Welding gas refers to the various gases used in welding processes to protect the weld area, control the arc, and influence the quality of the weld. Different types of welding require different gases, including:

Argon (Ar): Commonly used in MIG (Metal Inert Gas) and TIG (Tungsten Inert Gas) welding. Argon is an inert gas that helps protect the weld from oxidation and contamination, providing a stable arc and a clean weld.

Carbon Dioxide (CO₂): Often used in MIG welding, either alone or mixed with other gases. It is less expensive than argon but can lead to more spatter and a rougher weld finish. It is effective for welding thicker materials.

Helium (He): Used in TIG welding, often mixed with argon. Helium provides a hotter arc and can improve penetration and weld speed, especially for materials with high thermal conductivity like aluminum and copper.

Oxygen (O₂): Sometimes used in small amounts in conjunction with acetylene for oxy-acetylene welding. Oxygen helps increase the flame temperature and is used in cutting and brazing processes.

Acetylene (C₂H₂): Commonly used with oxygen in oxy-acetylene welding. It produces a high-temperature flame suitable for cutting, welding, and brazing metals.

The choice of welding gas depends on the type of welding process, the materials being welded, and the desired weld characteristics