How To Weld Cast Iron With A MIG Welder

Due to only just 50% success chances in welding cast iron you essentially need to know how to weld cast iron with a MIG welder correctly. There are many risks of cracking or damaging the material when you finish welding it. Therefore, cast iron welding demands to be performed in a precise manner.

The good news is if you follow the steps exactly as they are, you can weld the durable and efficient cast iron with a MIG welder. With precautions, you have to be careful enough to perform the right steps that are the basis of welding. Below we are shedding light on how to weld cast iron with a MIG welder!

Welding Cast Iron with A MIG Welder

Since cast iron welding is a somewhat venerable process, the identification of alloy becomes the first step you should be concerned about. Due to the high carbon content, it’s hard and hence it adds to its hard to bend it! Therefore, welding cast Iron is pretty difficult and a careful process. However, with the below-mentioned steps, you will get an idea about how you can efficiently weld cast iron using a MIG welder!

Pre- and post-heating preparation

Pre- and post is one of the first and most important steps for cast iron welding. Since it’s already a brittle material, only heat can be the apparent solution to make it ready for welding. For the recommended pre-heat of cast iron, you should keep the cast iron pieces in the range of 260 – 650 degrees Celsius. Beware of the temperature beyond 780 degrees. It will ruin your effort by overheating the material.

Heat management while welding

Due to the temperamental nature of cast iron, preheat and post-heat should be done rightly. Even if the temperature changes from room temperature to the welding one, cracks are likely to occur on the material. Not only this but also the heat control is super venerable for cast iron welding. If you cool the material rather fast, it can face stress, and hence the result will be in fracture or fissures.

Rod selection

Rod selection is yet another important factor for welding cast iron with a MIG welder. Mainly the rod which is considered best for cast iron should be machine-able, soft, and contains metals like copper or nickel. These high-level metals work well when phosphorus is produced when you weld cast iron.

Slow weld

For cast iron welding, you should apply a low current and keep each movement highly stealthy to ensure the safety of the material. Work inch by inch. You should wait at least 45 seconds after each weld for proper heat (neither let it too cool nor keep it too hot). Check out if there are any cracks, seal it with the sealing compound.

MIG Welder Cast Iron Tips

  • The MIG wire should be nickel, however, it is pretty cost-effective. You can also use a stainless steel wire
  • For gas, 80 % Argon, 20% Carbon Dioxide will work best but the rust’s risk is there


Welding cast iron is not easy. It comes with a high risk of cracks, damage, and above all temperature management is something that becomes the major careful factor. However with practice and following guidelines you can certainly ace the welding process. Hopefully, this guide will help you find your quarry in an effective manner.