Characterising hydrogen induced cracking of alloy 625+using correlative SEM - EDX and NanoSIMS

Hydrogen induced cracking behaviour of O&G nickel alloy 625+ (UNS N07716) was investigated. Deuterium was introduced electrochemically into samples by cathodic polarisation (3.5 wt.% NaCl center dot D2O) under different mechanical conditions. Subsequently, deuterium distributions were mapped using NanoSIMS. Deuterium was used as an isotopic tracer instead of hydrogen to avoid the detection of hydrogen artefacts. Complimentary image analysis using scanning electron microscopy (SEM) and low voltage energy dispersive X-ray (EDX) allowed the identification of microstructural features corresponding to deuterium enrichments. The results provided experimental evidence of enrichments at dislocation slip bands (DSB), twin boundary and grain boundary features that include sigma precipitates.

Automated summary

This study investigated the hydrogen induced cracking behavior of O&G nickel alloy 625+ (UNS N07716) using deuterium as an isotopic tracer. The results showed enrichments at dislocation slip bands, twin boundary, and grain boundary features, providing experimental evidence of the phenomenon. Analysis using scanning electron microscopy and energy dispersive X-ray techniques helped in identifying the microstructural features corresponding to deuterium enrichments.