What issue arises in fusion welding due to oxygen exposure?

In fusion welding, when oxygen is present during the welding process, it can lead to oxidation of the weld metal. This oxidation occurs because the high temperatures achieved during the welding process can react with the oxygen in the environment, forming oxides on the surface of the weld pool. These oxides can impair the quality of the weld by preventing proper fusion of the base materials and introducing inclusions, which can weaken the joint and lead to defects such as lack of penetration, poor mechanical properties, and compromised corrosion resistance.

This issue is critical since maintaining a clean and controlled atmosphere during welding helps ensure a strong, durable weld. Proper shielding gases and techniques are employed to minimize oxygen exposure and avoid oxidation, which can significantly impact the structural integrity of the welded parts. Understanding the nature of oxidation helps welders take necessary precautions to create high-quality welds.