Ultrasonic characterization of microstructural changes due to static recrystallization and grain growth in Inconel 625 and Inconel 718 superalloys.

In many metallic materials such as Inconel superalloys, the microstructure and grain size play an important role in their mechanical and physical properties and could impact the performance during long-term service at the operational temperature. Therefore, on-site detection of the microstructural transformation (such as recrystallization and grain growth) is of primary importance from a structural integrity point of view. Nondestructive evaluation methods such as the ultrasonic attenuation measurement offer a unique advantage that they can be used to evaluate the microstructure evolution of a component during fabrication or service operation.