Which of the following discontinuities is classified as a finishing processing discontinuity?

In the context of visual testing and discontinuities, finishing processing discontinuities refer to flaws that occur as a result of the final processing stages of a material or component. These discontinuities can arise from processes such as heat treatment, machining, or surface finishing.

Heat-treat crack is classified as a finishing processing discontinuity because it typically develops due to the stresses that are introduced during the heat treatment process. This process involves heating a material to a specific temperature and then cooling it, which can lead to uneven contraction or expansion and ultimately result in cracks if the material is not handled properly.

The other options represent different types of discontinuities that do not specifically arise from finishing processes. For instance, fatigue cracks typically develop over time due to repetitive stress rather than a finishing process, while stress-corrosion cracks result from environmental factors combined with stress, and laminations are often related to flaws in the manufacturing process or issues with material integrity rather than finishing. By understanding the specific conditions that lead to each type of discontinuity, one can better identify and classify them appropriately in visual testing assessments.