What Is a Discontinuity in Welding

Weld discontinuities can be defined as “an interruption of the typical structure of a weld, such as a lack of homogeneity in the mechanical, metallurgical or physical characteristics of the weld.” Weld discontinuities include porosity, slag inclusions, incomplete fusion, incomplete joint penetration, excessive melt- …

What is the difference between a discontinuity and a defect?

All welding defects are developed discontinuities. If a discontinuity renders a weld incompetent or lowers its quality, it would be classified as a defect. Defects make the product risky to use or substandard. It is up to the quality control to decide whether the discontinuity qualifies as a defect or not.

What are the weld discontinuities and their causes?

• Porosity. Porosity occurs when gas becomes trapped in the weld pool, forming permanent bubbles as the metal cools from a liquid state back to a solid. …
• Inclusions. …
• Inadequate Joint Penetration. …
• Incomplete Fusion. …
• Arc Strikes. …
• Overlap.