Acoustic emission during hydrogen charging of a pipeline steel

Abstract

Acoustic emission (AE) during hydrogen-induced cracking (HIC) of low-carbon pipeline steel immersed into H2S containing media was investigated aiming at discriminating between damage mechanisms and getting a better insight on the kinetics of damage. Two kinds of steel samples - sensitive and resistant to hydrogen induced cracking - were tested. Three different kinds of acoustic emission signals were discriminated by a cluster analysis involving either spectral shape recognition or parametric c-means classifier. It is demonstrated that AE is associated with three primary mechanisms involving hydrogen bubbles evolution, sulfide film formation and fracture due to HIC. Hence, AE is shown to be very efficient for quantitative description of hydrogen induced damage accumulation in steels. © 2011 ISIJ.