How To Weld Cast Iron With A Mig Welder Perfectly

Cast iron is made of iron-carbon alloys, and the carbon content in this iron is more than 2%. One can easily fix this iron because of its low melting temperature. If you want to know how to weld cast iron with a MIG welder, you will need to know the melting temperature and the right procedure of welding cast iron.

Possessing sufficient knowledge about welding will help anyone to fix any crack or crevice in the iron. There are several welders like – MIG (metal inert gas), TIG (tungsten inert gas), Arc, and so on. Each of these welders has unique advantages. In this article, we will focus only on the cast iron with a MIG welder.

How To Weld Cast Iron With A Mig Welder

The Right Way to Weld Cast Iron

Before start fixing or repairing, it is a must to realize how difficult it is to weld a cast iron. If an individual does it in the wrong way, he may result in developing further cracks. Welding a cast iron is so hard that, most of the time, moderately experienced people have a 50% chance of being successful.

The most important way to weld a cast iron is to handle the iron carefully while welding it. To do this, it is better to know the proportion of the materials, which make the iron very hard and strong. It also indicates the temperature that the iron can stand with before cracking. You should to know What Kind Of Welding Rod To Use On Cast Iron before start.

How to Weld Cast Iron with a MIG Welder


There is a rule of thumb while welding cast iron – be slow and low. Try to apply lower currents and move slowly. At a time, work about an inch and wait for at least 45 seconds between two segments

In this way, we can avoid overheating as well as creating residual stresses, which can cause a fracture in the cast iron.

While welding a cast iron, be careful with it because of its carbon content. The carbon is responsible for causing the entire structure to shrink and crack quickly if the temperature can pass a specific temperature.

Therefore, always stay alert and be attentive while welding a cast iron. You should regard the following as the main concern –

Pre-heat preparation:

Pre-heat preparation before welding cast iron is very important. Raising temperature too fast can cause cracking because the metal, in this case, is changing its temperature very fast. As a result, stress develops, which is responsible for cracking the structure. This is why you need to pre-heat the metal slowly. Temperature above 780⁰C will overheat the iron.

Heat management during welding:

While welding the iron, the most crucial part is to manage the heat properly. In this process, you have to avoid overheating and creating any residual stress as any of these can cause a crack in the iron.

Post-heat preparation:

During post-heat preparation, it can be an excellent idea to wrap the structure with a material that can cool down the iron slowly. Some DIY welders use charcoal BBQ to lower the temperature slowly. If you cool down the structure too fast, it will go through stress and can cause a fracture.

While welding with a MIG welder, try to follow these steps carefully to avoid any difficulties and to make the welding a perfect one –

It is required to have a standard MIG welder, standard argon-carbon dioxide welding gas, standard steel MIG wire.

Find the area to be welded and clean and grind the area thoroughly.

Weld in smaller stitches, which shouldn’t exceed 5 to 10 mm deep.

Between two stitches, try to leave a 20 mm gap.

Never try to weld the metal deeply in a pass. So, root it, then follow “step 1” again.

Don’t cool down the welded area rapidly. Leave it for some time, so that it can cool down slowly.

Continue welding the structure carefully.

David Ferguson

A professional and passionate welder, a writer who loves to write about the welding and plasma cutting tools. In this site, you will get all the information about welding tools in depth. Just share your feedback and suggestion that will help the website to grow more. Find me: Facebook

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