The Importance of Gases in the Welding Process

Welding is a fabrication technique in which two or more parts are fused together with heat, pressure, or both to form a join that will hold when they cool. The weld quality, droplet transfer, current transfer, and, welding speed are all affected by the gas used. 

The main goal when using gases to weld is to keep the weld pool as safe as possible. Other considerations include keeping welds clean on the opposite side of the seam, and shielding the arc from impurities such as air, dust, and other gases [1]. 

Gases used for Welding and Cutting Metals

There are two types of gases: inert and reactive. When in contact with other substances or temperatures, inert gases do not alter or generate change. Reactive gases, on the other hand, have the opposite effect. They react in a variety of ways, causing other substances and/or themselves to change state. 

The following gases are utilised in welding and cutting processes [2].

• Acetylene, propane, and butane are known as fuel gases

• Oxygen, used with fuel gases and in small amounts in some shielding gas mixtures

•  Carbon dioxide, argon, and helium are known as shielding gases.

Argon

Argon is in charge of all the shielding agents on the planet. It has good penetrating power and can keep a consistent arc to make welding easier. It can be used to weld sheet metal using gas tungsten arc welding, because it provides a higher level of weld puddle control.

Carbon Dioxide (CO₂)

Pure CO₂ allows for an extremely deep weld penetration, which is advantageous when welding thicker materials. When combined with other gases, however, it generates a less stable arc and more splatter.

Compressed Air

Compressed air is utilised in welding in a variety of ways. Compressed air is commonly used to clear dust, swarf, and other dry materials from the workshop. Air nozzles attached to compressors with hoses spray air out to blow away dirt [3].

Oxygen

Oxygen is currently considered a raw ingredient in the welding industry. The production of modern steel necessitates a large amount of oxygen. In blast furnaces, Oxygen is required for flame enrichment in the pre-treatment of iron to eliminate faults in blooms, slabs, and billets.

Acetylene

Oxyacetylene welding, often known as gas welding, is a welding procedure that uses the combustion of Oxygen and Acetylene. When combined in the proper proportions in a hand-held torch or blowpipe, a relatively hot flame with a temperature of around 3,200 degrees is created. The high flame temperature makes acetylene a suitable choice for gas welding steels. Acetylene also produces a reducing zone, which is used to easily clean metal surfaces.

Helium

Helium is commonly employed as a welder shielding gas due of its high thermal conductivity, ability to deliver a wider and shallower application penetration pattern during the welding process, and ability to increase wetting of the weld bead. The welding sector, on the other hand, is facing some difficulties due to the impending helium scarcity.

Nitrogen

Nitrogen increases weld penetration and arc stability. Gas blends containing nitrogen can increase the mechanical properties of alloys containing nitrogen and prevent pitting corrosion and nitrogen loss from the metal. 

Mixed Gases

There are many different gases to choose from, each of which excels in different areas and falls short in others. Mixed gases provide a useful balance for combining the strengths of several gases to create a harmonised product with outstanding outcomes.