Identify the reasons why carbon dioxide may not be used as a shielding gas.

1. Carbon dioxide can react with certain metals, such as aluminum, causing porosity and other defects in the weld.

2. Carbon dioxide can produce a more turbulent arc compared to other shielding gases, which may result in spatter and a less stable welding process.

3. Carbon dioxide can lead to increased oxidation of the weld pool, especially in certain materials like stainless steel, which can affect the quality and integrity of the weld.

4. Carbon dioxide can be more prone to causing atmospheric contamination, such as moisture and impurities, which can negatively impact the weld quality.

5. Carbon dioxide can be less effective at shielding the weld pool compared to other gases, such as argon or helium, leading to potential issues with weld penetration and overall weld quality.

1. Carbon steel corrosion: Carbon dioxide is a reducing gas. It can cause corrosion of carbon steel.
2. Increased porosity: Carbon dioxide can increase the porosity of welds.
3. Weld metal embrittlement: Carbon dioxide can embrittle weld metal.
4. Reduced weld strength: Carbon dioxide can reduce the strength of welds.
5. Excess penetration: Carbon dioxide can cause excess penetration of welds.
6. Arc instability: Carbon dioxide can cause arc instability.