Which discontinuity would you expect to find in the base metal?

Lamination is a type of discontinuity that occurs in the base metal due to its internal structure, often resulting from improper manufacturing processes or conditions during the production of the steel. It is characterized by the presence of thin, planar separations or layers within the metal, which can compromise its integrity and performance, particularly under stress. Laminations may not be visibly apparent on the surface but can significantly impact the mechanical properties and performance of the material.

In contrast, other discontinuities such as porosity and inclusions are typically associated with the welding process itself rather than inherent characteristics of the base metal. Porosity originates from trapped gas during solidification, while inclusions are unwanted materials or oxides that may introduce weaknesses. Cracking also results from thermal stresses or improper welding techniques, often occurring during or after the welding process rather than being a pre-existing condition in the base metal. Thus, lamination uniquely fits as a discontinuity directly found in the base metal.