Characterization of diffusion bonds of titanium plates using transmitted ultrasonic signals

Abstract

The ratio of the spectra of the ultrasonic signals transmitted through diffusion-bonded plates and through the corresponding water-path is used to evaluate parameters related to deterioration in the diffusion bond, where bond deterioration is defined as reduction of the elastic constants and the mass density in the bond layer as compared to the base material. When deterioration exists, the even resonance frequencies in the ratio spectrum are shifted increasingly toward the odd ones as the frequency increases. The more deterioration and the higher the frequency, the larger shift is observed. An inverse procedure is developed to determine bond-layer parameters such as phase velocity, effective thickness and mass density for diffusion-bonded titanium plates, by minimizing the error between measured and theoretical ratios. The procedure is first tested on simulated data. Measured ratios for cases of bond deterioration are then used to determine bond parameters. The results show that the technique can be applied to the characterization of diffusion bond deterioration.