Effect of Hydrogenation on Fracture Mode of a Reactor Pressure Vessel Steel

Abstract

The conditions for hydrogen-induced intergranular fracture in an artificially embrittled, low-alloyed reactor pressure vessel were investigated using fracture toughness and stress corrosion cracking tests. The specimens were taken from two locations: the heat affected zone beneath the cladding and the base material directly below the heat-affected zone. A hydrogenating system allowed the tests to be carried out on both pre-hydrogenated specimens or with continuous hydrogenation during testing itself. Overall the results demonstrate a detrimental effect of hydrogen on sub-critical crack growth resistance of both materials. At 120¿C (close to the upper shelf) it led to a lower energy ductile fracture mode and isolated instances of transgranular fracture. At ambient temperature (in the ductile to brittle transition regime) some mixed intergranular and transgranular sub-critical crack growth was observed.JRC.DG.F.8-Renewable Energy (Ispra