Discontinuity• An interruption of the typical structure of a

material, such as a lack of homogeneity in its mechanical, metallurgical, or physical characteristics. A discontinuity is not necessarily a defect.

Weld Joint Discontinuities• Misalignment (hi-lo)• Undercut• Underfill• Concavity or Convexity• Excessive reinforcement• Improper reinforcement• Overlap• Burn-through• Incomplete or Insufficient

Penetration• Incomplete Fusion• Surface irregularity

– Overlap• Arc Strikes

• Inclusions– Slag– Wagontracks– Tungsten

• Spatter• Arc Craters• Cracks

– Longitudinal– Transverse– Crater– Throat– Toe– Root– Underbead and

Heat-affected zone– Hot– Cold or delayed

• Base Metal Discontinuities– Lamellar tearing– Laminations and

Delaminations– Laps and Seams

• Porosity– Uniformly Scattered– Cluster– Linear– Piping

• Heat-affected zone microstructure alteration

• Base Plate laminations• Size or dimensions

Defect• A flaw or flaws that by nature or accumulated

effect render a part or product unable to meet minimum applicable acceptance standards or specifications. The term designates rejectability.

4

Types of Defect:The following figures give a rough survey about the

classification of welding defects to DIN 8524. This standard does

not classify existing welding defects according to their origin but

only to their appearance.

Welding defect

5

1- Defect Class: Shape Defects

Welding defect

6

Welding defect

7

2- Defect Class: Cracks and Cavities

Welding defect

8

Welding defect

9

Welding defect

10

3- Defect Class: Lack of Fusion, Insufficient Through-Weld

Welding defect

11

Welding defect

12

4- Defect Class: Solid Inclusions

Welding defect

13

Welding defect