Strain-assisted transport of hydrogen and related effects on the intergranular stress corrosion cracking of alloy 600

Publisher Summary The strain-assisted transport and redistribution of tritium in tritiated tensile specimens are investigated by β counting at room temperature in order to characterize the interactions of hydrogen with moving dislocations in Ni-based alloys. A predictive analysis of the existence of these interactions as a function of the most pertinent parameters such as temperature, hydrogen activity, strain level, and strain rate is performed and compared with the results of experiments designed to characterize the mechanism of hydrogen-induced intergranular fracture. Tensile tests conducted on hydrogen precharged tensile specimens of alloy 600 at various temperatures and strain rates shows that hydrogen-induced intergranular cracking requires hydrogen segregation to grain boundaries during plastic deformation. These experimental data are used to identify a temperature/strain rate domain at which hydrogen-induced intergranular rupture of alloy 600 is observed. Its concordance with the domain of hydrogen transport by dislocations provides support for a major influence of a mechanism of hydrogen-accelerated transport and supersaturation in the vicinity of grain boundaries. This influence is apparent in the intergranular rupture observed in the 180–500 K temperature range.