Mechanical Properties Degradation at Room Temperature in ZRY-4 by Hydrogen Brittleness

A hot rolled Zircaloy-4 alloy, annealed with a final cold rolling, presenting rounded grains, was studied. Hydrogen cathodic charge with a homogenization heat treatment was used to pre-charge the specimens with different hydrogen contents. Hydrogen embrittlement susceptibility analysis was held using J integral and J-R curve results from CT specimens (compact tension specimens) tested at room temperature. As J IC values showed scatter, toughness was evaluated for deltaa = 1mm. Toughness clearly tended to decrease as hydrogen content increased abruptly for low H contents and gradually for high contents. A few specimens with high hydrogen content failed in brittle mode, or presented instability and posterior crack arrest. Fractographic observations showed that, despite the records had presented no signs of brittle fracture, certain specimens showed cleavage-like zones. More cleavage-like area percentage was present the higher the hydrogen content was.