Hydrogen damage detection by ultrasonic spectral analysis

The non-destructive testing technique known as ultrasonic spectral analysis was applied to steel samples for the detection of minute cracks produced by hydrogen in a H 2S environment. The cracks were characterized and quantified by metallographic analysis and compared with the ultrasonic results. The backwall echoes and the backscattered signals were analyzed in the frequency domain and the characteristics of these spectra were evaluated by second order moments, which emphasizes the higher frequency components. The second order moments showed a greater variability for hydrogen attacked materials than for non-attacked ones, denoting good sensitivity to this type of material degradation.