Which method can be used to check for metallurgical damage at a hot spot?

The most effective method to check for metallurgical damage at a hot spot is through the use of boat samples or replication. This technique involves taking a small sample from the area of concern and analyzing its microstructure, which provides direct information about any alterations in the material properties due to heat, stress, or other factors. By recreating the material's surface on an epoxy mount, the metallurgical characteristics can be closely examined under a microscope, allowing for the identification of damage such as grain growth, softening, or phase changes that may not be visible through other inspection methods.

While visual inspection can help detect surface anomalies, it does not provide the detailed internal characteristics needed to assess metallurgical condition. Non-destructive testing methods can reveal certain flaws or discontinuities within the material, but they might not specifically pinpoint metallurgical changes in the microstructure. Corrosion mapping is valuable for identifying and quantifying corrosion but does not directly assess the metallurgical integrity at hot spots caused by thermal stresses. Therefore, boat sampling or replication stands out as the most direct and thorough method for evaluating metallurgical damage in these scenarios.