Why is it important to control the gas flow rate during GTAW?

Maintaining the protective gas envelope is crucial in Gas Tungsten Arc Welding (GTAW) because this envelope protects the molten weld pool and the tungsten electrode from contamination by atmospheric gases such as oxygen and nitrogen. If the gas flow rate is too low, the protective shield may not adequately cover the weld area, leading to oxidation or nitriding of the weld metal, which can negatively affect the mechanical properties and appearance of the finished weld. Conversely, excessively high gas flow rates can cause turbulence in the gas shield, which might also allow atmospheric gases to undermine the integrity of the weld. Thus, controlling the gas flow rate ensures that the shielding gas effectively protects the weld from atmospheric contaminants, ultimately leading to stronger and more reliable welds.