Behavior and rupture of hydrided ZIRCALOY-4 tubes and sheets

The mechanical behavior and rupture mechanisms of ZIRCALOY-4 guide tubes and sheet containing 150 to 1200 wt ppm hydrogen have been investigated at room temperature. Sheets were notched to study the influence of geometrical defects on rupture. It is shown that hydrides strengthened the material, as maximum stresses sustained by the material are increased with increasing hydrogen contents. On the other hand, ductility is reduced. The material also exhibits a strong anisotropy due to its pronounced texture. Metallographic examinations have shown that damage by hydride cracking is a continuous process that starts after the onset of necking. Notches reduce ductility. A modified Gurson-Tvergaard model was used to represent the material behavior and rupture. Numerical simulation using the finite element method demonstrates the strong influence of plastic anisotropy on the behavior of structures and rupture modes.