What is the consequence of using insufficient shielding gas during MIG welding?

Using insufficient shielding gas during MIG welding primarily increases the risk of weld defects such as porosity. Shielding gas plays a crucial role in protecting the molten weld pool from contamination by atmospheric gases like oxygen and nitrogen, which can lead to various defects. When the shielding gas supply is inadequate, these gases can interact with the molten metal, resulting in trapped gas bubbles within the weld. This condition is known as porosity and can significantly weaken the weld, leading to structural integrity issues.

Furthermore, insufficient shielding gas can also affect other aspects of the weld, such as penetration and bead shape, but the primary and most immediate consequence is the introduction of contaminants, which manifests as porosity. This defect can compromise the overall quality and performance of the welded joint, making the careful management of shielding gas a vital component of successful MIG welding practices.