Welding is a complex process that requires specially mixed shielding gases and the perfect mix of gases. The success of any welding process is greatly influenced by the quality of the shielding gas used.
According to the American Welding Society, shielding gases represent a staggering 70% of the total variable cost of welding! With the right mix and flow of shielding gas, welders can expect increased productivity, cleaner welds, improved joint integrity and reduced spatter. So then.
. what is shielding gas in welding? In this article we’ll take an in-depth look into the modern world of shielding gases and the importance of selecting the right gas for the job.
What is Shielding Gas in Welding?
Welding is a specific process of joining two metal components or components of other materials together. Among numerous welding techniques, one of the most advanced techniques used today is shielded metal arc (SMA) or electric arc welding.A protective layer of inert gas is used to protect the weld area while welding using SMA. This protective layer of gas is known as a shielding gas.
Properties of Shielding Gas
Shielding gas has to meet certain requirements in order to be used for SMA welding. These requirements are as follows :- It should be chemically inert and non-toxic.
- It should not react with the material being welded or any component of the welding flux.
- It must be able to maintain a uniform arc while welding.
- It should be able to reduce the risk of oxidation, distinguishment, or other forms of contamination.
Types Of Shielding Gases
The common types of shielding gas used in SMA welding include argon, carbon dioxide, hydrogen, helium, and nitrogen. Each type of these gases has its own set of advantages and disadvantages.- Argon: Argon is an inert and non-toxic gas that is commonly used for shielding SMA welding processes due to its low cost. Its most significant advantage is its high arc stability, which helps reduce oxidation and improve weld quality.
- Carbon Dioxide: Carbon dioxide is an acidic gas that helps to produce deep, narrow welds and has quick arc starts.
However, its main disadvantage is that it requires higher current levels than Argon.
- Hydrogen: Hydrogen provides better weld penetration than argon and carbon dioxide, making it suitable for welding thin and multilayer metals. Its main disadvantage is that it is highly combustible and must be used in very low concentrations.
- Helium: Helium is another inert gas used as a shielding gas. It produces higher weld speeds and deeper penetration levels than other gases but its cost is high.
- Nitrogen: Nitrogen is a non-toxic and non-reactive gas that is commonly used to weld thicker materials. It is more economical than other types of shielding gases. However, its main disadvantage is that it is not as efficient in controlling oxidation as other shielding gases.