Guide to Welding Carbon Steel
In welding carbon steel, you can use carbon dioxide by itself or you can also use a mixture of gases. There are some gases that are mixed in order to do MIG welding and these gases include carbon dioxide (CO2), argon (Ar), and oxygen (O) which is the least common among them.
You can use carbon dioxide (CO2) gas by itself and the kind of weld that it produces are deep and penetrating. The reason why carbon dioxide is not really the best option although it produces deep weld is that the final result appears rough, and during welding there is a lot of smoke produced compared to using the other shielding cases.
Welder most often use the mixture of argon and carbon dioxide gases when welding carbon steel. 90% or more argon, 5% or more carbon dioxide, and 5% or less oxygen are the components of the gas mixture for welding. When oxygen is added in small amount while welding, it produces a hotter, smoother arc which makes oxygen necessary for welding even though it adversely affects the quality of the weld. If you will use this welding gas mixture, then you need to consider three things namely cost, metal thickness, and weld quality.
The cost is not a big deal if you are just MIG welding as a hobby. However, if cost is a big factor then you should go with CO2 or a high percentage of CO2 gas mixture.
When selecting shielding gas, metal thickness also plays a big role. Pure CO2 or a high percentage of CO2/argon gas mixture is used on thinner metals. The reason for this is that on thin metals you typically weld using a short circuit metal transfer. Use 75 % or more argon, and the rest CO2 and 5% or less oxygen for thicker metals and globular or spray transfer types.
When changing the gas type, weld quality is affected. For deep penetration, use CO2. You need to add argon or use a high percentage of argon gas mixture for a smoother weld. This works well and makes globular and spray transfer easier to set.
If you use C25 or 25% argon and 25% carbon dioxide, you are using the best all-around welding gas for carbon steel. This mixture works well from thin to thick steel and the machine can be set to produce any transfer type. It has a smooth weld, and the arc can be stiff to soft depending on the voltage settings and wire feed speed. This mixture will make it possible for your to weld in all positions.
Although carbon dioxide can be purely used for welding carbon steel, sometimes it is best to use a mixture of argon and carbon dioxide to get a good results on your welding project.