Abstract
Acoustic emission is a transient elastic wave generated by rapid energy release during plastic deformation. The microsecond temporal resolution of AE technique offers a distinct advantage to study the kinetics of plastic deformation, moreover the information obtained are representative of entire volume being probed. In this work, the hydrogen embrittlement behavior of the Inconel 625 alloy is evaluated by the slow strain rate tensile test equipped with acoustic emission (AE) and digital image correlation (DIC) techniques. Hydrogen charging induced surface slip steps observed on sample charged at high cathodic current density and the corresponding internal stress generated during charging is estimated using thermal desorption spectroscopy (TDS) and the X-ray diffraction (XRD) techniques. With the help of acoustic emission result along with SEM characterization methods - electron backscatter diffraction (EBSD) and Electron channeling contrast imaging (ECCI), the kinetics of crack evolution and fracture behavior of different hydrogen charged sample is investigated in detail. Postmortem characterization of fractured sample shows both intergranular (IG) and transgranular cracks (TG). Statistical crack analysis reveals transition from TG to IG, the competition between two crack modes were explained based on hydrogen concentration profile.