What is the typical penetrant indication for a forging lap?

The correct choice reflects that a forging lap typically results in a continuous line being indicated during penetrant testing. This is due to the nature of how laps form in forgings. A lap occurs when an undesired fold or overlap of material happens during the forging process, which can create a continuous crack-like defect along the surface. When penetrant materials are applied, they seep into these discontinuities, leading to a clear, identifiable indication that appears as a continuous line. This helps inspectors easily detect laps and take corrective measures.

In comparison, the other options indicate different types of indications that are typically associated with other types of defects. While a series of dots might suggest a different flaw type such as porosity, a zigzag pattern could indicate issues related to misalignment or certain types of cracks, and 'no indication' would imply that the surface is intact without defects. Each of these does not accurately represent the typical appearance of a forging lap during penetrant testing.