Role of temperature and strain rate on the hydrogen-induced intergranular rupture in alloy 600

Tensile tests were conducted at various temperatures (77 to 550 K) and strain rates (10(-5) to 10(-1) s(-1)) in order to study the effects of hydrogen on the ductility loss and the intergranular fracture of hydrogen-charged (32 wt ppm) tensile specimens of alloy 600. The H-induced intergranular cracking was shown to require H segregation to grain boundaries (GBs) during plastic deformation. The concordance between the temperature/strain rate domains, where H-induced intergranular rupture of alloy 600 is observed and those of H transport by dislocations, is in favor of a major influence of this mechanism of H transport on the intergranular rupture of H-charged alloy 600 in the 180 to 500 K temperature range. The possible contribution of this mechanism to intergranular stress corrosion cracking (IGSCC) of alloy 600 in the pressurized water reactor (PWR) environment is discussed.