Metal Inert Gas Welding, often known as MIG welding, refers to an arc welding process. A solid wire electrode has to be heated and driven into the weld pool during the arc welding process using a welding gun. The welding gas also feeds a shielding gas into the weld pool. The two materials are melted together to form a joint.
This popular arc welding process was patented in 1949 for the first time. It was initially used to weld aluminum. A solid wire electrode was combined with helium gas since it was readily available. The process would later become popular in the UK from 1952. In the UK, welders used it to weld aluminum. The shielding gas used during that period was argon.
The welders also used metal active gas or MAG welding for carbon steels. They would use argon-CO2 mixtures as the shielding gas. However, MIG welding became popular than MAG since it is more productive and has better deposition rates. Let us look at the gas used for MIG welding.
Best Gases Used for MIG Welding
The role of the shielding gas is to protect the arc and weld pool from contamination. Welders can use a wide range of gases to protect the weld pool and the arc. These gases are can either be inert or non-inert gases. Let us take a closer look at these gases below:
- Non-Inert Gases
Also known as semi-inert gases, these gases provide average resistance to chemical changes when protecting the weld pool and the arc. That is why semi-inert gases are relatively cheaper than inert gases. You can even mix these gases with argon to save your money.
One of the most popular semi-inert gas used for MIG welding is carbon. It can be used on its own or mixed with argon. If carbon is combined with argon, it has to be incorporated in a ratio for complex projects. Carbon is usually used for MIG welding because it penetrates the arc better than other gases. Welders can use a low proportion of carbon to argon for better welds and reduced porosity. However, the arc created by carbon is harsher and requires more cleaning.
Oxygen is the next non-inert gas you can use for MIG welding. It should be used in small proportions to strengthen the arc. It is advisable to use oxygen when you require more penetration into thicker metals. It will also be handy for stainless steel projects. Using too much oxygen encourages oxidization, which can be detrimental to your project.
- Inert Gases
Popularly known as noble gases, inert gases offer high resistance to chemical changes in normal conditions. Due to their inert nature, noble gases protect the weld pool and the arc better than semi-inert and non-inert gases.
Argon and helium are the most popular gases used for a MIG welder. They can also be used for TIG welding. The good thing with argon is that you can use it when welding mild steel. You can use it alone or mix it with other gases to increase penetration. On the other hand, helium gets hotter faster than argon and creates a deeper weld. Helium also reduces porosity. That is why it is more expensive than argon.
You can mix the two gas with cheaper gases to bring the cost down. Besides, you will have to mix the gases if you are not welding nonferrous metals, including copper and aluminum.
When working on your MIG welding project, it is best to evaluate what works for you according to your goals and budget. Checking the base material’s thickness and post-weld cleanup is also vital.