Validation of mathematical models of the ultrasonic inspection of steel components

Nineteen combinations of defects and probes were chosen to test the models (Table 1). The defects were fabricated by diffusion bonding and were embedded in parallelepiped blocks with rectified faces (Fig. 1). The measurements on strip-like defects were carried out at the CISE Laboratories (Milan, Italy) as part of the PISC II parametric study on the effect of defect features on their ultrasonic response. The measurements on circular defects were performed at the NDE Laboratories of the JRC-Ispra. Figures 2 and 3 illustrate sample-results. The experimental results led to the conclusion that the models are quite powerful. In fact, good agreement was obtained between theoretical predictions and experimental data concerning quantities such as amplitude, wave form, width and peak position of the scattered signal. Some discrepancies between experimental results and theoretical predictions were also recorded, leading to a deeper examination of the models and consequent improvement of the software. The model valisation performed by the Reference Laboratory benefited the PISC members by leading not only to the improvement of the models, but also to their dissemination among other PISC members. The data generated by the measurements carried out during PISC are still used for further validation work, as in the case of further development of materials necessary for the qualification of inspection procedures based on ultrasonic techniques.