Final answer:
Undercut refers to the protrusion of the weld metal over the toe of the weld. It is caused by improper welding techniques or settings.
Step-by-step explanation:
The protrusion of the weld metal over the toe of the weld is known as undercut. Undercut refers to the groove or depression created in the base metal adjacent to the weld metal due to improper welding techniques or settings.
For example, when welding two pieces of metal together, if the heat input is too high or the welding speed is too slow, it can result in excessive melt-through and protrusion of the weld metal over the toe, causing undercut.
Correcting and preventing undercut is important for maintaining the structural integrity of the weld and ensuring its strength and durability.