EFFECTS OF THE HYDRIDE CONCENTRATION AND THE NEAR CRACK TIP GRADIENT ON THE FRACTURE TOUGHNESS OF ZIRCALOY-4

GRACIELA BERTOLINO; JUAN PEREZ-IPIÑA; GABRIEL MEYER

Torino, Italia

Conferencia; ICF XI, XI International Conference on Fracture; 2005

ICF

The influence of concentration and distribution of hydrides as well as temperature on the fracture toughness of a Zircaloy-4 commercial alloy was studied in this work. Toughness was measured on CT specimens and the analysis was performed in terms of the J-integral resistance curves. The specimens were fatigue pre-cracked and hydrogen charged before testing them at different temperatures in the range of 293 to 473 K. The influence of a homogeneous hydrogen distribution was compared to a hydride concentration at the crack tip due to the presence of a mode I stress state during the H charge. The influence of the H content reducing the material toughness was important even at very low concentrations, being partially restored when the test temperature increased. The specimens charged under Mode I load presented reduced toughness values, and also fractured in brittle mode. The existence of a ductile-to-brittle transition is discussed.