What are shielding gases used for in arc welding?

Shielding gases play a crucial role in arc welding by displacing oxygen and other atmospheric gases, which can adversely affect the quality of the weld. When a welding arc is created, the intense heat generates molten metal that, if exposed to oxygen, can lead to oxidation. This oxidation can cause defects such as porosity, inclusions, and a weakened weld joint. By using shielding gases, such as argon, carbon dioxide, or a mixture of both, welders create an inert atmosphere around the weld pool, effectively protecting it from environmental contaminants. This protective layer ensures that the molten metal solidifies properly, resulting in a strong and high-quality weld.

In contrast, the other options do not accurately describe the primary purpose of shielding gases. While preventing moisture is important in certain contexts, it is not the main function of shielding gases in arc welding. Enhancing the color of the weld is irrelevant to the structural integrity of the weld itself and is not related to the use of shielding gases. Cooling the welding equipment is also not a function of shielding gases; instead, cooling mechanisms are typically handled through other means, such as water or air cooling systems.