Identify a disadvantage of using pure CO2 as a shielding gas in GMAW.

Using pure CO2 as a shielding gas in Gas Metal Arc Welding (GMAW) has notable disadvantages, one of which is that it creates a more unstable arc compared to argon. The nature of CO2 leads to increased sensitivity to variations in both wire feed speed and travel speed, which may result in arc wander or fluctuations during welding. This instability can complicate the welding process, making it challenging to achieve consistent weld quality.

In contrast, argon provides a more stable arc due to its inert nature, allowing for smoother transitions and a more controllable welding process. This stability is especially important when precision and quality are paramount, as it influences bead appearance and penetration characteristics.

While factors such as cost, cooling rates, and equipment requirements are relevant considerations in the choice of shielding gas, the key issue with CO2 is its impact on arc stability, affecting the overall welding performance.