AWS Welding Inspection and Testing Certification Practice Test

Which weld discontinuity results from weld metal flowing out of the joint and laying on the base metal surface without fusing?

1. Undercut

2. Underfill

3. Overlap

4. Incomplete fusion

The correct answer is: Overlap

Overlap is a specific type of weld discontinuity that occurs when the weld metal flows out of the joint and onto the base metal without fusing properly. This phenomenon can happen if the welding technique is not executed correctly or if the parameters are not optimal, leading to a lack of sufficient heat to create a proper bond between the weld metal and the base material. This discontinuity is characterized by a buildup of welding material along the edge of the base metal, which can negatively affect the strength and integrity of the weld. Overlap does not create a proper fusion joint, thereby compromising the intended performance of the weld. In contrast, undercut refers to the groove or recess that occurs in the base metal at the edge of the weld due to excessive melting, while underfill refers to insufficient weld metal within the joint. Incomplete fusion describes a scenario where the weld metal does not properly bond to the base metal, but it does not specifically indicate that the weld metal has overflowed onto the base material as seen in overlap. Understanding these distinctions helps in recognizing the specific nature of various weld discontinuities and the importance of quality control in welding processes.