Hydrogen embrittlement resistance of GRCop-84

GRCop-84 contains approximately 5.5 wt% Nb. Nb can react with hydrogen and embrittle easily. Previous work had indicated the thermodynamic possibility that Cr2Nb could react with hydrogen and form niobium hydrides in the presence of high pressure hydrogen. In this study, samples were charged with hydrogen and tested in both high pressure gaseous H2 and He environments to determine if measurable differences existed which indicate that hydrogen embrittlement occurs in GRCop-84. Tensile, notched tensile, stress rupture and low cycle fatigue properties were surveyed. High pressure H2 environment stress rupture testing resulted in a lower reduction in area than a high pressure He environment, and the LCF lives at high strain ranges fall below the lower 95% confidence interval for the baseline data, but in general no significant differences were noted either between H2 and He environment tests or between H charged materials and the baseline, uncharged extruded GRCop-84 data sets. There was also no discernable evidence of the formation of hydrides or changes in fracture morphology indicating hydrogen embrittlement occurred.