of carbon makes it harder to weld which will be free from the crack.
I hope you got a bit idea about the welding rod for cast iron & know what kind of welding rod to use on cast iron.
