Define "undercut" in welding.

Undercut in welding refers to a groove that is created in the base material due to excessive melting during the welding process. This phenomenon occurs along the edges of the weld and can compromise the integrity of the joint by reducing the material thickness. The presence of an undercut signifies that the welding parameters, such as voltage or travel speed, may not have been adequately optimized. When too much heat is applied, it can erode the base metal adjacent to the weld, leading to this undesired defect.

Understanding undercut is crucial for achieving strong welds, as it directly impacts the structure's strength and aesthetic finish. Proper training allows welders to recognize and correct conditions that could lead to undercut, ensuring high-quality welding practices are followed.