How can a rough forging discontinuity characterized by excessive working and varying cavities be identified?

The identification of a rough forging discontinuity characterized by excessive working and varying cavities is best associated with a burst. A burst typically occurs due to overstressing the material during the forging process, leading to surface ruptures or internal cracks. These defects can appear as irregularities on the surface, indicating that the metal has been subjected to excessive deformation.

In this context, the presence of varying cavities is a key indicator of burst, as these cavities often result from the separation of the material layers under stress, which manifests as flaws in the final product. The rough texture combined with irregular cavities signifies that the forging process has exceeded the material's limits, resulting in compromised structural integrity, which is a hallmark of burst defects.

Other types of discontinuities, such as shrinkage, pipe, and lamination, have distinct characteristics that do not involve the same level of excessive working and irregular cavity formation. For example, shrinkage refers to voids that develop as the metal cools and solidifies, pipe relates to internal cavities that form during solidification, and lamination refers to layers of metal separating from one another. Thus, the specific attributes of burst make it the correct identification for rough forging discontinuities characterized by these issues.