In welding, what does the term "penetration" refer to?

The term "penetration" in welding specifically refers to the depth of the weld into the base metal. This means it is the measure of how deep the molten weld metal extends into the base material being welded. Adequate penetration is crucial because it ensures a strong bond between the weld and the base metal, which is essential for the integrity and strength of the finished weld joint.

When the penetration is too shallow, it may lead to a weak joint that could fail under stress or load. Conversely, excessive penetration may also be problematic, as it could weaken the base metal or result in an undesirably large heat-affected zone. Understanding penetration helps welders control their technique and settings, ensuring they achieve the right depth for a robust and reliable weld.