Acoustic-emission investigation of the sensitivity of spring steel to hydrogen degradation

Abstract

By using the results of tensile tests of cylindrical and flat specimens, we determined the sensitivity of spring steel to hydrogen embrittlement. As criteria, we use the moment of the beginning of generation of acoustic-emission signals and the sum of their amplitudes. We have shown that, in the course of deformation of specimens of nonhydrogenated steel, the acoustic emission signals are characterized by low values of the sum of amplitudes and a total count of pulses exceeding the discrimination level. The maximal amplitudes, fixed at the output of a primary transducer of acoustic-emission signals, are some-what higher with a smaller number of events for nonhydrogenated specimens than for hydrogenated ones. It is possible to determine the tendency of a material to hydrogen degradation through violation of the Kaiser effect. Additional information on hydrogen degradation can also be obtained by spectral characteristics of acoustic-emission signals.