What is a common defect arising from improper GMAW techniques?

Porosity and lack of fusion are indeed common defects that can arise from improper Gas Metal Arc Welding (GMAW) techniques. Porosity refers to the presence of gas pockets trapped within the weld metal, which can weaken the weld and affect its overall integrity. This issue typically occurs when contaminants such as moisture, oil, or rust are present on the surface to be welded or when the shielding gas coverage is inadequate.

Lack of fusion, on the other hand, occurs when the molten weld metal does not adequately bond with the base metal or with previous layers of weld metal. This can happen due to insufficient heat input, an incorrect travel speed, or improper technique, resulting in a weak joint that may fail under stress.

Both of these defects can significantly compromise the performance and strength of the welded joint, making it crucial for welders to adhere to proper GMAW techniques and to ensure adequate preparation and control throughout the welding process. This understanding highlights the importance of technique and preparation in successful GMAW.