In gas metal arc welding, what is the purpose of the shielding gas?

In gas metal arc welding (GMAW), the shielding gas plays a crucial role in the welding process as it serves to protect the molten weld pool from atmospheric contamination, particularly oxidation and other harmful elements. When metal is heated to its molten state during welding, it is highly reactive and can react with ambient elements like oxygen, nitrogen, and moisture, which can compromise the quality and integrity of the weld.

By providing a protective barrier, the shielding gas ensures that the welding arc can proceed without introducing impurities that could lead to defects such as porosity or weak bonds in the finished weld. This prevention of oxidation is essential for achieving a clean and strong weld.

In contrast, cooling the weld is generally addressed through the selection of the material and the methods used to manage heat during the process, while weld color is affected by several factors, including material composition and post-weld treatments rather than just the shielding gas. The notion of adding strength to the weld is more related to the quality of the filler material and the welding technique employed rather than the action of the shielding gas itself.