Ultrasonic characterization of continuously cast rod by resonance acoustic spectroscopy

The principles of resonance acoustic spectroscopy (RAS) are applied to large-grained transversely isotropic copper rods, produced by the Ohno continuous casting process. It was determined that certain resonance frequencies and associated mode shapes are primarily dependent on cross sectional-averaged material properties, and are relatively independent of grain size below a critical value. However, for cases where the average grain cross sectional diameter is greater than 10% of the ultrasonic wavelength, it was found that the resonance spectrum is significantly distorted from its theoretical profile. This indicates that RAS could be applied in an on-line setting for non-destructive characterization of the grain structure. For smaller-grained samples produced at relatively high casting speeds, a series of resonance measurements can be used to determine four of the five independent elastic constants, with an estimated uncertainty of 1–2%.