Which of the following is a potential discontinuity in a forging?

The correct choice regarding a potential discontinuity in a forging is a lap. A lap occurs when there is a folding over of the metal during the forging process, which can result from inadequate material flow or improper die design. This can create a weak point, or discontinuity, in the forged component, potentially affecting its overall mechanical properties. Laps can often be detected through visual inspection and non-destructive testing methods.

In the context of the other choices, a void typically refers to an air pocket or cavity that can form in cast materials rather than in forged materials. A crack is a failure that can occur due to excessive stress or improper handling but is not specifically recognized as a discontinuity inherent to the forging process itself. A seam is associated with defects in processes like welding or casting where two surfaces may not fuse properly; however, it is less commonly labeled as a discontinuity in the context of forging.

Thus, laps can significantly compromise the integrity of forged components, making it crucial for inspectors and manufacturers to identify and mitigate this type of discontinuity.