AWS Welding Inspection and Testing Certification Practice Test

What is the welding discontinuity defined as a lack of fusion between the weld metal and the base metal?

1. Pores

2. Undercut

3. Incomplete fusion

4. Overlapping

The correct answer is: Incomplete fusion

The term that describes a lack of fusion between the weld metal and the base metal is indeed incomplete fusion. This discontinuity occurs when there is insufficient melting of the base material or the weld metal during the welding process, leading to a void where the weld should have adhered to the base material. Incomplete fusion can compromise the structural integrity of a weld because it creates a weak point within the joint, which may lead to failure under load or stress. The continuity of the weld joint is essential for ensuring that the welded assembly can withstand operational conditions. Identifying and remedying incomplete fusion is crucial during the welding inspection process, as this can help prevent potential failures in the final product. In contrast, other types of welding discontinuities listed in the options are different phenomena. Pores refer to gas entrapment within the weld metal, undercut is a groove or depression along the edge of the weld, and overlapping occurs when the weld metal does not properly fill the joint, creating a flap of metal rather than fusing properly. Each of these discontinuities has its own implications for weld quality but does not denote the specific issue of fusion between the weld and base material.